Greenhouse gases act as a layer of insulation, trapping some of the sun's warmth before it is released back into space. This process is known as the greenhouse gas effect. The primary greenhouse gases from energy production and consumption are methane and carbon dioxide. The rate at which we have added greenhouse gases to the atmosphere since industrialization is the leading cause of climate change. Climate change is causing extreme weather events, like droughts, floods, fires, and hurricanes. These events will increase in frequency if we do not reduce emissions in the atmosphere. For much of human history, greenhouse gases in the atmosphere have been kept at safe levels by natural carbon sinks, such as oceans, forests, and wetlands. However, we are now adding greenhouse gases to the atmosphere faster than natural carbon sinks can absorb them. When people talk about climate change, they often reference the average increase in temperature around the world. For instance, the intergovernmental panel on climate change, the ipcc, has recommended a cap of 1.5 degrees celsius as the maximum amount of average warming that can happen while maintaining a safe environment for people.