Soil Matters

This Simple Thing Is a Powerhouse in Combatting Climate Change

Duane Hovorka, Agriculture Program Director
Wetland in Washington State - credit David Mark, Pixabay

Wetlands provide a long list of well-known benefits: They hold and store floodwaters, recharge groundwater, protect coastal areas, filter chemicals from our waters, provide food and habitat for fish and wildlife, and can provide forage for livestock in dry times. Wetlands also have a less well-known benefit: They store vast amounts of carbon in their muck soils.

Wetlands support plants that have evolved to love soggy soils. In upland areas, bacteria and fungi in the soil break down the leaves and roots of the plants that die back each year, releasing the nutrients and carbon for new plants. In soggy wetland soil, starved of oxygen, those bacteria and fungi cannot do their job as well. Over years and decades the dead leaves, roots, and other organic matter in that wetland soil build and build. That organic matter is mostly carbon, converted by plants from CO2 in the air through photosynthesis.

The differences in soil organic matter can be stark. In cropland degraded by decades of conventional tillage and chemical use, the level of organic matter in the soil is often just one to two percent. Healthy cropland farmed with soil health practices can have four to six percent organic matter. An unbroken native prairie might contain eight to 12 percent organic matter. Soil in a well-functioning wetland can have 15 to 30 percent organic matter.

While the Earth's remaining wetlands occupy just five to eight percent of the planet’s total land surface, they hold 20 to 30 percent of our world’s total soil carbon. Imagine what that figure could be today if America hadn’t lost half of its wetlands to draining or filling since colonial times. When wetlands are drained or destroyed, their soil carbon is released by microbes into the atmosphere, where it can contribute to climate change. But when wetlands are restored, wetland plants can once again take large amounts of carbon dioxide from the air and store it in the soil.

The implications seem clear. To be successful, strategies to tackle climate change must protect our remaining wetlands from destruction and must work to restore damaged wetlands.

Finding Solutions

In February, both House and Senate Agriculture Committees held hearings on climate change and agriculture, and much of the focus was on farming practices that can store carbon in the soil. The discussions were fruitful, but largely missing was the role of wetland restoration and protection as a climate solution.

One member of Congress who clearly understands the issue is Rep. Chellie Pingree, one of the very few farmers in Congress. In April 2021, Rep. Pingree introduced the Agriculture Resilience Act, legislation designed to leverage agricultural solutions to reduce greenhouse gas pollution, store atmospheric carbon in the soil, and make our farms and ranches more resilient to our changing climate.

The bill takes a comprehensive approach, and one important element is an increase in the budget for the Agriculture Conservation Easement Program (ACEP), which helps purchase conservation easements on wetlands, grassland, and other farmlands. Through ACEP and a predecessor the Wetlands Reserve Program, the U.S. Department of Agriculture has restored and protected about 3 million acres of rural wetlands since 1990.

Rep. Pingree's bill would increase the annual ACEP budget to $700 million per year. With that increase, the program could protect 800,000 acres of wetlands or more over the next decade.  The bill would also provide a tax break for landowners who sell a permanent conservation easement to protect their wetland, prairie, or other farmland.

Restoring and protecting wetlands provides an additional important benefit with respect to climate change: It helps us adapt to the changes in climate that are already occurring. Wetlands protect coastlines from wind, rain and waves brought by fiercer storms and hurricanes. As rainfall comes in heavier but less frequent bursts in many places, wetlands reduce flooding by storing that rainwater and slowly releasing the runoff.


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