What caused the pause in global warming?

Question

Wage Slave's answer to my previous question

"If you believe Dr. James Hansen, the "pause" began in 2002. He used the five year mean global temperature to determine the start point. It is in a (non-peer reviewed) he co-authored in January 2013."

Answer 1

why there is a pause in global warming, it’s not considered as being definitive.



The pause began in 1998 (see below) and coincides perfectly with the switch from positive to negative in the Pacific Decadal Oscillation.



In Sept 1998 the PDO Index was just about at an all time high, it then switched to the negative phase and is now at the all time low.



If we measure the extra heat that’s gone into the oceans since 1998, we find that annually five times as much additional heat has been absorbed by the oceans post 1998 than in the 20 years previous. This additional heat energy accounts for 80% of the so called “missing heat”. The remaining 20% can be accounted for by other factors such as negative oceanic oscillations, reduced solar activity, increased atmospheric aerosols etc. Altogether between 90% and 110% of the missing heat can be accounted for.



One point that often gets overlooked is that the current natural variations (such as the PDO) should be causing significant but short-term cooling. It’s because there’s an active warming influence that temperatures are stable and not falling.



As to when the pause actually began – that depends how you measure temperature trends. Using the 30-year rule, then 2013 was the first year since 1965 when the average global temperature fell. Using a 10 year running average then temps stabilised in 2006, with a five year RA they’ve decreased slightly since 2003 (or 2002 using GISS, which I assume is what Hansen would have used).



Ignoring any trends than 1998 could be argued to be the start of the pause. However, this doesn’t adequately account for the fact that 1998 was the year of the strongest El Nino on record and therefore temperatures were artificially inflated. Take ENSO out of the equation and you’d have to conclude it was either 2002 or 2005.

Answer 2

With something as chaotic as the climate, I would expect to see pauses whether or not warming is occurring. We can point to things like PDO, but let's be honest and say that our understanding of the climate is not so great that errors in predictions cannot be made.



Personally, this is why I have so much trouble with the models and the fear. I look at the graph of the temp, and it looks linear to me. It certainly does not look exponential. Linear implies a 0.8-1.0 degree increase in the next 100 years, not 3-9. Further, just predicting out 100 years annoys me as a statistician. It is nearly impossible to predict anything out for 100 years, let alone soemthing as chaotic as the climate. And to do so with those small error bars... I don't think so. I think they need to pay some statisticians to work on their models.



Hey dook,

That 70th percentile math student that you mentioned, if they actually know what an exponential curve looks like might also note that the graph you provided looks a whole lot more linear than exponential.



Also giving BA to someone you blocked is pretty odd. If you think my answers are always so bad that blocking is warranted, then how would I possibly ever warrant a BA??? Also, my machine still has the old YA format, so I can't see you questions.

Answer 3

I'll give you credit, CR. You took me seriously. And our collective understanding of climate dynamics has increased here in the Y!A community.



Indeed, it is the PDO which is responsible for the pause in surface temperatures. As others have pointed out, surface temperatures represent only a small part of the heat retained by the earth. The real story is in the oceans.

Answer 4

"A lot of people ask me: 'Has there been a pause in global warming because, like, temperatures aren't increasing as fast as they were a decade ago?'" Willis says.



"And I always say, you know, paws are for kittens and puppies, because global warming is definitely still increasing," Willis continues, smiling at his wordplay, as graphics of cute baby animals fill the screen.



It's true that Willis and nearly every other climate scientist dismiss the idea that global warming has paused. Yet the fact remains that average surface temperatures worldwide have not increased since around the turn of the century.



To the casual observer, the lack of warming at the Earth's surface, contrasted to climate scientists' insistence that the planet is still warming, might seem like a conundrum.



As scientists like Willis explain, though, most of the extra heat trapped by greenhouse gases does not warm the Earth's surface anyway.



Why do rising sea levels ignore the pause?

"Over 90 percent of the heat that we trap ... is warming the oceans," Willis said.



So as a measure of global warming, surface temperatures are not a good yardstick, because the atmosphere can only hold a small percentage of the heat that is trapped, he said.



Rather, the oceans should be the primary barometer of global climate change.



And they are certainly changing. Sea levels are going up "like gangbusters," Willis said.



The recent Intergovernmental Panel on Climate Change physical science draft report, released in late September, said it is a near certainty that rates of sea-level rise -- pushed up largely because warmer water expands -- have accelerated over the last two centuries.



The IPCC also reported it was very likely that rates of sea-level rise from 1993 to 2010 had almost doubled, from a 0.067-inch-per-year average rate for the 20th century to a 0.125-inch-per-year average rate.

Answer 5

Climate is chaotic. Some natural factors outweight the natural warming that has been happening for centuries as well as the warming from greenhouse gases. It remains to be seen whether this pause will continue. I think the pause tells us that the warming from greenhouse gases will likely be on the low end of IPCC predictions and not the 4-5C or more suggested by Joe Romm and others.

Answer 6

I would suggest "temporary slowdown in the rate of increase" is a better phrase than "pause."



As any 70th percentile SAT Math student could note, with a quick glance at the first graph here:

http://en.wikipedia.org/wiki/Global_warming

what has happened from 2005 to 2013 seems so far notably different than what happened in the 1940s. In the 1940s, there was an actual noticeable DIP in temps, with the result that the century and a third long trend from 1880 to 1980 "paused" during all of 1940-80.

The long term trend is what really counts, of course, not the medium term ups and downs, BECAUSE over the next century of two, the effect of CO2 on climate is CUMULATIVE. Nevertheless, the best estimates seem to indicate a number of decade or so long natural cycles, El Nino, etc. on which are superimposed one-off naturals events such as volcanoes, temporary man-made effect such as the SO2, etc areosol cooling, and of all that overlayed on the long term effect of CO2 going up to and well beyond anywhere it has been in the history of homo sapiens.

Answer 7

The Pacific decadal oscillation turning negative, and the sun going from a modern solar maximum, to more of a minimum.

Answer 8

There is NO pause. When are you deniers going to get that through your thick heads? There is NO pause.



And we know why the pause is occurring regardless. When are you deniers going to get that through your thick heads? We know why the pause is occurring, which it isn't, but we know why it is.



http://www.care2.com/causes/heres-why-theres-been-a-pause-in-global-warming-and-its-about-to-end.html

Answer 9

The Sun.

Answer 10

No pause in AGW itself, only in surface temps. How can the 17 warmest years on record happening in the last 18 years indicate a pause in AGW NOT Only in the eyes and minds of the most ignorant deniers

Answer 11

What "pause" ?! One Persons "pause"- does not a Reality- Make. ;)