An Arctic Crystal Ball: Long-term Experiments as a Window into the New Arctic
The New Arctic is upon us now and the changes are accelerating rapidly. Yet, what the Arctic System will look like, and how the major biogeochemical cycles (carbon, water and nutrients) will behave and interact over the next 5, 10, 20 years is uncertain, but globally tremendously important. Thus, any insight as to the behavior of the New Arctic is extremely valuable, as we considering mitigation, adaptation and resource management practices.
Long-term field experiments that attempt to mimic the New and forthcoming Arctic are a powerful means by which we can transport ourselves into the future Arctic, providing an Arctic Crystal Ball of sorts. The International Tundra Experiment (ITEX), that has been underway all across the Arctic since the early 1990’s and in Arctic Alaska since 1994; has created a future Arctic with warmer temperatures (such as those that might be reached by ~2030 or sooner) and deeper snow conditions that will accompany the warmer north.
Today, the New Arctic is the subject of global discussions with an array of postulates and suggestions across the scientific community that is often based on past and current observations (e.g. sea ice extent, tundra greenness) that can be decades long or by traveling back-to-the-future with palaeo- archives visiting different histories of the earth that look like what is ahead (Eemain Period, ~120,000 years ago).
We now know have strong evidence that snowier winters in the New Arctic result in a dramatically different tundra ecosystem; as just discovered by UArctic Research Chair, Professor Jeff Welker and colleagues. This NSF and DoE funded team show that deeper snow; through a series of biophysical changes to the Arctic has the net effect of capturing more C, than it releases, becoming a carbon sink that can be almost 300-times the rate of conditions today.
This dramatic change in the tundra landscape and it’s sequestering of C will result from 3 interacting processes: first-deeper snow in winter results in soils that are less cold (ie. warmer); b) warmer soils in winter accelerate microbial activity and the decomposition of organic matter leading to more N available to plants in the next spring and summer, c) shrubs are the life form that has a inherent ability to capture this “extra” N and the extra snow-melt water and thus flourish dramatically, d) 10-fold increases in shrub leaf area, stem and root biomass contribute to soil C inputs and the dramatics increases in soil C sequestration rates.
Main photo: Northern Alaska with a view to the Brooks Range looking south across the tussock tundra landscapes in the foreground. These tussock tundra systems are becoming snowier and subsequently becoming dominated by shrubs that are leading to greater above and belowground biomass that is being sequester at much higher rates, creating a negative feedback to rising atmospheric CO2 levels (DeFranco et al. 2020).