Using Natural Forces to Fight Climate Change

While the term natural climate solutions  has lately gained currency, there’s nothing new about nature’s ability to renew and restore itself. For eons, the earth’s forests, wetlands, grasslands, tundra, mangrove swamps and even farmland have absorbed the greenhouse gases that fuel climate change. And with a little help from humans, they can store far more carbon dioxide, methane and other gases than they do now.

“Long before humans existed, the planet came up with an incredibly innovative solution to the same problem we face now: too much greenhouse gas in the atmosphere,” said Peter Ellis, director of global climate science for The Nature Conservancy. “That solution, ‘invented’ by evolution over 3 billion years ago, is called photosynthesis. Since then, nature has honed photosynthesis to perfection and has used it to regulate the amount of carbon dioxide in the atmosphere.

“Also, it just so happens that this natural climate solution is pretty good at providing other good stuff like clean water, clean air, biodiversity, healthy soil and improved human well-being, not to mention a generally more interesting planet to live on.”

As this TNC video shows, our society counts on innovations such as electric vehicles, renewable energy and reduced fossil fuel use to reverse global warming. Useful as these technical fixes may be, scientists doubt that humans can MacGyver their way out of the climate crisis. Only by enlisting nature’s help, Ellis said, can we limit global warming to the 2 °C increase set by the Paris Climate agreement.

For land trusts this means maximizing the ecological condition of lands already in their care. With the right management, a forest or wetland can increase its ability to store carbon – much as tuning-up a car’s engine will heighten its fuel-efficiency.

For instance, improved forest management  can help working forests store more carbon even as they expand timber yield. This may include removing vines and thinning smaller defective trees to hasten the growth of more desirable species. Using controlled burns will reduce the fuel loads that cause severe forest fires, while in hilly terrain, land managers may use domestic goats to munch down fire-prone shrubs. Meanwhile, replacing invasives with native trees and plants will build the biodiversity that helps landscapes weather the extremes of climate change.

No one will ever confuse a row-crop farm with a stand of old-growth sequoia. Yet in the United States, a 2019 report from the National Academy of Sciences found that farmland could sequester up to 250 tonnes. That’s about 4% of the nation’s annual emissions.

It begins with the soil, which on a farm stores organic matter from previous harvests, much as fallen leaves and woody debris accumulate on the forest floor. With standard farming practices, as farmers disc and turn the soil for planting, the trapped carbon returns to the atmosphere. Not so with carbon farming. Through practices such as no-till, farmers can plant and harvest crops without excess soil disturbance. With a no-till planter they insert seeds into the soil, yet keep the surface organic matter in place. No-till methods also leave the dead roots from the last year’s plants intact, which adds fertility to the soil and provides channels for rain and irrigation water to penetrate. With more organic matter, soils act as sponges to store water; a crucial capability as drought and heat waves become more frequent due to climate change.

Cover crops also play a crucial role in no-till farming systems. After the fall harvest, no-till farmers plant a hardy mix of annuals such as rye, winter wheat, crimson clover and hairy vetch. As cover crops grow they stabilize the soil to prevent erosion and provide winter grazing for deer and small mammals. Their growth suppresses weeds, and when they die-off in spring, their leaves, stems and roots add more mulch to the soil.

For land trusts whose properties include farms and ranches, carbon farming complements the practices used to maintain natural areas. Together, farms and forests create a mosaic of protected lands that demonstrate the many facets of conservation.

The term blue carbon describes the coastal vegetation, such as mangrove swamps, salt marshes and seagrasses that store carbon. While wetlands make up a small percentage of the world’s lands, they store more carbon per hectare of land (hectare = 2.47) than any other system.

For ecosystems to sequester blue carbon, Macreadie et al. report that three key environmental processes must be managed: nutrient inputs, bioturbation (the disturbance of sediment deposits) and hydrology. Growing evidence suggests that managing these three processes can increase long-term storage capacity in wetland systems.

Yet along with serving as carbon sinks, coastal wetlands can also function as toxin catchment basins, given their downstream location from urban areas and rivers. Pollutants such as fertilizer runoff, sewage overflows and heavy metals can accumulate and threaten the vitality of these priceless coastal habitats. With watershed-level planning, land trusts can work with governments and businesses to find and stop pollution at its source. Our coastal wetlands deserve better, as do the myriad fish, wildlife and aquatic creatures that make these marshy sanctuaries home.