In anticipation of the new Fifth Assessment of the IPCC (AR5) which will be released tomorrow, there are a number of good backgrounders online. Here are some of the best.
Let me extract the key points and figures. Back in July, scientist Dana Nuccitelli summarized a new study, “Distinctive climate signals in reanalysis of global ocean heat content“:
- Completely contrary to the popular contrarian myth, global warming has accelerated, with more overall global warming in the past 15 years than the prior 15 years. This is because about 90% of overall global warming goes into heating the oceans, and the oceans have been warming dramatically.
- As suspected, much of the ‘missing heat’ Kevin Trenberth previously talked about has been found in the deep oceans. Consistent with the results of Nuccitelli et al. (2012), this study finds that 30% of the ocean warming over the past decade has occurred in the deeper oceans below 700 meters, which they note is unprecedented over at least the past half century.
- Some recent studies have concluded based on the slowed global surface warming over the past decade that the sensitivity of the climate to the increased greenhouse effect is somewhat lower than the IPCC best estimate. Those studies are fundamentally flawed because they do not account for the warming of the deep oceans.
- The slowed surface air warming over the past decade has lulled many people into a false and unwarranted sense of security.
And let’s not forget another key indicator of accelerating warming — the accelerating melting of the great ice sheets as documented in the most comprehensive analysis of satellite altimetry, interferometry, and gravimetry data sets to date:
Okay, so it’s clearly misleading to say the planet has stopped warming. What’s actually going on? It’s pretty nuanced: According to the leaked IPCC draft report, the rate of warming at the planet’s surface (technically, the “global mean surface temperature”) is lower over the last 15 years, kind of like a car easing off the accelerator. The draft states that the rate of surface warming from 1998-2012 was 0.05 degrees Celsius per decade. But over the entire period from 1951 to 2012, it was 0.12 degrees Celsius per decade. (Keep in mind that not every aspect of the climate system necessarily reflects this “slowdown”: Arctic sea ice, for instance, hit a record low in 2007 and then another record low in 2012.)
How significant is the surface temperature slowdown in the context of global warming as a whole? The slowdown is certainly big enough to measure—or else we wouldn’t be discussing it—but not a huge deal in the context of the climate system. That’s because surface temperature itself, while a useful measurement, only captures a small part of what’s actually happening to the planet.
Since 1975, global average surface air temperature has increased at a rate of 0.17 deg.C/decade (estimated by linear regression using either the NASA GISS or HadCRUT4 data sets). But the rate of increase hasn’t been perfectly constant over that entire time span.
As a matter of fact, there’s a 15-year time span during which the rate is notably different. Fifteen whole years!!! By at least one calculation, the difference is “statistically significant.”
Does this mean that global warming is wrong? That the computer models are utter junk? That this whole climate science thing is just a hoax, a nefarious scheme to cheat us all out of tax dollars in order to support the lifestyle of gaudy luxury that we all know scientists wallow in? (Science: money for nothin’ and your chicks for free…)That 15-year time span covers the years 1992 through 2006, during which the rate of warming was 0.28 deg.C/decade. That’s a lot faster than the warming rate from 1975 to now.
Zeke Hausfather at the Yale Forum:
In recent years, a global network of automated buoys has offered a much-improved picture of what is going on below the surface in the ocean. These buoys automatically dive deep down into the ocean every day, taking temperature measurements as they slowly rise, and transmitting that data back to a central database via satellite. The figure below, via Argo, shows the location of buoys currently active in the world’s oceans.
While measurements of deep-ocean temperatures existed further back in the past, they were taken only in limited locations until 1999, when Argo buoys were widely deployed. However, scientists for far longer have been able to use more limited data to reconstruct temperatures down to depths of 2,000 meters, as shown in the figure below.
Total ocean heat content has increased by around 170 Zettajoules since 1970, and about 255 Zettajoulessince 1955. This increased temperature has caused the oceans (0-2,000 meters) to warm about 0.09 C over this period. As the UK’s Met Office points out, if the same amount of energy had gone into the lower atmosphere it would of caused about 36 C (nearly 65 degrees F) warming! The oceans are by far the largest heat sink for the Earth, absorbing the vast majority of extra heat trapped in the system by increasing concentrations of greenhouse gases.
If you have not read them, take in Stefan Rahmstorf’s piece here, as well as another good one by Zeke Hausfather.
And, of course, my latest video which should be sufficient to put down most denialist water-cooler climate experts in just a few minutes.
Only Spm tomorrow , no?
that is my understanding. the rest will dribble out over a year.
IPCC not known for media savvy.
Actually, the IPCC is very media savvy. It’s science savviness that they lack.
right. that’s why we have you, Dave.
I think only the WG1 report comes out tomorrow.
You’re right, omnologos. I thought the WG1 report was coming out today. But all they have up there today is the “Summary For Policymakers.” The page now says, “The Final Draft of the Working Group I contribution to the IPCC Fifth Assessment Report will be available here on 30 September.”
It also says, “54677 COMMENTS,” but they haven’t released the experts’ comments yet, either. Hopefully they’ll be released with the WG1 report, on Monday.
It appears that by dribbling it out in little pieces they hope to generate a steady stream of news stories. I’m sure it will, too. The IPCC is nothing if not media savvy.
Temperatures are not measured in Joules.
Also, by “reconstruct temperatures” I think you really mean “speculate about temperatures.” It is very unlikely that ocean heat content was really spiking during the frigid 1970s.
However, I suspect that ocean temperatures were rising during the 1990s. That’s a plausible explanation for the striking difference between sea-level measurements by TOPEX/Poseidon satellite altimetry (3.12 mm/yr) and sea-level measurements by coastal tide gauges (avg. less than half that), since the former are directly affected by thermal expansion, and the later negligibly so. (An alternate explanation is simply that the TOPEX/Poseidon measurements were wrong.)
‘Temperatures are not measured in Joules.’
Pedantry.
Hausfather:
The increased
or
The (resulting) increase in temperature….
Happy now?
I rather think a scientist of the calibre of Hausfather is aware that temperature is not heat, don’t you?
His graph is nothing but speculation, and it’s inconsistent with the accompanying text.
Look at that graph: it shows about 220 zettajoules increase from 1970 to present (increasing from about -40 to +180), but the text says the increase was only 170 zettajoules.
It hardly matters, because both numbers are pure speculation. 43 years of precise ocean heat content numbers? Who does he think he’s kidding?
In fact, he (and the Met Office) claim to have ocean heat content numbers back to 1955*! What a joke.
Like so much of the so-called “data” that underpins climate alarmism, it’s baseless nonsense.
* 255 zettajoules to date in the quoted passage, 240 zettajoules to 2010 in the cited unsigned Met Office document
True that Zeke Hausfather’s discussion did not smoothly shift units between energy and temperature. He’d probably edit those two sentences if given the chance. However, that criticism is a tad picky given that the specific heat of water is well understood.
I suspect that ocean heat accumulation and surface temperature changes are counter-cyclical. Is it plausible that ocean heat content increases more rapidly when air temperature decreases, and increases more slowly when air temperature is sharply higher, such as in 1998 El Nino event when an unusual amount of heat was released from the ocean?
Charles, when you turn the stove temperature higher does your food cook more slowly, and when you reduce the flame does the food cook more quickly?
No. El Niño events are associated with spikes in both air and water temperatures, not with air temperatures going up as water temperatures drop. In general, warmer air causes warmer water, and vice-versa, because the rate of heat transfer increases with increases in temperature difference.
I know of just one negative temperature feedback mechanism, in the Arctic, which resembles what you’re describing. Warmer air temperatures contribute to reduced Arctic ice cover. Reduced ice cover increases evaporative heat loss from the Arctic ocean, cooling the water before it sinks in the Atlantic Conveyor. (Also, increased evaporation causes increased snowfall and harsher winters in Europe and Asia.)
Do you know of any others?
How f*****g dare anyone out there make fun of daveburton. After all he’s been through!!
…
HE’S A HUMAN! (ah! ooh!) What you don’t realize is that daveburton is making you all this money and all you do is write a bunch of crap about him.
He hasn’t performed on stage in years. His song is called “There is no sea level rise” for a reason because all you people want is MORE! MORE-MORE, MORE: MORE!.
LEAVE HIM ALONE! You are lucky he even performed for you B******S!
LEAVE daveburton ALONE!…..Please.
Gingerbaker, I know you’re trying to be funny, but please do not make up things I’ve never said, put them in quotes, and attribute them to me. Not even in jest.
I have seen quite a lot of conflicting reports on the numbers involved in this report, so just a link to statistics from the IPCC on the effort (and mix of geographical areas the experts were drawn from ) that has gone into this assessment report which are nicely summarized towards bottom of page:
http://www.ipcc.ch/activities/activities.shtml
One problem is their tendency to ignore the comments they get from their experts.
The purpose of soliciting experts’ comments on the FOD was supposedly to allow them to identify and correct errors, when writing the SOD. But the WG1 SOD contained many of the same errors which the FOD contained, despite those errors having been identified in experts’ FOD comments. In a few hours we’ll find out whether they also ignored our comments identifying errors in the SOD when they wrote the Final Draft. I hope not, but I’m pessimistic.
You sound like Judith C. and her magnificent supporters – all I have hear is negativity and doubt – trouble with ARGO is that there or the other blah blah etc etc … , sorry GingerBaker I liked your solo on Toad and NSU
Whoops, not a few hours, a few days.