They hope to achieve the target of "net zero" by 2050, to help slow global warming.
What does 'net zero' mean?
Net zero means not adding to the amount of greenhouse gases in the atmosphere.
Achieving it means reducing emissions as much as possible, as well as balancing out any that remain by removing an equivalent amount.
Greenhouse gases like carbon dioxide (CO2) are released when we burn oil, gas and coal for our homes, factories and transport. Methane is produced through farming and landfill. These gases cause global warming by trapping the sun's energy.
The COP26 global climate summit in Glasgow in November is seen as crucial if climate change is to be brought under control. Almost 200 countries are being asked for their plans to cut emissions, and it could lead to major changes to our everyday lives.