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Human-caused climate change
UN climate treaty 1992; Kyoto Protocol 1997; Paris Agreement December 12, 2015· Event· Global
Well documentedSolid records, physical evidence or scientific consensus.
Global warming caused mainly by burning coal, oil and gas, which adds heat-trapping carbon dioxide to the atmosphere.
See it on the History map →What happened
Scientists showed in the 1800s that carbon dioxide traps heat. Burning fossil fuels has raised its level from about 280 parts per million before industry to over 420 today. Earth has warmed about 1.3°C since the late 1800s, bringing more heat waves, heavier downpours, melting ice and rising seas. Governments signed a UN climate treaty in 1992, the Kyoto Protocol in 1997 and the Paris Agreement in 2015, aiming to hold warming well below 2°C.
Why it matters
It is a long-term risk to coasts, farming, insurance costs and property values, and is driving a historic shift from fossil fuels to renewable energy.
How we know
Thermometer records since the 1850s, the Mauna Loa CO2 record since 1958, ice cores, satellites, and the UN's IPCC reports, which call human influence 'unequivocal'.
Still debated
Exactly how much warming each added tonne of CO2 brings, and how fast ice sheets and other tipping points could change, remain uncertain.
Connections (5)
▸Industrial Revolution started the CO2 emissions driving Human-caused climate changeWell documented
The connection
Industry ran on coal, then oil and gas. Burning them releases carbon dioxide that stays in the air for centuries. Atmospheric CO2 has risen about 50% since the 1700s, and nearly all warming since the late 1800s is attributed to human emissions. Each wave of industrialization, from Britain to China, added more.
When and how
Britain from about 1760, spreading to Europe, the US and Japan by 1900, and to most of the world after 1950, when emissions soared.
How we know
Ice cores show CO2 roughly flat for thousands of years, then rising with industry; its chemical fingerprint (carbon isotopes) shows it comes from fossil fuels.
Debates and open questions
Geologists rejected a formal 'Anthropocene' epoch in 2024; whether the human-shaped era began with industry or the 1950s boom is still argued.
▸China's reform and opening turned China into the top emitter driving Human-caused climate changeWell documented
The connection
China's boom ran largely on coal. Its carbon emissions rose from about 1.5 billion tonnes a year in 1980 to roughly 12 billion now, and it passed the US as the top annual emitter around 2006. It produces about 30% of global emissions, though it also leads the world in building solar, wind and electric cars.
When and how
China, especially after 2000; Chinese coal use roughly tripled between 2000 and 2013.
How we know
Emissions data from the Global Carbon Project and the International Energy Agency; China's own figures are broadly similar.
Debates and open questions
The US has still emitted more in total since 1850, and much Chinese output makes goods for Western buyers; how to share responsibility is disputed.
▸Human-caused climate change risks echoing the warming behind the Permian extinction ('the Great Dying')Debated
The connection
The Great Dying was driven by a huge release of carbon dioxide that warmed the planet and acidified the oceans. Today's emissions are far smaller in total so far, but are being added at a rate that may exceed the Permian's. Scientists study the Permian as a worst-case example of what rapid carbon release can do.
When and how
The Permian event: Siberia, about 252 million years ago. Today: worldwide since the 1800s, as people burn coal, oil and gas.
How sure are we?
Permian rocks record warming, ocean acidification and oxygen loss; similar trends are measured today. The comparison is an analogy, not a prediction.
Debates and open questions
How close the parallel is remains argued: today's warming is far smaller so far, and whether ecosystems could pass similar tipping points is uncertain.
▸End of the last Ice Age was natural warming far slower than Human-caused climate changeWell documented
The connection
Ending the Ice Age warmed the planet about 4–7°C (7–13°F) over several thousand years, driven by orbital shifts amplified by carbon dioxide. Today's human-caused warming, about 1.3°C since the late 1800s and driven by burning fossil fuels, is happening at least ten times faster.
When and how
Deglaciation from about 19,000 to 11,700 years ago, worldwide; modern warming since the Industrial Revolution, accelerating after 1950.
How we know
Ice cores, ocean sediments and other natural archives measure past rates; thermometers and satellites measure today's.
Debates and open questions
Past rates vary by region and method, and how ice sheets will respond to today's much faster warming is a major open question.
▸United Nations hosts the global treaty talks on Human-caused climate changeWell documented
The connection
UN agencies set up the Intergovernmental Panel on Climate Change (IPCC) in 1988 to assess the science. The UN Framework Convention on Climate Change, signed at the 1992 Rio Earth Summit, holds yearly conferences of nearly 200 countries, called COPs, which produced the Kyoto Protocol (1997) and the Paris Agreement (2015).
When and how
Rio de Janeiro (1992), Kyoto (1997), Paris (2015), and annual COP meetings since 1995, the first held in Berlin.
How we know
The treaty texts, conference records, and the IPCC's assessment reports, the sixth completed in 2023.
Debates and open questions
Whether consensus-based UN talks can cut emissions fast enough is debated; national pledges so far fall short of the Paris goal of well below 2°C of warming.