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Dr Gideon Polya
Dr Gideon Polya

What Top World Scientists Say About the Climate Emergency

We are familiar with the notion of getting an expert second opinion when an expert medical specialist has diagnosed life threatening circumstances. However a second opinion that is a bit more optimistic simply decreases the perceived odds of death somewhat – the dire initial prediction remains.

Leading world climate experts offer the expert diagnosis that the World faces a life-threatening Climate Emergency requiring urgent action to stop carbon pollution and indeed to reduce existing atmosphere greenhouse gas (GHG) pollution.

"Hopefully these quotes and links will be useful in YOUR advocacy on behalf of the Planet and also help you convince your climate sceptic friends."
However such expert advice is countermanded by inexpert, non-scientist politicians and corporate spokespersons with vested interests in fossil fuel burning and their inexpert climate sceptic supporters. These climate sceptics and "business as usual" advocates are merely expressing inexpert partisan opinions that would be seen as dishonest and dangerously irresponsible in the context of expert medical specialist diagnosis of life threatening circumstances.

Below are about 2 dozen recent, Web-documented, expert statements from outstanding, world-leading climate change experts, other eminent scientific experts and top scientific organizations with expertise to make authoritative comments about the Climate Emergency and related matters.

These 2 dozen statements can be regarded as expert specialist diagnoses on the environmental health of the Planet's biosphere. We can seek expert second opinions by all means but these statements represent dire warnings that cannot be ignored.


Dr James Hansen (top US climate scientist; Director, NASA Goddard Institute for Space Studies; member of the prestigious US National Academy of Sciences; 2007 Award for Scientific Freedom and Responsibility of the prestigious American Association for the Advancement of Science; see: for 1880-present NASA GISS Global Temperature graphed data see: http://data.giss.nasa.gov/gistemp/ and http://data.giss.nasa.gov/gistemp/graphs/):

(a) With 8 UK, French and US climate change scientist co-authors (2008):

"Paleoclimate data show that climate sensitivity is ~3 deg-C for doubled CO2 [carbon dioxide; atmospheric CO2 280 ppm pre-industrial], including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6 deg-C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, large scale glaciation occurring when CO2 fell to 450 +/- 100 ppm [parts per million], a level that will be exceeded within decades, barring prompt policy changes. If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects."

See: http://arxiv.org/abs/0804.1126

(B) In relation to the recent book "Climate Code Red. The case for emergency action" by David Spratt and Philip Sutton: “A compelling case … we face a climate emergency.â€

© 2007 (Hansen, J., Mki. Sato, P. Kharecha, G. Russell, D.W. Lea, and M. Siddall, 2007: Climate change and trace gases. Phil. Trans. Royal. Soc. A, 365, 1925-1954):

“Paleoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the "albedo flip" property of water substance, provides a powerful trigger mechanism. A climate forcing that "flips" the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Ice sheet and ocean inertia provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the 2nd largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the 3rd largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon ("black soot") has a high global warming potential (~2000, 500, and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could still "save the Arctic", while also having major benefits for human health, agricultural productivity, and the global environment.â€

See: http://pubs.giss.nasa.gov/abstracts/2007/Hansen_etal_2.html).

(d) 2008, in an address to the US National Press Club and a briefing to the US House Select Committee on Energy Independence & Global Warming Congressional Committee:

“CEOs of fossil energy companies know what they are doing and are aware of long-term consequences of business as usual. In my opinion, these CEOs should be tried for high crimes against humanity and nature.â€

See: http://olumbia.edu/.../20080623.pdf


Dr Rajendra Pachauri (2008) (economist and environmental scientist; chairman of the Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC)):

“[The UN negotiations] must progress rapidly, otherwise I am afraid that not only future generations but even this generation will treat us as having been irresponsible…The EU has to lead. If the EU does not lead, I am afraid that any attempt to bring about change and to manage the problem of climate change will collapse…Today there is a high level of expectation. If the EU does not lead, you will not be able to bring the US on board, North America, on board. You will not be able to bring on board other countries in the world as well…we would have to stabilise the greenhouse-gas concentration at more or less the level at which we are today. But in order to do that [to limit the overall warming since pre-industrial times to 2 C (3.6 F)], we have a window of opportunity of only seven years because emissions will have to peak by 2015 and reduce after that. We cannot permit a longer delay…The very wise target that the EU had set of 2.0 C (3.6 F) may need to be looked at once more, because the impacts are turning out to be more serious than we had estimated earlier.â€

See: http://afp.google.com/.../


Dr Graeme Pearman (2008) (top Australian climate scientist; Chief of CSIRO Atmospheric Research in Australia from 1992 to 2002; world expert on increasing levels of CO2 and global warming):

"This science tells us that the world's climate is changing and that the change is primarily because of an increase of greenhouse gases in the atmosphere due to human activities. We are changing the climate. Very recent science suggests that climate change may be happening faster than we expected and that we and other species on the planet are more vulnerable to change than we thought. This is now forcing serious consideration of rapid responses by all nations as we work to tackle this shared problem. Challenges in this quest include a general community lack of appreciation of the significance of what appears to be small shifts in global average temperature, incompleteness of the knowledge-base and the need to respond using risk management."

See: http://monash.edu.au/.../climate-change.html


Professor David de Kretser, A.C., Governor of Victoria, Australia (2008) (eminent Australian medical scientist) in launching the book “Climate Code Red. The case for emergency action†by David Spratt and Philip Sutton (Scribe, Melbourne, 2008):

“The book draws on a vast array of information to build a cogent and compelling case that we do have a genuine emergency on our hands if we are to limit the rise of greenhouse gas emissions to a level at which we can limit the degradation of our planet to manageable levels … There is no doubt in my mind that this is the greatest problem confronting mankind at this time and that it has reached the level of a state of emergency.â€

See: http://scribepublications.com.au/.../climatecodered


Dr James Lovelock (top UK climate scientist; Fellow of the Royal Society; proponent of the Gaia hypothesis):

(a) 2006:

“In Chapter 1 I describe a simple model where the sensitive part of the Earth system is the ocean; as it warms, so the area of the sea that can support the growth of algae grows smaller as it is driven ever closer to the poles, until algal growth ceases. The discontinuity comes because algae in the ocean both pump down carbon dioxide [by photosynthesis] and produce clouds [through cloud-seeding dimethyl sulphide production]. (Algae floating in the ocean actively remove carbon dioxide from the air and use it for growth; we call the process “pumping down†to distinguish it from the passive and reversible removal of carbon dioxide as it dissolves in rain or sea water). The threshold for the failure of the algae is about 500 parts per million (ppm) of carbon dioxide, about the same as it is for Greenland’s unstoppable melting.â€

See: “The Revenge of Gaiaâ€, Allen Lane, London; p51

(B) 2007:

“Most of the large climate models used to predict future climates still rely mainly on atmospheric physics, and this includes the models on which the IPCC report is based. The influence of the clouds and the ocean are incompletely included and that of the Earth's natural ecosystems hardly at all. Present day climate models are good at explaining past climates but seem unable to agree on the course of global heating beyond about 2050, by the end of the century predictions vary over a wide range. This stark view was reinforced in May this year by the publication by Rahmstorf and his colleagues ["Recent Climate Observations Compared to Projections", Science 4 May 2007: Vol. 316. no. 5825, p. 709] of high quality measurements of the rise in global mean temperature, sea level and CO2. These showed that even the gloomiest predictions of the IPCC were underestimating the severity of climate change now.â€

See: http://jameslovelock.org/page24.html

© 2006:

“When Malthus first warned of the overpopulation of the Earth in 1800, there were only one billion of us. He has been derided ever since, yet I think he was right. One billion is about the right number and I fear that we will reach it not by our own choice but by attrition.â€

See: http://independent.co.uk/.../

(d) 2008:

“I hate academia. Most of the scientists who work there are not free men any more and they can't speak out. That's no way to do science.â€

See: http://guardian.co.uk/.../desertification.ethicalliving


Professor David Pimentel (1998) (Professor of Ecology and Agricultural Science at the College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA):

“At present, humans face serious malnutrition, land degradation, water pollution and shortages, and declining fossil energy resources. In addition, with related changes in the natural environment, many thousands of species are being lost forever. If the human population increases dramatically over the next several decades, as it is projected to do, the strains on these limited resources will grow as well. Some people are starting to ask just how many people the Earth can support if we want to cease degrading the environment and move to a sustainable solar energy system? There is no solid answer yet, but the best estimate is that Earth can support about 1 to 2 billion people with an American Standard of living, good health, nutrition, prosperity, personal dignity and freedom. This estimate suggests an optimal U.S. population of 100 to 200 million. To achieve this goal, humans must first stabilize their population and then gradually reduce their numbers to achieve a sustainable society in terms of both economics and environmental resources. With fair policies and realistic incentives, such a reduction in the human population can be achieved over the next century.â€

See: http://populationpress.org/essays/essay-pimentel.html


Dr Timothy Searchinger and colleagues (“Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Changeâ€, Science 29 February 2008, Vol. 319. no. 5867, pp. 1238 – 1240):

“Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products.â€


Dr Joseph Fargione and colleagues (“Land Clearing and the Biofuel Carbon Debtâ€, Science 29 February 2008, Vol. 319. no. 5867, pp. 1235 – 1238):

“Increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to low-carbon fuels a high priority. Biofuels are a potential low-carbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food crop–based biofuels in Brazil, Southeast Asia, and the United States creates a "biofuel carbon debt" by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions that these biofuels would provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on degraded and abandoned agricultural lands planted with perennials incur little or no carbon debt and can offer immediate and sustained GHG advantages.â€


Professors O. Hoegh-Guldberg, P. J. Mumby and colleagues (Coral Reefs Under Rapid Climate Change and Ocean Acidification, Science 14 December 2007: Vol. 318. no. 5857, pp. 1737 – 1742:

“Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse.â€


Dr Chris Thomas and numerous colleagues (Extinction risk from climate change, Nature 427, 145-148, 2004):

“Climate change over the past approx30 years has produced numerous shifts in the distributions and abundances of species and has been implicated in one species-level extinction. Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15–37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction (approx18%) than mid-range (approx24%) and maximum-change (approx35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.â€


Dr Cynthia Rosenzweig, Professor David D. Karoly and numerous other colleagues (2008) (Attributing physical and biological impacts to anthropogenic climate change. Nature, 453, 353-357, 2008):

“Significant changes in physical and biological systems are occurring on all continents and in most oceans, with a concentration of available data in Europe and North America. Most of these changes are in the direction expected with warming temperature. Here we show that these changes in natural systems since at least 1970 are occurring in regions of observed temperature increases, and that these temperature increases at continental scales cannot be explained by natural climate variations alone. Given the conclusions from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report that most of the observed increase in global average temperatures since the mid-twentieth century is very likely to be due to the observed increase in anthropogenic greenhouse gas concentrations, and furthermore that it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica, we conclude that anthropogenic climate change is having a significant impact on physical and biological systems globally and in some continents.â€

See: http://pubs.giss.nasa.gov/.../Rosenzweig_etal_1.html


Dr Andrew Balmford and numerous colleagues (Science 9 August 2002, Economic Reasons for Conserving Wild Nature, Science Vol. 297, pp. 950 – 953): “On the eve of the World Summit on Sustainable Development, it is timely to assess progress over the 10 years since its predecessor in Rio de Janeiro. Loss and degradation of remaining natural habitats has continued largely unabated. However, evidence has been accumulating that such systems generate marked economic benefits, which the available data suggest exceed those obtained from continued habitat conversion. We estimate that the overall benefit:cost ratio of an effective global program for the conservation of remaining wild nature is at least 100:1.â€

See: http://www.sciencemag.org/.../950


Dr Phillip S. Levin and Dr Donald A. Levin (2002) (Dr Donald A. Levin is Professor of Biology, University of Texas, Austin; his son Dr Phillip Levin is a biologist with the National Marine Fisheries Service):

“The numbers are grim: Some 2,000 species of Pacific Island birds (about 15 percent of the world total) have gone extinct since human colonization. Roughly 20 of the 297 known mussel and clam species and 40 of about 950 fishes have perished in North America in the past century. On average, one extinction happens somewhere on earth every 20 minutes. Ecologists estimate that half of all living bird and mammal species will be gone within 200 or 300 years. Although crude and occasionally controversial, such statistics illustrate the extent of the current upheaval, which spans the globe and affects a broad array of plants and animals…The current losses are, however, exceptional. Rates of extinction appear now to be 100 to 1,000 times greater than background levels, qualifying the present as an era of “mass extinctionâ€. The globe has experienced similar waves of destruction just five times in the past.â€

See: http://soc.duke.edu/.../the_real_biodiversity_crisis.html


Dr John Holdren (2008) (Professor of Environmental Policy at the Kennedy School of Government at Harvard University; Director of the Woods Hole Research Center; recent Chairman of the American Association for the Advancement of Science):

“I don’t like the term “global warming,†because it’s misleading. It implies something that’s mainly about temperature, that’s gradual, and that’s uniform across the planet. And in fact, temperature is only one of the things that’s changing. It’s a sort of an index of the state of climate. The whole climate is changing: the winds, the ocean currents, the storm patterns, snow packs, snowmelt, flooding, droughts. Temperature is just a bit of it. It’s also highly non-uniform. The largest changes are occurring in the far north in the Arctic, in the Antarctic Peninsula in the far south. It is certainly not gradual, in the sense that it is rapid compared to the capacity of ecosystems to adjust. It’s rapid compared to the capacity of human systems to adjust… I think that most people, even most scientists, continue to underestimate how far down the path to climate catastrophe we’ve already traveled. We are committed, the United States and 190 other countries are committed, under the Framework Convention on Climate Change to avoid dangerous human interference in the climate system. And the fact is, it’s already too late to do that. We’re already experiencing dangerous interference. Floods, major floods, are up all over the world. Wildfires are up in almost every region of the world where wildfires have been a problem. Wildfires erupt fourfold in the last thirty years in the western United States.â€

See: http://www.democracynow.org/.../


Professor Tim Flannery (2008) (eminent Australian mammalogist, palaeontologist and climate change activist):

“[inserting global dimming sulphur into the stratosphere] would change the colour of the sky. It's the last resort that we have, it's the last barrier to a climate collapse. We need to be ready to start doing it in perhaps five years time if we fail to achieve what we're trying to achieve…The consequences of doing that are unknown …The current burden of greenhouse gas in the atmosphere is in fact more than sufficient to cause catastrophic climate change… Everything's going in the wrong direction at the moment, timelines are getting shorter, the amount of pollution in the atmosphere is growing…It's extremely urgent."

See: http://news.com.au/.../


The UK Royal Society (founded in 1660; “the Royal Society, the national academy of science of the UK and the Commonwealth, is at the cutting edge of scientific progressâ€; the Royal Society is one of the world’s most prestigious scientific bodies and its members include the most outstanding British and Commonwealth scientists):

“Climate change controversies: a simple guide. The Royal Society has produced this overview of the current state of scientific understanding of climate change to help non-experts better understand some of the debates in this complex area of science. This is not intended to provide exhaustive answers to every contentious argument that has been put forward by those who seek to distort and undermine the science of climate change and deny the seriousness of the potential consequences of global warming. Instead, the Society - as the UK's national academy of science - responds here to eight key arguments that are currently in circulation by setting out, in simple terms, where the weight of scientific evidence lies.â€

See: http://royalsociety.org/page.asp?id=6229


The Intergovernmental Panel on Climate Change (IPCC), 2007 (the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988; it has produced 4 successive Assessment Reports, the last being the Fourth in 2007):

“Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level … Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.â€

See IPCC, 2007 Summary for Policymakers.


American Association for the Advancement of Science (AAAS), 2006 (founded in 1848, AAAS serves some 262 affiliated societies and academies of science, serving 10 million individuals; the AAAS journal Science has the largest paid circulation of any peer-reviewed general science journal in the world, with an estimated total readership of 1 million):

“The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society. Accumulating data from across the globe reveal a wide array of effects: rapidly melting glaciers, destabilization of major ice sheets, increases in extreme weather, rising sea level, shifts in species ranges, and more. The pace of change and the evidence of harm have increased markedly over the last five years. The time to control greenhouse gas emissions is now.â€

See: http://www.aaas.org/news/releases/2007/0218am_statement.shtml


US National Academy of Sciences (US PNAS) and 10 other national science academies, 2005 (the US PNAS is one of the world’s most prestigious scientific bodies and its members include the most outstanding US scientists):

“The US National Academy of Sciences joined 10 other national science academies today in calling on world leaders, particularly those of the G-8 countries meeting next month in Scotland, to acknowledge that the threat of climate change is clear and increasing, to address its causes, and to prepare for its consequences. Sufficient scientific understanding of climate change exists for all nations to identify cost-effective steps that can be taken now to contribute to substantial and long-term reductions in net global greenhouse gas emissions that cause global warming. The statement echoes the findings and recommendations of several previous reports by the US National Academies.â€

See: http://nationalacademies.org/onpi/06072005.pdf


Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) (Australia’s premier scientific research organization), Climate Change in Australia Technical Report 2007:

“The key findings of this report includes that by 2030, temperatures will rise by about 1 ºC over Australia – a little less in coastal areas, and a little more inland - later in the century, warming depends on the extent of greenhouse gas emissions. If emissions are low, warming of between 1 ºC and 2.5 ºC is likely by around 2070, with a best estimate of 1.8 ºC. Under a high emission scenario, the best estimate warming is 3.4 ºC, with a range of 2.2 ºC to 5 ºC.â€

See: http://www.csiro.au/resources/ps3j6.html#2

This collection of key quotes from top world scientific experts was put together for the Melbourne-based Yarra Valley Climate Action Group (YVCAG) which is associated with the new Australian climate action umbrella organization the Climate Emergency Network (CEN).

Hopefully these quotes and links will be useful in YOUR advocacy on behalf of the Planet and also help you convince your climate sceptic friends. Please tell everyone you can.

Dr Gideon Polya published some 130 works in a 4 decade scientific career, most recently a huge pharmacological reference text "Biochemical Targets of Plant Bioactive Compounds" (CRC Press/Taylor & Francis, New York & London, 2003). He has just published “Body Count. Global avoidable mortality since 1950†(G.M. Polya, Melbourne, 2007: http://mwcnews.net and http://globalbodycount.blogspot.com);

see also his contribution “Australian complicity in Iraq mass mortality†in “Lies, Deep Fries & Statistics†(edited by Robyn Williams, ABC Books, Sydney, 2007). He is currently preparing a revised and updated version of his 1998 book “Jane Austen and the Black Hole of British History†as biofuel-, globalization- and climate-driven global food price increases threaten a possibly 100-fold greater famine catastrophe than the man-made famine in British-ruled India that killed 6-7 million Indians in the "forgotten" World War 2 Bengal Famine (see recent BBC broadcast involving Dr Polya, Economics Nobel Laureate Professor Amartya Sen and others).

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