Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.
The largest driver of warming is the emission of gases that create a greenhouse effect, of which more than 90% are carbon dioxide and methane. Fossil fuel burning for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and the chemical reactions in certain manufacturing processes. The human cause of climate change is not disputed by any scientific body of national or international standing. Temperature rise is amplified by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour, and changes to land and ocean carbon sinks.
On land, where temperatures have risen about twice as fast as the global average, deserts are expanding and heat waves and wildfires are becoming more common.