Summary

Agreement among climate scientists and scientific organizations that the globe is warming and humans are contributing to it is nearly unanimous, and the hard evidence to back up that position is readily available. Concentrations of carbon dioxide in the atmosphere are the highest they’ve been any time in the last 400,000 years; arctic ice is melting; and the global temperature has been steadily increasing, with all ten of the warmest years since recordkeeping began occurring within the last 12 years. As recently as 2008, the political consensus roughly mirrored the scientific consensus on the reality of climate change, but thanks to a concerted effort from corporations and industries that stand to benefit financially from lax oversight of emissions, the conservative establishment has slowly embraced climate change skepticism, with some flat-out denying that warming is occurring and others merely hedging on whether or not it’s a problem that needs to be addressed.

Many National Conservative Figures Are Climate Skeptics – A Change From 2008

In 2008, Both GOP And Democratic Candidates Believed In Global Warming. From the New York Times: “In 2008, both the Democratic and Republican candidates for president, Barack Obama and John McCain, warned about man-made global warming and supported legislation to curb emissions.” [New York Times, 10/15/11]

By 2012, GOP Presidential Candidates Were Skeptical Of Climate Science. From the New York Times: “But two years later, now that nearly every other nation accepts climate change as a pressing problem, America has turned agnostic on the issue. In the crowded Republican presidential field, most seem to agree with Gov. Rick Perry of Texas that ‘the science is not settled’ on man-made global warming, as he said in a debate last month. Alone among Republicans onstage that night, Jon M. Huntsman Jr. said that he trusted scientists’ view that the problem was real.” [New York Times, 10/15/11]

Pawlenty, Huntsman, Gingrich, And Romney All ‘Softened’ Their Positions On Climate Change. From USA Today: “One thing that Tim Pawlenty, Jon Huntsman, Newt Gingrich and Mitt Romney have in common: These GOP presidential contenders all are running away from their past positions on global warming, driven by their party’s loud doubters who question the science and disdain government solutions. All four have stepped back from previous stances on the issue, either apologizing outright or softening what they said earlier. And those who haven’t fully recanted are under pressure to do so.” [USA Today, 5/27/11]

• Romney: “I’m Not Willing To … Spend Trillions Of Dollars On Something I Don’t Know The Answer To.” According to NPR, Mitt Romney made the following statement during a campaign stop in New Hampshire on August 24, 2011: “Do I think the world’s getting hotter? Yeah, I don’t know that but I think that it is. I don’t know if it’s mostly caused by humans… What I’m not willing to do is spend trillions of dollars on something I don’t know the answer to.” [Mitt Romney Statement via NPR.org, 8/24/11]

Skepticism About Global Warming Has Become A Virtual Requirement For GOP Politicians. From the New York Times: “In the United States, the right wing of the Republican Party has managed to turn skepticism about man-made global warming into a requirement for electability, forming an unlikely triad with antiabortion and gun-rights beliefs.” [New York Times, 10/15/11]

GOP Politicians’ Growing Hostility To Climate Change Science Mirrors Conservative Voters’ Increasing Skepticism. From USA Today: “It’s an indicator of a shift on the issue among conservative Republicans, who have an outsized influence in the party’s presidential primary elections. Over the last few years, Gallup polling has shown a decline in the share of Americans saying that global warming’s effects have already begun — from a high of 61 percent in 2008 to 49 percent in March. The change is driven almost entirely by conservatives. In 2008, 50 percent of conservatives said they believed global warming already is having effects; that figure dropped to 30 percent this year. By contrast, among liberals and moderates there’s been relatively little movement, and broad majorities say warming is having an impact now.” [USA Today, 5/27/11]

GOP Energy And Commerce Chair Disputes That Global Warming Is Caused By Human Activity. From the Huffington Post: “Rep. Fred Upton (R-Mich.), the new chair of the House Energy and Commerce Committee, revealed in an interview that although he does believe that the climate is changing, he does not believe that humans play a role in this change. This is not the first time Upton has cast doubt on humans’ role in global warming. Upton had previously written that the EPA’s plan to regulate carbon emissions was ‘an unconstitutional power grab that will kill millions of jobs – unless Congress steps in.’” [HuffingtonPost.com, 2/8/11]

GOP Chair Of Science And Technology Committee: “I Don’t Think We Can Control What God Controls.” From an interview Rep. Ralph Hall (R-TX), chairman of the Committee on Science, Space, and Technology, gave to the National Journal, via Science magazine:

NJ: Do you think climate change is causing the earth to become warmer?

Hall: I can’t say it doesn’t have a percentage of effects on it – one percent, three percent, five percent. But I don’t think it’s the cause. I don’t think we can control what God controls.

We put $32 billion into it and don’t see very much change.

NJ: Last year the Proceedings of the National Academies of Science published a survey finding that 97 percent of scientists were in consensus that human activities lead to global warming.

Hall: And they each get $5,000 for every report like that they give out. That’s just my guess. I don’t have any proof of that. But I don’t believe ’em. I still want to listen to ’em and believe what I believe I ought to believe.

NJ: Have you read Governor Perry’s book, Fed Up?

Hall: Yes.

NJ: He essentially says climate science may be a conspiracy theory or may be put forth by scientists who are working together to put forth findings in order to get funding. Are you on the same page as Gov. Perry on this?

Hall: I’m pretty close. I think we ought to have an honest ear to science. They can come before my committee. I always put someone to come and testify when they’re testifying against it to give them the other side. I think we oughta listen to ’em. I just don’t think we oughta mind ’em.

Because what have we got for the $32 billion we spent?

NJ: Do you mean the $32 billion that was spent in the stimulus?

Hall: I mean everything that’s been spent knocking and pushing global warming. I’m really more fearful of freezing. And I don’t have any science to prove that. But we have a lot of science that tells us they’re not basing it on real scientific facts. And we need to listen to more. I’m willing to listen for more. [Science, 12/14/11, emphasis original]

Florida Sen. Marco Rubio Used To Support Efforts To Address Climate Change But Now Doesn’t “Think There’s The Scientific Evidence To Justify It.” From Mother Jones: “As speaker of the Florida Legislature, Rubio shepherded a landmark bill to limit greenhouse gas emissions, voiced caution about drilling off the Sunshine State’s coast, and argued that climate change was real. ‘Global warming, dependence on foreign sources of fuel, and capitalism have come together to create opportunities for us that were unimaginable just a few short  years ago,’ he told his House colleagues in 2007. Of drilling, he said it should only be done if it could be proven environmentally safe, and it wasn’t a silver bullet: ‘Even if we started drilling tomorrow morning, it could take close to 10 years before we start seeing the benefits.’ But as soon as he jumped into the US Senate race, his love for Mother Earth faded. He stumped for a Palinesque pro-oil campaign called ‘Drill Here, Drill Now.’ He ridiculed cap-and-trade emissions plans as ‘European-style’ or ‘California-style’ social engineering. And he attacked his Senate opponent, the moderate Republican-turned-independent Charlie Crist, as ‘a believer in man-made global warming.’ ‘I don’t think there’s the scientific evidence to justify it,’ he told the Tampa Tribune.” [MotherJones.com, 4/27/12]

Climate Change: The Hard Science

Gases Naturally Present In The Atmosphere Trap Heat And Warm The Earth — The Greenhouse Effect. According to the Environmental Protection Agency: “The Earth absorbs energy from the Sun, and also radiates energy back into space. However, much of this energy going back to space is absorbed by ‘greenhouse’ gases in the atmosphere. Because the atmosphere then radiates most of this energy back to the Earth’s surface, our planet is warmer than it would be if the atmosphere did not contain these gases. Without this natural ‘greenhouse effect,’ temperatures would be about 60ºF lower than they are now, and life as we know it today would not be possible.” [EPA.gov, accessed 5/17/12, internal citation removed]

• The Validity Of The Greenhouse Effect Is “Not In Dispute.” From NASA:

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.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. [Climate.NASA.gov, accessed 5/17/12, internal citation removed]

Gases That Contribute To The Greenhouse Effect Include Carbon Dioxide And Methane. From the Environmental Protection Agency:

Some greenhouse gases such as carbon dioxide occur naturally and are emitted to the atmosphere through natural processes and human activities. Other greenhouse gases (e.g., fluorinated gases) are created and emitted solely through human activities. The principal greenhouse gases that enter the atmosphere because of human activities are:

• Carbon Dioxide (CO2): Carbon dioxide enters the atmosphere through the burning of fossil fuels (oil, natural gas, and coal), solid waste, trees and wood products, and also as a result of other chemical reactions (e.g., manufacture of cement). Carbon dioxide is also removed from the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological carbon cycle.
• Methane (CH4): Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.
• Nitrous Oxide (N2O): Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.
• Fluorinated Gases: Hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for ozone-depleting substances (i.e., CFCs, HCFCs, and halons). These gases are typically emitted in smaller quantities, but because they are potent greenhouse gases, they are sometimes referred to as High Global Warming Potential gases (“High GWP gases”). [EPA.gov, accessed 5/17/12]

It Is ‘Virtually Certain’ That Human Activity Is Changing The Atmospheric Composition. According to the Environmental Protection Agency:

Scientists know with virtual certainty that:

• Human activities are changing the composition of Earth’s atmosphere. Increasing levels of greenhouse gases like carbon dioxide (CO2) in the atmosphere since pre-industrial times are well-documented and understood.
• The atmospheric buildup of CO2 and other greenhouse gases is largely the result of human activities such as the burning of fossil fuels. [EPA.gov, accessed 5/17/12]

Higher Levels Of Greenhouse Gases, Especially Carbon Dioxide And Methane, Are Increasing The Greenhouse Effect. From the Environmental Protection Agency: “During the past century humans have substantially added to the amount of greenhouse gases in the atmosphere by burning fossil fuels such as coal, natural gas, oil and gasoline to power our cars, factories, utilities and appliances. The added gases — primarily carbon dioxide and methane — are enhancing the natural greenhouse effect, and likely contributing to an increase in global average temperature and related climate changes.” [EPA.gov, accessed 5/17/12]

The Earth Is Warming: The Evidence

The Global Surface Temperature Has Been Rising Continuously. The following chart from NASA shows the change in global surface temperature since 1880 as a one-year average (pink) and a five-year average (red). The baseline (zero) is the average surface temperature between 1951-1980:

[Climate.NASA.gov, accessed 5/15/12]

• The 20 Warmest Years On Record Have Occurred Since 1981. From NASA: “All three major global surface temperature reconstructions show that Earth has warmed since 1880. Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years.” [Climate.NASA.gov, accessed 5/15/12, internal citation removed]
• 2010 Is Tied With 2005 For The Warmest Year On Record. From the National Oceanic and Atmospheric Administration: “According to NOAA scientists, 2010 tied with 2005 as the warmest year of the global surface temperature record, beginning in 1880. This was the 34th consecutive year with global temperatures above the 20th century average.” [NOAA.gov, 1/12/11]
• 2011 Was The 35^th Consecutive Year Annual Global Temperatures Were Above Average. From the National Oceanic and Atmospheric Association’s 2011 State of the Climate Global Analysis: “The annual global combined land and ocean surface temperature was 0.51°C (0.92°F) above the 20th century average of 13.9°C (57.0°F). This marks the 35^th consecutive year, since 1976, that the yearly global temperature was above average.” [NOAA.gov, December 2011]
• 2010 And 2011 Saw The Greatest Global Precipitation On Record. From the National Oceanic and Atmospheric Association’s 2011 State of the Climate Global Analysis: “The 2011 globally-averaged precipitation over land was the second wettest year on record, behind 2010.” [NOAA.gov, 1/12/11]

Carbon Dioxide Content Is The Highest It’s Ever Been. The following chart from NASA shows the carbon dioxide levels in the atmosphere from over 400,000 years ago to the present day:

[Climate.NASA.gov, accessed 5/15/12]

• Carbon Dioxide Emissions Jumped By Largest Amount On Record In 2010. According to the New York Times: “Global emissions of carbon dioxide from fossil-fuel burning jumped by the largest amount on record last year, upending the notion that the brief decline during the recession might persist through the recovery. Emissions rose 5.9 percent in 2010, according to an analysis released Sunday by the Global Carbon Project, an international collaboration of scientists tracking the numbers. Scientists with the group said the increase, a half-billion extra tons of carbon pumped into the air, was almost certainly the largest absolute jump in any year since the Industrial Revolution, and the largest percentage increase since 2003.” [New York Times, 12/4/11]

Arctic Sea Ice Has Been Declining Since 1979. The following chart from NASA charts the area covered by Arctic sea ice each year in September, when coverage reaches its lowest point each year. According to NASA, September Arctic sea ice is currently declining at a rate of 11.5 percent per decade:

[Climate.NASA.gov, accessed 5/15/12]

Sea Levels Have Been Consistently Rising Since 1870. The following chart from NASA shows the change in the sea level since 1870. According to NASA, “[s]ea level rise is caused by the expansion of sea water as it warms up in response to climate change and the widespread melting of land ice”:

[Climate.NASA.gov, accessed 5/15/12]

• The Rate At Which Sea Levels Have Risen In Last 10 Years Is Almost Double The Rate Of The Last Century. From NASA: “Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.” [Climate.NASA.gov, accessed 5/15/12]

Climate Change Is Happening Independently Of Solar Activity And Climate Patterns Like El Niño

Many Prior Climate Changes – Such As Ice Ages – Were Caused By Variations In Earth’s Orbit Affecting How Much Solar Energy Reached Earth. From NASA: “The Earth’s climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives. 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.” [Climate.NASA.gov, accessed 5/15/12]

There Is Abundant Evidence That Current Warming Is Not Caused By Changes In Sun’s Energy Output. From NASA:

[S]everal lines of evidence show that current global warming cannot be explained by changes in energy from the sun:

• Since 1750, the average amount of energy coming from the Sun either remained constant or increased slightly.
• If the warming were caused by a more active sun, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere, and a warming at the surface and in the lower parts of the atmosphere. That’s because greenhouse gasses are trapping heat in the lower atmosphere.
• Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases. [Climate.NASA.gov, accessed 5/15/12]

In The 2000s, A Solar Output Decline Impacted Amount Of Solar Energy Earth Received, But Temperatures Kept Increasing. From NASA: “Even though the 2000s witnessed a solar output decline resulting in an unusually deep solar minimum in 2007-2009, surface temperatures continue to increase.” [Climate.NASA.gov, accessed 5/15/12]

Global Warming Has Progressed Independently Of El Niño And La Niña. The following chart shows global temperature anomalies since 1950, with El Niño years in red and La Niña years in blue:

[NOAA.gov, December 2011]

Nearly All Climate Scientists And Scientific Organizations Agree: Humans Are Contributing To Global Warming

“Vast Majority Of The World’s Active Climate Scientists Accept The Evidence For Global Warming.” From the New York Times’ energy and environment blog: “William R.L. Anderegg, a doctoral candidate at Stanford University, and his fellow authors compiled a database of 1,372 climate researchers. They then focused on scientists who had published at least 20 papers on climate, as a way to concentrate on those most active in the field. That produced a list of 908 researchers whose work was subjected to close scrutiny. The authors then classified those researchers as convinced or unconvinced by the evidence for human-induced climate change, based on such factors as whether they have signed public statements endorsing or dissenting from the big United Nations reports raising alarm about the issue. Then the authors analyzed how often each scientist had been published in the climate-science literature, as well as how often each had been cited in other papers. (The latter is a standard measure of scientific credibility and influence.) The results are pretty conclusive. The new research supports the idea that the vast majority of the world’s active climate scientists accept the evidence for global warming as well as the case that human activities are the principal cause of it. For example, of the top 50 climate researchers identified by the study (as ranked by the number of papers they had published), only 2 percent fell into the camp of climate dissenters. Of the top 200 researchers, only 2.5 percent fell into the dissenter camp. That is consistent with past work, including opinion polls, suggesting that 97 to 98 percent of working climate scientists accept the evidence for human-induced climate change.” [NYTimes.com, 6/22/10]

• Most Climate Science Skeptics “Aren’t Actively Publishing In The Field.” From the New York Times’ energy and environment blog: “The study demonstrates that most of the scientists who have been publicly identified as climate skeptics are not actively publishing in the field. And the handful who are tend to have a slim track record, with about half as many papers published as the scientists who accept the mainstream view. The skeptics are also less influential, as judged by how often their scientific papers are cited in the work of other climate scientists.” [NYTimes.com, 6/22/10]

NASA, NOAA, National Academy, And Other Scientific Organizations Support Theory That Human Activity Has Contributed To Global Warming. From the Washington Post: “That the planet has warmed is a fact hardly anyone disputes — it has been measured with instruments on land and sea and in space. That humans have contributed to the warming through industrial activities is a theory supported by multiple scientific organizations, including the National Academy of Sciences, the American Association for the Advancement of Science, the U.S. Global Change Research Program, the National Oceanic and Atmospheric Administration, and NASA.” [Washington Post, 8/19/11]

IPCC: “Warming Of The Climate System Is Unequivocal.” From the “Summary for Policymakers” section of the Intergovernmental Panel on Climate Change’s 2007 report: “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.” [IPCC.ch, 2007]

• IPCC Is A Collaboration Of Nearly 200 Countries. From the Intergovernmental Panel on Climate Change’s website: “The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. The UN General Assembly endorsed the action by WMO and UNEP in jointly establishing the IPCC. […] Thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis. […] The IPCC is an intergovernmental body. It is open to all member countries of the United Nations (UN) and WMO. Currently 195 countries are members of the IPCC.” [IPCC.ch, 5/17/12]

National Academy Of Science: “A Strong, Credible Body Of Scientific Evidence Shows That Climate Change Is Occurring.” From a National Academy of Science report on climate change: “A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems.” [National Academy of Science, “Advancing the Science of Climate Change,” 2010]

Over 200 Members Of National Academy Signed A Letter Stating There Is “Compelling, Comprehensive, And Consistent Objective Evidence” For Climate Change. From a letter signed by over 200 members of the National Academy of Sciences via Science magazine: “We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet. […] There is compelling, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystems on which we depend.” [ScienceMag.org, 5/7/10]

U.K.’s Met Office: “Overwhelming And Growing” Evidence That Warming Is Due To Higher Amounts Of Greenhouse Gases. From the United Kingdom’s Met Office: “There are only a few plausible things that could cause this sudden warming of our climate – more energy from the sun, big natural variations in our climate, or an increased greenhouse effect. Scientists have done lots of research on the energy we get from the Sun and have been able to rule that out as the main cause. Lots of natural cycles have been identified in the climate, such as El Niño, but none of the one’s we know about could cause the relatively big, long-term changes we’ve seen. Therefore, there’s overwhelming and growing evidence that the warming we’ve seen is due to increasing amounts of greenhouse gases in the atmosphere. It’s very likely this warming has been caused by human activity, such as burning fossil fuels (like petrol and coal) and changing land use (such as chopping down forests for cattle grazing).” [MetOffice.gov.uk, accessed 5/17/12]

Panetta: Climate Change Is A National Security Issue. From remarks Defense Secretary Leon Panetta gave on May 2, 2012, at an Environmental Defense Fund event: “Our mission at the Department is to secure this nation against threats to our homeland and to our people. In the 21st century, the reality is that there are environmental threats which constitute threats to our national security. For example, the area of climate change has a dramatic impact on national security: rising sea levels, to severe droughts, to the melting of the polar caps, to more frequent and devastating natural disasters all raise demand for humanitarian assistance and disaster relief.” [Leon Panetta Remarks via NYTimes.com, 5/3/12]

18 Scientific Societies Signed Letter Urging Congress To Take Climate Change Seriously. From a letter signed by leaders from 18 scientific associations such as the American Geophysical Union: “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.” [Scientific Associations’ Letter via UCSUSA.org, 10/21/09]

American Meteorological Society: Human Activity Is A Major Contributor To Climate Change Over Last Half Century. From an “Information Statement” issued by the American Meteorological Society: “Climate has changed throughout geological history, for many natural reasons such as changes in the sun’s energy received  by Earth arising from slow orbital changes, or changes in the sun’s energy reaching  Earth’s surface  due  to volcanic eruptions. In  recent decades, humans have  increasingly affected local, regional, and global climate by altering the flows of radiative energy and water through the Earth system (resulting in changes in temperature, winds, rainfall, etc.), which comprises the atmosphere, land surface, vegetation, ocean, land ice, and sea ice. 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.” [American Meteorological Society Statement, 2/1/07]

American Geophysical Union: Earth’s Climate Is “Clearly” Warming And Changes Are Best Explained By Human Activity. From a position statement of the 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.” [AGU.org, December 2007]

American Physical Society: The Evidence For Global Warming Is “Incontrovertible.” From a resolution adopted by the American Physical Society: “Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth’s climate. Greenhouse gases include carbon dioxide as well as methane, nitrous oxide and other gases. They are emitted from fossil fuel combustion and a range of industrial and agricultural processes. 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 Physical Society Statement via UCSUSA.org, 11/18/07]

American Association for the Advancement of Science: “The Scientific Evidence Is Clear.” From the American Association for the Advancement of Science Board Statement on Climate Change: “The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.” [AAAS.org, 12/9/06]

Geological Society Of America: “Human Activities … Account For Most Of The Warming Since The Middle 1900s.” From a position statement from the 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.” [GeoSociety.org, April 2010]

American Chemical Society: “Climate Change Is Real.” From the American Chemical Society’s position statement on global climate change: “The Earth’s climate is the product of complex, highly dynamic, and often nonlinear, interactions among physical, chemical, and biological processes occurring at many scales in the atmosphere; at terrestrial, fresh water and marine surfaces; and in the depths of the oceans and landforms. While recent research advances in Earth systems science have greatly strengthened our understanding of prior and current climate properties and processes, our ability to quantitatively predict how the future climate will respond to continued and increasing greenhouse-gas and fine-particle emissions is still limited. Even more limited is our ability to precisely predict how the Earth’s ecological and human systems will respond to climate changes. However, comprehensive scientific assessments of our current and potential future climates clearly indicate that climate change is real, largely attributable to emissions from human activities, and potentially a very serious problem.” [ACS.org, 2010-2013]

Consequences Of Ignoring Global Warming

Effects Of Greenhouse Gas Buildup Are Delayed And Won’t Be Fully Felt For A Few Decades. From the Washington Post: “But the flattening of the trend has inspired skeptics to declare that global warming is over or that these are natural fluctuations not driven by human activity. Scientists say that’s hardly the case, noting that multiple factors are dampening the warming trend, including sunlight-blocking volcanic aerosols and soot emitted from China’s proliferating coal-fired power plants. And they stress that the effects of greenhouse gases build over time. ‘The full impact of the greenhouse gases that we’ve already added to the system today won’t be felt for 20 or 30 years,’ said Bill Chameides, dean of the Nicholas School of the Environment at Duke University and co-author of a recent National Academy of Sciences report, ‘America’s Climate Choices.’” [Washington Post, 8/19/11]

Scientists Predict Global Temperature Will Increase Up To 10 Degrees Over The Next Century. From NASA: “Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gasses produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century.” [Climate.NASA.gov, 5/15/12]

Higher Temperatures Come With A Variety Of Anticipated Consequences. From the National Academy of Science:

Projected impacts of future climate change include:

• Water availability will decrease in many areas that are already drought-prone and in areas where rivers are fed by glaciers or snowpack;
• A higher fraction of rainfall will fall in the form of heavy precipitation, increasing the risk of flooding and, in some regions, the spread of water-borne illness;
• People and ecosystems in coastal zones will be exposed to higher storm surges, intrusion of salt water into freshwater aquifers, and other risks as sea levels rise;
• Coral reefs will experience widespread bleaching as a result of increasing temperatures, rising sea levels, and ocean acidification. [National Academy of Science, “Advancing the Science of Climate Change,” 2010]

Climate Change May Increase Severe Weather Events. From the United Kingdom’s Met Office: “Experts predict that fierce storms and floods, such as those that brought chaos to parts of the UK in October 2000, are likely to become more frequent in the future. Over the past 100 years, warming has been accompanied by a reduction in the frequency of frosts and an increase in the number of heatwaves in many parts of the world. The amount of rainfall is getting heavier in some countries in terms of volume per downpour.” [MetOffice.gov.uk, accessed 5/17/12]

Climate Change May Be Affecting The Water Cycle More Than Previously Thought. From the New York Times: “New research suggests that global warming is causing the cycle of evaporation and rainfall over the oceans to intensify more than scientists had expected, an ominous finding that may indicate a higher potential for extreme weather in coming decades. By measuring changes in salinity on the ocean’s surface, the researchers inferred that the water cycle had accelerated by about 4 percent over the last half century. That does not sound particularly large, but it is twice the figure generated from computerized analyses of the climate. If the estimate holds up, it implies that the water cycle could quicken by as much as 20 percent later in this century as the planet warms, potentially leading to more droughts and floods.” [New York Times, 4/27/12]

Climate Change May Increase Severity Of Hurricanes. From the U.S. Global Change Research Program: “Likely future changes for the United States and surrounding coastal waters include more intense hurricanes with related increases in wind, rain, and storm surges (but not necessarily an increase in the number of these storms that make landfall), as well as drier conditions in the Southwest and Caribbean. These changes will affect human health, water supply, agriculture, coastal areas, and many other aspects of society and the natural environment.” [GlobalChange.gov, 2009]

Climate Change May Lead To Increased Flooding And Drought In Different Areas Around the Globe. From the U.S. Global Change Research Program: “Climate change will stress water resources. Water is an issue in every region, but the nature of the potential impacts varies. Drought, related to reduced precipitation, increased evaporation, and increased water loss from plants, is an important issue in many regions, especially in the West. Floods and water quality problems are likely to be amplified by climate change in most regions. Declines in mountain snowpack are important in the West and Alaska where snowpack provides vital natural water storage.” [GlobalChange.gov, 2009, emphasis removed]

Climate Change May Harm Crop And Livestock Production. From the U.S. Global Change Research Program: “Crop and livestock production will be increasingly challenged. Many crops show positive responses to elevated responses to carbon dioxide. However, increased heat, pests, water stress, diseases, and weather extremes will pose adaptation challenges for crop and livestock production.” [GlobalChange.gov, 2009, emphasis removed]

• Climate Change Will Likely Have A Greater Impact On Corn Prices Than Will Oil Prices, Trade Policies, Or Biofuel Mandates. From the New York Times: “Researchers have found that climate change is likely to have far greater influence on the volatility of corn prices over the next three decades than factors that recently have been blamed for price swings — like oil prices, trade policies and government biofuel mandates. The new study, published on Sunday in the journal Nature Climate Change, suggests that unless farmers develop more heat-tolerant corn varieties or gradually move corn production from the United States into Canada, frequent heat waves will cause sharp price spikes. […] [T]he analysis found that a moderate warming trend was likely to increase the number of days of severe heat in the growing season, thus doubling the volatility of corn yields. Using economic, climatic and agricultural data, the study found that if climate change stayed within the internationally accepted range of two degrees Celsius over the next 20 years or so, temperature changes would make those heat waves more common.” [New York Times, 4/22/12]

Climate Change Will Pose Public Health Challenges. From the U.S. Global Change Research Program: “Risks to human health will increase. Health impacts of climate change are related to heat stress, waterborne diseases, poor air quality, extreme weather events, and diseases transmitted by insects and rodents.” [GlobalChange.gov, 2009, emphasis removed]