The global average temperature has been rising since the mid-19th century, mostly due to human activities, according to a recent report by the Intergovernmental Panel on Climate Change (IPCC). This warming is caused by adding more heat-trapping gases to Earth’s atmosphere. Some of these gases, like carbon dioxide, are emitted when fossil fuels are burned. Others, like methane and nitrous oxide, are produced by farming and other human activities. In addition, volcanic eruptions can add to greenhouse gas levels in the atmosphere by releasing ash and smoke.
Historically, the levels of these gases have been relatively stable. But, in the last few decades, humans have added more than enough to significantly increase the atmospheric concentration of these gases and cause a rapid global temperature rise unparalleled in the Earth’s history.
Warming temperatures are already causing many effects, including the melting of sea ice and glaciers in cold regions, sea level rise, and more extreme heat waves. In addition, the increased temperatures are affecting the geographic ranges of plants and animals, and are changing the way they live and breed. Some species are adapting to these changes, while others are not and may become extinct.
Other natural factors can also change the Earth’s climate, such as solar radiation variations, cyclical ocean patterns, and variations in the Sun’s energy output, but they contribute only about two percent of the current global warming. The IPCC’s Sixth Assessment Report says that continuing to emit so much carbon dioxide will make it nearly impossible to limit the global warming to less than 1.5 degrees Celsius, as was agreed in a Paris climate agreement.
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