The 2007-2008 Global Cooling Event: Evidence for Clouds as the Cause
September 26th, 2009 by Roy W. Spencer, Ph. D.
As I work on finishing our forcing/feedback paper for re-submission to Journal of Geophysical Research – a process that has been going on for months now – I keep finding new pieces of evidence in the data that keep changing the paper’s focus in small ways.
For instance, yesterday I realized that NASA Langley has recently updated their CERES global radiative budget measurement dataset through 2008 (it had previously ran from March 2000 through August 2007).
I’ve been anxiously awaiting this update because of the major global cooling event we saw during late 2007 and early 2008. A plot of daily running 91-day global averages in UAH lower tropospheric (LT) temperature anomalies is shown below, which reveals the dramatic 2007-08 cool event.
I was especially interested to see if this was caused by a natural increase in low clouds reducing the amount of sunlight absorbed by the climate system. As readers of my blog know, I believe that most climate change – including “global warming” – in the last 100 years or more has been caused by natural changes in low cloud cover, which in turn have been caused by natural, chaotic fluctuations in global circulation patterns in the atmosphere-ocean system. The leading candidate for this, in my opinion, is the Pacific Decadal Oscillation…possibly augmented by more frequent El Nino activity in the last 30 years.
Now that we have 9 years of CERES data from the Terra satellite, we can more closely examine a possible low cloud connection to climate change. The next figure shows the changes in the Earth’s net radiative balance as measured by the Terra CERES system. By “net” I mean the sum of reflected shortwave energy (sunlight), or “SW”, and emitted longwave energy (infrared) or “LW”.
The changes in the radiative balance of the Earth seen above can be thought of conceptually in terms of forcing and feedback, which are combined together in some unknown proportion that varies over time. Making the interpretation even more uncertain is that some proportion of the feedback is due not only to radiative forcing, but also to non-radiative forcing of temperature change.
So the variations we see in the above chart is the combined result of three processes: (1) radiative forcing (both internal and external), which can be expected to cause a temperature change; (2) radiative feedback upon any radiatively forced temperature changes; and (3) radiative feedback upon any NON-radiatively forced temperature changes (e.g., from tropical intraseasonal oscillations in rainfall). It turns out that feedback can only be uniquely measured in response to NON-radiatively forced temperature changes, but that’s a different discussion.
The SW component of the total flux measured by CERES looks like this…note the large spike upward in reflected sunlight coinciding with the late 2007 cooling:
And here’s the LW (infrared) component…note the very low emission late in 2007, a portion of which must be from the colder atmosphere emitting less infrared radiation.
As I discuss at length in the paper I am preparing, the physical interpretation of which of these 3 processes is dominant is helped by drawing a phase space diagram of the Net (LW+SW) radiative flux anomalies versus temperature anomalies (now shown as monthly running 3-month averages), which shows that the 2007-08 cooling event has a classic radiative forcing signature:
The spiral (or loop) pattern is the result of the fact that the temperature response of the ocean lags the forcing. This is in contrast to feedback, a process for which there is no time lag. The dashed line represents the feedback I believe to be operating in the climate system on these interannual (year-to-year) time scales, around 6 W m-2 K-1 as we published in 2007…and as Lindzen and Choi (2009) recently published from the older Earth Radiation Budget Satellite data.
The ability to separate forcing from feedback is crucial in the global warming debate. While this signature of internal radiative forcing of the 2007-08 event is clear, it is not possible to determine the feedback in response to that temperature change – it’s signature is overwhelmed by the radiative forcing.
Since the fluctuations in Net (LW+SW) radiative flux are a combination of forcing and feedback, we can use the tropospheric temperature variations to remove an estimate of the feedback component in order to isolate the forcing. [While experts will questions this step, it is entirely consistent with the procedures of Forster and Gregory (2006 J. Climate) and Forster and Taylor (2006 J. of Climate), who subtracted known radiative forcings from the total flux to isolate the feedback].
The method is simple: The forcing equals the Net flux minus the feedback parameter (6 W m-2 K-1) times the LT temperature variations shown in the first figure above. The result looks like this:
What we see are 3 major peaks in radiant energy loss forcing the system: in 2000, 2004, and late 2007. If you look at the features in the separate SW and LW plots above, it is obvious the main signature is in the SW…probably due to natural increases in cloud cover, mostly low clouds, causing internal radiative forcing of the system
If we instead assume a much smaller feedback parameter, say in the mid-range of what the IPCC models exhibit, 1.5 W m-2 K-1, then the estimate of the radiative forcing looks like this:
Note the trend lines in either case show a net increase of at least 1 W m-2 in the radiant energy entering the climate system. The anthropogenic greenhouse gas component of this would be (I believe) about 0.4 W m-2, or a little less that half. I’ll update this if someone gives me a better estimate.
So, what might all of this mean in the climate debate? First, nature can cause some pretty substantial forcings…what if these occur on the time scales associated with global warming (decades to centuries)?
But what is really curious is that the 9-year change in radiative forcing (warming influence) of the system seen in the last two figures is at least TWICE that expected from the carbon dioxide component alone, and yet essentially no warming has occurred over that period (see first illustration above). How could this be, if the climate system is as sensitive as the IPCC claims it to be?
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“But what is really curious is that the 9-year change in radiative forcing (warming influence) of the system seen in the last two figures is at least TWICE that expected from the carbon dioxide component alone, and yet essentially no warming has occurred over that period (see first illustration above). How could this be, if the climate system is as sensitive as the IPCC claims it to be?”
That was precisely the point of Lindzen’s recent devastating (to alarmists) paper: you can *measure* sensitivity from events like this, and the plug numbers in the gcm models are (unsurprisingly) all absurdly high.
Couple that with the expected missing tropical tropospheric water-vapor feedback hotspot and all the measurable evidence indicates that the alarmism is a crock based on apparently wishful over estimations of H20 feedback.
We need to keep reminding everyone that this sensitivity is an *input* to the GCMs, i.e. the models are irrelevant because without positive water vapor feedback CO2 warming is small compared to natural variability.
What “proof” the alarmists have of high H20 sensitivity amounts to a claim that they cannot otherwise explain the warming from 1970 to 1998. That’s one of the weakest widely-defended arguments in the history of science.
We also have heard for 20 years now that someday we’ll have powerful enough computers for models with the cellular resolution to model clouds. I find it highly suspicious that there’s not a hint of even a very slow small scaled simple cloud model that supports warmism — despite a 1000x improvement in computing capabilities in the past 20 years. Indeed Lindzen’s “Iris” theory — which at least explains the absence of a tropical tropospheric hot spot — is all we really have.
It’s so sad to see science so captured by political interests.
I think I’ve never heard so loud
The quiet message in a cloud.
===================
Dr. Spencer,
Your recent findings could easily be explained by Dark Enthalpy
Climate Change is not for you or me to alter. It is not for you or me to decide to change which way it goes. It is not yours or my decision to make. How arrogant it is of us to think we have any say in which way the climate of our planet is to go.
The harshest thing we could possibly throw at planet Earth would pale in comparison to the Mt. Vesuvius volcanic eruption that completely destroyed the Roman towns of Pompeii and Herculaneum in Italy: 79 A.D. Or consider Mount Krakatoa, Indonesia: On August 27, 1883, Mount Krakatau exploded with such force that it was heard in Australia, over 2,000 miles away. The force of the eruption triggered a series of tsunamis that reached the Hawaiian islands and the coast of South America, killing more than 36,000 people. The five cubic miles of ejecta covered the surrounding areas in darkness for over two days and caused a series of dramatic sunsets around the world throughout the following year. The explosion and subsequent collapse of the volcano left only a remnant of the island above sea level. Yes, around the world.
Events such as these have the power to alter the climate of our planet, but even events of this magnitude have only a temporary affect on the global climate. Within some short years the climate re-balances itself. If all the nukes in the world were to explode in one place, it would pale in comparison to a Krakatau type event. Don’t think you have any say in the matter of climate change, because you don’t.
jeez (18:44:42) :
Your recent findings could easily be explained by Dark Enthalpy
It is also well-known that candles do not spread light, rather they suck up the dark, just look at their wicks.
How many PPM of H2O are there in the atmosphere at any given time? What is the history?
Kasmir 18:26:32
Mistaking the 1970-1998 warm-up as being caused by CO2 is the grandest example ever of the Post Hoc, Ergo Propter Hoc logical fallacy. And really, that’s all it was. It’s just stunning that so many fell for it.
==========================
Silly human race,
Yours is no Disgrace – Yes
Thread music.
“the temperature response of the ocean lags the forcing. This is in contrast to feedback, a process for which there is no time lag.”
I am not a climate scientist, I do electronics and the systems I deal with are simple compared with the climate, however …
It would take some strong arguments to convince me that the overall system response has significant delay but the feedback doesn’t. It may be possible that part of the system has rapid feedback but it is likely that the system as a whole has significantly delayed feedback. It also seems to me that, if you ignore the whole system feedback term, you will never be able to model the system accurately.
My candidate for overall system feedback is something like this: There are decadal oscillations in the Pacific and Atlantic oceans. That means that the system’s response to a forcing is delayed by years. The ocean influences the atmosphere and thereby influences cloud formation. The clouds influence inputs to and outputs from the system. There’s your feedback, years after the original forcing.
“the temperature response of the ocean lags the forcing. This is in contrast to feedback, a process for which there is no time lag.”
I made the observation a few weeks ago; the temperature response of the ocean “due to solar activity” lags the forcing. I do tend to believe the Sun is also a factor.
Your are both wrong gentlemen over dark enthalpy and candle wicks.
T’was the electric light that slew the ghost.
Now all we need is a big enough lantern to get rid of all that dark matter that seems to be clogging up the universe.
Kindest Regards
“The ability to separate forcing from feedback is crucial in the global warming debate.”
Profound statement….and profound post.
Bravo.
Chris
Norfolk, VA, USA
Beneath Dr. Roy’s first chart is a link via the word “candidate” to one of his earlier reports. Include this in your reading.
His work, and studies and reports by others, marginalize the role of CO2 in climate change. The problem now is that a multitude of things, or pieces, have been put forward to account for the changes seen at different time scales. These pieces have not been put into a coherent whole that is sufficiently simple that I can present it to anyone. A comparison may be made to the notion of continental drift (matching coasts but no mechanism) and plate tectonics (messy details still being investigated) but considered sound science nevertheless.
So, say I buy that the cold phase of the PDO causes more clouds that block solar energy and the atmosphere cools. However, the PDO index is not easily explained to just about anyone, and we are still left with what causes the shift in the PDO index (or any of the other ocean descriptors.)
When a coherent story can be cobbled together from all the pieces such that a non-scientist can grasp its reasonableness in an under 10 minute explanation, then I think the CAGW train can be derailed. Until then it is only being slowed. Thus the big push to enact laws and treaties before someone makes a new story believable.
I love the honesty of this thread.
[snip – your email address of “nospam@hotmail.com” is invalid, in that it does not reach you directly. Per our posted policy on the policy page, your participation is denied, sorry. If you wish to use a valid email address, you can post a comment.]
John F. Hultquist (21:54:38) :
Yes, and Global Warming will cause an Ice Age, freezing instantly anyone in it’s path, and re-installing Laurentide subroutine in 2 short weeks.
So, with the several years of bare minimum Solar Activity running down the ocean’s heat, the lag of which is just now starting to be felt, the cooling of 2007-8 will be repeated until the system stabilizes to the new input. Riding the Bucking Bronco of Climate Change.
Jerky (22:19:02) :
The link you provide leads to an analysis that relies on bogus temperatures about which readers of this site are well aware.
Perhaps instead of your misdirected remark you could read what is presented in this current post and comment on it, either pro or con, based on your analysis of it. I’d be happy to read your respectable comments rather than having wasted time reading the snide renderings of someone else. Thanks for wasting my time. Translation: I’ll not read anything by Jerky again.
The Europeans are socialists. It’s only logical they would be the first people on the planet to accept the blame for climate change.
jeez (18:44:42) :
Dr. Spencer,
Your recent findings could easily be explained by Dark Enthalpy
Enthalpy is the amount of internal energy of a thermodynamic system plus the product of its volume by the pressure exerted on that thermodynamic system by an external operator. U = E + VP
Well intentioned questions:
What’s “dark” enthalpy? Enthalpy cannot be known directly, so it would have been ignored absolutely if not were by the changes (ΔU) in the internal energy of the thermodynamic systems. Then, is enthalpy always “dark” because we cannot measure it directly or what are you talking about?
Another definition for enthalpy is ΔU = Cp (T2 – T1). It is the change of internal energy what we know as “enthalpy”; how could a variation be “dark”?
Nasif Nahle
Perhaps this could help?
rbateman (22:34:39) : Riding the Bucking Bronco of Climate Change.
I like that!
Some people want to visit Rome or Paris, or another famous place. I would like to stand at the apex of the Laurentide Ice Sheet and take a digital panorama of the landscape. I likely will need more than two weeks to accomplish this as it is a little late in the 2009 season. Winning a small lottery would help too. So let’s not install that subroutine without a holding clause in front of it. Thanks.
There are 1000 different ways to say the same thing. It is important that you figure out what those 1000 different ways are and use them. As long as those 1000 different ways same thing, make the same point, and convey the same message as the original way. Hearing the same thing said the same way over and over again gets boring. Kids don’t like to here that.
Oh yeah, there was serious movie about that, wasn’t there? It was a real blockbuster and totally believable!
Just in case there’s someone who doesn’t implicitly get sarcasm…
[/sarc]
a jones (20:30:06) :
Now all we need is a big enough lantern to get rid of all that dark matter that seems to be clogging up the universe.
“Let there be light! And there was!” (I. Asimov among others)
Leif Svalgaard (18:51:22) :
It is also well-known that candles do not spread light, rather they suck up the dark, just look at their wicks.
Eureka, you have found it.
That’s what’s wrong with the Sun, it’s ill from sucking up the cold darkness of Insterstellar Space too fast.
Let’s call that the Solar Ice Cream Headache Theory.
You get a vote for quote of the week.
Leif Svalgaard (18:51:22) :
jeez (18:44:42) :
Your recent findings could easily be explained by Dark Enthalpy
It is also well-known that candles do not spread light, rather they suck up the dark, just look at their wicks.
So Leif subscribes to the Darkon theory. Something I’ve always found fascinating whenever photons seem so passe at the moment. I just noticed this effect earlier when I was paying $2.69 a gallon to have previous transportation sucked out of my vehicle. Hmmm, I see a new thread starting when my favorite solar scientist submits to the dark side.
Leif Svalgaard (18:51:22) : “It is also well-known that candles do not spread light, rather they suck up the dark, just look at their wicks.”
A noted astronomer once assured me at a party that days were “longer in the zummer und shorter in the vinter, because heat expands und cold contrakts!”