Short answers, pulled from the story.
Present-day climate change is driven by human activities, especially the burning of fossil fuels like coal, oil, and natural gas since the Industrial Revolution. These activities, along with deforestation and some agricultural and industrial practices, release greenhouse gases that trap heat near the Earth's surface. Earth's atmosphere now holds roughly 50% more carbon dioxide than at the end of the pre-industrial era.
In 2024, the warmest year on record since tracking began in 1850, the Earth reached +1.60 C above the pre-industrial baseline. The 2014-2023 decade averaged 1.19 C above the 1850-1900 baseline. Surface temperature has been rising at a rate of around 0.2 C per decade.
Global warming refers only to the increase in global average surface temperature, while climate change describes both that warming and its wider effects on Earth's climate system, such as changes in precipitation. The term global warming appeared as early as 1975 and became popular after James Hansen used it in his 1988 Senate testimony, while climate change has been the more common term since the 2000s.
Climate change threatens people with increased flooding, extreme heat, food and water scarcity, more disease, and economic loss, and can drive migration and conflict. The World Health Organization calls it one of the biggest threats to global health in the 21st century, and the World Economic Forum expects 14.5 million more deaths due to climate change by 2050. Poorer communities emit the least but are most vulnerable and least able to adapt.
Under the 2015 Paris Agreement, nations collectively agreed to keep warming well below 2 C, with an aspirational goal of keeping it under 1.5 C. Unlike the Kyoto Protocol it replaced, the Paris Agreement set no binding emission targets, instead requiring countries to set ever more ambitious goals and reevaluate them every five years. With pledges made as of 2024, there is a 66% chance of keeping warming under 2.8 C by the end of the century.
Climate change can be mitigated by reducing greenhouse gas emissions and by removing carbon dioxide from the atmosphere. Fossil fuels can be phased out by ending their subsidies, conserving energy, and switching to wind, solar, hydro, and nuclear power, while cleanly generated electricity replaces fossil fuels in transport, heating, and industry. Carbon can also be removed through reforestation and farming methods that store carbon in soil.
Joseph Fourier proposed the greenhouse effect in the 1820s to explain why Earth was warmer than sunlight alone could account for. In 1856, Eunice Newton Foote showed that air with carbon dioxide warmed more than dry air, and starting in 1859, John Tyndall established that water vapour, methane, and carbon dioxide absorb radiated heat. Svante Arrhenius published the first climate model of its kind in 1896.