17 January 2015
While there was huge press coverage over the last couple of days about the NASA/NOAA Announcement that 2014 was the hottest on record, the behind the scenes science is actually very fascinating. In spite of the serious threat we face from burning fossil fuels and it’s likely consequences, the science of trying to understand our climate system in even more detail is actually a rather riveting detective story.
First a little background, before I post a video you really should watch. Although 13 of the last 15 years have been the hottest on record globally, the rate of temperature rise has actually slowed down dramatically over the past decade. Now, the climate deniers with a political axe to grind or a bubble to protect will all scream that this just proves that all that science, and all of those science organizations like the Royal Society and the National Academies, along with NASA, NOAA, the AMS and the rest are all wrong. Science does not work that way though, and we know that CO2 and greenhouse gases trap heat, and we know it beyond doubt because it is understood down to the level of quantum physics, so the question is this: If the greenhouse gases are going up (and they are, with NO doubt) then where is the added heat being trapped going?
Gerald Meehl at NCAR thinks he knows, and he made a very good case for it in a talk at the AMS Annual Meeting in Phoenix this month. He has co-authored a paper in NATURE about it and others are researching this as well and the answer is it’s going into the deep cold oceans. How they know this is what is really fascinating, and instead of just taking their word for it, or assuming I am telling you the truth, why don’t you watch him explain how they know.
Now after the video below, I am going to write a very short summary of what he said, because I am used to meteorological speak, and sometimes what I think is plain and easy to understand is not (at least that’s what my wife says!). I suspect that most folks will understand the video perfectly though. Note: The video will open in a separate window.
Very short summary:
A natural oscillation of sea surface temps. in the Pacific (called the Pacific Decadal Oscillation (or IPO/PDO) has been in a negative phase for about the past decade and it matches this slow down in the surface temp. rise. Climate models that simulate climate and weather (and have greenhouse gases rising at the rate we are observing) also show these slow downs.
This gave Meehl an idea. Look at the model data during these model slowdowns and see where it got warmer and where it did not. He found that the deep oceans were getting the extra heat. Remember here, that the extra heat had to go somewhere, because we can calculate based on the greenhouse gas levels just how much extra heat (in watts per sq.meter) is being trapped. Others have looked into this, and it seems that their research has ruled out other possibilities, and in many cases confirmed what his group found.
There is strong evidence that when the PDO goes back to the positive phase, we will see a rapid warming of the surface air again. Thus ends the very short summary.