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Global warming is unpaused and stuck on fast forward, new research shows

Posted on 10 December 2013 by dana1981

New research by Kevin Trenberth and John Fasullo of the National Center for Atmospheric Research investigates how the warming of the Earth's climate has behaved over the past 15 years compared with the previous few decades. They conclude that while the rate of increase of average global surface temperatures has slowed since 1998, melting of Arctic ice, rising sea levels, and warming oceans have continued apace.

The widespread mainstream media focus on the slowed global surface warming has led some climate scientists like Trenberth and Fasullo to investigate its causes and how much various factors have contributed to the so-called 'pause' or 'hiatus.' However, the authors note that while the increase in global temperatures has slowed, the oceans have taken up heat at a faster rate since the turn of the century. Over 90 percent of the overall extra heat goes into the oceans, with only about 2 percent heating the Earth's atmosphere. The myth of the 'pause' is based on ignoring 98 percent of global warming and focusing exclusively on the one bit that's slowed.

Focusing only on surface temperatures

Nevertheless, the causes of the slowed global surface temperature increase present an interesting scientific question. In examining changes in the activity of the sun and volcanoes, Trenberth and Fasullo estimated that they can account for no more than a 20 percent reduction in the Earth's energy imbalance, which is what causes global warming. Thus the cause of the slowed surface warming must primarily lie elsewhere, and ocean cycles are the most likely culprit.

Trenberth and Fasullo found that after the massive El Niño event in 1998, the Pacific Ocean appears to have shifted into a new mode of operation. Since that time, Trenberth's research has shown that the deep oceans have absorbed more heat than at any other time in the past 50 years.

As a recent paper published in the journal Nature showed, the Pacific Ocean in particular appears to be the key component of the climate's natural internal variability, and the main culprit behind the slowed global surface warming over the past 15 years. However, another important recent paper by Kevin Cowtan and Robert Way showed that the global surface temperature rise has not slowed as much as some previously thought; in fact, the surface warming since 1997 happened more than twice as fast as previous estimates.

Trenberth and Fasullo's new paper also casts doubt on the conclusions a few recent studies that estimated the Earth's climate is less sensitive to the increased greenhouse effect than previously thought. These studies have been based on measurements of recent climate change, including the warming of the oceans. Climate contrarians like Matt Ridley have of course emphasized their results, because these few papers seem to suggest the climate won't warm quite as much over the next century as climate scientists previously thought.

However, the type of approach taken by these studies suffers from some significant drawbacks. Mainly the size of the cooling effect due to human aerosol pollution remains highly uncertain, and while the oceans have been warming rapidly, just how rapidly is another unsettled question.

Previous estimates put the amount of heat accumulated by the world's oceans over the past decade equivalent to about 4 Hiroshima atomic bomb detonations per second, on average, but Trenberth's research puts the estimate equivalent to more than 6 detonations per second. Trenberth and Fasullo note that using their ocean heating estimate by itself would increase the equilibrium climate sensitivity estimate in the paper referenced by Ridley from 2°C to 2.5°C average global surface warming in response to a doubling of atmospheric carbon dioxide, and using other more widespread accepted values would bring the estimate in line with the standard value of 3°C. They thus note,

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Comments 1 to 7:

  1. It's been unfortunate that surface air temperatures are seen as the definitive measure of change to our climate; global heat content seems to be measuring more direct, actual change to the climate system. Keep at it Dana; like some metaphorical version of Ekman pumping, the understanding that the oceans are where most of the heat is (still) going and that there has been no 'pause' is gradually being carried deeper into the ocean of conscious and unconscious thinking and discussion of climate change.

    As for surface air temperatures, I though Foster and Rahmstorf did very well at showing that the 'pause' is an artifact of natural variation over an ongoing warming trend. Seems like even one or two more la Nina years than el Nino during a period of 15 years can and would create the illusion of warming speeding up, slowing down or pausing. 

    I'd like to point out that the 'pause' is evidence of ongoing global warming; up (more el Nino) and level off (more la Nina) is clearly indicative of warming. It would need to be up (el Ninos) and down (la Ninas) for warming to have 'stopped' or 'paused'. Up, level off, up level off, in staircase/Escalator style is warming.

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  2. Ken in Oz,

    I agree with what you have said, but many would not. Not because they can justify their opinion. Just because accepting this understanding would not be in their interest.

    Efforts to help people better understand any issue are indeed helpful, but there will always be a portion of the population that is unwilling to better understand something when 'it is likely not in their interest to better understand it'.

    What is unfortunate is how greed can cause people to want to believe what cannot be justified. Greedy people can always find fault with 'things that would show how unacceptable their desired pursuits are'.

    This issue is a great case study of the power of greed to affect the way people think, and its power to affect what they are willing to investigate more deeply and actually better understand.

    There have been many excellent presentations of what is being observed (not the forecasts, just the observed facts to date), that clearly indicate the flaws of claims that are made against the need for humans to stop burning fossil fuels so rapidly. They are made here, on other websites, and are even presented in mainstream media. Yet the unjustifiable claims continue to get repeated. Popularity clearly does not correlate with rational justification. The power of greed to affect people's behaviour is very significant. That is what the really greedy people among us count on.

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  3. Time to update the top right widget guys, to 6HB/s?

    It maybe a silly comment however I cannot help but saying the main science (i.e. IPCC and even widget now) underestimate AGW according to ignorant statistics. The best experts, e.g. Hansen, Stefan and now Kevin Trenberth, are saying "the better we look into the climate the more sensitive it appears to be". Even our own CW2013 provide some more evidence. Perhaps it's time to revise all Earth sensitivity parameters, less than 2 months after the releae of AR5!

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  4. Any thoughts on these recent MSM pieces on the "pause"?

    A NYT article saying that the pause can be largely attributed to the phase-out of ozone depleting chemicals that also happened to be strong GHG's.  Then, practically in the same breath, it goes on to say that the HFC's that replaced some of the banned/phased-out ozone depleting chemicals are also strong GHG's.  The missing link that would make a cogent story is that the HFC's are not as strong GHG's as the chemicals they replaced, but confusingly, the author says nothing about that.

    An article about perfluorotributylamine (PFTBA), an electronics testing / heat transfer agent chemical, which is apparently the most potent GHG of them all.  I include this as MSM because I heard about it on the radio last night (I think I was listening to WBEZ, Chicago's NPR station) - it always catches my attention when I passively hear climate "news" on the radio or TV because I'm so used to seeking out most of it online. I'm having trouble figuring out if anybody knows how much PFTBA there is floating around up there.  Wiley Online only seems to have Geophysical Research Letters through 16-Nov-2013, and I believe the above link says that the PFTBA article published 27-Nov-2013.  I suspect the overall effect of PFTBA is probably tiny compared to that of excess CO2 because of far lower concentration in the atmosphere, but wouldn't want to assume.  


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  5. I'm sorry, only the first link above has anything to do with the "pause"/"slowdown" - maybe PFTBA link should be snipped.

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  6. Here is a direct link to the paper mentioned in the NYT article:

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  7. As the Arctic warms and more storms (low pressure systems) occur in the Arctic, the Arctic Oscillation will be positive more often than previously. Winds will more often be toward the Arctic rather than away.  While this warms the Arctic, it takes heat away from lower latitudes which may explaing the temporary apparent cessation of warming of the atmosphere.  After all, most of the sensors are in mid latitudes, not in the Arctic. 

    By the by, it should be amusing, the year after the year there is zero ice in September in the Arctic.  There will probably be a recovery of some sort in this following year and no matter how small or big it is, the climate deniers will be able to claim an infinite ice recovery. (something divided by zero = infinity).

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