A Simple Step To Reduce Climate Change: More Trees

Planting trees as a partial solution to climate change has broad bipartisan appeal.

Glasgow—The 26th United Nations Climate Change Conference (COP26) draft decision document, which is supposed to incorporate countries' negotiated deals on how to address man-made climate change, includes language focused on protecting and using nature as a way to reduce future warming.

Specifically, the document "emphasizes the importance of protecting, conserving and restoring nature and ecosystems, including forests and other terrestrial and marine ecosystems, to achieve the Paris Agreement temperature goal by acting as sinks and reservoirs of greenhouse gases and protecting biodiversity, while ensuring social and environmental safeguards." In this case, "sinks and reservoirs" refer to natural ways to absorb and store carbon dioxide from the atmosphere.

The Paris Agreement aims to hold the increase in the global average temperature by 2100 to less than 2°C above pre-industrial levels. It also pursues a more ambitious effort to limit the temperature increase to 1.5°C above pre-industrial levels.

In support of the goal of using nature-based solutions to address climate change, the Glasgow Leaders' Declaration on Forests and Land Use was announced near the beginning of COP26 on November 2. So far, 137 countries have endorsed the goal of ending deforestation by 2030. Those countries account for about 91 percent of the world's forests, amounting to more than 14 million square miles. However, following the declaration's announcement, several countries with large forest areas (including Brazil and Indonesia) appear to have backtracked on their endorsements.

Forests can indeed absorb and store large amounts of atmospheric carbon dioxide, according to the United Nations Food and Agriculture Organization's (FAO) recent analysis of global forest lands' carbon dioxide emission and removal trends between 1990–2020. The analysis finds that deforestation was responsible for annual emissions of roughly 3 billion tons of carbon dioxide globally in the period from 2016–2020. At the same time, the remaining forests sequestered some 2.5 billion tons of carbon dioxide, resulting in net emissions of about 0.5 billion tons of carbon dioxide per year from forest lands to the atmosphere.

The good news is that the global rate of deforestation has been slowing over the past three decades. The FAO finds that the rate of annual net forest loss declined from 7.8 million hectares (30,000 square miles) in the period from 1990–2000 to 5.2 million hectares (20,000 square miles) between 2000–2010, reaching 4.7 million hectares (18,000) between 2010–2020. For reference, 18,000 square miles is a bit more than double the area of New Jersey. As the global rate of deforestation fell, carbon dioxide emissions from forests dropped by about one-third from 1990–2020, falling to about 3 billion tons of carbon dioxide per year in 2020.

The FAO report finds that through deforestation, Brazil and the Democratic Republic of the Congo each annually emit about 600 million tons of carbon dioxide, while Indonesia emits about 200 million tons of carbon dioxide. On the other hand, the countries whose forests absorbed the most carbon dioxide annually are China (650 million tons), Russia (620 million tons), the United States (350 million tons), and Brazil (300 million tons).

According to the U.S. Environmental Protection Agency's most recent inventory, American forests absorbed and stored 775 million tons of carbon dioxide in 2019, more than double the FAO's estimate. That cut U.S. emissions by nearly 12 percent.

In 2019, a team of Swiss researchers controversially estimated that worldwide an area of land about the size of the U.S. was potentially available for planting a trillion trees. That many trees could absorb as much as 100–200 million tons of carbon dioxide from the atmosphere and help keep global average temperatures from rising by more than 2°C above pre-industrial levels by 2100.

Such a nature-based solution to climate change has bipartisan appeal in the U.S. The Trillion Trees Act introduced in Congress earlier this year has numerous Republican and Democratic co-sponsors. The bill explicitly aims to "establish forest conservation practices through management, reforestation, and utilization which lead to the sequestration of greenhouse gases."