Home Research Temperature-induced climate change to cause increased release of soil carbon

Temperature-induced climate change to cause increased release of soil carbon

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Echoing previous studies that have suggested that there is a link between increase in temperatures around the world and increased release of carbon from soil, a new study published in journal Nature shows that climate change brought about by increasing temperatures will contribute to the release into the atmosphere of carbon that has long been locked up securely in the coldest reaches of our planet.

Previous studies have shown increase in temperatures will increase the microbial activity in soil and this in turn will cause release of carbon dioxide into the atmosphere. This carbon was otherwise locked away into the soil where it does almost no harm to the planet. Increase in temperatures cause thawing of some of the coldest places on Earth and this moderation of temperature facilitates increased microbial activity. In October a study published in Nature Communications identified regions worldwide that are most susceptible to dramatic permafrost thaw formations, known as thermokarst, and the resulting release of greenhouse gases. Researchers involved with the study found that about 20 per cent of the globe’s northern permafrost region is potential thermokarst landscape. The research can be used in infrastructure and ecosystem planning and greenhouse gas modeling.

In June another study showed permafrost below shallow Arctic lakes is thawing as a result of changing winter climate. While the rate of thawing isn’t substantial, researchers point out that accelerated rate of thawing of the permafrost is a question of when and not if. In the last week of November came results of another study wherein it was shown that permafrost loss due to a rapidly warming Alaska is leading to significant changes in the freshwater chemistry and hydrology of Alaska’s Yukon River Basin with potential global climate implications. Scientists pointed out that the results of the study have global climate change implications because of the cascading effects of such dramatic chemical changes on freshwater, oceanic and high-latitude ecosystems, the carbon cycle and the rural communities that depend on fish and wildlife in Alaska’s iconic Yukon River Basin.

All these and tens of similar studies are pointed to the dangers of increasing temperatures in some of the coldest areas on Earth and how this climate change will increase microbial activity and cause increased release of carbon. Soil is a huge reservoir of carbon — more carbon is stored underfoot than in the foliage above. This is especially true in the world’s coldest places, where slow microbial activity has helped keep the carbon locked away.

But the fate of carbon in soil has been an open question for scientists. Many past studies like the ones pointed out earlier have indicated that as temperatures rise, more carbon will be released from the soil into the air. But other findings suggest that this release of carbon could be balanced by other activity. For instance, plants will thrive more fully in some regions, sucking more carbon dioxide out of the air and into those plants and surrounding soil.

The direction of this exchange — from soil to air, or from air to plants and soil — and the rate are central to our planet’s future. When carbon dioxide is in the atmosphere it acts as a greenhouse gas, warming the planet, but in the soil it has less influence on climate.

To address the question, the team pulled together data from more than four dozen previous experiments from across North American, Europe and Asia — an “amazing data set,” according to Todd-Brown, that included direct measurements of the actual amounts of carbon in the soil. Each experiment included information on the amount of carbon that remained in soil as the land was warmed, compared to “control” plots of plants that were not warmed.

The team found that the rate of exchange between soil and air in these field studies varies depending on the temperature change, length of the study, and amount of carbon in the soil originally. Overall, the team noted that a large increase in the transfer of carbon from the soil to the atmosphere is possible, supporting previous conclusions from lab experiments. With warming temperatures and increased microbial activity, the researchers believe the transfer of carbon from the soil to the atmosphere will quicken, happening fastest in the world’s colder regions where soil carbon stocks are the highest and warming is expected to be greater. Whether this carbon would be offset by plants taking up more carbon is an open question, but the authors believe this is unlikely.

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