A group of scientists have just published a study that tries to explain why Antarctica isn’t warming as predicted, and its ice isn’t melting as climate models say it should be. As Reuters reports, the researchers identified flows of cold, deep water as the primary reason our models are failing down there:
A persistent chill in the ocean off Antarctica that defies the global warming blamed for melting Arctic ice at the other end of the planet is caused by cold waters welling up from the depths after hundreds of years, scientists said on Monday. […]
[An] upwelling of cold water helped to explain the persistence of sea ice but not its expansion, a trend other studies have linked to shifts in winds off the vast frozen continent. Monday’s report found that warm waters in the Gulf Stream cool as they flow north into the North Atlantic, then sink and loop south towards Antarctica as part of an aquatic conveyor belt that takes centuries to complete.
Eventually, gale force winds in the Southern Ocean around Antarctica blow surface waters northwards and draw the chill, ancient waters from the depths. That upwelling helps explain why the surface of the Southern Ocean have warmed by just 0.02 degree Celsius (0.036 Fahrenheit) per decade since 1950, a fraction of the global average of 0.08 degree (0.144F), the study said.
We’ve known for some time that Antarctica hasn’t been melting as fast as climate models predicted it ought to be, and scientists have been surprised to find the southern continent’s ice sheets have expanded in some places. Last fall a group of researchers issued a corrective to models that predicted that melting Antarctic ice could add a meter to global sea levels by the end of the century, calling that catastrophic future “implausible.”
Last September new research suggested that Antarctic water was capable of storing much more atmospheric carbon dioxide than previously believed—one of those rare examples of positive climate news. Now, scientists think they have a better handling on why those waters haven’t been warming as expected, and to the extent that we’re able to refine our knowledge of the way these important systems work, that’s encouraging progress.
But it should also serve as a warning to overzealous greens that point to climate models as fonts of infallible evidence for justifying their harebrained policy schemes. We can acknowledge that our climate is changing and that anthropogenic greenhouse gas emissions are a major driver behind rising surface temperatures while also pointing out that the details (wherein the proverbial devil lies) are a lot less clear. We’re constantly being surprised by observations that don’t square up with predicted outcomes, and scientists must then dutifully search for explanations. Discovering those explanations is therefore both edifying and humbling, and reminds us just how little we really know about our climate.