Climate change is a fact of life. We need to act urgently if we are to avoid an irreversible build-up of greenhouse gases (GHGs) and global warming at a potentially huge cost to the economy and society worldwide. Climate change mitigation is actions to limit the magnitude and/or rate of long-term climate change. Climate change mitigation generally involves reductions in human (anthropogenic) emissions of greenhouse gases (GHGs). Mitigation may also be achieved by increasing the capacity of carbon sinks, e.g., through reforestation. Mitigation policies can substantially reduce the risks associated with human-induced global warming. Examples of mitigation include switching to low-carbon energy sources, such as renewable and nuclear energy, and expanding forests and other "sinks" to remove greater amounts of carbon dioxide from the atmosphere. Energy efficiency may also play a role,[5] for example, through improving the insulation of buildings. Another approach to climate change mitigation is climate engineering. In my opinion In order to stop global warming before it is too late, it is not sufficient for countries to make only their own national power supplies environmentally friendly. It makes no difference to the atmosphere where carbon dioxide is emitted or avoided – ultimately, it is the overall pace of global carbon reduction that matters. Because investing in renewable is most effective at protecting the climate if it is done where those energy sources are most abundant, enormous potential can be realized through international co-operation