Back in September of 2020, we reported how the tundra in Russia's northwest Siberia was exploding as a 165-foot-deep (50-meter) crater tore open in the northwest region of an area typically considered one of the coldest on the planet.
Transforming into a forest
The new crater had become the latest sign of Siberia's extra hot summers caused by global warming. Now, a new report is revealing that the Siberian tundra could completely disappear by the year 2500 if climate change is not kept under control. What's worse, it will slowly transform into a forest.
What's even worse is that as the tundra's permafrost cover melts away, it could release into the atmosphere large amounts of stored greenhouse gases, up to 1,400 gigatons globally, worsening warming around the world.
"This was stunning for us to see how quickly the tundra will be turned over to forest," ecologist and forest modeler Stefan Kruse of the Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research in Bremerhaven, Germany told Live Science.
Kruse and his colleague, AWI professor Ulrike Herzschuh, have developed a new computer model that carefully examines the entire evolution of the Siberian tundra. More specifically, the model evaluates how trees grow and develop in the region.
It takes into account their entire life cycles, from when they disperse their seeds to when they grow into adult trees. It even evaluates how they cope with competition from other trees and deal with differences in temperatures and precipitations.
The researchers deduced that the trees that start growing northward in response to warming, will do so quickly and will not retreat even if temperatures cool down again. This will result in the tundra being separated into two mini-tundras: one in Chukotka in the far east and one on the Taymyr Peninsula in the far north.
Mature trees stay where they are
The researchers further studied what would happen if humanity were able to get temperatures to cool after the tundra became a forest. They discovered that the treeline would stay as it was, not retreating as swiftly as it had advanced. This is because mature trees can withstand a lot to stay firmly in the place where they have been planted.
Separating the tundra in two will have devastating consequences for the reindeer living in the region and for the Indigenous cultures that hunt them such as the Nenets people of northwestern Siberia. These animals typically migrate from north to south and back again throughout the year.
It remains a mystery how the forest expansion will impact their migration patterns and life cycles and how that will in turn influence the livelihood of the Nenets. Kruse further said that an entire culture (that of the Nenets) is dependent on the tundra. "If this gets lost, it will be a major loss for humanity," the researcher added.
So what can be done to avoid these negative consequences? "The best option would be to reduce global greenhouse gas emissions to reduce the pressure," Kruse told Live Science. "But nevertheless, if we cannot do that, one needs to do species conservation."
The study is published in the journal eLife.
The biodiversity of tundra areas in northern high latitudes is threatened by invasion of forests under global warming. However, poorly understood nonlinear responses of the treeline ecotone mean the timing and extent of tundra losses are unclear, but policymakers need such information to optimize conservation efforts. Our individual-based model LAVESI, developed for the Siberian tundra-taiga ecotone, can help improve our understanding. Consequently, we simulated treeline migration trajectories until the end of the millennium, causing a loss of tundra area when advancing north. Our simulations reveal that the treeline follows climate warming with a severe, century-long time lag, which is overcompensated by infilling of stands in the long run even when temperatures cool again. Our simulations reveal that only under ambitious mitigation strategies (relative concentration pathway 2.6) will ∼30% of original tundra areas remain in the north but separated into two disjunct refugia.