Renewable energy captures fossil-free power from sources such as wind or sun to generate electricity. This means that there are no CO2 emissions which are responsible for climate change.
By using new energy-efficient technologies to heat and cool buildings and provide light, we reduce the overall need to burn of fossil fuels, either to generate electricity or provide heat. The cleanest cheapest unit of energy is the one that is not needed at all.
We can decarbonize transportation by switching to electric vehicles. We can design more compact cities that make transit and active mobility such as walking and bicycling easier.