Global warming is the increase in Earth’s average surface temperature caused by human emissions of heat-trapping gases, primarily carbon dioxide, into the atmosphere. These gases build up in the atmosphere and prevent some of the Sun’s rays from being reflected back into space, causing the planet to warm.
The rate of climate change is accelerating, and some impacts are already happening. Temperatures are rising around the world, with most places warming faster than the global average. The Arctic is warming most rapidly of all, and the polar ice sheets are shrinking faster than expected. The oceans are also getting warmer, altering patterns of the water cycle and contributing to more intense and frequent heat waves.
Scientists know that humans have contributed to global warming, and they are confident that continued greenhouse gas emissions will cause further increases in Earth’s average surface temperature. They are also aware that the effects of global warming, including sea level rise and changes to ocean acidity, air temperatures, weather patterns, and stresses on plants and animals, will intensify over time.
Thousands of scientists and government reviewers have agreed that limiting the increase in Earth’s temperature to 1.5 degrees Celsius will help avoid the worst climate impacts and maintain a livable planet. A key challenge is to find ways to reduce greenhouse gas emissions while continuing economic development in developing countries. This is called “sustainable development,” and it will require a global effort to balance the needs of both people and nature.