Global warming is caused by human activity, specifically the burning of fossil fuels such as coal, oil, gasoline, and natural gas, which results in the greenhouse effect. The greenhouse effect occurs when carbon dioxide (CO2) and other air pollutants collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the earth’s surface. Normally this radiation would escape into space, but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter.
The main driver of climate change is the greenhouse effect. Some gases in the Earths atmosphere act a bit like the glass in a greenhouse, trapping the suns heat and stopping it from leaking back into space and causing global warming. Many of these greenhouse gases occur naturally, but human activities are increasing the concentrations of some of them in the atmosphere, in particular:
- carbon dioxide (CO2)
- methane
- nitrous oxide
- fluorinated gases
Natural causes, such as changes in solar radiation or volcanic activity, are estimated to have contributed less than plus or minus 0.1°C to total warming between 1890 and 2010.
The impacts of global warming are being felt everywhere. Extreme heat waves have caused tens of thousands of deaths around the world in recent years. The warming climate has also caused a decline in water supplies, reduced agricultural yields, and triggered heat-related health impacts in cities. In coastal areas, flooding and wildfires have become more frequent and severe.
