The ecosystems of the Arctic are undergoing unique changes. According to the latest data, such a surge in the last 200 thousand years has not happened even once, despite the past three global warming
All disputes and heated discussions about what is happening now with the climate of our planet are largely related to the fact that, unfortunately, we cannot reconstruct the Earth's climatic history in sufficient detail. And this is necessary in order to understand and compare the changes taking place now with what happened before.
American and Canadian scientists led by Dr. Yarrow Axford from the University of Colorado (Boulder, USA) managed to advance another 80 thousand years ago. They found out how the Arctic climate has changed over the past 200 thousand years.
“Our challenge was to fit the changes now taking place in the Arctic ecosystems into the context of the climatic fluctuations that have occurred in the Arctic over the past 200,000 years,” says Dr. Exford. Scientists have come to the conclusion that miracles have been happening in the Arctic since 1950. There have been no such changes in the Arctic ecosystems over the past 200 thousand years. Moreover, scientists add, even though the modern climate of the Arctic is very close to the climate of the early Holocene and the era of the last interglacial (5000-8000 years ago).
Mystery CF8
To reach this conclusion, Dr. Exford and his colleagues drilled the bottom of a lake on Baffin Island under the mysterious code name CF8. The three-meter core holds the entire multi-thousand-year history of the Arctic. “This lake is unique. Previously, it was not possible to cover such a long time period. The fact is that when a glacier sets in, it strongly disrupts all deposits. Therefore, very often it is simply impossible to restore all layers, and even in the correct sequence. CF8 gave us this opportunity - all the deposits are perfectly preserved there,”says Dr. Exford.
What can be found in sediments …
Scientists have found a lot of interesting things in the sediments of Lake CF8. First, they paid attention to how the accumulation of organic matter went. As the researchers explain, if there are a lot of organic matter in the layer, it means that the layer belongs to the interglacial period, when the ice melted and all organisms began to actively live. If there is very little or no organic matter, but there are only minerals, then this layer was formed during the cooling period. Scientists were interested in just organic matter - after all, by what organisms lived in a particular era, one can say what happened to their environment. Surprisingly, but in all layers, diatoms and mosquito larvae are well preserved. This was made possible by their chemical composition, says Dr. Exford. Diatoms have a well preserved silicon skeleton,and in mosquito larvae, the tiny chitinous capsules that once covered their tiny heads remain unchanged for hundreds of thousands of years.
Everything was already before
Based on the data obtained, scientists have identified three interglacial periods. Interestingly, each time the changes taking place in the communities were similar. For example, in the epoch of the last interglacial in the early Holocene, however, as in other interglacial epochs, as soon as the ice melted and became warmer, the bottom diatoms Flagilaria began to dominate in the lake. Then the dose of solar energy received over the summer began to decrease, which, according to many scientists, led to a cooling of the climate. Diatoms disappeared, and they were replaced by bell mosquitoes of the Chironomidae family. Such practically identical periodic fluctuations in ecosystems have occurred since ancient times. And this frequency was observed until 1950. And then they behaved, according to scientists, very strange.
20th century anomalies
In fact, all natural factors indicate that the cooling should continue. For example, research by Dr. Kaufman from Northern Arizona University concludes that the temperature in the Arctic should be 1.4 ° C lower than the actual one - what we have now.
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Modern warming is very similar to the climate of the last interglacial era, scientists say. But the whole paradox is that living organisms reacted to this warming in a completely different way than then. “The modern period is unique. For example, since 1950, the lake has experienced an unprecedented increase in the number of diatoms Eunotia exigua. Before that, these algae almost never appeared in the lake. The total amount of biomass has increased - we can tell this by the increase in chlorophyll content. The belling mosquitoes disappeared completely. We have not found analogues of such changes in the last 200 thousand years,”says Dr. Exford.
True, scientists have not yet begun to explain why such peculiar changes are taking place in the Arctic right now. This requires more multifaceted research, they said.