Climate modeling performed by the Intergovernmental Panel on Climate Change and other organizations provide predictions of what the world will look like given different emissions reductions scenarios. Warming of 1.5 degrees C would, at this point, require unprecedented reduction. Under the Paris Agreement, 2 degrees C of warming constitutes maximum acceptable risk. We achieve this through both reduction of emissions, and removal of prior carbon emissions from the atmosphere.
Figure S.1 from Negative Emissions Technologies and Reliable Sequestration (2019)
Project Drawdown, a nonprofit research organization, provides a list of the most impactful climate solutions based on total atmospheric CO2-EQ reductions in gigatons. For a full list of solutions, go to the Drawdown website. The following are the top ten solutions in terms of carbon emissions reductions: