Global warming is the rise of air temperature near Earth’s surface. The increase in temperatures is mostly caused by the buildup of atmospheric greenhouse gases, such as carbon dioxide and methane. These gases trap the sun’s heat and slow its loss to space, which causes temperatures to rise. The main cause of the buildup of these gases is human activity, including fossil fuel use and land clearing.
The global average surface temperature has been rising since the mid-1800s, according to NOAA records. The pace of change has accelerated in recent decades. Scientists have a high degree of confidence that the recent climate changes are caused by humans, in particular the accumulation of heat-trapping greenhouse gases.
Greenhouse gas emissions are mainly produced by burning fossil fuels — oil, coal and natural gas — which produce CO2 and other pollutants. Other causes include deforestation, where trees are cut down, and the growing livestock industry that produces methane and nitrous oxides. The evaporation of water also contributes to the buildup of greenhouse gases.
Warmer temperatures are disrupting the Earth’s normal balance and posing risks to all living things. They are causing sea levels to rise, endangering the homes of people living on low-lying islands. National Geographic Explorer Shireen Rahimi has been documenting the impacts of global warming on tropical coral reefs and encourages people to take action. Climate change affects everyone, but the countries and people that create more of the problem have a greater responsibility to reduce their emissions first.
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