Nature’s blanket is thinning

The Arctic’s enduring snow cover and vast ice fields make up its characteristic polar cryosphere. It is impossible to imagine the Arctic any other way. But as climate change spirals out of control and the goal of limiting warming to 1.5°C becomes harder to reach every day, we must prepare ourselves for a drastically different polar region—and, as PEKKA NIITTYNEN writes, so must the unique biota that inhabit the region.

Despite the rapid warming of the Arctic over the past few decades, most precipitation in the area still falls as snow. But numerous recent studies suggest that as the Arctic continues to warm at a rate faster than the rest of the planet, rainfall will soon surpass snowfall as the dominant form of precipitation. This shift will lead to a novel hydrological state with far-reaching consequences for Arctic ecosystems and beyond.

Although many ecosystem processes in the North are resistant to change—which means their transformations may lag behind the rising temperatures—the delicate Arctic snow cover may be different. The seasonal snow cover emerges and disappears each year, and each year, the snowpack is renewed. As a result, changes in temperature and precipitation patterns can have an immediate impact on snow timing and properties. A single heavy rain-on-snow event, for example, can dramatically alter snow conditions for the entire winter, devastating the life cycles of the Arctic fauna and flora that depend on specific snow conditions for necessities like insulation, dens, camouflage and access to food sources.

Wetter, heavier, icier snow

In a warming world, the physical properties of snow will change. Snow is likely to become wetter and heavier, with a greater probability of hard icy layers within the snowpack. Most northern regions will experience thinner snowpacks, and snow seasons will be shorter across all regions. This drastic alteration of the snow blanket—which has provided protection for low-growing Arctic flowers and overwintering insects—will have profound consequences.

Our biodiversity projections indicate that the future of Arctic vegetation is critically linked to the evolution of snow conditions. If the decrease in the duration of snow cover remains moderate—for example, shortening by 10 to 20 per cent—then the loss of local biodiversity may also be relatively small. However, if snow loss exceeds these levels, it will trigger accelerated rates of local extinctions among Arctic and alpine flora that are uniquely adapted to the cold.

Surpassing the 1.5°C warming limit will likely lead to exponential detrimental effects on Arctic biodiversity. Consequently, every tenth of a degree increase in warming must be limited: it will safeguard Arctic nature more effectively than any other conservation act can.

We should also remember that what happens in the Arctic will not stay in the Arctic. The circulation of matter and energy does not obey country borders or biome boundaries. Arctic snow and ice, particularly the enduring white blankets that have normally persisted until late summer, play a crucial role in regulating the Earth’s energy balance by reflecting sunlight back into space.

Impacts of a positive feedback loop

If this late-lying snow disappears, the Earth’s surface albedo will be affected. Darker, less reflective surfaces, such as exposed land or sea, absorb more solar energy, amplifying warming. This positive feedback loop, known as the snow-albedo feedback, will accelerate melting and lead to further temperature increases. It is one of the reasons why the Arctic is already warming faster than the rest of the world. But it is also contributing to climate change on a global scale.

A world where warming exceeds 1.5°C will have profound consequences for Arctic snow cover. Beyond that target, substantial changes to the unique life forms and overall biodiversity of the Arctic are inevitable. Shifting vegetation zones, alterations in plant phenology and productivity, and the loss of specialized Arctic biota underscore the urgent need to address climate change and protect the delicate ecosystems of the Arctic.

Many climate change-induced alterations in Arctic ecosystems will not follow a linear trajectory, but an exponential one. In other words, each additional unit of warming will trigger new ecosystem changes that are likely to be more detrimental than the previous ones. This means that every effective action we take to mitigate climate change matters. By preserving the Arctic’s snowy blankets, we can safeguard much more, including the area’s rich environment and biodiversity, cultural heritage and overall well-being.