Why Jumping Worms: Climate Change
Right now, the earth’s soil contains three times more carbon than the atmosphere, and it absorbs more every year.
This happens in a process called ‘soil carbon sequestration’. As plants grow, they pull carbon out of the air to use for energy. When the plant dies, its stored carbon enters the soil through soil microbe-mediated processes. Depending on factors like climate and other environmental conditions, carbon can remain in soil for decades, centuries, or millennia.
Soil-focused carbon sequestration is considered one of the most simple, inexpensive ways to capture large amounts of carbon. According to some estimates, we may be able to store between two to five gigatonnes of carbon per year if we adopted global carbon-saving measures, including protecting/restoring forests and practicing soil-building agriculture. That amount of sequestered carbon would get us to the low end of the IPCC goals for global carbon dioxide removal.
Global Models of Climate Change and CO2 Do Not Account for Earthworms
Invasive earthworms directly contribute to carbon loss from the soil by consuming the organic material; they also indirectly alter soil microbe-carbon cycles by changing microbial populations in ways we’re still figuring out.
These effects can be as potent as wildfire or deforestation. Globally, earthworms are estimated to increase carbon loss from soil by 33 percent on average. Models of the North American boreal forest suggest that invasive earthworms could reduce carbon stores there by 50 to 94 percent over the next century.
Most of the research so far has focused only on European worms. Healthy Soil Collaborative researchers are running pilot studies on jumping worm-soil carbon effects now, but we don’t have the data yet. However, for many of the following reasons, we suspect these worms will have an equal if not far greater impact on soil carbon stores.
Here’s what we suspect:
Their rapid life cycles and dense populations allow jumping worms to consume the forest floor much faster than other earthworms.
These worms also do not mix their castings deeper in the soil, which means there is no chance that the carbon in the decomposing organic matter in their castings could be buried and stabilized in deeper layers.
The unusual nature of jumping worm castings causes pronounced, dramatic erosion, which can itself cause carbon release by exposing deeper soils to the air.
Finally, the thick casting layer created by jumping worms is highly unusual. Because many native plants cannot root into this layer well, that means the subsequent generations of plants needed to continue pulling carbon out of the air to sequester into the soil are diminished.
It is imperative that we understand how much and how quickly jumping worms can alter soil carbon storage capacity. Knowing this data will not only inform important climate models, it will allow us to make a stronger case for jumping worm attention and research at a national scale.
Photo credit Maryam Nouri-Aiin