A human-caused climate change signal emerges from the noise

Nov 29, 2012

By comparing simulations from 20 different computer models to satellite observations, Lawrence Livermore climate scientists and colleagues from 16 other organizations have found that tropospheric and stratospheric temperature changes are clearly related to human activities.

The team looked at geographical patterns of atmospheric temperature change over the period of satellite observations. The team's goal of the study was to determine whether previous findings of a "discernible human influence" on tropospheric and stratospheric temperature were sensitive to current uncertainties in and satellite data.

The troposphere is the lowest portion of earth's atmosphere. The stratosphere sits just above the troposphere, between 6 and 30 miles above earth's surface.

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The satellite temperature data sets were produced by three different research groups, and rely on measurements of the microwave emissions of . Each group made different choices in processing these raw measurements, and in accounting for such complex effects as drifts in satellite orbits and in instrument calibrations.

The new climate model simulations analyzed by the team will form the scientific backbone of the upcoming 5th assessment of the , which is due out in 2014.

In both satellite observations and the computer model simulations of historical climate change, the lower stratosphere cools markedly over the past 33 years. This cooling is primarily a response to the human-caused depletion of . The observations and model simulations also show a common pattern of large-scale warming of the lower troposphere, with largest warming over the Arctic, and muted warming (or even cooling) over Antarctica. Tropospheric warming is mainly driven by human-caused increases in well-mixed .

"It's very unlikely that purely natural causes can explain these distinctive patterns of temperature change," said Laboratory atmospheric scientist Benjamin Santer, who is lead author of the paper appearing in the Nov. 29 online edition of the journal, Proceedings of the National Academy of Sciences. "No known mode of natural climate variability can cause sustained, global-scale warming of the troposphere and cooling of the ."

The team analyzed results from with specified historical changes in human and natural external factors, and from simulations with projected 21st century changes in greenhouse gases and anthropogenic aerosols. They also looked at simulations with no changes in external influences on climate, which provide information on the year-to-year and decade-to-decade "noise" of internal climate variability, arising from such natural phenomena as the El Niño/Southern Oscillation and the Pacific Decadal Oscillation.

The team used a standard "climate fingerprint" method to search for the model signal pattern (in response to human influences, the sun and volcanoes) in the satellite observations. The method quantifies the strength of the signal in observations, relative to the strength of the signal in natural climate noise.

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VendicarD
3.7 / 5 (21) Nov 29, 2012
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.
It isn't happening. It can't be happening.

And if it is happening, it still isn't happening.
Donutz
3.8 / 5 (5) Nov 29, 2012
Y'know, a midday chuckle ALWAYS feels good.
Telekinetic
2.9 / 5 (19) Nov 29, 2012
For me, it's more like a guffaw when I hear lame-brains contradicting climate scientists from Lawrence Livermore.
Caliban
3.7 / 5 (18) Nov 29, 2012
Suspiciously absent are the usual crowd of vocal denialists.

These findings validate AGW in such a fundamental way that it will take them some time to develop the disinformation strategy they will need to attempt to discredit the findings.

That's worth at least a chuckle, I believe.

thermodynamics
3.3 / 5 (12) Nov 29, 2012
The deniers will show up soon. They will follow the golden rule of finding something to complain about the people instead of the data. Expect remarks about Gore and Mann (who have nothing to do with this). Expect them to change the subject to their being able to look out their window and the sea level is no higher than it was 2 weeks ago. Have no fear, they will be here.
RazorsEdge
3 / 5 (4) Nov 29, 2012
From the abstract on PNAS: "On average, the models analyzed underestimate the observed cooling of the lower stratosphere and overestimate the warming of the troposphere."

Who could deny that?
ScooterG
1.7 / 5 (23) Nov 29, 2012
"Each group made different choices in processing these raw measurements, and in accounting for such complex effects as drifts in satellite orbits and in instrument calibrations."

This one statement causes me to doubt the study results. Chances are every person involved in this study relies on AGW for their livelihoods - the study can't help but be biased.
VendicarD
3.8 / 5 (17) Nov 29, 2012
In fact it shows that the general results are pretty much immune to those assumptions.

If they weren't immune, they couldn't be merged.

"This one statement causes me to doubt the study results." - ScooTard

Poor ScooTard. His knowledge of science is close to nill.
binghamjames
1.7 / 5 (12) Nov 29, 2012
What I find disturbing about this is how it yet again demonstrates people's proclivity to be so wrong about something of which they claim to know so much about. Silly since don't we all know there is as this is an uncharted territory of research of which we are just beginning to better understand. Yet in spite of our ignorance and lack of understanding about something which is so "critical" in nature, these know it all, ditto heads have no qualms or feel no shame about mouthing off about how silly all this global warming talk is and say how stupid you are for believing it. Now we have evidence that they are in fact simply talking out of their pie holes. I am sure we have all heard from these misinformed know-it-all's. Thankfully, now they are being silenced but only after the evidence is pointing to the abundantly obvious and not due to the fact of having any grey areas of research that one would should feel prudent to re-examined before forming an opinion.
Zarky
1.4 / 5 (10) Nov 29, 2012
>> "No known mode of natural climate variability can cause sustained, global-scale warming of the troposphere and cooling of the lower stratosphere." >

High level water vapour due to a drying atmosphere....AKA Ice Clouds
XIHIX
3 / 5 (10) Nov 30, 2012
Both 'teams' here need to stop this pissing-contest.

For those who deny global warming; get your head checked.

For those who deny a rich history of climate change and base
their very agressive policy decision making on recent studies
solely regarding human influence; get your head checked aswell.

For those who, whatever the cause, are contributing to dealing
with the adverse effects of climate change; keep up the good work.
ValeriaT
1.7 / 5 (10) Nov 30, 2012
We already know, that the weekends are more rainy than the rest of week. The human factor of weather is quite noticeable here. Of course, for judging of climatic changes the long term effects must be analyzed too. I don't think, that the people are responsible for main portion of global warming. They could be responsible for droughts with forming of aerosols, but the global temperature changes may be caused with geothermal and cosmic factors. In particular, I do presume, the heat content anomaly of global warming (the oceans are heating faster than the atmosphere, although the main change of carbon dioxide occurs in the atmosphere) is caused with geothermal origin of global warming. The Earth is heated with decay of radioactive elements in oceans and Earth crust, accelerated with elevated density of dark matter at the galactic plane.
ValeriaT
2.3 / 5 (8) Nov 30, 2012
This cooling is primarily a response to the human-caused depletion of stratospheric ozone.
But the depletion of stratospheric ozone may be caused with global warming too. I've some indicia for it in 2001 - 2010 period, when the speed of global warming lowered. The stratospheric ozone layer recovered slightly during this period, which was interpreted like the success of the freon ban. But just after that the speed of stratospheric ozone depletion accelerated again. It may be possible quite easily, that the changing concentration of ozone and carbon dioxide are both result of global warming - not vice-versa. The ideology should never mix with science.
CapitalismPrevails
2 / 5 (16) Nov 30, 2012
Benjamin Franklin, "Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety." All the AGW wackos need is a good crisis and people will fork over their freedoms and liberties.
RazorsEdge
2.8 / 5 (9) Nov 30, 2012
The deniers will show up soon. They will follow the golden rule of finding something to complain about the people instead of the data.


And they will throw out insults like "tard".
CapitalismPrevails
1.6 / 5 (14) Nov 30, 2012
Let me get this straight. So i'm suppose to believe what government organizations, like the Lawrence Livermore National Laboratory, feed to the masses? Did a separate entity cross reference/check this work? Were they more government organizations? And am i supposed to believe the LLNL doesn't have a vested interest in government grants?
CapitalismPrevails
1.3 / 5 (13) Nov 30, 2012
Were these entities just more government funded organizations? Why not have some research crowdfunded by Democrat and Republican voters?
Sanescience
3.3 / 5 (7) Nov 30, 2012
So billions upon billions of humans upon the earth are changing nearly every aspect of the environment. Cutting down forests, redirecting all the rivers to evaporate in new locations, depopulating the oceans of top level food chain, paving over large swaths of land with cities. And of course releasing gases into the atmosphere.

So lets obsess on the releasing gases, because all that other stuff certainty isn't an issue, or it is politically impossible to change. And since the population bomb number wasn't where the researches said it was, we can stop worrying about world population growth. Right?

Hope we get that off world colony going soon...
Telekinetic
3.3 / 5 (14) Nov 30, 2012
Let me get this straight. So i'm suppose to believe what government organizations, like the Lawrence Livermore National Laboratory, feed to the masses? Did a separate entity cross reference/check this work? Were they more government organizations? And am i supposed to believe the LLNL doesn't have a vested interest in government grants?

If anything, government-funded research organizations tend to be conservative and generally avoid making hysterical declarations to maintain public calm. Fringe science doesn't get a foot in the door of these institutions, yet your mental gyrations involving corruption in LLNL plus sixteen other research groups makes you appear to be a nut survivalist in a bomb shelter in Iowa. This last hurricane, the size of Europe, is obviously an unusual event that corroborates their findings.
RazorsEdge
1.8 / 5 (10) Nov 30, 2012
If anything, government-funded research organizations tend to be conservative and generally avoid making hysterical declarations to maintain public calm. Fringe science doesn't get a foot in the door of these institutions, yet your mental gyrations involving corruption in LLNL plus sixteen other research groups makes you appear to be a nut survivalist in a bomb shelter in Iowa. This last hurricane, the size of Europe, is obviously an unusual event that corroborates their findings.


The findings have nothing to do with storms. In any case they found what they were looking for in models. Conformation bias come to mind? And to cap it off their own summary says the models exaggerated what they were looking for! I have to think there is far more noise than signal.
Telekinetic
3.3 / 5 (12) Nov 30, 2012


The findings have nothing to do with storms. In any case they found what they were looking for in models. Conformation bias come to mind? And to cap it off their own summary says the models exaggerated what they were looking for! I have to think there is far more noise than signal.

Boy, are you dumb. The findings state clearly that there are no natural reasons for the climate changes in their study, therefore they can conclude that the changes are due to human activity:
"It's very unlikely that purely natural causes can explain these distinctive patterns of temperature change," said Laboratory atmospheric scientist Benjamin Santer, who is lead author of the paper appearing in the Nov. 29 online edition of the journal, Proceedings of the National Academy of Sciences. "No known mode of natural climate variability can cause sustained, global-scale warming of the troposphere and cooling of the lower stratosphere."
Pull your head out.
runrig
3.7 / 5 (3) Nov 30, 2012
Let me get this straight. So i'm suppose to believe what government organizations, like the Lawrence Livermore National Laboratory, feed to the masses? Did a separate entity cross reference/check this work? Were they more government organizations? And am i supposed to believe the LLNL doesn't have a vested interest in government grants?


No, you're supposed to believe the ignorant gainsayers. Why? because of course they know better .... they will tell you. The fact that those "organisations" have the most qualified people to tell "the masses" what the science says, matters not a jot. Because they are in the AGW industry and their jobs rely on it. It's all a global conspiracy I tell you !!!
rubberman
4.2 / 5 (5) Nov 30, 2012
Or...and I know it's a stretch, you can attempt to comprehend how lower atmospheric IR absorbtion affects the atmosphere above it. To put it simply, the more IR energy absorbed and transmitted back towards the earth by GHG's in the lower atmosphere, the less there is to be absorbed and transmitted in the upper atmosphere. Hence the lower atmosphere warms, the upper cools. This can only be accomplished by increasing GHG's.

"No known mode of natural climate variability can cause sustained, global-scale warming of the troposphere and cooling of the lower stratosphere." Ben Santer, from the article

This statement is true only because he used the word "known". It hasn't been witnessed by humanity until now, but it stands to reason that this has happened every time CO2 PPM rose dramatically in the past.
Caliban
5 / 5 (5) Nov 30, 2012
So billions upon billions of humans upon the earth are changing nearly every aspect of the environment. Cutting down forests, redirecting all the rivers to evaporate in new locations, depopulating the oceans of top level food chain, paving over large swaths of land with cities. And of course releasing gases into the atmosphere.

So lets obsess on the releasing gases, because all that other stuff certainty isn't an issue, or it is politically impossible to change. And since the population bomb number wasn't where the researches said it was, we can stop worrying about world population growth. Right?

Hope we get that off world colony going soon...


@sanescience,

All of these activities are what put the "A" in AGW, since all of them in one way or another contribute to warming, principally by increasing CO2 release.

Lex Talonis
2.6 / 5 (5) Dec 03, 2012
Jesus lives in low earth orbit, he controls all the weather and scientists from space.
RFRules
5 / 5 (1) Dec 03, 2012
Time for Fox News to send an email dictum update to all employees reiterating the ban on any free thought contradicting the C-suite anti-global warming by Humans edict. Full and robust debate, finding errors and contradictions in your own thoughts and observations, unfortunately lacking in today's minimally scientific populace.
RFRules
5 / 5 (1) Dec 03, 2012
Jesus lives in low earth orbit, he controls all the weather and scientists from space.

Clever summary of all the faults of just about all the responses - Too: political, religious, etc. Scientists need to consider all angles - and without blinkers - this is not easy - clinging to dogma is.

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