Forests are an essential part of the Earth's operating system. They reduce the accumulation of heat-trapping carbon dioxide in the atmosphere from fossil fuel burning, deforestation and land degradation by 30 % each year. This slows down the increase in global temperature and subsequent climate change. In the US, forests account for 12 % of national greenhouse gas emissions per year and store carbon in trees and soil over the long term. Mature and old forests with larger trees than younger forests play a significant role in sequestering carbon and keeping it out of the atmosphere. These forests are particularly resilient to fires and other natural disturbances as the climate warms. Most forests in the continental US have been logged several times. Today, only 3.9 % of forest stands in the entire United States are in public and private hands older than 100 years, and most of these areas contain relatively little carbon relative to their potential. (Beverly Law and William Moomaw, The Conversation)