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Abisko holds a position of deep interest to Sweden, with its dramatic Arctic landscapes and fascinating ecology and history. From 1913 researchers began recording climate date at the Abisko Scientific Research Station, built just one year before. With one of the longest weather data records in the Arctic, we can now understand the fluctuations in climate that have occurred over the last one hundred years, and look to the future of Abisko and the Arctic. Shrinking alpine glaciers, rising temperatures, shifting treelines and more tell a story of dramatic change here at the edge of Arctic climate region.
Most of us are interested in the day-to-day variations in wind, temperature, rain and snow at specific locations – after all, they have a direct impact on our lives. Even more interesting than just today’s weather, however, is looking across the days, weeks, seasons and years. Having long-term weather data can give us clues into how the climate is behaving.
Here at the Abisko Scientific Research Station we know the average monthly temperatures, the typical snow depths in winter, the amount of rain or snow that has fallen each month, and how long lake Torneträsk is covered by ice each year. All of these pieces of our climate puzzle come together to show a dramatically changing climate, especially over the last 30 years. Around the globe, temperatures are increasing and the climate is changing in multiple ways.
We will explore the changing climate of Abisko following four main themes and datasets: Temperature, Precipitation, Lake Ice Presence, and Snow Depth. Additionally, downstream effects of these changes are explored in the individual climate stories. In these you will gain an understanding of how decreasing snow depth will affect lemmings, for example.
Since the measurements started there is a clear trend of the first ice coming later and the ice thawing earlier, meaning the total time when the ice covers the lake gets shorter. As you can see in the diagramme the shorter ice period is connected to the warmer temperatures. A shorter time with ice means there is less time to build a thick ice layer which also leads to a faster thawing of the ice. Here the same effect comes in as we see with the decreased snow cover – the open water is darker than the ice and will warm up by the sun instead of reflecting the sun light (this is the albedo effect again). The lake has more time to warm up and thus getting warmer than before. Warmer water results in greater biological productivity (which increases the amount of CO2 exchanged with the atmosphere). For sure not all fish species will adapt to that.
Whenever climate change is spoken of, the main focus is on temperatures increasing, causing the warming of the planet. Abisko’s 100 + years of temperature data tells the same story.
Whenever climate change is spoken of, the main focus is on temperatures increasing, causing the warming of the planet. Abisko had an arctic climate until the late 1990s, early 2000s, with an annual mean temperature at or below 0° C. Comparing one year to the next doesn’t tell us much about whether it’s getting warmer or colder – mean temperature has always differed between years. However, when we look at many years together (in climate research it is common to look at 30 year intervals) and compare the mean temperature of one year with the average temperature of all years, we can tell if it was a warmer or colder year than average. The following graphic shows clearly that almost all of the last 30 years were warmer than the long-term average (1913-1960).
How will migrating birds, like the golden plover that overwinters in Africa, know when the right time is to come? Will bumblebees be born at the right time of the year, when plants are flowering? If animals and plants are out of sync, we call it a mismatch. Good timing, being at the right time and right place, is important for the plants and animals of Abisko. This likely mismatch means birds might arrive too late to breed and use all the surplus in food or bumblebees might be out at the wrong time to pollinate.
A warmer climate up here will prolong the growing season, which sounds positive. It is certainly true for some species, but not for all of them. New plants will come in from the south, creating a more fierce competition with the resident species of plants.
For many decades precipitation was only around 300mm per year, similar to levels in a desert. The air is very dry, particularly in winter, and while we do get snow it is much less than nearby Björkliden and Riksgränsen. During the last 30 years we have seen precipitation rates per year increase. This is connected to the higher temperatures, as warm air holds more moisture. From what we know so far this trend may continue and Abisko will get more snow and rain. Looking closer at monthly changes we can see which time of the year is getting wetter, or dryer.
More snow overall might keep the ground from freezing as hard, which will allow the permafrost to thaw more easily during the summer. This also has consequences for herbivores such as lemmings and reindeers. For lemmings a good snow layer in winter is important. They live under the snow, creating tunnels which they use to find food. For reindeers it is important how well the snow carries them. Wet and heavy snow is not good, as they have a hard time moving and as well removing the snow to get to lichens on the ground.