Natural climate solutions

Farmland near Leongatha, Victoria

The key to reducing greenhouse gas emissions is to switch all electricity generation to renewable sources, because, in principle, most activities can be electrified.  For example, we can heat our homes with electricity, not gas; we can electrify transport (and where we can't, we can create carbon-neutral fuels); we may even be able to electrify some industrial processes, such as making iron and steel.  But that will still leave agriculture and land clearing, which are responsible for 20% plus of emissions.   

The good news is that there are inexpensive changes we can make which could reduce net agricultural emissions to zero.

Conserving and restoring American forest, farm and natural lands could cut a substantial chunk of the country's emissions, helping meet greenhouse gas reduction goals without relying on undeveloped technologies, a new report finds.

A team of 38 researchers spent more than two years looking at "natural climate solutions"—a range of strategies that includes planting trees in cities, preventing the conversion of natural grassland to farmland and shifting to fertilizers that produce less greenhouse gas emissions.  

In a study published Wednesday in Science Advances, they report that these solutions, if deployed across agricultural lands, forests, grasslands and wetlands, could mitigate 21 percent of the country's net annual greenhouse gas emissions, getting the U.S. closer to meetings its goals under the Paris climate agreement.

The researchers found that reforestation had the single largest maximum potential to store carbon or take it up from the atmosphere—nearly 307 million metric tons. Most of the potential lies in forests in the Northeast and south-central regions of the country. "Natural forest management" strategies, which include things like extending harvest cycles or reduced-impact logging, could mitigate an additional 267 million metric tons. (The researchers calculated the overall net emissions of the U.S. as 5.8 billion metric tons, factoring in existing carbon sinks.)

The researchers looked at a number of solutions in agriculture, including avoiding the conversion of grassland to cropland, using cover crops planted in the off-season that add carbon to the soil, and using fertilizer more judiciously.  The solutions also included "biochar"—a form of charcoal made from a number of sources, including agricultural residue, that can be used to build healthier soil—and the practice of "alley cropping," or planting trees between crops.

Altogether these agricultural practices have the potential to mitigate nearly 440 million metric tons of carbon dioxide a year, the researchers found.

[Read more here]