And the culprits are hungry, iron-consuming microbes …
The earth is heating up. And that’s bad news for permafrost; a normally permanently frozen layer of soil. Rising global temperatures are causing frozen Arctic permafrost to thaw. This releases methane and carbon dioxide, which has been stored there for thousands of years. This has already been taken into account in climate models. But the amount of CO2 released by thawing Arctic permafrost may have been underestimated. Because what researchers haven’t thought of is hungry, iron-consuming soil microbes.
As mentioned, a lot of carbon is trapped in Arctic permafrost. The amount of carbon trapped in the permafrost is estimated to be four times the combined amount of CO2 that modern humans have emitted. It is therefore not without reason that scientists are concerned. Because if all the greenhouse gases harbored by permafrost manage to find their way into our atmosphere, it would have a huge impact on our global climate.
Scientists have therefore been trying for some time to better understand the processes behind the thaw. And in a new study researchers traveled to the Swedish nature reserve Stordalen Mire for this purpose. “The thawing of the permafrost is one of the greatest stories of our time,” says researcher Monique Patzner in an interview with Scientias.nl. “What’s going on isn’t a future concern. We are already experiencing it firsthand. Permafrost in our research area is expected to disappear completely by 2050. Every year, even in between seasons, we see changes and collapses in the field caused by the loss of permafrost. This means that the transformation is going very fast. ”
Not only in Sweden is permafrost melting away. Scientists in Alaska also see permafrost thawing. That’s because it has become a lot rainier in Alaska. In fact, the US state is experiencing its rainiest five years in a row ever. So instead of snow, rain will come down. And that’s pretty disturbing. Because the rain ensures that more and more permafrost disappears. In addition, also have industrious beavers have a finger in the pie. How? Armed with their sharp teeth, the beavers build dams on shrubs and trees, creating small pools that grow into new lakes that sometimes span several acres. And that goes fast. In just five years, beavers living in northwest Alaska have created 56 new lakes. Even existing lakes expand at the hands of the beaver. And that comes at the expense of vulnerable permafrost. The water is warmer than the surrounding ground. And so these lakes and ponds can accelerate the permafrost thaw.
While that is alarming enough, the researchers have now found that we may have underestimated the amount of CO2 released by thawing Arctic permafrost. In fact, much more CO2 can be released than ours worstcasemodels have predicted. And according to the researchers, that is because we have not taken into account very active soil microbes. Researchers have been aware for some time that microorganisms play a key role in the release of CO2 when permafrost melts. In response to rising temperatures, microbes in the soil wake up and begin to break down organic matter that has been stored in the permafrost for years. This releases CO2 and methane. But researchers have now discovered that soil microbes may play an even bigger role than thought.
The mineral iron was believed to bind carbon even when permafrost thaws. But researchers in the new study have found that hungry microbes hiding in the Arctic soil turn off iron’s ability to hold on to carbon. “Frozen soil has a high oxygen content, which keeps the iron minerals stable and allows carbon to bind to it,” explains researcher Carsten Müller. “But as soon as the ice melts and turns into water, the oxygen content drops and the iron becomes unstable. At the same time, the ice provides access to bacteria. And they then use the iron minerals as a food source. While they eat, the bonds that contain carbon are destroyed and it is released into the atmosphere as a greenhouse gas. ” These are disturbing findings. Because the amount of extra carbon that can be released – and is currently still captured and bound by the iron – is estimated to be approximately two to five times the amount of carbon that is released annually by anthropogenic emissions from fossil fuels. “This means that we have found a major new source of CO2 emissions that should be included in climate models and further studied,” says Müller.
Although the researchers only studied one swamp area in Abisko, Sweden, they decided to compare their results with data from other parts of the Northern Hemisphere. And it shows that the new results may also apply to other permafrost areas. It’s pretty worrisome. Although there is also a lot that we do not know. Although carbon stored in permafrost thousands of years old has a major impact on our global climate, researchers actually know very little about the mechanisms that determine whether soil carbon is converted into greenhouse gases. Most of the climate research in the Arctic focuses on the amount of stored carbon and how sensitive it is to climate change. Much less attention has been paid to the deeper mechanisms that trap carbon in the soil. “The question remains, for example, whether the carbon released by permafrost thaw is really emitted as greenhouse gas emissions, or is re-stored, for example in increasing biomass,” says Patzner. We also do not know exactly which micro-organisms are the culprits. “Which microbes consume the iron and thus release the associated organic carbon is currently the focus of our ongoing studies,” Patzner continues. “It is also very important to further determine the amount of iron in deeper layers, the amount of carbon bound to reactive iron minerals in the numerous permafrost regions and the bioavailability of this carbon after its release.”
All in all, this research once again shows the complex mechanisms of our earth. “The study gives us a better understanding of the complex processes that take place in these complex permafrost areas,” says Patzner. “This is fundamental to determine the rates of greenhouse gas emissions such as carbon dioxide and methane, which is necessary to make better predictions about climate change.” It also means that there is a good chance that we will have to revise our current climate models. And that because of tiny microbes that are hungry for their environment far below our feet.
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