Climate change is definitely not a competition, but if it were, arctic tundra and boreal forests would be crushing it by getting hotter and changing faster than the rest of the world.
Due to a phenomenon called Arctic amplification, these ecosystems are warming alarmingly fast, at twice the rate of other global ecosystems.
But these ecosystems also store huge amounts of carbon in soil and permafrost (aka frozen, ancient soil), more than twice the carbon that is currently in the atmosphere. As these ecosystems heat up, this carbon becomes increasingly vulnerable to microbial decomposition and release to the atmosphere. That in turn exacerbates warming, creating a feedback loop where warming begets carbon loss begets warming etc.
So not only are these ecosystems winning at climate change by feeling the brunt of climate impacts, when it comes to carbon and the potential to release even more global warming gases to the atmosphere, they also have the most to lose.
Boreal Forests at Risk
The Arctic, as a geographic region (above 66°N), has received well deserved attention as of late. Record breaking sea ice loss is eroding coastlines, devastating communities, and may even be contributing to the recent spike in Gray whale deaths. The Arctic has also become a defining example of US climate inaction and deception, with the Trump administration lauding warming temperatures in the region as good for business and burying important scientific material when making decisions about drilling in the Arctic National Wildlife Refuge.
And while the Arctic deserves all the attention it receives and more, coverage about ice, tundra and coastlines don’t do the region justice, when it also includes carbon rich boreal forests. These forests (some of which are IN the Arctic circle) play an equally important role in global carbon dynamics and are experiencing many of the same ecological and climatological impacts (namely permafrost thaw, species shifts, and carbon loss). But like Kelly and Michelle in Destiny’s Child (#RecycledJokes), the importance of boreal forests is largely overlooked, even though its fate is critical to our future climate.
Boreal forests, also called taiga, are dominated by coniferous and deciduous species like pine, fir, spruce, larch, birch, alder, and willow. Interspersed within these forested ecosystems are bogs and wetlands that create a rich mosaic of habitat on the landscape. Boreal zones are also home to many iconic species like salmon, grizzly bears, wolves, and moose, not to mention iconic locales like Denali National Park in Alaska.
For millennia, boreal forests have been carbon sinks, taking up more carbon than they released. This is primarily due to the fact that, in such cold temperatures and harsh conditions, plants take up more CO2 than microbes break down and release back to the atmosphere, leading to the large accumulations of below ground carbon that we see now.
Much of this carbon is now locked away as permafrost, which is precisely what it sounds like – permanently frozen ground. It underlays most of the boreal forest (as seen below), and stores HUGE amounts of carbon. It’s made of ice, rocks, and soil, with soil being where the bulk of the carbon in these ecosystems is stored. Permafrost can be “continuous” – i.e. frozen all year round – or discontinuous – where patches of permafrost are interspersed with non-permafrost (but still carbon rich) soil.
In both types, we’ve also observed an uptick in permafrost failures, known as thermokarst. Rapidly thawing permafrost visibly disturbs the landscape by destabilizing what would be solid ground, causing depressions, slumps and thermokarst lakes. As permafrost melts, shallow root systems and loss of solid ground can cause some boreal tree species to tilt or even fall over, leading to the appearance of drunken trees.
These visible changes to boreal forests are important reminders of how climate change can modify our ecosystems. However, the unseen consequences of permafrost thaw are far more insidious, because these failures expose huge amounts of ancient carbon to microbial decomposition.
So as temperatures rise and microbes begin to feast on newly available carbon, boreal forests may be shifting from a sink to a source, and thus releasing more carbon to the atmosphere than plants take up.
Boreal forests (and their vast stores of carbon) are also under threat from wildfires and lightning strikes. Wildfires affect the largest land area of any disturbance in boreal forests, and are projected to increase in frequency and size with continued climate warming.
Boreal ecosystems are also under threat from increased localized lightning strikes due to climate change. As lightning strikes increase, so do wildfires which send massive amounts of carbon dioxide, methane, and black particulate matter into the atmosphere AND increase rates of permafrost thaw. Just like arctic warming can impact weather patterns around the globe, carbon released from these ecosystems will also have a global impact.
Boreal and arctic regions are harbingers of climate change to come for the rest of the world. Their fate not only serves as the opening act of our climate drama, but will also play a key role in regulating the intensity and extent of impacts throughout the rest of the world.