Two new studies are telling us more about how Global Warming is changing our oceans. The first suggests that the upper part of the southern oceans are warming anywhere from 48-152% more than had been previously measured.
One of the problems that scientists have is that most of the worlds population and advanced economies are in the northern hemisphere, while most of the worlds water is in the southern hemisphere. So it's harder to get as much accurate data about what's happening to the southern oceans.
We know the oceans are absorbing much of the extra heat that Global Warming is causing, but the details of where the heat is going are still being worked out and these 2 studies take a big step forward in that understanding.
Here's some of the nitty gritty.
The rate of warming of the top 700 metres of the ocean in the Southern Hemisphere may have been underestimated, reports a paper published online in Nature Climate Change, whereas another independent study finds the deep ocean (below a depth of 2 kilometres) has not warmed and has had a negligible contribution to sea-level rise for the period 2005 to 2013.
Paul Durack and colleagues combine climate model results with direct measurements and satellite sea-level data to study upper-ocean warming trends since the 1970s. They find that the reported observational warming rates have poor agreement with the model results and they attribute this to poor sampling in the Southern Hemisphere. Using data from the better sampled Northern Hemisphere, they suggest that estimates of the warming rates for the Southern Hemisphere should be increased by 48–152%.
And via a
report in the BBC:
the scientists found that the rate of upper-ocean warming between 1970 and 2004 had been seriously underestimated. That inaccuracy is specific to the Southern Hemisphere, but is big enough, the scientists suggest, that global upper-ocean warming rates are also "biased low" - to the tune of 24% to 55%.
So we're finding that new measurements of the upper Southern Hemisphere are more in agreement with the models (a strike against the constant denialist BS that the models are wrong) than with the very limited data points in the southern oceans.
The other study finds that the deep oceans are not absorbing the heat that some scientists speculated about.
This adds up to 2.9mm yr-1 which is more than has been seen overall – implying that an offsetting decrease is taking place due to cooling in the deep oceans. The residual of those numbers implies a deep ocean cooled rather than warmed in the period from the 2005 to about 2013 and that this cooling equivalent to a decrease in sea level of −0.13 mm yr–1.
The significance of this result is that it implies that the so called missing energy is not to be found in the deep ocean as many climate scientists have suggested.
So we have the upper ocean warming faster than we thought, but the lower ocean not warming at all or even cooling a bit.
I've written several diaries here about El Nino. El Nino has a direct impact on me since it often means we get huge snow storms during the winter, which makes it very difficult for me to get out of the Mountains. But this year has been really weird. In late spring, a monster Kelvin wave was forecasting a mean El Nino for the winter. Then it died out and was followed by a much weaker Kelvin wave. Here's the latest for the tropical Sea Surface Temperatures.
If we were going to get a strong El Nino this winter, we would normally be looking for a big red streak extending from near Peru, westward out into the Pacific. Instead we have this big blob of warm water in the north and broken blotches of warm water in the south.
Now El Nino is kind of an upper ocean phenomena that has a pretty big impact on our weather. One of the predictions for Global Warming is that when you add energy to the atmosphere you're going to get uncertainty and extremes. Now we've got a couple of new studies that show we're adding more energy to the upper ocean than we thought, and we've got this weird, almost but not quite El Nino that may or may not form. Kinda makes you wonder.
Out experiment with changing planet earth continues and future generations of our children may not be very happy with the final results.