Glaciers and permafrost are components of the cryosphere (derived from the Greek words kryos for “cold” or “ice” and sphaira for “globe”, i.e. the frozen parts of the Earth system). Since they represent a thermal condition, they are intimately linked to climate. Over the next century, climate is projected to warm by several degrees, and worryingly, we are already seeing the loss of glaciers and permafrost worldwide.
Glaciers (from the French word glace for “ice”) are masses of ice which form where snow accumulates more than it melts during the summer months. This causes layers of snow and ice to build up, which is gradually compressed into ice by the weight of the overlying layers. Glaciers predominantly occur in the ice sheets of Greenland and Antarctica as well as in smaller masses throughout the Arctic and at high elevations. Glaciers impact global climate by reflecting incoming solar radiation (known as the albedo effect) and keeping the climate mild. Once they disappear, the darker land surface below absorbs radiation which causes more warming and ultimately more ice loss, a process called a “positive feedback loop”. Glaciers are also important early indicators of climate change as they react faster to warming than other parts of the Earth system. Once the ice melts, it flows into the sea and causes the sea level to rise around the globe and change the chemistry of the ocean. Glaciers are also the largest store of fresh water around the planet, particularly alpine glaciers near the Equator. Once these glaciers disappear they will no longer provide fresh water to these regions. Science plays an essential role in helping to better understand glacial dynamics and change so we can accurately model future impacts of climate change.
Photo: Nordenskiöldbreen is a glacier located in Spitsbergen, Svalbard. It is the first glacier I ever saw in person and I was mesmerized. The blue ice is breathtaking. The bit of rock sticking out the top is called a “nunatuk”.
Permafrost is ground (rock or soil) which stays below 0°C for two or more years. Its presence is linked to cold climates, and is therefore only found at high latitudes and altitudes. The depth of the permafrost is linked to how long the air is cold – longer cold periods lead to deeper permafrost. Some areas at the highest latitudes and altitudes are underlain by thick, cold permafrost which will mostly remain unchanged over the next century. However, it is expected that permafrost will disappear completely at more southern latitudes and lower altitudes where it is thin, discontinuous, and just below 0°C. Permafrost thaw is important in several ways. Firstly, the thaw in regions where permafrost contains an abundance of ice can lead to ground settlement as the ice melts and flows away. Ground settlement can change local hydrology and ground stability, and be damaging to ecosystems and highly destructive to infrastructure. Secondly, some permafrost contains old frozen plant material and carbon, and thawing of this permafrost will release this carbon into the atmosphere, acting as another positive feedback loop to climate change. It is imperative that we better understand how permafrost is transforming so we can predict and adapt to future changes as the climate warms.
Photo: Drilling a borehole to measure the temperatures of permafrost near Fort Providence, Canada. We are monitoring changes in permafrost conditions following forest fires, which are increasing in frequency and magnitude as the climate warms.