This is part of a series on the effects of climate change.
What causes global warming?
According to the Intergovernmental Panel on Climate Change, human activities have unequivocally caused global warming. This has mainly occurred due to a much higher buildup of greenhouse gas emissions in the atmosphere from activities such as burning fossil fuels, deforestation, and farming. Greenhouse gases like carbon dioxide and methane trap heat in the atmosphere, which in turn warms the planet in a process known as the greenhouse effect. As of 2022, the global temperature had increased by 1.2 degrees above the pre-industrial average.In 2015, nearly 200 nations adopted the Paris Agreement. The international treaty commits countries to limit global warming to well below two degrees Celsius, targeting 1.5 degrees Celsius, in a bid to mitigate the worst impacts of climate change. Nevertheless, in a scenario where all announced net-zero targets, long-term targets, and Nationally Determined Contributions were fully implemented, the global mean temperature increase would reach two degrees Celsius by 2100. Based on current policies, as of November 2022, the world is heading for 2.7 degrees Celsius of warming above pre-industrial levels by the end of the century.
The effects of global warming
The impacts of a warming climate are numerous and severe, from extreme heat waves, deadly droughts, and wildfires to rising sea levels and melting ice caps. The maximum extent of global sea ice, which is typically recorded in November of each year, has shrunk over the past four decades as a result of global warming. In November 2022, it stood at 24.8 million square kilometers, a 10 percent decline compared with 1980.Global warming also drives heat waves that are becoming more frequent and intense. In 2021, western North America was hit by one of the most extreme heat events ever recorded, with record-breaking high temperatures felt across the U.S. states of Washington, Oregon, and California and western Canada. The intense heat caused more than 1,000 fatalities, making it one of the deadliest global weather events that year. Summer heat waves also swept across the Northern Hemisphere in 2022. There were an estimated 61,000 heat-related deaths recorded in Europe, the continent's hottest season on record. A consequence of a warming world is an increase in the frequency of extreme temperature events worldwide. Projections for a one-degree-Celsius warming scenario estimate 2.8 extreme heat events per decade, but this doubles to 5.6 events under two degrees Celsius of warming.
