I found this excellent summary of Global Warming 2013 via Neven’s Arctic Sea Ice Blog. It was a post on Judith Curry’s Climate Etc. R. Gates has given me permission to repeat it here. I have added the headings and some formatting.
R. Gates, a Skeptical Warmist | December 31, 2013 at 12:47 pm
As we ring out 2013, as an honest skeptic, I like to look back at the year and see what actual climate events of the year might cause me to modify or abandon my warmist position on AGW. Let’s take a look at a few of highlights of the 2013 Climate Year:
The lack of new records in 2013
1. The Top Story of the the 2013 Climate Year is probably the lack of any new global tropospheric records. This flattening of the rise in tropospheric records continues a10-15 year trend.
As a skeptic, I might take this to be evidence that “global warming” has stopped, but of course, being a knowledgeable skeptic and knowing that at least 50% of tropospheric heat comes from the ocean, we have to look back to the ocean to see what might be going on.
Looking closer at the facts, we know that since at least the early 2000′s we’ve been in a cool phase PDO mode. That certainly provided some of the lack of upward movement in tropospheric temperatures. Digging deeper, some excellent analysis of optical depth reading in the stratosphere show that there has been a modest increase in natural volcanic aerosols in the past decade.
Finally of course (and a distant 3rd), we know we are in a rather low point (from a multi-decadal perspective) in solar output). Some experts have even posited we could see a Maunder Minimum II (Some have called the Eddy Minimum) developing. Finally, over the past year or more we’ve seen a “La Nada’” in the ENSO cycle, meaning that the net latent and sensible heat flux from the Pacific has been just about average, with no boost nor slowdown that we would get from a El Niño or La Niña, respectively.
These four factors seem to play hugely into the role of continuing a flattening to the rise in tropospheric temperatures. It is interesting then that the natural forcings all seem set at neutral or negative (cooling), except for the AMO, and yet 2013 will very likely turn out to be the warmest non-El Nino year (all record warm years have been El Niño years). Thus, even with the La Nada ENSO condition, a bit more aerosols in the stratosphere, a sleepy sun, a cool phase PDO, 2013 will still be in the top 4 warmest years, with all warmer years being strong El Niño Years.
Not strong evidence for me to alter my warmist position, as CO2, methane, and N20 are at their highest levels in millions of years and these seem to be holding their own against natural negative forcings.
Ocean Heat Content reached instrument record levels in 2013
2) Ocean Heat Content reached instrument record levels in 2013. Yes, the uncertainty (especially going back before ARGO) is higher than anyone would like, but continued rising sea levels and paleoclimate data seem to strongly confirm that the oceans continue to retain more energy than they are giving off to the atmosphere.
This net slowdown in latent and sensible heat flow from ocean to atmosphere is precisely what would be expected in for the planets key climate energy storage vessel in light of continued greenhouse gas concentration increases. Less net energy will be flowing from ocean to space. Ocean Heat Content is the most important single gauge we have for the actual climate sensitivity to rising greenhouse gas concentrations, as this is where the bulk of the energy imbalance will naturally go and this heat ultimately drives the climate system.
The continued rise in Ocean Heat Content in 2013 confirms the energy imbalance continues in the system.
A “recovery” in Arctic Sea ice extent
3. 2013 saw a “recovery” in Arctic Sea ice extent after the amazing record setting low we saw in 2012. A cooler summer in the Arctic with conditions favorable to ice seems to be part of the dynamics this year. I note the similar nature of a “recovery” in 2008 after 2007′s then record setting year.
One dynamic of interest discussed on blogs like Neven’s is the fact that there is a real physical reason why ice might “recover” after a record setting year. Ice acts as an insulator to the sensible and latent heat flux from ocean to atmosphere. During a record setting low year, more heat is released from Arctic waters with less ice to hold it in. Thus, the 2013 “recovery” seems to be of similar fashion to that of 2008.
With continued net energy growing in the ocean globally, and some of that being advected to the Arctic, we can expect the long-term trend in Arctic sea ice to continue downward, with a new low to come in the next few years, despite the “recovery” of 2013.
In the other hemisphere, Antarctic sea ice continued it’s longer-term slow rise. Numerous studies have looked at the role of winds creating the conditions for this. As an honest skeptical warmist, this is an area of natural interest. I also note that the net loss of continental glacial ice from both Antarctica and Greenland continued strongly in 2013. Another sign the net energy of the climate system continues to grow.
2013 will end in the top 5 most damaging years from a weather catastrophe standpoint
4. 2013 will end in the top 5 most damaging years from a weather catastrophe standpoint, with the monster typhoon that killed thousands in the Pacific being the most notable event. More than actual numbers in terms of financial or lives lost, I look at the dynamics of unusual events.
We had very unusual historic flooding here in my home state of Colorado, caused by a “stuck” jet-stream bringing up moisture (i.e. energy) from the tropics, leading to a year’s worth of rain falling in a day or two. This high-amplitude and “stuck” weather systems is the kind of thing that caused the March 2012 U.S. heatwave, the Russian Heat wave a few years back, and several other extreme flooding, cold, and heatwave events over the past several years.
Though these kinds of extreme weather events have always occurred, according to some research being done we can expect more of them as the climate warms. No conclusion can be drawn from any one year or any one storm of course, so this kind of “weather weirding” is something that will take a long-term analysis, and thus, 2013 neither adds to nor detracts from my warmist position, though my personal experience was of the most unusual September (from a moisture perspective).
Overall then, there was nothing to detract or cause me to alter my warmist position in 2013, and several things (continued total ice mass loss, continued ocean heat content growth, warmest non-El Nino year) to reinforce my warmist position. Looking forward to 2014, a better chance for at least a mild El Niño event could force 2014 into the warmest year territory globally, though for the Aussies, 2013 already will take that mark.
Thank you R.Gates
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