Down to a science : The evidence is mounting and the polar ice caps are already melting. So what does all of this mean for polar bears and for us?

Temperatures and Sea Levels Rising

The Earth’s climate is changing: since the start of the Industrial Revolution, the burning of fossil fuels such as oil, coal and gas have driven up average global temperatures by approximately 1 degree Fahrenheit. Such increases are projected not only to continue, but increase—according to the Intergovernmental Panel on Climate Change (IPCC), by anywhere between 2.5 and 10.4 degrees Fahrenheit over the course of this century.

This warming is not, and will not be, uniform. Warming in the Arctic is projected to be two to three times the global average, and already, temperature increases in the region are far exceeding those in more temperate zones. In Alaska and western Canada, winter temperatures have increased by as much as 5-7 degrees F over the past fifty years; over the next 100 years, annual average temperatures are projected to rise 5-9 degrees F over land and up to 13 degrees F over the ocean. Winter temperatures are projected to increase by 7-13 degrees F over land and by 13-18 degrees F over the ocean.

The Arctic Retreat

The Arctic is on the frontlines of global warming, with temperatures on average climbing at a rate nearly twice that of the rest of the globe. Because warming is intensified in the Arctic, it serves as a harbinger for changes at lower and mid-latitudes.

There are several reasons why temperature increases are greater in the Arctic. For example, because the Arctic is drier than the tropics, a greater amount of the solar radiation it receives goes into warming, rather than into evaporation. In addition, the depth of the atmosphere that has to be warmed in order for surface temperatures to increase is much shallower at the poles than at the equator.

In addition, there are two principal causes for accelerated arctic warming. The first is the albedo or reflectivity of the snow and ice covering much of the Arctic compared with the ocean and land that lies beneath it. Owing to their light color, ice and snow have very high albedo, meaning they reflect most of the sunlight and solar energy that reaches the earth. On the other hand, the land and sea that lie beneath the ice and snow are dark and have very low albedo. They absorb, rather than reflect, more of the solar energy in the sunlight that reaches the earth. As the sea ice and snow melt, more of the Arctic Ocean and land are exposed. This in turn means more solar radiation is absorbed, which results in the land and ocean heating up, which means more ice and snow melts.

The second factor is permafrost, the layer of frozen soil that blankets land in the Arctic. Billions of tons of carbon have been locked up for millions of years in permafrost. Warmer temperatures have resulted in the permafrost beginning to thaw, and as it does, it releases carbon into the atmosphere in the form of methane, a greenhouse gas 20 times more potent than carbon dioxide. Similar to the situation with melting ice and snow, as the permafrost melts, it releases methane which causes more warming, which means more permafrost melts.

Scientists use the term “feedback loop” to describe this type of effect. The warming caused by melting sea ice, snow and permafrost has been likened to a runaway freight train since at some point, it may be impossible to slow or even stop the warming.

These feedback loops in the Arctic serve to amplify the human-induced warming caused by the burning of fossil fuels such as oil, coal and gas. We can’t control the runaway freight train of feedback loops taking place in the Arctic, but we can step on the brakes by cutting back on our use of fossil fuels.