Abstract
The high Arctic is the fastest warming region on Earth, evidenced by extreme near-surface temperature increase in non-summer seasons, recent rapid sea ice decline and permafrost melting since the early 1990’s. Understanding the impact of climate change on the sensitive Arctic ecosystem to climate change has so far been hampered by the lack of time-constrained, high-resolution records and by implicit climate data analyses. Here, we show evidence of sharp growth in freshwater green algae as well as distinct diatom assemblage changes since ~1995, retrieved from a high-Arctic (80 °N) lake sediment record on Barentsøya (Svalbard). The proxy record approaches an annual to biennial resolution. Combining remote sensing and in-situ climate data, we show that this ecological change is concurrent with, and is likely driven by, the atmospheric warming and a sharp decrease in the length of the sea ice covered period in the region, and throughout the Arctic. Moreover, this research demonstrates the value of palaeoclimate records in pristine environments for supporting and extending instrumental records. Our results reinforce and extend observations from other sites that the high Arctic has already undergone rapid ecological changes in response to on-going climate change, and will continue to do so in the future.
Highlights
Over the past three decades, atmospheric warming has accelerated at a fast rate, disproportionally affecting the high Arctic
In this study we combine ecological data from the high Arctic spanning the last century with climate observations
Since we have no daily temperature observations available for the time period before 1960, and no sea ice cover data before 1979, it is challenging to extend the direct comparison between climate and ecology further back in time
Summary
Over the past three decades, atmospheric warming has accelerated at a fast rate, disproportionally affecting the high Arctic. In the period 2000–2016, high Arctic (70–90°N) near-surface temperatures exceeded those of 1961– 1990 by 1.8 °C1,2, almost 2.7 times more than the global mean. Atmospheric warming leads to, and is enhanced by, concurrent changes in other Arctic climate components[3], most importantly sea ice loss. Less sea ice leads to a lower surface albedo, and promotes heat trapping clouds and enhances atmospheric moisture[4]. Towards the East and North, the Atlantic waters lose influence, and East Svalbard climate is increasingly controlled by the Barents Sea. Annual mean temperatures on East Spitsbergen, Edgeøya, and Barentsøya (Fig. 1) are about 4–8 °C lower than on the western coasts[18], and sea ice coverage in Storfjorden and Freemansundet is much more extensive year-round
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