Summer ice has crashed since 1979, when satellites first measured ice coverage of the Arctic ocean. Now, a paper in Science has predicted when we will see an ocean completely devoid of ice. In the process, the authors have quantified the damage each tonne of carbon dioxide does to the (un)frozen North when released into the atmosphere.
If you look at a chart of minimum ice coverage over the last 37 years, it is clear that there is a downward trend. Nevertheless, there is enough noise around the signal that it is not possible to predict from year to year how much ice coverage will remain.
Finding the pattern in noisy data is what statisticians live for, however. Dr Dirk Notz of the Max Planck Institute for Meteorology and Dr Julienne Stroeve of the US National Snow and Ice Data Center worked together to figure out how long it will be before an Arctic summer is completely free of sea ice if we keep emitting greenhouse gasses at the current rate.
Notz and Stroeve found that for every tonne of CO2 (less than the average American emits every month), there is 3 square meters (32 square feet) less ice in the Arctic come September. On that basis, we get to emit another trillion metric tonnes of carbon dioxide before the late summer ice disappears entirely.
With the world emitting almost 36 billion tonnes of carbon dioxide equivalent a year, at current rates the world will hit the point where northern sea ice is practically gone by around about 2045.
The loss of ice is disastrous for wildlife (yes, we've already done the compulsory polar bear shot). It also accelerates the warming of the rest of the planet, since water absorbs much more heat than ice. Furthermore, there is increasing evidence that the loss of ice contributes to wild weather at temperate locations.
The average individual in America releases enough greenhouses gasses to melt 50 square meters (540 square feet) of the Arctic, equal to the size of a small apartment. For a typical EU citizen, the figure is 20 square meters (215 square feet).
For those who prefer their information in a visual form, NASA has created this video of how ice has expanded and contracted with the seasons over four decades. As the video demonstrates, the thickness of the ice, which is related to its age, is as important as the area that is covered.