Atmospheric Chemistry and Physics (March 22, 2016, v16 p3761-3812; doi:10.5194/acp-16-3761-2016) / by James Hansen et al.
[Washington Post] Hansen and his colleagues think that major melting of Greenland and Antarctica can not only happen quite fast — leading to as much as several meters of sea level rise in the space of a century, depending on how quickly melt rates double — but that this melting will have dramatic climate change consequences, beyond merely raising sea levels.
That’s because, they postulate, melting will cause a “stratification” of the polar oceans. What this means is that it will trap a pool of cold, fresh meltwater atop the ocean surface, with a warmer ocean layer beneath. We have actually seen a possible hint of this with the anomalously cold “blob” of ocean water off the southern coast of Greenland, which some have attributed to Greenland’s melting.
Indeed, shortly before the new paper’s publication, the National Oceanic and Atmospheric Administration released new recent data on the globe’s temperature that certainly bears a resemblance to what Hansen is talking about. For not only was the globe at a record warmth overall over the last three months, but it also showed anomalous cool patches in regions that Hansen suspects are being caused by ice melt – below Greenland, and also off the tip of the Antarctic peninsula.
“My interpretation is that this is the beginning,” Hansen says of these cool patches in curious parts of the global ocean. “And it’s one or two decades sooner than in our model.”
However, when it comes to both the melt rates for Greenland and Antarctica, and also these cool ocean patches, we have a very limited time span of observations. It is far from clear, yet, that Hansen’s interpretation of them will prevail, and the new study also suggests closely observing these areas in coming years…