evidence: In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is primarily caused by humans burning fossil fuels since the Industrial Revolution.[3][4] Fossil fuel use, deforestation, and some agricultural and industrial practices add to greenhouse gases.[5] These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary greenhouse gas driving global warming, has grown by about 50% and is at levels unseen for millions of years.[6] [...] Radiative feedbacks are physical processes that influence the rate of global warming in response to warming. For instance, warmer air can hold more moisture, and water vapour itself is a potent greenhouse gas.[167] Warmer air can also result in clouds becoming higher and thinner, where they act as an insulator and warm the planet.[172] Another major feedback is the reduction of snow cover and sea ice in the Arctic, reducing the reflectivity of the Earth's surface there and contributing to amplification of Arctic temperature changes.[173][174] Arctic amplification is also thawing permafrost, which releases methane and CO2 into the atmosphere.[175]