The Arctic disproportionately feels the effects of climate change; here, average air surface temperatures have risen almost twice as much as global averages (1). You know the drill: summers are getting hotter, winters are getting shorter, and sea ice is disappearing. But what about the short season that heralds the end of cold and darkness – spring? How is spring changing in the Arctic, and why is this important?
Spring is a period of rapid change in the Arctic, largely due to snowmelt. As snow and ice melts across Northern Canada, meltwater enters rivers that drain into the Arctic Ocean. The Arctic Ocean receives most of its’ freshwater input from spring snowmelt (2). Freshwater input influences salinity stratification, which is how saline and freshwater is distributed in the ocean. This stratification is an important driver in regulating global ocean circulation, or how water moves throughout earth’s oceans (2). How much snowmelt enters the ocean – and when, can also influence the formation and loss of sea ice (2). Winter precipitation is projected to increase in the Arctic, leading to more snow accumulation over winter and higher snowmelt magnitudes (3). Freshwater influx to the Arctic Ocean has already increased by 14% from 1980-2009 and is projected to increase by 10-30% by 2100 (2).
A small stream near Yellowknife, NT. This picture was taken in May and shows high stream flow during the peak of the snowmelt period. The same spot was almost dried up by August!
Snowmelt also drives rapid chemical and biological change in ecosystems, particularly in Northern latitudes. Microbes munch on organic matter, often in its dissolved form in water. How easy this organic matter is to eat depends on its bioavailability. In other words, organic matter that hasn’t been subjected to lots of previous microbial degradation is yummier, or more bioavailable… and spring organic matter is very yummy! As meltwater flows over the land, it picks up organic matter from fresh leaf litter and from soil that’s undergone little previous decomposition (4). As a result, microbes respire (eat – and release CO2) at a much higher rate in spring; some studies have shown it can even offset up to 41% of summer CO2 uptake from vegetation growth (3).
Spring symbolizes a fresh start, a time of dynamic changes. In a warming climate, nowhere better represents dynamic change than the Arctic. Teasing apart how spring will evolve in the future is a complicated task, its emergent effects even harder to predict. What is for certain? Spring will never be the same.
D. J. Tenenbaum, Environmental Health Perspectives. 113 (2005), doi:10.1289/ehp.113-a91a.
R. Ahmed, T. Prowse, Y. Dibike, B. Bonsal, H. O’Neil, Water. 12 (2020), doi:10.3390/w12041189.
K. A. Arndt, D. A. Lipson, J. Hashemi, W. C. Oechel, D. Zona, Global Change Biology. 26 (2020), doi:10.1111/gcb.15193.
K. Kaiser, M. Canedo-Oropeza, R. McMahon, R. M. W. Amon, Scientific Reports. 7 (2017), doi:10.1038/s41598-017-12729-1.