Scientific Opinion on Climate Change

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Blogger Laurence Lewis assembled the following collection of quotes from respected, scientific bodies and associations regarding the reality of anthropogenic climate change. We feel it is worth highlighting these quotes to emphasize that there is no genuine scientific debate on this point.

In May of 2010, the Los Angeles Times reported:

In a sharp change from its cautious approach in the past, the National Academy of Sciences on Wednesday called for taxes on carbon emissions, a cap-and-trade program for such emissions or some other strong action to curb runaway global warming.

Such actions, which would increase the cost of using coal and petroleum — at least in the immediate future — are necessary because “climate change is occurring, the Earth is warming … concentrations of carbon dioxide are increasing, and there are very clear fingerprints that link [those effects] to humans,” said Pamela A. Matson of Stanford University, who chaired one of five panels organized by the academy at the request of Congress to look at the science of climate change and how the nation should respond.

The three reports issued Wednesday, totaling more than 860 pages, provide the broad outlines for a U.S. response to the threat; two more reports are to come.

“This is the most comprehensive report ever on climate change,” said atmospheric scientist Ralph J. Cicerone, the president of the academy. They outline “why the U.S. should act now to reduce greenhouse gas emissions and why we should have a national strategy to adapt to the inevitable.”

And the press release from the National Academies:

The compelling case that climate change is occurring and is caused in large part by human activities is based on a strong, credible body of evidence, says Advancing the Science of Climate Change, one of the new reports. While noting that there is always more to learn and that the scientific process is never “closed,” the report emphasizes that multiple lines of evidence support scientific understanding of climate change. The core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious debate and careful evaluation of alternative explanations.

“Climate change is occurring, is caused largely by human activities, and poses significant risks for — and in many cases is already affecting — a broad range of human and natural systems,” the report concludes. It calls for a new era of climate change science where an emphasis is placed on “fundamental, use-inspired” research, which not only improves understanding of the causes and consequences of climate change but also is useful to decision makers at the local, regional, national, and international levels acting to limit and adapt to climate change. Seven cross-cutting research themes are identified to support this more comprehensive and integrative scientific enterprise.

National Oceanic and Atmospheric Administration:

The 2009 State of the Climate report released today draws on data for 10 key climate indicators that all point to the same finding: the scientific evidence that our world is warming is unmistakable. More than 300 scientists from 160 research groups in 48 countries contributed to the report, which confirms that the past decade was the warmest on record and that the Earth has been growing warmer over the last 50 years.

American Association for the Advancement of Science (pdf):

The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.

National Aeronautics and Space Administration (NASA):

The current warming trend is of particular significance because most of it is very likely human-induced and proceeding at a rate that is unprecedented in the past 1,300 years.
Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale. Studying these climate data collected over many years reveal the signals of a changing climate.

Certain facts about Earth’s climate are not in dispute:

  • The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th century.2 Their ability to affect the transfer of infrared energy through the atmosphere is the scientific basis of many JPL-designed instruments, such as AIRS. Increased levels of greenhouse gases must cause the Earth to warm in response.
  • Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s climate responds to changes in solar output, in the Earth’s orbit, and in greenhouse gas levels. They also show that in the past, large changes in climate have happened very quickly, geologically-speaking: in tens of years, not in millions or even thousands.

American Physical Society (pdf):

The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now.

American Geophysical Union:

The Earth’s climate is now clearly out of balance and is warming. Many components of the climate system-including the temperatures of the atmosphere, land and ocean, the extent of sea ice and mountain glaciers, the sea level, the distribution of precipitation, and the length of seasons-are now changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century. Global average surface temperatures increased on average by about 0.6¡C over the period 1956-2006. As of 2006, eleven of the previous twelve years were warmer than any others since 1850. The observed rapid retreat of Arctic sea ice is expected to continue and lead to the disappearance of summertime ice within this century. Evidence from most oceans and all continents except Antarctica shows warming attributable to human activities.

American Chemical Society:

Careful and comprehensive scientific assessments have clearly demonstrated that the Earth’s climate system is changing rapidly in response to growing atmospheric burdens of greenhouse gases and absorbing aerosol particles (IPCC, 2007). There is very little room for doubt that observed climate trends are due to human activities. The threats are serious and action is urgently needed to mitigate the risks of climate change.

American Meteorological Society (pdf):

Indeed, strong observational evidence and results from modeling studies indicate that, at least over the last 50 years, human activities are a major contributor to climate change.

Direct human impact is through changes in the concentration of certain trace gases such as carbon dioxide, chlorofluorocarbons, methane, nitrous oxide, ozone, and water vapor, known collectively as greenhouse gases.

Geological Society of America:

Decades of scientific research have shown that climate can change from both natural and anthropogenic causes. The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2006), and the Intergovernmental Panel on Climate Change (IPCC, 2007) that global climate has warmed and that human activities (mainly greenhouse‐gas emissions) account for most of the warming since the middle 1900s. If current trends continue, the projected increase in global temperature by the end of the twentyfirst century will result in large impacts on humans and other species. Addressing the challenges posed by climate change will require a combination of adaptation to the changes that are likely to occur and global reductions of CO2 emissions from anthropogenic sources.

Joint statement by the American Association for the Advancement of Science, American Chemical Society, American Geophysical Union, American Institute of Biological Sciences, American Meteorological Society, American Society of Agronomy, American Society of Plant Biologists, American Statistical Association, Association of Ecosystem Research Centers, Botanical Society of America, Crop Science Society of America, Ecological Society of America, Natural Science Collections Alliance, Organization of Biological Field Stations, Society for Industrial and Applied Mathematics, Society of Systematic Biologists, Soil Science Society of America, University Corporation for Atmospheric Research:

Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science. Moreover, there is strong evidence that ongoing climate change will have broad impacts on society, including the global economy and on the environment.

Joint statement (pdf) by the Science Academies of the G8+5 (Canada, France, Germany, Italy, Japan, Russia, United Kingdom, United States, Brazil, China, India, Mexico and South Africa):

The IPCC 2007 Fourth Assessment of climate change science concluded that large reductions in the emissions of greenhouse gases, principally CO2, are needed soon to slow the increase of atmospheric concentrations, and avoid reaching unacceptable levels.

However, climate change is happening even faster than previously estimated; global CO2 emissions since 2000 have been higher than even the highest predictions, Arctic sea ice has been melting at rates much faster than predicted, and the rise in the sea level has become more rapid. Feedbacks in the climate system might lead to much more rapid climate changes.

The need for urgent action to address climate change is now indisputable. For example, limiting global warming to 2°C would require a very rapid worldwide implementation of all currently available low carbon technologies. The G8+5 should lead the transition to an energy efficient and low carbon world economy, and foster innovation and research and development for both mitigation and adaptation technologies. Capitalizing on new technologies will require a major scientific effort and policy initiatives to accelerate adoption of new technologies. The need to find solutions to climate change presents a huge but as yet unrealized opportunity for the creation of new jobs and for the stimulation of new and emerging markets. The role of innovation in delivering energy efficiency and a low carbon world should become a major part of the efforts to rebuild the global economy.

European Academy of Sciences and Arts (pdf):

Most of the climatic warming over the last 50 years is likely to have been caused by increased concentrations of greenhouse gases in the atmosphere. Documented long-term climate changes include changes in Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones.

Australian Institute of Physics (pdf):

Policy: The AIP supports a reduction of the green house gas emissions that are leading to increased global temperatures, and encourages research that works towards this goal.

Reason: Research in Australia and overseas shows that an increase in global temperature will adversely affect the Earth’s climate patterns. The melting of the polar ice caps, combined with thermal expansion, will lead to rises in sea levels that may impact adversely on our coastal cities. The impact of these changes on biodiversity will fundamentally change the ecology of Earth.

International Union of Geodesy and Geophysics (pdf):


Continuing reliance on combustion of fossil fuels as the world’s primary source of energy will lead to much higher atmospheric concentrations of greenhouse gases, which will, in turn, cause significant increases in surface temperature, sea level, ocean acidification, and their related consequences to the environment and society;

Stabilization of climate to avoid “dangerous anthropogenic interference with the climate system”, as called for in the UN Framework Convention on Climate Change, will require significant cutbacks in greenhouse gas emissions during the 21st century; and

Mitigation of and adaptation to climate change can be made more effective by reducing uncertainties regarding feedbacks and the associated mechanisms;


Nations collectively to begin to reduce sharply global atmospheric emissions of greenhouse gases and absorbing aerosols, with the goal of urgently halting their accumulation in the atmosphere and holding atmospheric levels at their lowest practicable value;

National and international agencies to adequately support comprehensive observation and research programs that can clarify the urgency and extent of needed mitigation and promote adaptation to the consequences of climate change;

Resource managers, planners, and leaders of public and private organizations to incorporate information on ongoing and projected changes in climate and its ramifications into their decision-making, with goals of limiting emissions, reducing the negative consequences of climate change, and enhancing adaptation, public well-being, safety, and economic vitality; and

Organizations around the world to join with IUGG and its member Associations to encourage scientists to communicate freely and widely with public and private decision-makers about the consequences and risks of on-going climate change and actions that can be taken to limit climate change and promote adaptation; and


To act with its member Associations to develop and implement an integrated communication and outreach plan to increase public understanding of the nature and implications of human-induced impacts on the Earth system, with the aim of reducing detrimental consequences.

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