So what has happened over the last 30 years? Progress has been made in fits and starts, but not nearly enough has been done to confront the planet-altering magnitude of what we have unleashed. Here’s a look at some of what has occurred:
Areport to Congressby the Environmental Protection Agency warns that global warming caused by industrial pollutants is likely to shrink forests, destroy most coastal wetlands, reduce water quality and quantity in many areas and otherwise cause extensive environmental disruption in the United States over the next century.
The United Nations and the World Meteorological Organizationformthe Intergovernmental Panel on Climate Change to report to world leaders on the science of climate change.
Britain’s prime minister, Margaret Thatcher, who earned a degree in chemistry at Oxford,tells the United Nationsin a speech, “We are seeing a vast increase in the amount of carbon dioxide reaching the atmosphere.” She warns that, as a result, “change in futureis likely to be more fundamental and more widespread than anything we have known hitherto.” Shecalls for a global treatyon climate change.
In itsfirst report, the Intergovernmental Panel on Climate Changesays that“human activities are substantially increasing the atmospheric concentrations of the greenhouse gases” and will lead to a predicted “increase of global mean temperature during the” 21st century “of about 0.3 degrees Celsius per decade,” which it says is “greater than that seen over the past 10,000 years.” That’s a little more than a half-degree Fahrenheit per decade.
Aninternal studyby the oil giant Exxon finds that “warming will clearly affect sea ice, icebergs, permafrost and sea levels” in the Arctic and that “higher sea levels and bigger waves” could “damage the company’s existing and future coastal and offshore infrastructure.”
The United States and 171 other nations, meeting at the Earth Summit in Brazil,sign a treatyon climate change to limit greenhouse gas emissions to a level that will not interfere with the planet’s climate. But the deal lacks mechanisms to achieve that goal.
President Bill Clinton proposes a federal tax on fossil energy sources to help reduce carbon dioxide emissions. The measure narrowly passes the House of Representatives butdies in the Senate; a gasoline tax increase of 4.3 cents per gallon becomes law instead, the last time federal energy taxes have been raised.
Countries that signed the Earth Summit agreement in 1992agree to negotiate“binding targets” on emissions for major developed countries like the United States, but set significantly less stringent requirements for developing countries like China and India.
Climate change playsalmost no rolein the presidential campaign, with no mentions in the presidential debates and only a passing reference in the vice-presidential debate.
Delegates in 1997 from about 170 countries met in Kyoto, Japan, for the United Nations Framework Convention on Climate Change.CreditToru Yamanaka/Agence France-Presse — Getty Images
Concentrations of carbon dioxide, the main greenhouse gas, reachthe highest levelsin at least 400,000 years, as measured in Arctic ice cores.
More than 1,500 scientists from 63 countries, including 110 Nobel Prize winners, issuea call to action: “A broad consensus among the world’s climatologists is that there is now a discernible human influence on global climate” that represents “one of the most serious threats to the planet and to future generations.”
One hundred and ninety-two nationsagree totheKyoto Protocolto fight global warming. The agreement requires the United States and other developed countries to cut greenhouse gas emissions, but not developing countries like China.
The global average temperature of 58 degrees Fahrenheit isthe warmestsince reliable records began about 120 years ago.
Industry opponents of the Kyoto Protocoldraft a proposalto spend millions of dollars to convince the public that the environmental accord is based on shaky science.
In the presidential campaign, George W. Bush, the Republican nominee,promises to cutcarbon dioxide emissions from power plants, while Al Gore, the Democratic candidate, calls for aggressive climate policies but does not make climate change a major campaign issue andmentions it only oncein the debates.
Under strong pressure from conservative Republicans and industry groups, President Bush says his administration will not seek to regulate emissions of carbon dioxide from power plants. reversing a campaign pledge. He also sayshe will seek to withdrawthe United States from the Kyoto climate accord and that the United States will not comply with its emissions-reduction targets.
President Bush proposes avoluntary planinvolving tax credits and other incentives to encourage businesses and farmers to reduce their greenhouse gas emissions.
The Senatevotes 55 to 43 against a billsponsored by Senator John McCain, a Republican from Arizona, and Senator Joe Lieberman, a Democrat from Connecticut, to limit carbon dioxide emissions by creating a market-driven “cap and trade” program. Only four Republicans vote yes.
The Republican campaign adviser Frank Luntzwrites a memoto party officials noting: “Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly. Therefore, you need to continue to make the lack of scientific certainty a primary issue.”
Climate scientists across the globeoverwhelming agreethat evidence of climate change is clear and persuasive, according to a detailed analysis in Science Magazine by the science historian Naomi Oreskes. As she puts it: “Many details about climate interactions are not well understood, and there are ample grounds for continued research to provide a better basis for understanding climate dynamics. The question of what to do about climate change is also still open. But there is a scientific consensus on the reality of anthropogenic climate change. Climate scientists have repeatedly tried to make this clear. It is time for the rest of us to listen.”
Congress passesan energy policy actthat provides tax and other incentives for some low emissions energy sources, including nuclear power, hydropower and wind and solar power. But it also continues large subsidies for fossil fuels.
A Beijing street this year.CreditTim Graham/Getty Images
With its rapid industrialization, China surpasses the United States as the world’s biggest emitter of greenhouse gases.
Congress raises auto fuel efficiency standards for the first time since 1976.
The House of Representatives passesa cap-and-trade billthat would require cuts in greenhouse gas emissions of 17 percent below 2005 levels by 2020 and 83 percent by 2050. Only eight Republicans vote yes. The bill never receives a vote in the Senate, even though Democrats control 57 seats and two independents caucus with them.
The American Petroleum Institute, funded by major oil companies, helpsorganize and payfor the first Tea Party rallies, including protests against the House-passed cap-and-trade legislation.
President Obama says the United Stateswill cut greenhouse gas emissionsby 17 percent below 2005 levels by 2020 as part of the Copenhagen Accord signed by 193 nations. Large developing nations, including China, also pledge reductions, though they are voluntary.
The International Energy Agency reports that global energy-related emissions of carbon dioxidehit a highof 30.6 billion tons, an increase of 1.6 billion tons over 2009.
President Obama reaches an agreement with American auto companies toraise fuel efficiency standardsto 54 miles per gallon by 2025, the largest emissions-cutting action of his presidency.
More than half of all carbon dioxide emissions from fossil fuels combustion since the Industrial Revolution began in 1751have occurredjust since the mid-1980s, according to a study by scientists for the United States government.
Greenhouse gas emissions in the United States decline slightly, but China’shave increasedby about 170 percent since 1999.
In his acceptance speech to become the Republican presidential nominee, Mitt Romney mocks President Obama’s climate efforts: “President Obama promised to slow the rise of the oceans and to heal the planet. My promise is to help you and your family.”
Scientists report that concentrations of carbon dioxidereached a record 400 parts per millionin the atmosphere, the highest levels in at least three million years, before human beings evolved, and that global emissions rose by 60 percent between 1990 and 2013.
In his second Inaugural Address, President Obama calls climate change theleading issue of our time.“We will respond to the threat of climate change, knowing that failure to do so would betray our children and future generations.”
More than 60 percent of all carbon dioxide emissions come fromsix nations: China, 30 percent; the United States, 16 percent; India, 6 percent; Russia, 5 percent; Japan, 4 percent; and Germany, 3 percent.
President Obama and President Xi Jinping of Chinaannounce limitson greenhouse gas emissions; the United States agrees to cut emissions by 26 to 28 percent below 2005 levels by 2025; China says it will begin scaling back emissions before 2030. The agreement sets the stage for a global climate deal.
A United Nations study finds that even if global greenhouse gas emissions are cut to the level required to keep temperature rise below 3.6 degrees Fahrenheit or 2 degrees Celsius, the cost of climate change adaptation in developing countries is likely to reach two to three times previous estimates of $70 billion to $100 billion per year by 2050
The Paris climate accordis approved by 195 nations, including the United States, marking the first time that all major nations pledge to make emissions reductions to limit the global average temperature increase to less than 3.6 degrees Fahrenheit.
The Republican-controlled Congress votes to phase out tax credits for wind and solar energy by 2020; various tax incentives for fossil fuel production remain. President Obama signs the bill, citing support from the renewable energy industry.
2016 is thewarmest year on record, the third consecutive year that a global annual temperature record has been set, and the40th consecutive yearthat annual temperatures have been above the 20th-century average. The five warmest years have all occurred since 2010.
James Hansen and other scientists publish research finding that current global temperatures are thehighest in at least 115,000 years, when sea levels were 20 to 30 feet higher than today.
Nearly all of the 16 Republican presidential hopefulsdeny the science of climate change, and none support the Paris climate agreement. Donald Trump pledges to “cancel” American involvement in the Paris accord.
Not a single questionon climate change is asked by moderators in any of the four presidential or vice-presidential debates.
The United States joins with 189 other countriesto phase outhydrofluorocarbons, gases used as refrigerants, a move that will stave off nearly a degree Fahrenheit of warming by 2100.
Mr. Trump is elected president following a campaign in which he called for more fossil fuel drilling, fewer environmental regulations and vowed to pull the United States out of the Paris climate accord. “Regulations that shut down hundreds of coal-fired power plants and block the construction of new ones — how stupid is that?”Mr. Trump askedduring the campaign.
Following up on his campaign promises, President Trumpsigns an executive orderdirecting his administration to undo regulations to cut emissions from the electric power sector; orders the resumption of the federal coal leasing program; says he will seek to weaken fuel economy standards for cars and light trucks; and proposes to cut the budget of the Environmental Protection Agency by 30 percent. He also says he will withdraw the United States from the Paris climate accord.
Hurricane Harvey unleashes 50 inches of rain,the largest rainfallin United States history, paralyzing five million in Houston, killing 30, with a price tag of at least tens of billions of dollars to federal taxpayers. Multiple peer-reviewed studies find that Hurricane Harvey was made as much as 40 percent larger and more intense because of warming Gulf of Mexico waters tied to the changing climate.
More than30 leading climate science and policy experts, including Nobel Prize winners, say that limiting global temperatures to below 3.6 degrees Fahrenheit will require removing fossil fuels from the global energy system by 2050, reducing emissions of super greenhouse gas pollutants like HFCs, methane and black carbon rapidly by 2030, and extracting carbon dioxide directly from the atmosphere.
A wildfire raging through Paradise, Calif., in November.CreditNoah Berger/Associated Press
Concentrations of carbon dioxide in the atmosphere reach 410 parts per million, thehighest levelin at leastthree million years
President Trump insists coalis the keyto the country’s energy and economic future and orders Energy Secretary Rick Perry to take immediate steps to prevent market shutdowns of coal plants.
The Trump administration says it willroll back fuel economy standardsset by the Obama administration for cars and light trucks, a move that would increase greenhouse gas emissions in the United States by an amount greater than many midsize countries put out in a year.
In another move to undo the Obama climate legacy, the Trump administration proposesletting states set their own coal emissions regulations, upending rules to reduce carbon dioxide emissions from coal-fired power plants. Many experts say this will cause greenhouse gas emissions from the power sector to begin rising for the first time in decades.
After falling for more than a decade, carbon dioxide emissions in the United States areset to riseby 2.5 percent in 2018. Global emissions grew by 1.6 percent in 2017 and will increase by about 2.7 percent in 2018.
Go. Jerry Brown of Californiasigns legislationrequiring that 100 percent of the state’s electricity come from carbon-free sources by 2045.
Thirteen federal agencies presentthe starkest warnings to dateof the consequences of climate change for the United States, predicting in a report that if significant steps are not taken to rein in global warming, the damage will knock as much as 10 percent off the size of the American economy by century’s end. The report warns of devastating effects on the economy, health and the environment, including record wildfires in California, crop failures in the Midwest and crumbling infrastructure in the South.
An international team of scientistsfindsa growing likelihood that runaway warming could destabilize the entire global climate system and lead to a “Hothouse Earth” that in the long term will push global average temperatures to seven to nine degrees Fahrenheit warmer than preindustrial temperatures, with seas 60 to 200 feet higher than today. “Humanity is now facing the need for critical decisions and actions that could influence our future for centuries, if not millennia,”the scientists write.
Paul Bledsoe is strategic adviser at theProgressive Policy Instituteand a lecturer at American University’s Center for Environmental Studies. He served on the White House Climate Change Task Force under President Bill Clinton.