Climate History: The World Reacts
Scientists, politicians, and citizens navigate the new climate reality.
First Earth Day celebration
The first Earth Day is the largest demonstration in American history, with 20 million participants around the country. The event was conceived as a “teach-in” by Wisconsin Senator Gaylord Nelson. Thousands of schools across the country joined in.
Nixon creates the EPA
President Richard Nixon creates the Environmental Protection Agency to protect human health and the environment. Later that month, the Clean Air Act—which regulates the emissions of hazardous air pollutants—passes unopposed in the Senate.
National Research Council predicts future temperature rise
The Council’s landmark Charney Report predicts that a doubling of CO2 will cause global temperature to rise by 3°C ± 1.5°C—a prediction that has remained consistent since. The report lays the groundwork for larger studies of human-caused climate change.
International collaboration on climate change
The United Nations establishes the Intergovernmental Panel on Climate Change (IPCC). The panel is an international scientific body that provides objective scientific assessments of climate change and its impacts.
The IPCC issues its first assessment report. The panel cautiously concludes, “[Recent warming] is broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability.”
The second IPCC report comes to a stronger conclusion: “The balance of evidence suggests a discernible human influence on global climate.”
The third IPCC report reveals a shifting scientific consensus: “Most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.”
The fourth assessment report shows increasing certainty about climate change—and earns the IPCC a Nobel Prize. “Warming of the climate system is unequivocal.”
The fifth IPCC assessment arrives with firm conviction: “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”
The IPCC Special Report on Global Warming of 1.5°C describes clear benefits from limiting global warming to 1.5°C above the pre-industrial temperature, but achieving this goal requires “rapid, far-reaching and unprecedented changes in all aspects of society.”
NASA testifies to Congress on global warming
During an exceptionally hot and dry summer, NASA climatologist James Hansen testifies to Congress. He tells them that NASA is 99% sure that the observed global warming trend is not a natural variation but is attributable to the buildup of atmospheric greenhouse gases caused by human activity.
Earth Summit in Rio de Janeiro
The summit establishes the U.N. Framework Convention on Climate Change (UNFCCC), a treaty to prevent risky human interference with the climate. George H.W. Bush signs it, saying, "The United States will continue to lead the world in taking economically sensible actions to reduce the threat of climate change."
Kyoto Protocol signed
Following up on the UNFCCC, the protocol negotiated in Kyoto, Japan establishes mandatory targets for major developed countries to reduce greenhouse gas emissions to at least 5% below 1990 levels by 2012. The Clinton administration signs it, but the U.S. Senate refuses to ratify.
A campaign of misinformation
The American Petroleum Institute—a trade association whose members include BP, Chevron, ExxonMobil, and Shell Oil—outlines a plan for climate deception. According to leaked memos, scientists are paid to deny human-caused climate change. The goal is to make the public believe there is no scientific consensus.
Hurricane Katrina rips through the Gulf Coast. 1,500 people die in the storm and its aftermath. It is the costliest hurricane in the nation’s history. The disaster provokes scientific study into the link between such storms and climate change and sparks debate about the future of extreme weather.
An Inconvenient Truth premieres
The climate change documentary, produced by former Vice President Al Gore, is a huge success. It wins two Academy Awards and helps bring climate change into the broader public conversation. It also politicizes the topic—for some, Gore’s participation in the film marked it as a liberal issue.
Massachusetts v. EPA
The Supreme Court rules that the EPA, under the Clean Air Act, must regulate carbon pollution as a threat to public health and welfare.
The UN Climate Change Conference in Paris
The conference results in the Paris Climate Agreement—the most comprehensive international response to human-caused climate change in history. The accord has since been signed by every nation in the world.
U.S. withdraws from Paris Climate Agreement
President Trump announces that he will withdraw the United States from the international agreement, claiming the accord would hurt the American economy. Every other nation in the world is a signatory.
IPCC Special Report on Global Warming of 1.5°C
The IPCC releases an updated assessment of human-induced climate change, warning that the traditionally accepted limit of 2°C global warming constituting “dangerous interference in the Earth’s climate system” is too high. Limiting global warming to 1.5°C would require rapid, far-reaching and unprecedented changes in all aspects of society, but with clear benefits to people and natural ecosystems.
National Climate Assessment Report
The U.S. government releases its Fourth National Climate Assessment as a joint effort from fourteen federal agencies. The report concludes that the Earth’s climate is now changing faster than at any point in the history of modern civilization, primarily as a result of human activities.