The Arctic Sea is losing summer sea ice. This statement alone is hardly newsworthy. But today, the Guardian reported that the amount of ice in the Arctic this summer has fallen to a record low, opening the Northwest Passage around the northern coast of Canada to shipping without an icebreaker for the first time since records have been kept (1972). All in all, the Arctic has lost a third of its total sea ice in the last 30 years (since measurements have been made) and is already down to 57% of the average sea ice in the period of 1979 to 2002, and the ice hasn’t finished melting this year.
If this rapid loss continues, the Arctic will be entirely clear of summer ice by 2030, instead of the 2050 to 2100 as estimated by the IPCC models. Of course, this year could be anomalous – there are always unusually cold or hot years that are only really important if they represent a trend. Unfortunately, as this press release from the National Center for Atmospheric Research in Boulder, Colorado points out, the IPCC models all produce significantly more yearly ice than the actual observed trends.
The Arctic is warming up – this is a fact of the data. As it does so, it will result in more heating because open water absorbs much more solar radiation than ice does, producing a feedback that will increase global heating more than anticipated. Add to this the fact that Greenland’s glaciers and the Ross Ice Shelf are melting faster than the IPCC models anticipate (the actual observed melting since 2001 has tracked the uppermost bound of the model, not the average of all the different models, indicating that the IPCC sea level rise models are overly conservative) and decarbonizing our carbon economy becomes vitally important. Not because melting sea ice raises the ocean level (it doesn’t), but because both effects are happening at or beyond the IPCC modeled limits. This means that the consensus-based IPCC global heating models are overly conservative and that at least some effects of global heating are likely to be significantly worse than the IPCC estimates.