Like the canary in the coal mine, or the Ontario riding of Sarnia-Lambton, so the polar oceans are showing us the future: of our climate and, eventually, our planet. Especially in Canada, we've all heard it: people struggling through the fifteenth day of an extreme cold alert, or a snowstorm that has dumped drifts the size of Winnebagoes on their driveway, will joke, "Ha! So much for Global Warming!!"
Actually, those situations are pretty accurate indicators of global warming. Both extreme cold and hugely increased precipitation are symptoms of climate change. The overall temperature on Earth is actually rising, but paradoxically, in the Northern Hemispehere, the strongest evidence of this appears in the winter. Prolonged periods of high atmospheric pressure (the result of a stalled jet stream) with clear skies and freezing temperatures, are interspersed with very heavy snowfalls, due to large amounts of water from the lakes being drawn up and dumped on shore as "lake effect" snow.
In the Arctic Ocean, melting sea ice is welcomed by industry, particularly cargo, transport, and oil and gas companies. It's a curse, however, for those whose lives and livelihoods depend on the Arctic biosphere's staying frozen.
Climate researchers consider thirty years a useful period for establishing a trend, and 1971-2001 has been used as a benchmark to study the effect of climate change on things like sea ice, glaciers, and other measurable natural indicators. For example, in 2015, the Greenland ice reached its lowest maximum extent on record. The maximum extent is the furthest point the sea ice reaches before it begins to melt: this year, it went less far than at any other time on record. Not only that, but the melt began sooner--in February rather than March.
This is significant because ice melts exponentially, something called the albedo, the ratio of reflection of the Sun's heat back into the atmosphere. Snow-covered ice is white and has a high albedo (from the Latin "alba" for white), reflecting 85 per cent of the sunlight back into the atmosphere and absorbing only 15 per cent of the heat. Open water, however, is dark in colour and absorbs 93 per cent of the heat. And the more dark, open water there is, the warmer things get, faster.
It's also less salty and less dense because sea ice is essentially frozen fresh water. All these factors are working together to disrupt the balance of warmer and colder, salty, briny, and fresh water that forms the thermohaline circulation system of currents swirling through the oceans on Earth. Those currents and their temperatures, in turn, affect the winds and the rainfall and the rest of the elements that make up our climate.
The other thing about sea ice is that it stays in one place, or occasionally floats about in the form of icebergs, which really only damage human beings when we sail into them. When the sea ice melts, however, it has to go somewhere, and the ocean levels rise--up to 3mm per year, but that could increase. Not a lot, but the sea level has risen 10 inches since 1879, and the trend means the rise will get more rapid. This will affect humans, especially those living on the coasts.
Some people who do accept that our climate is changing claim that it is not as a result of human activity but rather evidence of a natural cycle. Researchers in Greenland have drilled cores two miles deep into the ice in order to discover what the climate was like in the past. Each year's frozen matter, like the rings on a tree, reveals crucal information about the climate: tiny air bubbles trap the historic atmosphere, which can be analyzed for carbon dioxide and other gasses; dust blown around the world by winds, can show what the temperatures were like. It is evident that the history of the Earth is one of rapidly cycling changes in climate. In fact, our own "Halocene" era is unique in that it has been so stable. Change has happened before, but the difference this time is the very, very short space of time in which the change is happening: years rather than decades.
The fact that the Northwest Passage through the Canadian Arctic has become navigable for part of the summer is a pretty clear indicator that the polar climate has changed, irreversibly... The sea ice that once choked the waters of the passage will never return to its previous levels, and as new ice forms it will be thinner and melt more easily. It is ironic that one of the beneficiaries of this change is the energy industry: as the area opens up, more licenses will be granted for energy exploration, oil and gas drilling, and possibly even fracking. And yet, it is burning fossil fuels that has caused the greenhouse gasses that have led to climate change in the first place....
The effect of the changes in water and ice is being amplified by changes on land, in the permafrost. The permafrost is a layer of rock or soil, beneath the surface, that remains frozen. The soil above it freezes and thaws with the seasons, but the permafrost does what its name implies: stays frozen. For thousands of years, structures built on the permafrost have taken this into consideration. But now, communities across the Arctic are seeing their infrastructure crumble because the foundations are shifting with the melting earth.
Civil engineers will need to work out new methods of building for this new environment: the ice roads and airstrips that underpin the movement of cargo and people in the North are no longer reliable, buckling and cracking with the melt.
Ancient hunting routes that the Inuit rely on to get migrating game are disappearing or impassable now, and these changes are amongst the saddest of the emerging effects on the Inuit. In testimony given to a study by the government of Nunavut, elders said that they can no longer read the signs that used to give them crucial information about weather and the natural world. Things have changed beyond recognition and they worry that they will be unable to pass these skills on to the next generation.