How ‘Natural Geoengineering’ Can Help Slow Global Warming
An overlooked tool in fighting climate change is enhancing biodiversity to maximize the ability of ecosystems to store carbon. Key to that strategy is preserving top predators to control populations of herbivores, whose grazing reduces the amount of CO2 that ecosystems absorb.
As natural wonders go, perhaps the most awe-inspiring is the annual migration of 1.2 million wildebeest flowing across East Africa’s vast Serengeti grassland. It would be a tragedy to lose these animals. But we almost did in the mid-20th century when, decimated by disease and poaching, their numbers crashed to 300,000.
The consequences of that collapse were profound. Much of the Serengeti ecosystem remained ungrazed. The accumulating dead and dried grass in turn became fuel for massive wildfires, which annually burned up to 80 percent of the area, making the Serengeti an important regional source of carbon dioxide emissions.
Then, conservation programs to eradicate disease and crack down on poaching led to the recovery of the wildebeest, restoring the grazing system and reversing the extent of the large-scale wildfires. Grazing now causes much of the carbon in grass to be released as animal dung, which is in turn incorporated by insects into soil reservoirs that are not prone to burning. The Serengeti ecosystem has now reverted to a carbon dioxide sink so large that it is estimated to offset all of East Africa’s current annual fossil fuel carbon emissions.
The wildebeest decline and recovery taught a valuable lesson, not only in how easy it is to loose an iconic animal species, but, more importantly, how the loss of a single species can have far-reaching ramifications for ecosystems — and the climate.
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