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1. Citado en Martin Palmer with Victoria Finlay (2003) – Faith in Conservation: New Approaches to Religions and the Environment – Alliance of Religions and Conservation (ARC): Secretary General; Media advisor – http://siteresources.worldbank.org/intbiodiversity/214584-1112712965549/20480342/FaithInConservationNewApproachesPreface2003.pdf
   “I am deeply convinced that that the new millenium we have just entered will decide the fate of the human species… The first three decades of this century are likely to be decisive. Not that we face the prospect of extintion as a species during this period but we will set, irrevocably, the direction that will determine the survival or the demise of human life as we know it. Surely the divine source of all life, which most call God, could not have presented us with a more paradoxical challenge.”
2. Richard Monastersky (2009) – Climate crunch: A Burden Beyond Bearing – Nature, 458:1091-1094 doi:10.1038/4581091a – 30/04/2009
   “The climate situation may be even worse than you think … That’s an extremely difficult target  … our options are essentially exhausted. We have to bend down our emissions by 2020.” The world would have to limit emissions of all greenhouse gases to the equivalent of 400 GT of carbon to stand a 75% chance of avoiding more than 2 ºC of warming.” – Peer-reviewed
3. Mark New, Diana Liverman and Kevin Anderson (2009) – Mind the Gap – Nature Reports Climate Change doi:10.1038/climate.2009.126 – Published online 03/12/2009 – http://www.nature.com/climate/2009/0912/full/climate.2009.126.html
   “Policymakers must aim to avoid a 2 °C temperature rise, but plan to adapt to 4 °C … While adapting to a 2 °C temperature rise may mostly involve adjustments of existing practices, a world at 4 °C presents large and complex challenges that are likely to require fundamental socioeconomic and technological transformations, rather than adjustments — assuming such transformations are achievable through planning at all. Moving from 2 to 4 °C would also bring, for any particular location, an accumulating load of increasingly severe impacts. While one or a few impacts considered in isolation may be manageable, a ‘perfect storm’ of multiple severe impacts may be catastrophic.”
4. Bob Colmes – Posthuman Earth: How the planet will recover from us – New Scientist 2728 – 30/09/2009 – http://www.newscientist.com/article/mg20427281.300-posthuman-earth-how-the-planet-will-recover-from-us.html
   «If we were to blow all the fossil fuels into the atmosphere, temperatures would go up to the point where both of these reservoirs of [methane] would be released,» says oceanographer David Archer of the University of Chicago. No one knows how catastrophic the resulting warming might be. That’s why climatologists are looking with increasing interest at a time 55 million years ago called the PalaeoceneEocene thermal maximum, when temperatures rose by up to 9 °C in a few thousand years roughly equivalent to the direst forecasts for present day warming.”
5. Environmental Audit: Minutes of Evidence – House of Commons, 20/03/2004 – http://www.publications.parliament.uk/pa/cm200304/cmselect/cmenvaud/490/4033001.htm
   “Professor Sir David King, Chief Scientific Adviser to the Government and Head of Office of Science and Technology, and Ms Claire Durkin, Director, Head of Energy Innovation and Business Unit, Department of Trade and Industry, examined. “Fifty-five million years ago was a time when there was no ice on the earth; the Antarctic was the most habitable place for mammals, because it was the coolest place, and the rest of the earth was rather inhabitable because it was so hot. It is estimated that it was roughly 1,000 parts per million then, and the important thing is that if we carry on business as usual we will hit 1,000 parts per million around the end of this century. So it seems to me that it is clear on a global and geological scale that climate change is the most serious problem we are faced with this century.”
6. Carlos Gay-García, Francisco Estrada and Armando Sánchez (2009) – Global and hemispheric temperatures revisited – Climatic Change 94:333-349 doi:10.1007/s10584-008-9524-8 – Published online 05/12/2008 – Centro de Ciencias de la Atmósfera, UNAM – Peer-reviewed
   “Here we present an analysis of the time series properties of global and hemispheric temperatures using modern econometric techniques. Results show that: The temperature series can be better described as trend-stationary processes with a onetime permanent shock which cannot be interpreted as part of the natural variability; climate change has affected the mean of the processes but not their variability; it has manifested in two stages in global and Northern Hemisphere temperatures during the last century, while a second stage is yet possible in the Southern Hemisphere;In terms of Article 2 of the Framework Convention on Climate Change it can be argued that significant (dangerous) anthropogenic interference with the climate system has already occurred … Moreover, the post-break global temperature trend is very close to the “the tolerable window” (Bruckner and Schellnhuber 1999) of 0.2◦C/decade originally proposed by the German Advisory Council on Global Change (WBGU) and the late trend shown by the Northern Hemisphere has already surpassed it. Quoting Tony Blair (Joachim et al. 2006): “what level of greenhouse gases in the atmosphere is self-evidently too much?”, it looks like we might have already exceeded it.»
7. Katherine Richardson et al (2009) – Climate Change: Global Risks, Challenges & Decisions – International Scientific Congress Climate Change, Synthesis Report – Australian National University, ETH Zürich, National University of Singapore, Peking University, University of California – Berkeley, University of Cambridge, University of Copenhagen, University of Oxford, The University of Tokyo, Yale University – Peer-reviewed
   “A 2 ºC guardrail, which was thought in 2001 to have avoided serious risks for all five reasons for concern, is now inadequate to avoid serious risks to many unique and threatened ecosystems and to avoid a large increase in the risks associated with extreme weather events. Third, the risks of large scale discontinuities, such as the tipping elements described above, were considered to be very low in 2001 for a 2 ºC increase but are now considered to be moderate for the same increase. In summary, although a 2 ºC rise in temperature above pre-industrial remains the most commonly quoted guardrail for avoiding dangerous climate change, it nevertheless carries significant risks of deleterious impacts for society and the environment.”
8. Katherine Richardson et al (2009) – Climate Change: Global Risks, Challenges & Decisions – International Scientific Congress Climate Change, Synthesis Report – Australian National University, ETH Zürich, National University of Singapore, Peking University, University of California – Berkeley, University of Cambridge, University of Copenhagen, University of Oxford, The University of Tokyo, Yale University – Peer-reviewed
   “Recent observations confirm — the worst case IPCC scenarios are being realised. For many key parameters, the climate system is already moving beyond the bounds of natural variability within which our society and economy have developed and thrived. —- There is a significant risk that many of the trends will accelerate, leading to an increasing risk of abrupt or irreversible climatic shifts».
9. George Monbiot – If we behave as if it’s too late, then our prophecy is bound to come true – The Guardian, 17/03/2009 – http://www.guardian.co.uk/commentisfree/2009/mar/17/monbiot-copenhagen-emission-cuts
   “Quietly in public, loudly in private, climate scientists everywhere are saying the same thing: it’s over … It is the obvious if unspoken conclusion of scores of scientific papers. Recent work by scientists at the Tyndall Centre for Climate Change Research, for instance, suggests that even global cuts of 3% a year, starting in 2020, could leave us with 4C of warming by the end of the century.”
10. David Adam – World will not meet 2 ºC warming target, climate change experts agree – The Guardian, 14/04/2009 – http://www.guardian.co.uk/environment/2009/apr/14/global-warming-target-2c
    “Guardian poll reveals almost nine out of 10 climate experts do not believe current political efforts will keep warming below 2 ºC …An average rise of 4-5 ºC by the end of this century is more likely, they say, given soaring carbon emissions and political constraints. Such a change would disrupt food and water supplies, exterminate thousands of species of plants and animals and trigger massive sea level rises.”
11. David G. Victor (2009) – Global warming: why the 2 °C goal is a political delusion – Nature 459:909 – 18/06/2009 – Energy and Sustainable Development, Stanford University – Peer-reviewed
    “Real outcomes might be plagued by interactions that doom the planet to warming of 2 °C (or more), whether or not emissions are cut. Even with a big dose of luck, the effort needed to get to 2 °C would be heroic, as Allen and colleagues indicate, and probably far beyond what real governments can achieve.”
12. Gaia Vince – How to survive the coming century – New Scientist 2697 – 25/02/2009 – http://www.newscientist.com/article/mg20126971.700-how-to-survive-the-coming-century.html
    “Alligators basking off the English coast; a vast Brazilian desert; the mythical lost cities of Saigon, New Orleans, Venice and Mumbai; and 90 per cent of humanity vanished. Welcome to the world warmed by 4 °C … A 4 ºC could easily occur. The 2007 report of the International Panel of Climate change, whose conclusions are generally accepted as conservative, predicted a rise of anywhere between 2 ºC and 6.4 ºC this century. And, in August 2008, Bob Watson, former chair of the IPCC, warned the world should work on mitigation and adaptation strategies to ‘prepare for a 4 ºC of warming’. A key factor in how well we deal in a warmer world is how much time we have to adapt. According to models, we could cook the planet by 4ºC by 2100. Some scientists fear that we may get there as soon as 2050. If this happens, the ramifications for life on Earth are so terrifying that some scientists contacted for this article preferred not to contemplate them.”
13. Gaia Vince – How to survive the coming century – New Scientist 2697 – 25/02/2009 – http://www.newscientist.com/article/mg20126971.700-how-to-survive-the-coming-century.html
    “According to models, we could cook the planet by 4 °C by 2100. Some scientists fear that we may get there as soon as 2050. If this happens, the ramifications for life on Earth are so terrifying that many scientists contacted for this article preferred not to contemplate them (…)”
14. Malcolm Gladwell (2000) – The Tipping Point. How Little Things can Make a Big Difference – Little, Brown and Company. Boston, 2000 – ISBN: 0-349-114463
15. Malcolm Gladwell – Wikipedia – http://es.wikipedia.org/wiki/Malcolm_Gladwell 30/01/2010
    “Malcolm Gladwell (nacido británico  el 3 de septiembre de 1963) es un periodista, escritor y sociólogo canadiense. Reside en Nueva York. Ha estado trabajando para The New Yorker desde 1996. Es conocido principalmente por ser autor de los libros: The Tipping Point (2000) (traducido como La clave del éxito)…”
16. Tipping point (sociology) – Wikipedia – http://en.wikipedia.org/wiki/Tipping_point(sociology)
    “In sociology, a tipping point or angle of repose is the event of a previously rare phenomenon becoming rapidly and dramatically more common. The phrase was coined in its sociological use by Morton Grodzins, by analogy with the fact in physics that adding a small amount of weight to a balanced object can cause it to suddenly and completely topple. Grodzins studied integrating American neighborhoods in the early 1960s. He discovered that most of the white families remained in the neighborhood as long as the comparative number of black families remained very small. But, at a certain point, when «one too many» black families arrived, the remaining white families would move out en masse in a process known as white flight. He called that moment the «tipping point». The idea was expanded and built upon by Nobel Prize-winner Thomas Schelling in 1972. A similar idea underlies Mark Granovetter’s threshold model of collective behavior.”
17. Gabrielle Walker (2006) – The tipping point of the iceberg – Nature 441:802-805 doi:10.1038/441802a – 15/06/2006 – Peer-reviewed
    “The idea that passing some hidden threshold will drastically worsen man-made climate change has been around for decades, normally couched in technical terms such as ‘nonlinearity’, ‘positive feedback’ and ‘hysteresis’. In 2004, 45 newspaper articles mentioned a ‘tipping point’ in connection with climate change; in the first five months of this year, 234 such articles were published. “Warming hits tipping point,” one UK newspaper recently warned on its front page; “Climate nears point of no return,” asserted another. The idea is spreading like a contagion …  A tipping point usually means the moment at which internal dynamics start to propel a change previously driven by external forces.”
18. Timothy M. Lenton and Hans Joachim Schellnhuber (2007) – Tipping the scales – Nature Reports Climate Change 1:97-98 doi:10.1038/climate.2007.65 – 22/11/2007 – School of Environmental Sciences, University of East Anglia; Potsdam Institute for Climate Impact Research – http://www.nature.com/climate/2007/0712/full/climate.2007.65.html – Peer-reviewed
    “Such highly non-linear transitions, where «a small forcing can make a big difference», have been described as ‘tipping points’. For clarity, we have recently introduced the term ‘tipping element’ to describe those components of the Earth System that are at least sub-continental in scale and can be switched — under particular conditions — into a qualitatively different state by small perturbations.”
19. Timothy M. Lenton et al (2008) – Tipping elements in the Earth’s climate system  – Proceedings of the National Academy of Sciences PNAS 105:1786-1793 doi:10.1073/pnas.0705414105 – 12/02/2008 – School of Environmental Sciences, University of East Anglia, and Tyndall Centre for Climate Change Research – 7 authors – Peer-reviewed
    “We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.”
20. Jonathan M. Gregory et al (2004) – Threatened loss of the Greenland ice-sheet – Nature 428:616-616 doi:10.1038/428616a – 08/04/2004 – Department of Meteorology, University of Reading – 3 authors – Peer-reviewed
    «The Greenland ice-sheet would melt faster in a warmer climate and is likely to be eliminated — except for residual glaciers in the mountains — if the annual average temperature in Greenland increases by more than about 3 °C. This could raise the global average sea-level by 7 metres over a period of 1,000 years or more. We show here that concentrations of greenhouse gases will probably have reached levels before the year 2100 that are sufficient to raise the temperature past this warming threshold … Climate change caused by higher greenhouse-gas concentrations is expected to produce both higher temperatures and greater precipitation, but most studies conclude that the increase in melting will outweigh the increase in snowfall (ref). For an annual average warming of more than 2.7 °C, the melting exceeds the snowfall (ref) – a situation in which the ice-sheet must contract, even if iceberg production is reduced to zero as it retreats from the coast. For a warming of 3 °C, the ice-sheet loses mass slowly (refs) and over millennia might approach a steady state in a smaller inland form.»
21. J. Michael T. Thompson and Jan Sieber (2010) – Predicting Climate Tipping As A Noisy Bifurcation: A Review – International Journal of Bifurcation and Chaos (accepted) – Department of Applied Mathematics & Theoretical Physics, Cambridge University, Centre for Mathematical Sciences, Wilberforce Road, Cambridge; School of Engineering (Sixth Century Professor), Aberdeen University; Department of Mathematics, University of Portsmouth – http://www.ucl.ac.uk/~ucess21/Thompson2010 off JS web.pdf – Peer-reviewed
22. Ulrich Schnabel (2003) – God’s Formula and Devil’s Contribution: Science in the Press – Public Understanding of Science 12:255-259 doi:10.1177/0963662503123004 – 01/07/2003 – Science editor, Die Zeit – Peer-reviewed
    “Scientists often complain, that journalists do not describe the “real” scientific work, but rather present an exaggerated—often alarmistic—negative image of science. But the contrary is also true: There is a tendency in the press to report about science in a very positive, even ecstatic way. In fact, there are two types of exaggeration: Scientists are either described as heroic figures, that bring “God’s formula” down to earth. Or they are portrayed as some form of fallen angel, whose science has turned into something evil and frightening – which is the devil’s contribution to the story of scientific glory. But this is not a unique feature of science-journalism; popular articles often carry an emotional message to attract attention. While politicians know (and use) this knowledge for a long time, it seems especially hard for scientists to accept it. But in order to make Public Understanding of Science successful, scientists should try to understand the laws and mechanisms of journalism. Recommendations as the Guidelines of the Royal Society can be helpful.”
23. James Hansen (2005) – A slippery slope: How much global warming constitutes “dangerous anthropogenic interference”. An Editorial Essay – Climatic Change 68:269–279 doi:10.1007/s10584-005-4135-0 – NASA Goddard Institute for Space Studies and Columbia University Earth Institute – Peer-reviewed
    “I realize that I am no glaciologist and could be wrong about the ice sheets. Perhaps, as IPCC (2001) and more recent global models suggest, the ice sheets are quite stable and may even grow with doubling of CO2. I hope those authors are right. But I doubt it.”
24. Michael E. Mann (2009) – Defining dangerous anthropogenic interference – Proceedings of the National Academy of Sciences PNAS 106:4065-4066 doi:10.1073/pnas.0901303106 – 17/03/2009 – Earth System Science Center, Department of Meteorology, Pennsylvania State University – Peer-reviewed
    “The risk is even greater than might be apparent from the foregoing discussion … First, it is quite possible that we will peak at greenhouse gas levels higher than the stabilization targets … Second, the precise magnitude of positive carbon cycle feedback is not known, and surprises could be in store. Finally, there is the so-called ‘Faustian Bargain’ (ref) that we have already entered into with respect to the offsetting impact of anthropogenic aerosols.”
25. James Hansen (2003) – Defusing the global warming time bomb – Scientific American, March 2004 – NASA Goddard Institute for Space Studies and Columbia University Earth Institute – http://www.sciam.com/media/pdf/hansen.pdf
    “The peak rate of deglaciation following the last Ice Age was … about one meter of sea-level rise every 20 years, which was maintained for several centuries.”
26. Tim Lenton (2008) – Appendix 1: Formal Definition of a Tipping Element and Its Tipping Point – Proceedings of the National Academy of Sciences PNAS – 12/02/2008 – http://www.pnas.org/content/suppl/2008/02/07/0705414105.DC1/05414Appendixes.pdf – Peer-reviewed
    «The Antarctic ozone hole is a tipping element that has al- ready been tipped by human activity. It is widely believed that the stratospheric ozone layer has been saved by the Montreal protocol. However, Europe in particular could face a climate change-induced ozone hole [refs]. Global warming implies global cooling of the stratosphere that supports formation of ice clouds, which in turn provide a catalyst for stratospheric ozone destruc- tion. Furthermore, there exists a strong coupling between the troposphere and the stratosphere in the Northern Annular Mode (NAM) and strong syn- ergistic interactions between stratospheric ozone depletion and greenhouse warming are possible [ref]. However, more studies are required to assess whether this is a potential tipping element.»
27. Hans Joachim Schellnhuber (2009) – Tipping elements in the Earth system – Proceedings of the National Academy of Sciences PNAS 106:20561-20563 doi:10.1073/pnas.0911106106 – 08/12/2009 – Potsdam Institute for Climate Impact Research – Peer-reviewed
    «Many of the articles in this Special Feature sketch the research way forward, but it seems that we have to live with at least another decade of tantalizing ignorance concerning the most worrying potential impacts of global warming.»
28. Michael D. Mastrandrea and Stephen H. Schneider (2004) – Probabilistic Integrated Assessment of ‘Dangerous’ Climate Change – Science 304:571-575 – 23/04/2004 – Interdisciplinary Graduate Program in Environment and Resources; Department of Biological Sciences and Center for Environmental Science and Policy, Stanford University – Peer-reviewed
    “This research suggests a clear message: It is possible that some thresholds for dangerous anthropogenic interference with the climate system are already exceeded, and it is likely that more such thresholds are approaching. Despite great uncertainty in many aspects of integrated assessment, prudent actions can substantially reduce the likelihood and thus the risks of dangerous anthropogenic interference.”
29. Foundation for the Future – Anthropogenic Climate Destabilization: A Worst-case Scenario – Bellevue, Washington, 12-14/09/2008 – http://www.futurefoundation.org/documents/HUM_ExecSum_ClimateDestabilization.pdf
    “David Wasdell, who uses a systems dynamics approach based not on modeling but on tracking complex feedback dynamics, said that climate stabilization is not about stopping catastrophic impacts but about stopping runaway behavior in a dynamic system, and he believes that the early stages of runaway climate changes have already commenced, with no naturally occurring negative feedback process able to contain the effect. Most of the systems are already in net amplifying feedback, so “the hotter the Earth gets, the faster it gets hotter,” he said. In order to deal with the worst case, humankind will have to generate a negative feedback intervention of sufficient power to overcome and reverse not just what has already occurred, but what continues to occur.”
30. Tim Lenton (2008) – Appendix 1: Formal Definition of a Tipping Element and Its Tipping Point – Proceedings of the National Academy of Sciences PNAS – 12/02/2008 – http://www.pnas.org/content/suppl/2008/02/07/0705414105.DC1/05414Appendixes.pdf – Peer-reviewed
    “Previously, if a formal definition of tipping phenomena where `little things make a big difference was attempted’, it usually referred to equilibrium prop- erties such as, e.g., the existence of bifurcation points [1, Box 1.1 thereof]. However, only in case of a slow forcing of the system (compared to its response time) have such definitions in terms of equilibrium properties something to say about whether at a particular moment in time a small change of controls will lead to a large change of the system in the future. In the general case of arbitrary forcing, the system response will depend on the trajectory of the control after the small change is applied. Furthermore, important systems may be controlled by the rate of a forcing in addition to the forcing itself. If tipping points in real systems depend on such forcing rates, it will generally be impossible to define them in terms of equilibrium properties. To account for all this complexity arising from the (forcing) path dependency of tipping dynamics, we ask whether maintaining a small change in control for at least some time TR (to be defined) will inevitably lead to a large change of the system, i.e., independently of what might happen to the controls thereafter.”
31. Jeff Ridley et al (2009) – Thresholds for irreversible decline of the Greenland ice sheet – Climate Dynamics doi 10.1007/s00382-009-0646-0 – Published online 21/08/2009 – Met Office Hadley Centre – 4 authors – Peer-reviewed
32. Jeff Ridley et al (2009) – Thresholds for irreversible decline of the Greenland ice sheet – Climate Dynamics doi 10.1007/s00382-009-0646-0 – Published online 21/08/2009 – Met Office Hadley Centre – 4 authors – Peer-reviewed
33. Jeff Ridley et al (2009) – Thresholds for irreversible decline of the Greenland ice sheet – Climate Dynamics doi 10.1007/s00382-009-0646-0 – Published online 21/08/2009 – Met Office Hadley Centre – 4 authors – Peer-reviewed
34. Jonathan A. Foley (2005) – Tipping Points in the Tundra – Science 310:627-628 doi:10.1126/science.1120104 – 28/10/2005 – Center for Sustainability and the Global Environment (SAGE), Nelson Institute for Environmental Studies, University of Wisconsin – Peer-reviewed
    “Chapin et al. provide the best empirical evidence for this climate feedback mechanism to date; these results need to be more fully incorporated into models of future climate change.”
35. Stephen H. Schneider (2004) – Abrupt Non-Linear Climate Change, Irreversibility and Surprise – Global Environmental Change 14:245–258 – Peer-reviewed
    “Responses of the coupled systems to external forcing can become quite complicated. For example, one emergent property increasingly evident in climate and biological systems is that of irreversibility or hysteresis—changes that persist in the new post-disturbance state even when the original level of forcing is restored. This irreversibility can be a consequence of multiple stable equilibria in the coupled system—that is, the same forcing might produce different responses depending on the pathway followed by the system.”
36. Susan Solomon et al (2009) – Irreversible climate change due to carbon dioxide emissions – Proceedings of the National Academy of Sciences PNAS 106:10933-10938 doi:10.1073/pnas.0812721106 – 28/01/2009 – Peer-reviewed
    “The climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1.000 years after emissions stop.”
37. Ferran P. Vilar – Los estados estables del sistema climático – Usted no se lo Cree 16/12/2009 – https://ustednoselocree.com/2009/12/16/estados-estables/
38. The 2°C target. Background on Impacts, Emission Pathways, Mitigation Options and Costs – Information Reference Document Prepared and adopted by EU Climate Change Expert Group ‘EG Science’ – 09/07/2008
    “This paper outlines the scientific background for the EU climate protection target – the 2 ºC limit – established by the EU Governments in 1996 and reaffirmed since then by the Environment Council 2003, and European Council, 2005, 2007 … IPCC AR4: Significant global impacts on ecosystems and water resources are likely at global temperature rises of between 1 and 2°C, and the risks of net negative impacts on global food production occur at temperature increases upwards from 2-2.5°C, compared to pre-industrial levels.”
39. Jeffrey P. Severinghaus et al (1998) – Timing of abrupt climate change at the end of the Younger Dryas interval from thermally fractionated gases in polar ice – Nature 391:141-146 doi:10.1038/34346 – Graduate School of Oceanography, University of Rhode Island – 5 authors – Peer-reviewed
    “The climate change was synchronous (within a few decades) over a region of at least hemispheric extent, and providing constraints on previously proposed mechanisms of climate change at this time … during the Younger Dryas, the summit of Greenland was 15 ± 3 ºC colder than today.”
40. Bill Hare – The EU, the IPCC and 2 ºC – Talk – Potsdam Institute for Climate Impact Research – 08/10/2008 – Potsdam Insitute for Climate Impact Research
    “1989 UNEP Advisory Group: Greater than 1.0°C above pre-industrial levels “may elicit rapid, unpredictable and non-linear responses that could lead to extensive ecosystem damage”; 2ºC increase was determined to be “an upper limit beyond which the risks of grave damage to ecosystems, and of non-linear responses, are expected to increase rapidly … – 30% target in 2020 is not enough for 2 ºC and nor is 2050 ambition”
41. James Hansen et al (2005) – Earth’s Energy Imbalance: Confirmation and Implications – Science 308:1431-1435 doi:10.1126/science.1110252 – NASA Goddard Institute for Space Studies and Columbia University Earth Institute – 15 authors – Peer-reviewed
    “This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include (i) the expectation of additional global warming of about 0.6 ºC without further change of atmospheric composition; (ii) the confirmation of the climate system’s lag in responding to forcings, implying the need for anticipatory actions to avoid any specified level of climate change; and (iii) the likelihood of acceleration of ice sheet disintegration and sea level rise.”
42. James Hansen (2006) – Communicating Dangers and Opportunities in Global Warming – American Geophysical Union, 14/12/2006 – http://www.columbia.edu/~jeh1/2006/AGU_20061214.pdf
    “There is about one-half °C global warming “in-the-pipeline”, because of the ocean’s thermal inertia, due to gases already in the air. And because of energy infrastructure, such as power plants, enough gases for another half degree will be added even if we decide now to replace business-as-usual with an alternative scenario, in which we begin to phase down emissions of uncaptured CO₂ in a gradual, economically-sound way. In practice, what that means is that we will have to phase out use of coal except at power plants where it can be captured and sequestered. And we must stretch the supplies of readily available gas and oil, so that alternative energy sources can be developed without squeezing fuels out of shale and tar, unless the same criteria are applied as for coal.”
43. Veerabhadran Ramanathan and Y. Feng (2008) – On avoiding dangerous anthropogenic interference with the climate system: Formidable challenges ahead – Proceedings of the National Academy of Sciences PNAS 105:14245-14250 doi:10.1073/pnas.0803838105 – Scripps Institution of Oceanography, University of California at San Diego – Peer-reviewed
    “About 90% or more of the rest of the committed warming of 1.6 °C will unfold during the 21st century, determined by the rate of the unmasking of the aerosol cooling effect by air pollution abatement laws and by the rate of release of the GHGs-forcing stored in the oceans. The accompanying sea-level rise can continue for more than several centuries. Lastly, even the most aggressive CO₂ mitigation steps as envisioned now can only limit further additions to the committed warming, but not reduce the already committed GHGs warming of 2.4°C”
44. Katherine Richardson (2009) – International Scientific Congress Climate Change: Global Risks, Challenges & Decisions – Synthesis Report – Copenhaguen, 10-12/03/2009 – http://www.climatecongress.ku.dk – Peer-reviewed
    “A 2 ºC guardrail, which was thought in 2001 to have avoided serious risks for all five reasons for concern, is now inadequate to avoid serious risks to many unique and threatened ecosystems and to avoid a large increase in the risks associated with extreme weather events. Third, the risks of large scale discontinuities, such as the tipping elements described above, were considered to be very low in 2001 for a 2 ºC increase but are now considered to be moderate for the same increase. In summary, although a 2 ºC rise in temperature above pre-industrial remains the most commonly quoted guardrail for avoiding dangerous climate change, it nevertheless carries significant risks of deleterious impacts for society and the environment.”
45. David Wasdell (2008) – We Have a Problem. Feedback Dynamics and the Acceleration of Climate Change – Director, Apollo-Gaia Project – The Club of Rome: International Conference on Managing the Interconnected Challenges of Climate Change, Energy Security and Water – http://www.clubofrome.org/eng/meetings/winterthur_2008/presentations/David_Wasdell.pdf
    “It is three-and-a-half years since the original analysis of the Feedback Dynamics of Climate change was shared with HRH El Hassan bin Talal, the then President of the Club of Rome. He subsequently invited me to introduce the material at the next meeting of the Club in Norfolk, Virginia, and since then there has been an unrelenting process of testing, challenge and revision of the analysis. It is a privilege to have the opportunity to share the current version with you at this International Conference of the Club of Rome … Perhaps the final word should be left to Gene Kranz, mission controller of Apollo 13 as he led the team struggling to bring the crippled space-capsule safely back to earth: “Failure is not an option”.»
46. David Wasdell (2006) – Beyond the Tipping Point. Feedback Dynamics and the Acceleration of Climate Change: An Update of the Scientific Analysis – The Meridian Programme – http://www.meridian.org.uk/_PDFs/FeedbackDynamics.pdf
    “It will require a much more drastic intervention than reducing greenhouse gas emissions … That is a massive challenge which constitutes a state of global emergency”
47. UN chief makes Antarctica visit – BBC News, 10/11/2007 – http://news.bbc.co.uk/2/hi/science/nature/7088435.stm
    “Ban Ki-Moon: The biggest challenge to humanity in the 21st Century … This is an emergency, and for emergency situations we need emergency action”
48. Reuters – UN chief says global warming is ‘an emergency’ – ABC News, 11/11/2007 – http://www.abc.net.au/news/stories/2007/11/11/2087480.htm
    “The Antarctic Peninsula has warmed faster than anywhere else on Earth in the last 50 years, making the continent a fitting destination for Mr Ban, who has made climate change a priority since he took office earlier this year. «I need a political answer. This is an emergency and for emergency situations we need emergency action,» he said during a visit to three scientific bases on the barren continent, where temperatures are their highest in about 1,800 years.”
49. Hans Joachim Schellnhuber (2009) – Terra Quasi-Incognita: Beyond the 2°C Line – International Climate Conference: 4 Degrees and Beyond – Oxford, 29-30/09/2009 – http://www.eci.ox.ac.uk/4degrees/ppt/1-1schellnhuber.pdf
50. Mark Lynas (2008) – Six Degrees wins prestigious Royal Society prize – Marc Lynas blog – 18/06/2008 – http://beta.marklynas.org/2008/6/18/six-degrees-wins-presitigious-royal-society-prize
    “Much to the surprise of its author, Six Degrees has scooped the prestigious Royal Society Science Books Prize, triumphing over such strong contenders as Steve Jones’s ‘Coral: A pessimist in paradise’, and J. Craig Venter’s ‘A Life Decoded’.”
51. David Archer (2005) – The fate of fossil fuel CO₂ in geologic time – Journal of Geophysical Research 110 C09S05 doi:10.1029/2004JC002625 – Department of the Geophysical Sciences, University of Chicago – Peer-reviewed
    “The mean lifetime of anthropogenic CO₂ is dominated by the long tail, resulting in a range of 30-35 kyr. The long lifetime of fossil fuel carbon release implies that the anthropogenic climate perturbation may have time to interact with ice sheets, methane clathrate deposits, and glacial/interglacial climate dynamics.”
52. James Hansen et al (2005) – Efficacy of climate forcings – Journal of Geophysical Research 110: D18104 doi:10.1029/2005JD005776 – 28/09/2005 – 45 authors – NASA Goddard Institute for Space Studies and Columbia University Earth Institute – Peer-reviewed
    “Thus the total effective CH4 forcing is ~0.80 W/m2. Given that the direct forcing (Fa) of CH4 is 0.55 W/m2, this implies an overall, direct plus indirect, efficacy of ~145%. The direct plus indirect CH4 effective forcing for 1750–2000 is thus ~50% of the CO₂ forcing.”
53. Katharine Sanderson (2009) – Aerosols make methane more potent – Nature News doi:10.1038/news.2009.1049 – 29/10/2009 – http://www.nature.com/news/2009/091029/full/news.2009.1049.html
    “The International Panel on Climate Change (IPCC) and treaties such as the Kyoto Protocol assume methane to be, tonne-for-tonne, 25 times more potent than carbon dioxide at warming the planet. But the interaction with aerosols bumps up methane’s relative global warming potential (GWP) to about 33, though there is a lot of uncertainty around the exact figure. In the Kyoto Protocol, GWPs are used to govern emissions trading.” – Peer-reviewed
54. Andrew E. Dessler and Steven C. Sherwood (2009) – A Matter of Humidity – Science 323:1020-1021 doi:10.1126/science.1171264 – 20/02/2009 – Texas A&M University; Climate Change Research Centre, University of New South Wales, Sydney – Peer-reviewed
    “How strong a part does water vapor play in global warming? … the water vapor feedback is virtually certain to be strongly positive, with most evidence supporting a magnitude of 1.5 to 2.0 W/m2/K, sufficient to roughly double the warming that would otherwise occur.”
55. A.L. Westerling et al (2006) – Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity – Science 313:940-943 doi:10.1126/science.1128 – Scripps Institution of Oceanography, La Jolla – 4 authors – Peer-reviewed
    “Robust statistical associations between wildfire and hydroclimate in western forests indicate that increased wildfire activity over recent decades reflects sub-regional responses to changes in climate. Historical wildfire observations exhibit an abrupt transition in the mid-1980s from a regime of infrequent large wildfires of short (average of 1 week) duration to one with much more frequent and longer burning (5 weeks) fires.”
56. Ben Bond-Lamberty and Allison Thomson (2010) – Temperature-associated increases in the global soil respiration record – Nature 464:579-582 doi:10.1038/nature08930 – 25/03/2010 – Pacific Northwest National Laboratory, Joint Global Change Research Institute at the University of Maryland – Peer-reviewed
    “We find that the air temperature anomaly (the deviation from the 1961–1990 mean) is significantly and positively correlated with changes in RS. We estimate that the global RS in 2008 (that is, the flux integrated over the Earth’s land surface over 2008) was 98 ± 12 Pg C and that it increased by 0.1 Pg C yr-1 between 1989 and 2008, implying a global RS response to air temperature (Q10) of 1.5. An increasing global RS value does not necessarily constitute a positive feedback to the atmosphere, as it could be driven by higher carbon inputs to soil rather than by mobilization of stored older carbon. The available data are, however, consistent with an acceleration of the terrestrial carbon cycle in response to global climate change.”
57. F.S. Chapin III et al (2005) – Role of Land-Surface Changes in Arctic Summer Warming – Science 310:657-660 doi:10.1126/science.1117368 – 22/09/2005 – Institute of Arctic Biology; University of Alaska Fairbanks – 21 authors – Peer-reviewed
    “Reduced snow cover and albedo (reflectivity) in the summertime Arctic landscape, caused by global warming, has added local atmospheric heating “similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO₂ … Continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating 2-7 times’.”
58. Vladimir E. Romanovsky et al (2001) – Permafrost Temperature Dynamics Along the East Siberian Transect and an Alaskan Transect (Extended Abstract) – Tôhoku Geophysical Journal 36:224-229 – 08/11/2000 – Geophysical Institute , University of Alaska Fairbanks – 5 authors
59. Bruce Buffett and David Archer (2004) – Global inventory of methane clathrate: sensitivity to changes in the deep ocean – Earth and Planetary Science Letters 227:185-199 – 08/10/2004 – Department of Geophysical Sciences, The University of Chicago – Peer-reviewed
    “Global estimate of 3.10¹⁸ g of carbon (3.000 Gton C) in clathrate and 2.10¹⁸ g (2.000 Gton C) in methane bubbles. The predicted methane inventory decreases by 85% in response to 3 ºC of warming. Conversely, the methane inventory increases by a factor of 2 if the O₂ concentration of the deep ocean decreases by 40 µM or carbon rain increases by 50% (due to an increase in primary production). Changes in sea level have a small effect.”
60. Amanda Leigh Mascarelli (2009) – A Sleeping giant? – Nature Reports Climate Change doi:10.1038/climate.2009.24 – 05/03/2009 – http://www.nature.com/climate/2009/0904/full/climate.2009.24.html – Peer-reviewed
    “These deposits rival fossil fuels in terms of their size. It’s like having a whole additional supply of coal, oil and natural gas out there that we can’t control.” – James White
61. David Archer et al (2009) – Ocean methane hydrates as a slow tipping point in the global carbon cycle – Proceedings of the National Academy of Sciences PNAS Early Edition doi:10.1073/pnas.0800885105 – 09/09/2008 – Department of Geophysical Sciences, University of Chicago – Peer-reviewed
    “A critical bubble volume fraction threshold has been proposed as a critical threshold at which gas migrates all through the sediment column … is therefore conservative in its prediction of releasable methane, finding only 35 Pg of C released after 3 °C of uniform warming by using a 10% critical bubble volume. If 2.5% bubble volume is taken as critical, then 940 Pg of C might escape in response to 3 °C warming. This hydrate model embedded into a global climate model predicts ~0.4–0.5 °C additional warming from the hydrate response to fossil fuel CO₂ release, initially because of methane, but persisting through the 10-kyr duration of the simulations because of the CO₂ oxidation product of methane … The results of this paper should be regarded as a progress report rather than as a definitive statement about the methane cycle in the real ocean.”
62. Océano Ártico – Wikipedia – http://es.wikipedia.org/wiki/Océano_Ártico – 14/06/2010
    “Ocupa una extensión de unos 14.100.000 km² y las profundidades de este océano oscilan entre los 2.000 m y 4.000 m en la región central, y los 100 m en la plataforma continental; siendo su media de unos 1.500 m.”
63. Editorial: Climate crunch warning – New Scientist, 27/03/2009 – http://www.newscientist.com/article/mg20127012.700-climate-crunch-warning.html
    “One of the factors behind the credit crunch was a failure to see the big picture: a riskier deal is a lot riskier when everyone is making similar gambles. Once things start going wrong, there can be a domino effect … an unquantifiable risk is not the same as no risk. As the financial collapse shows, sometimes the doomsayers get it right.”
64. Jianhua Lu and Ming Cai (2010) – Quantifying contributions to polar warming amplification in an idealized coupled general circulation model – Climate Dynamics 34:669-687 doi:10.1007/s00382-009-0673-x – Department of Meteorology, Florida State University – Published online: 03/10/2009 – Peer-reviewed
    “An idealized coupled general circulation model is used to demonstrate that the surface warming due to the doubling of CO₂ can still be stronger in high latitudes than in low latitudes even without the negative evaporation feedback in low latitudes and positive ice-albedo feedback in high latitudes, as well as without the poleward latent heat transport … As a result, the final warming pattern shows the co-existence of a reduction of the meridional temperature gradient at the surface and in the lower troposphere with an increase of the meridional temperature gradient in the upper troposphere. In the tropics, the total warming in the upper troposphere is stronger than the surface warming.”
65. IPCC TAR – Peer-reviewed
66. G.M. Woodwell et al (2002) – Biotic Feedbacks in the Warming of the Earth – Climatic Change 40:495–518 DOI: 10.1023/A:1005345429236 – The Woods Hole Research Center – 6 authors – Peer-reviewed
    «Despite the importance of positive feedbacks and the recent rise in surface temperatures, terrestrial ecosystems seem to have been accumulating carbon over the last decades. The mechanisms responsible are thought to include increased nitrogen mobilization as a result of human activities, and two negative feedbacks: CO₂ fertilization and the warming of the earth, itself, which is thought to lead to an accumulation of carbon on land through increased mineralization of nutrients and, as a result, increased plant growth. The relative importance of these mechanisms is unknown, but collectively they appear to have been more important over the last century than a positive feedback through warming-enhanced respiration. The recent rate of increase in temperature, however, leads to concern that we are entering a new phase in climate, one in which the enhanced greenhouse effect is emerging as the dominant influence on the temperature of the earth. Two observations support this concern. One is the negative correlation between temperature and global uptake of carbon by terrestrial ecosystems. The second is the positive correlation between temperature and the heat-trapping gas content of the atmosphere. While CO₂ fertilization or nitrogen mobilization (either directly or through a warming-enhanced mineralization) may partially counter the effects of a warming-enhanced respiration, the effect of temperature on the metabolism of terrestrial ecosystems suggests that these processes will not entirely compensate for emissions of carbon resulting directly from industrial and land-use practices and indirectly from the warming itself. The magnitude of the positive feedback, releasing additional CO₂, CH4, and N2O, is potentially large enough to affect the rate of warming significantly.»
67. Appy Sluijs et al (2006) – Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum – Nature 441:610-613 doi:10.1038/nature04668 – 01/06/2006 – 15 authos + 302 expedtion – Peer-reviewed
    “The Palaeocene/Eocene thermal maximum, 55 million years ago, was a brief period of widespread, extreme climatic warming (refs) that was associated with massive atmospheric greenhouse gas input4. Although aspects of the resulting environmental changes are well documented at low latitudes, no data were available to quantify simultaneous changes in the Arctic region. We show that sea surface temperatures near the North Pole increased from ~18 ºC to over 23 ºC during this event. Such warmvalues imply the absence of ice and thus exclude the influence of ice-albedo feedbacks on this Arctic warming. At the same time, sea level rose while anoxic and euxinic conditions developed in the ocean’s bottom waters and photic zone, respectively. Increasing temperature and sea level match expectations based on palaeoclimate model simulations6, but the absolute polar temperatures that we derive before, during and after the event are suggests that higher-than-modern greenhouse gas concentrations must have operated in conjunction with other feedback mechanisms— perhaps polar stratospheric clouds (ref) or hurricane-induced ocean mixing (ref) – to amplify early Palaeogene polar temperature.”
68. James Hansen (2008) – Climate Threat to the Planet: The Venus Syndrome – Bjerknes Lecture, American Geophysical Union, San Francisco, 17/12/2008 – NASA Goddard Institute for Space Studies and Columbia University Earth Institute
    “The Venus syndrome is the greatest threat to the planet, to humanity’s continued existence… Now the danger that we face is the Venus syndrome. There is no escape from the Venus Syndrome. Venus will never have oceans again.”
69. S.I. Rasool and C. De Bergh (1970) – The Runaway Greenhouse and the Accumulation of CO₂ in the Venus Atmosphere – Nature 226:1037 doi:10.1038/2261037a0 – Institute for Space Studies, Goddard Space Flight Center, NASA – http://pubs.giss.nasa.gov/docs/1970/1970_Rasool_DeBergh.pdf – Peer-reviewed
    “Conditions on Earth would be as hostile as on Venus if the Erath were closer to the Sun by only 6-10 million miles.”
70. Climate and Evolution – European Space Agency, 28/11/2007 – http://www.esa.int/SPECIALS/Venus_Express/SEMGK373R8F_1.html
    “How did Venus turn out like this? ’Venus has suffered a radical climate disaster but we don’t yet know how, why and when,’ says David Grinspoon, a Venus Express interdisciplinary scientist from the Denver Museum of Nature and Science, Colorado, USA. The disaster was the loss of Venus’s water. If you could condense all of the water vapour in Venus’s atmosphere, it would create a thin covering of water just 3-cm thick. For comparison, if Earth were a smooth ball, all of the water in the oceans and atmosphere would create a covering 3-km deep. Venus may once have had this much water as well but it has been gradually stripped off into space by the collision of energetic particles from the Sun. Today, Venus Express has shown that the last remnants of the process are still taking place with the escape of hydrogen and oxygen from the top of the atmosphere.”
71. Rasmus Benestad and Ray Pierrehumbert – Lessons from Venus – Real Climate, 11/04/2006 – http://www.realclimate.org/index.php/archives/2006/04/lessons-from-venus/
    “The Earth may well succumb to a runaway greenhouse as the Sun continues to brighten over the next billion years or so, but the amount of CO₂ we could add to the atmosphere by burning all available fossil fuel reserves would not move us significantly closer to the runaway greenhouse threshold. There are plenty of nightmares lurking in anthropogenic global warming, but the runaway greenhouse is not among them. The applicability to Venus of concepts originating in the study of Earth climate is a testament to the beauty and generality of the physical underpinnings of climate science.”
72. James Hansen (2008) – Climate Threat to the Planet: The Venus Syndrome – Bjerknes Lecture, American Geophysical Union, San Francisco, 17/12/2008 – NASA Goddard Institute for Space Studies and Columbia University Earth Institute
    “What is different about the human-made forcing is the rapidity at which we are increasing it, on the time scale of a century or a few centuries. It does not provide enough time for negative feedbacks, such as changes in the weathering rate, to be a major factor. There is also a danger that humans could cause the release of methane hydrates, perhaps more rapidly than in some of the cases in the geologic record. In my opinion, if we burn all the coal, there is a good chance that we will initiate the runaway greenhouse effect. If we also burn the tar sands and tar shale (a.k.a. oil shale), I think it is a dead certainty.”
73. James Lovelock (2009) – The Vanishing Face of Gaia. A Final Warning – Allen Lane, Penguin Books – ISBN 978-1-846-14185-0 – 178 págs – Pág. 55
    “It seems that enough of us could survive to carry on our species, but there is an overriding need that reduces the carrying capacity of the Earth even further and that is the requirements of Gaia herself. There is much more to survival than human needs alone… Otherwise, our planet would move inexorably to the intolerably hot and utterly barren equilibrium state, something that eventually would be an average between Mars and Venus”
74. Peter Schwartz and Doug Randall (2003) – An Abrupt Climate Change Scenario and Its Implications for United States National Security: Imagining the Unthinkable – The Pentagon – October 2003 – http://www.climate.org/PDF/clim_change_scenario.pdf
    “Abrupt climate change is likely to stretch carrying capacity well beyond its already precarious limits. And there’s a natural tendency or need for carrying capacity to become realigned. As abrupt climate change lowers the world’s carrying capacity aggressive wars are likely to be fought over food, water, and energy. Deaths from war as well as starvation and disease will decrease population size, which overtime, will re-balance with carrying capacity.”
75. Pushker Kharecha and James Hansen (2008) – Implications of “peak oil” for atmospheric CO2 and climate – Global Biogeochemistry Cycles 22 GB3012 doi:10.1029/2007GB003142 – 17/03/2008 – NASA Goddard Institute for Space Studies and Columbia University Earth Institute
    “Peak CO₂ in the BAU scenario is ~575 ppm in 2100, with fuel emissions alone raising CO₂ to over 560 ppm (Fig. 4a). This is more than double the pre-industrial CO₂ amount of ~280 ppm and already far past the 450 ppm threshold under consideration. Likely nonlinearities in the carbon cycle with such large CO₂ amounts would make the real-world peak CO₂ even greater, as would any contribution from unconventional fossil fuels.”
76. Michiel van den Broeke et al (2009) – Partitioning Recent Greenland Mass Loss – Science 326:984-986 doi:10.1126/science.1178176 – Institute for Marine and Atmospheric Research, Utrecht University – 13/11/2009 – 9 authors
    “The total 2000–2008 mass loss of ~1500 gigatons, equivalent to 0.46 millimeters per year of global sea level rise, is equally split between surface processes (runoff and precipitation) and ice dynamics. Without the moderating effects of increased snowfall and refreezing, post-1996 Greenland ice sheet mass losses would have been 100% higher. Since 2006, high summer melt rates have increased Greenland ice sheet mass loss to 273 gigatons per year (0.75 millimeters per year of equivalent sea level rise).”
77. Thomas L. Mote (2007) – Greenland surface melt trends 1973–2007: Evidence of a large increase in 2007 – Geophysical Research Letters 35:L2170 doi:10.1029/2007GL031976 – Climatology Research Laboratory, Department of Geography, University of Georgia – 30/11/2007
    “Results show a large increase in melt in summer 2007, 60% more than the previous high in 1998. During summer 2007, some locations south of 70°N had as many as 50 more days of melt than average. Melt occurred as much as 30 days earlier than average. The SMD is shown to be significantly related to temperatures at coastal meteorological stations, although 2007 had more melt than might be expected based on the summer temperature record.”
78. Isabella Velicogna (2009) – Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE – Geophysical Research Letters 36 L19503 doi:10.1029/2009GL040222 – Department of Earth System Science, University of California; Jet Propulsion Laboratory, California Institute of Technology  – 13/10/2009
    “Between April 2002 and February 2009 … we find that during this time period the mass loss of the ice sheets is not a constant, but accelerating with time, i.e., that the GRACE observations are better represented by a quadratic trend than by a linear one, implying that the ice sheets contribution to sea level becomes larger with time. In Greenland, the mass loss increased from 137 Gt/yr in 2002–2003 to 286 Gt/yr in 2007–2009, i.e., an acceleration of −30 ± 11 Gt/yr2 in 2002–2009.”
79. Isabella Velicogna (2009) – Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE – Geophysical Research Letters 36 L19503 doi:10.1029/2009GL040222 – Department of Earth System Science, University of California; Jet Propulsion Laboratory, California Institute of Technology  – 13/10/2009
    “Between April 2002 and February 2009 … we find that during this time period the mass loss of the ice sheets is not a constant, but accelerating with time, i.e., that the GRACE observations are better represented by a quadratic trend than by a linear one, implying that the ice sheets contribution to sea level becomes larger with time …  In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of −26 ± 14 Gt/yr2 in 2002–2009. The observed acceleration in ice sheet mass loss helps reconcile GRACE ice mass estimates obtained for different time periods.”
80. Ted Trainer (2010) – Can renewables etc. solve the greenhouse problem? The negative case – Energy Policy 38:4107-4114 doi:10.1016/j.enpol.2010.03.037 – 07/05/2010 – Social Work, University of NSW, Australia
    “Virtually all current discussion of climate change and energy problems proceeds on the assumption that technical solutions are possible within basically affluent-consumer societies. There is however a substantial case that this assumption is mistaken. This case derives from a consideration of the scale of the tasks and of the limits of non-carbon energy sources, focusing especially on the need for redundant capacity in winter. The first line of argument is to do with the extremely high capital cost of the supply system that would be required, and the second is to do with the problems set by the intermittency of renewable sources. It is concluded that the general climate change and energy problem cannot be solved without large scale reductions in rates of economic production and consumption, and therefore without transition to fundamentally different social structures and systems.”
81. James Hansen et al (2010) – Global Surface Temperature Change – To be submitted to Reviews of Geophysics – NASA Goddard Institute for Space Studies – 4 authors – http://data.giss.nasa.gov/gistemp/paper/gistemp2010_draft0601.pdf
    “Figure 21 gives the lie to the frequent assertion that «global warming stopped in 1998». Of course it is possible to find almost any trend for a limited period via judicious choice of start and end dates of a data set that has high temporal resolution, but that is not a meaningful exercise. Even a more moderate assessment, «the trend in global surface temperature has been nearly flat since the late 1990s despite continuing increases in the forcing due to the sum of the well-mixed greenhouse gases» [Solomon et al., 2009], is not supported by our data. On the contrary, we conclude that there has been no reduction in the global warming trend of 0.15-0.20°C/decade that began in the late 1970s”
82. Josefino C. Comiso (2006) – Arctic warming signals from satellite observations – Weather 61:70-76 doi: 10.1256/wea.222.05 – March 2006 – NASA/Goddard Space Flight Center
    “Satellite infrared data reveal that since 1981, the Arctic region has been warming at a rate of 0.72 ± 0.10 ºC per decade inside the Arctic circle and 0.61 ± 0.08 ºC for the region >60°N …  The perennial ice cover has been anomalously low during the last four years and in seven of the last eight years. The updated trend in the loss of Arctic perennial ice cover is now 9.8% per decade, compared to the previous estimate of 8.9% per decade … The lengths of melt periods have also been quantified and estimated to be increasing at varying rates over sea-ice, the Greenland ice sheet, Northern Eurasia and northern part of North America, respectively, above 60°N … A good understanding of these results is of great importance because of possible contribution to sea-level rise. The lengths of melt period have also been shown to be considerable in other parts of the Arctic, especially in Northern Canada and Alaska where the trends in surface temperature are 0.82 ± 0.23 and 0.77 ± 0.19 ºC per decade, making the permafrost and thousands of glaciers vulnerable.”
83. James A. Screen and Ian Simmonds (2010) – The central role of diminishing sea ice in recent Arctic temperature amplification – Nature 464:1334-1337 doi:10.1038/nature09051 – School of Earth Sciences, University of Melbourne – 29/04/2010
    “Changes in cloud cover, in contrast, have not contributed strongly to recent warming. Increases in atmospheric water vapour content, partly in response to reduced sea ice cover, may have enhanced warming in the lower part of the atmosphere during summer and early autumn. We conclude that diminishing sea ice has had a leading role in recent Arctic temperature amplification.”
84. Naomi Oreskes and Jonathan Renouf – Jason and the secret climate change war – The Sunday Times – The Sunday Times 07/09/2008 – http://www.timesonline.co.uk/tol/news/environment/article4690900.ece
    “Right on the first page, the Jasons predicted that carbon dioxide levels in the atmosphere would double from their preindustrial levels by about 2035. Today it’s expected this will happen by about 2050. They suggested that this doubling of carbon dioxide would lead to an average warming across the planet of 2-3C. Again, that’s smack in the middle of today’s predictions. They warned that polar regions would warm by much more than the average, perhaps by as much as 10 ºC or 12 ºC. That prediction is already coming true.”
85. Syukuro Manabe and Ronald J. Stouffer (1980) – Sensitivity of a global climate model to an increase of CO2 concentration in the atmosphere – Journal of Geophysical Research 85:5529-5554 – 11/05/1980 – Geophysical Fluids Dynamic Laboratory
    “It is concluded that this seasonal asymmetry in the warming results from the reduction in the coverage and thickness of the sea ice. The warming of the model atmosphere results in an enrichment of the moisture content in the air and an increase in the poleward moisture transport. The additional moisture is picked up from the tropical ocean and is brought to high latitudes where both precipitation and runoff increase throughout the year. Further, the time of rapid snowmelt and maximum runoff becomes earlier.”
86. Rune Grand Graversen and Minghuai Wang (2009) – Polar amplification in a coupled climate model with locked albedo – Climate Dynamics doi 10.1007/s00382-009-0535-6 – 23/01/2009 – Department of Meteorology, Stockholm University, Royal Netherlands Meteorological Institute; Department of Atmospheric, Oceanic and Space Sciences, University of Michigan
    “Even though SAF [surface albedo feedback] is an important process underlying excessive warming at high latitudes, the Arctic amplification is only 15% larger in the variable than in the locked-albedo experiments. It is found that an increase of water vapour and total cloud cover lead to a greenhouse effect, which is larger in the Arctic than at lower latitudes. This is expected to explain a part of the Arctic surface–air-temperature amplification … An interesting question is to what extent these feedbacks, associated with an increase of the specific humidity, are induced by local changes in the Arctic or by long-way transport changes. At least a part of the water vapour associated with these feedbacks is most likely of a remote origin since the humidity transport across the Arctic boundary is larger in the forcing than in the control experiment.”
87. Marc C. Serreze et al (2009) – The emergence of surface-based Arctic amplification – The Cryosphere 3:11-19 – National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences University of Colorado – 04/02/2009
    “1) Starting in the late 1990s and relative to the 1979–2007 time period, Arctic Ocean SAT anomalies in the NCEP reanalysis turned positive in autumn and have subsequently grown; 2) Consistent with an anomalous surface heating source, development of the autumn warming pattern aligns with the observed reduction in September sea ice extent, and temperature anomalies strengthen from the lower troposphere to the surface; 3) Recent autumn warming is stronger in the Arctic than in lower latitudes; 4) Recent low level warming over the Arctic Ocean is less pronounced in winter when most open water areas have refrozen; 5) There is no enhanced surface warming in summer; 6) Conclusions 1–5 hold for both the NCEP and JRA-25 reanalyses, the major difference being that temperature anomalies in JRA-25 are somewhat smaller.”
88. James Hansen et al (2007) – Dangerous human-made interference with climate: a GISS modelE study – Atmospheric Chemistry in Physics 7:2287-312 – 07/05/2007 – 47 authors – NASA Goddard Institute for Space Studies and Columbia University Earth Institute
    “We suggest that Arctic climate change has been driven as much by pollutants (O3, its precursor CH4, and soot) as by CO2, offering hope that dual efforts to reduce pollutants and slow CO2 growth could minimize Arctic change … If CO2 growth in the 21st century is kept as small as in the alternative scenario, additional Arctic warming by 2050 is about the same as warming to date by non-CO2 forcings. Thus, in that case, reduction of some of the pollutants considered in Fig. 5 may make it possible to keep further Arctic warming very small and thus probably avoid loss of all sea ice. On the other hand, if CO2 growth follows a BAU scenario, the impact of reducing the non-CO2 forcings will be small by comparison and probably inconsequential.”
89. Abigail L. Swanna et al (2010) – Changes in Arctic vegetation amplify high-latitude warming through the greenhouse effect – Proceedings of the National Academy PNAS Early Edition doi:10.1073/pnas.0913846107 – December 2010 – Department of Earth & Planetary Science, University of California – 5 auhors
    “Land surface albedo change is considered to be the dominant mechanism by which trees directly modify climate at high-latitudes, but our findings suggest an additional mechanism through transpiration of water vapor and feedbacks from the ocean and sea-ice … The long-wave effects from changes in atmospheric moisture are not generally considered in studies of high-latitude vegetation change, but we find the radiative forcing from water vapor to be the same magnitude as the direct shortwave forcing from albedo, indicating that the energy budget of the entire column should be considered and not just the balance of surface fluxes.”
90. Stefan Rahmstorf et al (2005) – Thermohaline circulation hysteresis: A model intercomparison – Geophysical Research Letters 32 L23605 doi:10.1029/2005GL023655 – 06/12/2005 – Potsdam Institute for Climate Impact Research, Potsdam – 11 authors
    “All models show a characteristic hysteresis response of the thermohaline circulation to the freshwater forcing; which can be explained by Stommel’s salt advection feedback. The width of the hysteresis curves varies between 0.2 and 0.5 Sv in the models. Major differences are found in the location of present-day climate on the hysteresis diagram. In seven of the models, present-day climate for standard parameter choices is found in the bi-stable regime, in four models this climate is in the mono-stable regime. The proximity of the present-day climate to the Stommel bifurcation point, beyond which North Atlantic Deep Water formation cannot be sustained, varies from less than 0.1 Sv to over 0.5 Sv
91. Matthias Hofmann and Stefan Rahmstorf (2009) – On the stability of the Atlantic meridional overturning circulation – Proceedings of the National Academy of Sciences PNAS 106:20584-20589 doi:10.1073/pnas.0909146106 – 08/12/2009 – Potsdam Institute for Climate Impact Research
    “We find that a characteristic freshwater hysteresis also exists in the predominantly wind-driven, low-diffusion limit of the AMOC. However, the shape of the hysteresis changes, indicating that a convective instability rather than the advective Stommel feedback plays a dominant role. We show that model errors in the mean climate can make the hysteresis disappear … we discuss evidence that current models systematically overestimate the stability of the AMOC.”
92. Joseph Romm – Are Scientists Overestimating – or Underestimating – Climate Change – 23/08/2007 – http://climateprogress.org/2007/08/21/are-scientists-overestimating-or-underestimating-climate-change-part-i/
    “Failing that desperate effort, we would end up at mid-century with carbon emissions far above current levels, and concentrations at 500 ppm, rising 3 to 4 ppm a year–or even faster if the vicious cycles of the climate system have kicked in. That would propel us to the point of no return in the third quarter of this century.”
93. Joseph Romm – Are Scientists Overestimating – or Underestimating – Climate Change, Part III – Climate Progress, 28/03/2007 – http://climateprogress.org/2007/08/23/are-scientists-overestimating-or-underestimating-climate-change-part-iii/
    “While these projections were done with one of the world’s most sophisticated climate system models, the calculations do not include the feedback effect of the released carbon from the permafrost, which has locked in it more carbon than the atmosphere (and much of that is in the form of methane, a potent greenhouse gas). That is to say, the CO2 concentrations in the model rise only as a result of direct emissions from humans, with no extra emissions counted from soils or tundra. Thus they are conservative numbers–or overestimates–of how much CO2 concentrations have to rise to trigger irreversible melting.”
94. Darrell S. Kaufman et al (2009) – Recent Warming Reverses Long-Term Arctic Cooling – Science 325:1236-1239 doi:10,1126/science1173983 – 04/09/2009 – School of Earth Sciences and Environmental Sustainability, Northern Arizona University – 11 authors
    “The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000 … The warming during the 20th century (and first decade of the 21st century) contrasts sharply with the millennial-scale cooling, with the last half-century being the warmest of the past two millennia. Our synthesis, together with the instrumental record, suggests that the most recent 10-year interval (1999–2008) was the warmest of the past 200 decades. Temperatures were about 1.4°C higher than the projected value based on the linear cooling trend and were even more anomalous than previously documented.”
95. Ian Allison, Nathan Bindoff, Robert Bindschadler, Peter Cox, Nathalie de Noblet-Ducoudre , Matthew England, Jane Francis, Nicolas Gruber, Alan Haywood  , David Karoly , Georg Kaser, Corinne Le Quéré, Tim Lenton, Michael Mann, Ben McNeil, Andy Pitman, Stefan Rahmstorf , Eric Rignot, Hans Joachim Schellnhuber, Stephen Schneider, Steven Sherwood, Richard Somerville, Konrad Steffen, Eric Steig, Martin Visbeck, Andrew Weaver (2009) – The Copenhagen Diagnosis – UNSW Climate Change Research Centre Australia – November 2009 – http://www.copenhagendiagnosis.com/
96. Polar Ice Center – 06/06/2010 – http://psc.apl.washington.edu/ArcticSeaiceVolume/IceVolume.php
    “Sea Ice Volume is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at APL/PSC by Dr. J. Zhang and collaborators.  Anomalies for each day are calculated relative to the average  over the 1979 -2009 period for that day to remove the annual cycle. The model mean seasonal cycle of sea ice volume ranges from 28,600 km^3 in April to 14,400 km^3 in September.  The blue line represents the trend calculated from January 1 1979 to the most recent date indicated on the figure.  Total Arctic Ice Volume for March 2010 is 20,300 km^3, the lowest over the 1979-2009 period and 38% below the 1979 maximum. September Ice Volume was lowest in 2009 at 5,800 km^3 or 67% below its 1979 maximum. Shaded areas represent one and two standard deviations of the anomaly from the trend. Updates will be generated at 3-5 day intervals.”
97. D.A. Rothrock, Y. Yu, and G.A. Maykut (1999) – Thinning of the Arctic Sea-Ice Cover – Geophysical Research Letters 26:3469-3472 – 01/12/1999 – University of Washington, Seattle
    “Whether ice volume has reached a minimum in a multidecadal cycle or will continue the observed decline, this large thinning of the ice cover is a major climatic signal that needs to be accounted for in a successful theory of climate variability. There is not yet a good temporal record of ice draft over the Arctic Ocean; what we have constructed here is better thought of as two climatologies, one for 1958-1976 and another for 1993-1997.”
98. D.A. Rothrock, Y. Yu, and G.A. Maykut (1999) – Thinning of the Arctic Sea-Ice Cover – Geophysical Research Letters 26:3469-3472 – 01/12/1999 – University of Washington, Seattle
    “In summary, ice draft in the 1990s is over a meter thinner than two to four decades earlier. The mean draft has decreased from over 3 m to under 2 m, and volume is down by some 40% … The present analysis … shows a widespread decrease in ice draft within the central Arctic Ocean, with the strongest decrease occurring in the eastern Arctic. Not only is the ice cover thinner in the 1990s than earlier, it appears to be continuing to decline in some regions through four years of SCICEX cruises at a rate of about 0.1 m yr⁻¹.”
99. Joseph Romm – Arctic double stunner: Sea ice extent is now below 2007 levels, while volume hit record low for March. Summer poised to set new record – Climate Progress, 21/05/2010 – http://climateprogress.org/2010/05/21/arctic-sea-ice-area-extent-volume-record-low/
    “The volume record seems more probable given where the sea ice extent is now compared to 2007 and how much less volume we appear to be starting with right now.  Of course, the sea ice extent is more visible and anything less than the record of 2007 will no doubt be dismissed by some.  But at least with the the Polar Science Center work, we will have a nearly contemporaneous, well-validated model to track the volume.”
100. Más hielo en zonas delgadas
101. Dirk Notz (2009) – The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss – Proceedings of the National Academy of Sciences PNAS doi:10.1073/pnas.0902356106 – 02/11/2009 – Max Planck Institute for Meteorology
     “By using conceptual arguments, we review the recent findings that such a tipping point probably does not exist for the loss of Arctic summer sea ice. Hence, in a cooler climate, sea ice could recover rapidly from the loss it has experienced in recent years. In addition, we discuss why this recent rapid retreat of Arctic summer sea ice might largely be a consequence of a slow shift in ice-thickness distribution, which will lead to strongly increased year-to-year variability of the Arctic summer sea-ice extent. This variability will render seasonal forecasts of the Arctic summer sea-ice extent increasingly difficult. We also discuss why, in contrast to Arctic summer sea ice, a tipping point is more likely to exist for the loss of the Greenland ice sheet and the West Antarctic ice sheet.”
102. I. Eisenman and J. S. Wettlaufer (2009) – Nonlinear threshold behavior during the loss of Arctic sea ice – Proceedings of the National Academy PNAS 106:28-32 doi: 10.1073/pnas.0806887106 – Department of Earth and Planetary Sciences, Harvard University – 06/01/2009
     “Our analysis suggests that a sea-ice bifurcation threshold (or “tipping point”) caused by the ice–albedo feedback is not expected to occur in the transition from current perennial sea ice conditions to a seasonally ice-free Arctic Ocean, but that a bifurcation threshold associated with the sudden loss of the remaining seasonal ice cover may occur in response to further heating. These results may be interpreted by viewing the state of the Arctic Ocean as comprising a full seasonal cycle, which can include ice-covered periods as well as ice-free periods. The ice–albedo feedback promotes the existence of multiple states, allowing the possibility of abrupt transitions in the sea-ice cover as the Arctic is gradually forced to warm. Because a similar amount of solar radiation is incident at the surface during the first months to become ice free in a warming climate as during the final months to lose their ice in a further warmed climate, the ice–albedo feedback is similarly strong during both transitions. The asymmetry between these two transitions is associated with the fundamental nonlinearities of sea-ice thermodynamic effects, which make the Arctic climate more stable when sea ice is present than when the open ocean is exposed. Hence, when sea ice covers the Arctic Ocean during fewer months of the year, the state of the Arctic becomes less stable and more susceptible to destabilization by the ice–albedo feedback. In a warming climate, as discussed above, this causes irreversible threshold behavior during the potential distant loss of winter ice, but not during the more imminent possible loss of summer (September) ice.”
103. Paul Krugman – A counterintuitive train wreck – The New York Times, 16/10/2009 – http://krugman.blogs.nytimes.com/2009/10/16/a-counterintuitive-train-wreck/
     “Uh oh. I trust Joe Romm on climate — and his verdict on Superfreakonomics is pretty damning. I’ll get to work on the book myself, but it doesn’t look good. At first glance, though, what it looks like is that Levitt and Dubner have fallen into the trap of counterintuitiveness. For a long time, there’s been an accepted way for commentators on politics and to some extent economics to distinguish themselves: by shocking the bourgeoisie, in ways that of course aren’t really dangerous. Ann Coulter is making sense! Bush is good for the environment! You get the idea.”
104. Marika M. Holland et al (2008) – The Role of Natural Versus Forced Change in Future Rapid Summer Arctic Ice Loss – Geophysical Monograph Series [eds Deweaver ET, Bitz CM, Tremblay LB] (American Geophysical Union) 180:133–150 – http://www.cgd.ucar.edu/oce/mholland/papers/holland_AGU_DeWeaver_Ch10.pdf
     “We find little indication that a critical sea ice state is reached that then leads to rapid ice loss. Instead, our results suggest that the rapid ice loss events result from anthropogenic change reinforced by growing intrinsic variability. The natural variability in summer ice extent increases in the 21st century because of the thinning ice cover. As the ice thins, large regions can easily melt out, resulting in considerable ice extent variations. The important role of natural variability in the simulated rapid ice loss is such that we find little capability for predicting these events based on a knowledge of prior ice and ocean conditions. This is supported by results from sensitivity simulations initialized several years prior to an event, which exhibit little predictive skill.”
105. Dirk Notz (2009) – The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss – Proceedings of the National Academy of Sciences PNAS doi:10.1073/pnas.0902356106 – 02/11/2009 – Max Planck Institute for Meteorology
     “With a thinner ice-thickness distribution, the same amount of heat input leads to a much larger ice-free area, as has been noted by several previous studies (23–27). This relationship has sometimes been described as an increase in “open-water efficacy” (e.g., 26, 27). Because of the nonlinear ice-thickness distribution, a gradual thinning of the ice cover can initially lead to an acceleration, and, at some point, a very rapid loss of ice-covered area during summer.”
106. George Monbiot – If we behave as if it’s too late, then our prophecy is bound to come true – The Guardian, 17/03/2009 – http://www.guardian.co.uk/commentisfree/2009/mar/17/monbiot-copenhagen-emission-cuts
     “Quietly in public, loudly in private, climate scientists everywhere are saying the same thing: it’s over. The years in which more than 2 ºC of global warming could have been prevented have passed, the opportunities squandered by denial and delay. On current trajectories we’ll be lucky to get away with 4 ºC. Mitigation (limiting greenhouse gas pollution) has failed; now we must adapt to what nature sends our way. If we can”.
107. Donald L. Gautier et al (2009) – Assessment of Undiscovered Oil and Gas in the Arctic – Science 324:1175-1179 – 29/05/2009 – U.S. Geological Survey – 14 authors
     “Undiscovered natural gas is three times more abundant than oil in the Arctic and is largely concentrated in Russia. Oil resources, although important to the interests of Arctic countries, are probably not sufficient to substantially shift the current geographic pattern of world oil production … It is important to note that these estimates do not include technological or economic risks, so a substantial fraction of the estimated undiscovered resources might never be produced. Development will depend on market conditions, technological innovation, and the sizes of undiscovered accumulations. Moreover, these first estimates are, in many cases, based on very scant geological information, and our understanding of Arctic resources will certainly change as more data become available.”

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