Space is not as “clean” as it appears, because cosmic dust rains down on Earth and coats its surface. Researchers have discovered a new way to reconstruct Arctic sea ice cover over the last 30,000 years by analysing the presence of dust on seafloor sediments. The decline in Arctic sea ice can be monitored today by satellites. However, Science provides a much deeper look into the past and helps improve the predictions for sea ice behaviour under climate change scenarios. It’s not good news from the Arctic.
The latest information is mixed.
Space dust and Arctic Sea Ice.
Cosmic dust forms when comets and stars collide. This dust, as it travels through space, collects Helium-3. It is a rare element on Earth, which makes it easy to differentiate cosmic dust from sediments when they settle on Earth’s surface. Researchers theorized that, because space dust is constantly falling on Earth and in an even distribution, it would be able to help them trace the sea ice cover based on how much was found below the ocean sediments. Imagine Arctic ice shielding seafloors from cosmic dust. Its size and extent will depend on climate conditions at that time. There are few long-term records on Arctic sea ice, and filling this gap will help predict future climate effects. In a statement to the press, Frankie Pavia (a UW assistant oceanographer and lead study author) said, “If we are able to predict the spatial and temporal patterns of future ice cover decline, this will allow us better understand global warming and help prepare for changes in food webs, fishing and geopolitical movements.”
Tracing Arctic Ice Coverage during the Last Ice Age.
Researchers collected sediment cores at three sites. One was near the North Pole, which had year-round snow and ice. A second site was located close to seasonal ice edges in the month of September when the ice coverage is lowest. The third location used in 1980 for year-round snow but only freezes over in the winter. The cores were not easy to analyze. Pavia explained that “you’ve got this tiny amount of dust falling everywhere but also Earth sediments which are accumulating very quickly.” The samples were analyzed for traces of Helium-3 and revealed that the year-round presence of ice was correlated with lower amounts of cosmic debris. According to the release, overall, the team was able to reconstruct the sea ice history over the past 30,000 years.
These results are in line with our knowledge of the last Ice Age, which occurred around 20,000-years ago. At that time, almost no space debris was present in sediment. During the last deglaciation, roughly 15,000-years ago, the cosmic dust started to appear again in cores. The researchers examined the relationship between nutrient content in cores and sea ice cover. The team expected “an increase in consumption of nutrients in the Arctic by phytoplankton, which will have consequences for the foodweb.” It is believed that less ice will allow for more photosynthesis which, in turn, increases nutrient consumption. However, other possibilities, such as meltwater diluting nutrients are possible. This connection is still being researched, but this study shows that we need to sometimes look up to the stars to better understand Earth’s past. Read more
: Earthbound space dust comes from solar system’s edge
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- The article cites information published in Science.: Cosmic Dust reveals dynamic changes in central Arctic sea ice over the last 30,000 years.