Everybody knows that the sea-ice in the Arctic is melting. Now a new study shows just how severly this melting is proceeding.

2007 was the year where Arctic sea-ice gave us a scary example for what we have found true since then: that the IPCC report was not just describing true changes in our climatic system, but that these changes are often faster than some of the worst case scenarios of the climate models. The extent of the Arctic sea-ice had shrunk so much, that for the first time in human memory the Northwest passage was navigable (see Fig. 1).

 

If melting continues like that, then - so scientists fear - the summer Arctic sea-ice could be completely gone within 20 to 30 years; the tipping point for a complete melting of Arctic sea-ice in the summer even might have been crossed already (Lenton 2009).

 

Whereas we have been well informed about the extent of the Arctic sea ice, it was not clear by how much the Arctic had decreased in ice-thickness over the years. Here you might be in for a surprise if you are new to the topic of Arctic sea ice. Most people estimate its thickness between several 100 or several 1000 m. These estimates probably stem from images of Greenland, where the ice is indeed 2000 to 3000 m thick. However, the Arctic sea-ice is frozen ocean water, and it is extremely thin. On average, it used to be about 3 m thin (see Figure 2).

 

As figure 2 indicates, nowadays sea-ice is on average less than 2.5 m thick. That is likely less than the distance between the floor and the ceiling of your apartment. Not only that, but the extent of thin first year ice is increasing to the cost of thicker multi-year ice (see Fig. 3).

 

This increase in first year ice is happening as more and more multi-year ice is melting. In the winter, new  (first -year) ice is forming, which of course is thinner than ice that has been forming over several years. The problem is that thinner ice is melting faster than thicker ice. So we are in a typical positive feedback loop: the more ice is melting, the thinner will be the remaining ice, the fastter that ice is melting…

 

You might wonder why all this is worrisome. Quite a few people think that it is a great thing that the Arctic sea-ice will be melting, because we can then have shorter shipping routes, and we can have access to unexploited oil reserves. Indeed, this will bring amazing riches to a few people - over the short-term.

However, over the long-term the melting of the Arctic could be disastrous, as it triggers a positive feedback loop that could greatly warm our planet. And here is why:

 

The Arctic sea-ice functions as a huge fridge to our earth, because the sun’s rays are being reflected from the ice to 80-90%. However, when the sun’s rays hit water, their energy is absorbed by about 80%, and the water heats up. The more ice is melting, the more water is forming, the more heat is absorbed; thus,  more ice is melting, so that there is even more water surface which absorbs more heat…if this positive feedback loop causes the permafrost to melt faster, then another feedback loop will be added to the mix as greenhouse gases are released from the permafrost.

 

We need to avoid such positive feedback loops if we want to avoid creating an earth that will not represent the earth as we know it today. And we can only avoid those feedback loops if we act quickly and courageously to create an energy future that is void of any fossil fuels.

NASA 2009

CleanEnergyProject | Maiken Winter 2009