The Biggest Control Knob: CO2 in Earth's Climate History

By: Dr. Jeff Masters , 9:05 PM GMT on March 24, 2010

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It's been a busy past two months of weather and climate change news, and I haven't found time to blog about the research presented at December's American Geophysical (AGU) meeting in San Francisco. That is the world's largest scientific conference on climate change, and the place to be if you want to get the pulse of the planet. The keynote speech at the AGU meeting was given by Dr. Richard Alley of Penn State University. Dr. Alley is the Evan Pugh Professor of Geosciences at the Pennsylvania State University, and one of the most respected and widely published world experts on climate change. Dr. Alley has testified before Congress on climate change issues, served as lead author of "Chapter 4: Observations: Changes in Snow, Ice and Frozen Ground" for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), and is author of more than 170 peer-reviewed scientific articles on Earth's climate. He is also the author of a book I highly recommend--The Two Mile Time Machine, a superb account of Earth's climate history as deduced from the 2-mile long Greenland ice cores. A standing-room only audience of over 2,000 scientists packed the lecture hall Dr. Alley spoke at, and it was easy to see why--Alley is an excellent and engaging speaker. I highly recommend listening to his 45-minute talk via a very watchable recording showing his slides as he speaks in one corner of the video. If you want to understand why scientists are so certain of the link between CO2 and Earth's climate, this is a must-see lecture.


Figure 1. Dr. Richard Alley of Penn State University, delivering the keynote speech at the 2009 AGU conference on climate change.

The Biggest Control Knob: CO2 in Earth's Climate History
Earth's past climate has been shaped by a number of key "control knobs"--solar energy, greenhouse gas levels, and dust from volcanic eruptions, to name the three main ones. The main thrust of Dr. Alley's speech is that we have solid evidence now--some of it very new--that CO2 has dominated Earth's climate over the past 400 million years, making it the climate's "biggest control knob". Dr. Alley opens his talk by humorously discussing a letter from an irate Penn State alumnus. The alumnus complains that data of temperatures and CO2 levels from ice cores in Antarctica don't match:

"CO2 lags Earth's temperature...This one scientific fact which proves that CO2 is not the cause of recent warming, yet...Dr. Alley continues to mislead the scientific community and the general public about 'global warming'. His crimes against the scientific community, PSU, the citizens of this great country, and the citizens of the world are significant and must be dealt with severely to stop such shameful activities in the future".

Dr. Alley explains that the irate alumnus is talking about the Antarctic ice core record, which shows that as we emerged from each ice age, the temperature began increasing before the CO2 did, so increased CO2 was not responsible for the warmings that brought us out of these ice ages. Climate change scientists and skeptics alike agree that Earth's ice ages are caused by periodic variations in Earth's orbit called Milankovich Cycles. "There's no doubt that the ice ages are paced by the orbits", says Dr. Alley. "No way that the orbit knows to dial up CO2, and say 'change'. So it shouldn't be terribly surprising if the CO2 lags the temperature change. The temperature never goes very far without the CO2. The CO2 adds to the warming. How do we know that the CO2 adds to the warming? It's physics!"

Dr. Alley then discusses that the physics that govern how CO2 absorbs and re-emits heat energy, when plugged into state-of-the-art climate models, show that about half of the observed 5 - 6°C natural warming that occurred since the last ice age ended was due to extra CO2 added to the atmosphere. At the peak of the Ice Age, CO2 was about 190 ppm. By the end, it was about 280 ppm (Figure 1). Earth's orbital variations "forced" a warming, which caused more CO2 to escape from swamps and oceans, with a time lag of several centuries. The increased CO2 reinforced the warming, to double what it would have been otherwise--a positive feedback loop. "Higher CO2 may be forcing or feedback--a CO2 molecule is radiatively active regardless of how it got there", says Dr. Alley. "A CO2 molecule does not remember why it is there--it only remembers that it is there". In other words, the fact that higher CO2 levels did not trigger an end to the Ice Age does not mean that the CO2 had no warming effect. Half of the the observed 5 - 6°C natural warming that occurred since the last ice age ended was due to the extra CO2 added to the atmosphere. So, the irate PSU alumnus was half right. The CO2 does lag temperature. However, we can only explain approximately half of the warming since the last ice age ended if we leave out the increase in CO2 that has occurred. "If higher CO2 warms, Earth's climate history makes sense, with CO2 having caused or amplified the main changes. If CO2 doesn't warm, we have to explain why the physicists are so stupid, and we also have no way to explain how a lot of really inexplicable climate events happened over Earth's history. It's really that simple. We don't have any plausible alternative to that at this point".


Figure 2. Ice core record from Vostok, Antarctica, showing the near-simultaneous rise and fall of Antarctic temperature and CO2 levels through the last 350,00 years, spanning three ice age cycles. However, there is a lag of several centuries between the time the temperature increases and when the CO2 starts to increase. Image credit: Marian Koshland Science Museum of the National Academy of Sciences: Global Warming Facts and Our Futures, originally provided to that site by Kurt Cuffey, University of California, Berkely.

CO2 and temperatures rise and fall in synch
Dr. Alley continues with a discussion of how CO2 and temperature levels have risen and fallen in synch over most of geologic time. But for many years there was still a mystery: occasionally there were eras when temperature changes did not match CO2 changes. But new paleoclimate research, much of it just in the past two years, has shown that nearly all of these mis-matches were probably due to suspect data. For example, the mismatch in the Miocene Era has significantly improved, thanks to a new study published this year by Tripati et al. Another example occurs during the Ordovician Era 444 million years ago, as discussed in a recent post at the excellent skepticalscience.com blog.


Figure 3. Atmospheric CO2 and continental glaciation, 400 million years ago to the present. The vertical blue bars mark where ice ages have occurred. The length of the blue bars corresponds to how close to the Equator the ice sheets got (palaeolatitude, scale on the right side of the plot). The left scale shows atmospheric CO2 over the past 400 million years, as inferred from a model (green area) and from four different "proxy" fossil sources of CO2 information. This is Figure 6.1 of the Palaeoclimate chapter of the 2007 IPCC report.

Is there anything else we should be worried about?
Dr. Alley continues with a discussion of other influences that may be able to explain global warming, such as volcanos, changes in solar output, and cosmic rays. A whole bunch of the competing hypotheses don't work", says Dr. Alley. "When there's a bunch of big volcanos, they make it cool. If volcanos could get organized, they'd rule the world. There might be a tiny bit of organization due to flexing of the crust, but they're not controlling the world".

Regarding solar changes: "When the sun changes, it does seem to show up in the temperature record. As far back as we can see well, the sun is friendly, it doesn't change much. If the sun changed a lot, it would control things hugely. But it only changes really slowly--as far as we can tell. The record doesn't go back as far as we'd like, and there's work to be done here--but it just doesn't seem to be doing much".


Figure 4. Greenland ice core proxy measurements of temperature (top curve) and cosmic ray flux (bottom curve) for the past 60,000 years. The Earth's magnetic field weakened by 90% 40,000 years ago, for a period of about 1,000 years, but there was no change seen in the temperatures in Greenland.

Regarding cosmic rays: "The sun doesn't change much, but the sun modulates the cosmic rays, the cosmic rays modulate the clouds, the clouds modulate the temperature, and so the sun is amplified hugely. It's really interesting hypothesis, there's really good science to be done on this, but there's reason to think its a fine-tuning knob". He goes on to show an ice core example from a period 40,000 years ago (Figure 4) where the Earth magnetic field had near-zero strength for hundreds of years. This allowed a massive flux of cosmic rays to penetrate to the Earth's surface, creating a huge spike in ice core Beryllium-10, a radionuclide made by cosmic rays. If cosmic rays were important to climate, we would expect to see a corresponding major swing in temperature, but the ice core shows no change during the period of enhanced cosmic ray bombardment 40,000 years ago. "We had a big cosmic ray signal, and the climate ignores it", Dr. Alley comments.

How sensitive is climate to a doubling of CO2?
The IPCC report talks extensively about computer climate models' calculations of "climate sensitivity"--how much Earth's climate would warm if CO2 doubled from pre-industrial levels of 280 ppm, to 560 ppm (we're currently at 390 ppm). A mid-range number from the 2007 IPCC report often used by climatologists is that the climate sensitivity is 3°C for a doubling of CO2. Dr. Alley takes a look at what paleoclimate has to say about the climate sensitivity to CO2. "The models actually do pretty well when you compare them to the past. The best fit is 2.8°C.

Dr. Alley concludes, "Where we really stand now, is, we're not quite at the pound on the table, this story is very clearly not done. But an increasing body of science indicates that CO2 has been the most important controller of global average climate of the Earth."

I'll have a new post Sunday or Monday.

Jeff Masters

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624. Floodman
3:57 PM GMT on March 26, 2010
Good seeing you, Storm! How you doing?
Member Since: August 2, 2006 Posts: 10 Comments: 9922
622. Levi32
3:55 PM GMT on March 26, 2010
Quoting StormW:


I mean...for sure! We just finished pulling 9 named storms in a moderate to strong El Nino year...and things are changing.


Well, I agree, but I'll play devil's advocate anyway and point out that it's never impossible for anything to happen. Look at 1972, a strong El Nino year, which also peaked that December, and then 1973, which saw things reverse to a moderate-strong La Nina during the hurricane season.



1972:



1973:



I haven't done any research into why 1973 was such a bust. Maybe it was the sheer strength and rapid reversal into a strong La Nina, but in any case, you can never say never :)
Member Since: November 24, 2005 Posts: 635 Comments: 26684
621. Minnemike
3:53 PM GMT on March 26, 2010
616.. history is always only a second away. wild how true that becomes in our modern Wiki age!! those entries astound me too; entered before we can even digest any of the consequences...
Member Since: July 31, 2008 Posts: 0 Comments: 1320
620. BenBIogger
3:53 PM GMT on March 26, 2010
waiting on the COAPS model predictions.
Member Since: March 19, 2009 Posts: 0 Comments: 1421
619. CyclonicVoyage
3:53 PM GMT on March 26, 2010
Quoting TampaSpin:


I just realized it said West Florida. What the hell is wrong with the PanHandle or EAst Florida.....J/K you all know!


West hit in FL means, East & N in due time. Because of the geography of the peninsula, they should say just that the peninsula is at highest risk. These things don't loose much of it's punch on the way across the state.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
618. TampaSpin
3:51 PM GMT on March 26, 2010
Yonhap reported that another South Korean ship fired shots toward an unidentified target in the direction of North Korea. The Joint Chiefs official said he could not confirm the shooting but said the military was strengthening its vigilance in the area.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
616. AwakeInMaryland
3:49 PM GMT on March 26, 2010
Holy cow -- there's already a Wiki entry.

2010 Baengnyeong incident
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Location of Baengnyeong Island

On March 26, 2010, a South Korean Navy ship carrying more than 100 personnel sank in waters off the country's west coast near Baengnyeong Island in the Yellow Sea. The island, inside South Korea's (ROK) territorial waters, is located near the Northern Limit Line, dividing South from North Korea (DPRK).[1] There were no immediate reports of casualties and there was reportedly an unspecified explosion in the rear of the ship.[2] There were speculations a torpedo attack was a possible cause of the incident.

Later, it was reported that S. Korean Navy units shot at an unidentified ship toward North Korea.[3]

[edit] References

1. ^ http://news.bbc.co.uk/2/hi/asia-pacific/8589507.stm
2. ^ http://english.yonhapnews.co.kr/national/2010/03/26/18/0301000000AEN20100326008600320F.HTML
3. ^ http://english.yonhapnews.co.kr/national/2010/03/26/0301000000AEN20100326008700315.HTML

Stub icon This Korea-related article is a stub. You can help Wikipedia by expanding it.
Member Since: August 19, 2008 Posts: 32 Comments: 1918
614. TampaSpin
3:46 PM GMT on March 26, 2010
Quoting StormW:


What in the h#@$ are they smokin'?


Wow! The really need to go through withdraws and get off that stuff. Bro they also painted our Coastline as a target. Are they nuts. Everyone knows the Panhandle and East Florida is the target this year.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
613. wunderkidcayman
3:44 PM GMT on March 26, 2010
Quoting StormW:


What in the h#@$ are they smokin'?

LOL!!!!!!!!!!!!!!!!!!!
Member Since: June 13, 2009 Posts: 2 Comments: 12502
612. TampaSpin
3:43 PM GMT on March 26, 2010
Quoting nrtiwlnvragn:
Suprise, a below average seasonal forecast.

WRC's Hurricane OCSI Gives West Florida the Highest Chance of Experiencing a Tropical Storm or Hurricane This Summer. The OCSI Also Calls for a Below Average Season with Only 8 Named Storms.


I just realized it said West Florida. What the hell is wrong with the PanHandle or EAst Florida.....J/K you all know!
Member Since: September 2, 2007 Posts: 179 Comments: 20448
611. nrtiwlnvragn
3:43 PM GMT on March 26, 2010
606. TampaSpin
607. wunderkidcayman

I don't see that kind of season either, just putting it out there as another data source. Their method is, should I say "unique".
Member Since: September 23, 2005 Posts: 14 Comments: 11274
609. CyclonicVoyage
3:41 PM GMT on March 26, 2010
Quoting StormW:
How's this grab ya?

img src="Photobucket" alt="" />

I had posted the older one, earlier



Now that would be a welcome addition to the month of Sept if it comes to pass. Seems a lot is still dependent on the Waning El Nino and long term forecasts, this year especially, could be very dicey and unreliable. Above what is usually considered dicey in the first place that is.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
608. TampaSpin
3:40 PM GMT on March 26, 2010
Quoting niederwaldboy:
Now is the time, NUKE THEM!!!!!!!!!!!!


Thats a little Drastic but, YA! Kim Jong is gonna be trouble down the road for sure. I really don't think we should Nuke them YET!
Member Since: September 2, 2007 Posts: 179 Comments: 20448
607. wunderkidcayman
3:40 PM GMT on March 26, 2010
Quoting nrtiwlnvragn:
Suprise, a below average seasonal forecast.

WRC’s Hurricane OCSI Gives West Florida the Highest Chance of Experiencing a Tropical Storm or Hurricane This Summer. The OCSI Also Calls for a Below
Average Season with Only 8 Named Storms.

I rather wait till the CSU comes out next month before I agree with this
Member Since: June 13, 2009 Posts: 2 Comments: 12502
606. TampaSpin
3:38 PM GMT on March 26, 2010
Quoting nrtiwlnvragn:
Suprise, a below average seasonal forecast.

WRC's Hurricane OCSI Gives West Florida the Highest Chance of Experiencing a Tropical Storm or Hurricane This Summer. The OCSI Also Calls for a Below Average Season with Only 8 Named Storms.


I just don't see that. It appears to be a slight above average year coming IMO. But, its too early to tell yet.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
604. nrtiwlnvragn
3:35 PM GMT on March 26, 2010
603. TampaSpin
3:34 PM GMT on March 26, 2010
Quoting TampaSpin:
BREAKING NEWS
msnbc.com news services
updated 3 minutes ago
South Korea is investigating whether a naval ship sinking off the west coast of the peninsula was hit by a torpedo fired by the North.

The 1,500-ton vessel, which had more than 100 people on board, started sinking between 9 p.m. and 10 p.m. local time (8 a.m. to 9 a.m. ET) near the island of Baengnyeong in the Yellow Sea. There were unconfirmed reports it had already sunk.

South Korean broadcaster SBS said many sailors were feared dead. A rescue operation was under way.



This could get very nasty. Kim Jong is a nutt case! Big time!
Member Since: September 2, 2007 Posts: 179 Comments: 20448
602. TampaSpin
3:30 PM GMT on March 26, 2010
BREAKING NEWS
msnbc.com news services
updated 3 minutes ago
South Korea is investigating whether a naval ship sinking off the west coast of the peninsula was hit by a torpedo fired by the North.

The 1,500-ton vessel, which had more than 100 people on board, started sinking between 9 p.m. and 10 p.m. local time (8 a.m. to 9 a.m. ET) near the island of Baengnyeong in the Yellow Sea. There were unconfirmed reports it had already sunk.

South Korean broadcaster SBS said many sailors were feared dead. A rescue operation was under way.

Member Since: September 2, 2007 Posts: 179 Comments: 20448
601. AwakeInMaryland
3:26 PM GMT on March 26, 2010
593. Oy vey. "I feel your pain" (more Bill, lol)!
But I'm refusing a possible case of hives; benadryl doesn't really agree with me.
Member Since: August 19, 2008 Posts: 32 Comments: 1918
Quoting Seastep:
Breaking unconfirmed news: S. Korea may have torpedoed another unidentified ship.....


O no! Not good! Sides from other countries will now line up! Hopefully this can be settled somewhat peacefully but i doubt it.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
An endless -NAO,what ever happened to cycles?
Member Since: Posts: Comments:
592. Appreciate the heads-up. The New York Times has picked up this Reuters report (however, looks like Reuters picked it up from a S. Korean TV station, imo we still need to verify, verify, verify).

South Korean Ship Sinking - Report
By REUTERS
Published: March 26, 2010

Filed at 10:48 a.m. ET
Reuters

SEOUL (Reuters) - A South Korean naval ship with more than 100 on board was sinking Friday near North Korea and Seoul was looking into whether it was due to a torpedo attack by the North, South Korea's YTN TV network reported.

North Korea in recent weeks has said it was bolstering its defences in response to joint South Korean-U.S. military drills that were held this month.

(Reporting by Cho Mee-young and Jon Herskovitz; Editing by Alex Richardson)
Member Since: August 19, 2008 Posts: 32 Comments: 1918
Based on that map stormw posted it would tend to indicate a few storms out to sea. The determining factor of where a storm will make landfall is going to be dependent on what the current steering patterns are. Our atmosphere is just to complex and coupled to be able to determine what absolute locations might be impacted this tropical season. That said using climatology and examining similar patterns in data we can try to come to an educated conclusion of where the highest chance of seeing tropical activity could be.

adrian
Member Since: Posts: Comments:
double post, sorry
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Quoting AwakeInMaryland:

"Bill" scared the be-jeezus out of us for a bit. (scared Hillary & President Obama, too... sorry, just a little bit of lousy local humor.)

So, TampaTom...we're for Purdue tonight ("just one night") vs. Duke, yes?


This is where things get touchy...

If I follow my gut and cheer against Duke, that means the ACC is blanked from the elite 8... Not good for the conference. Suddenly, I have to hear from all these Atlantic 10 and Sun Valley conference boosters about how bad the ACC is...

If I do cheer for Duke... I may break out in hives and stop breathing...

Decisions decisions
Member Since: Posts: Comments:
Quoting Seastep:
Breaking unconfirmed news: S. Korea may have torpedoed another unidentified ship.....


a South Korean warship is currently sinking because of a suspected NORTH Korean torpedo attack.

BREAKING NEWS: South Korean ship with 100 on board sinks after 'torpedo attack by North Korea'


Member Since: Posts: Comments:
Member Since: March 19, 2009 Posts: 0 Comments: 1421
Quoting NEwxguy:
Jeff,the El Nino supplies the fuel for the storms and the -NAO brings them up the coast,and strenghtens them.Enough already,some people up here are still under water.

I know. My best friend lives in Windham, NH, and I have some other friends that live in Londonderry, NH. Fully aware of the flooding issues up there.

Hopefully, this next system stays away from the coast, and rains on the Gulf Stream or something.
Member Since: August 3, 2008 Posts: 16 Comments: 5890
It's March; that diagram will likley look considerably different in the next few months
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Torpedo attack?
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Quoting StormW:
How's this grab ya?

<>img src="Photobucket" alt="" />


Yes, its a recurvature setup, but look at the pressures in the Caribbean. *not* good for anyone on the Gulf Coast.
Member Since: August 3, 2008 Posts: 16 Comments: 5890
Breaking unconfirmed news: S. Korea may have torpedoed another unidentified ship.....
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Quoting TampaTom:
That must be why storms like Bill last year pulled north and turned away from the east coast...

"Bill" scared the be-jeezus out of us for a bit. (scared Hillary & President Obama, too... sorry, just a little bit of lousy local humor.)

So, TampaTom...we're for Purdue tonight ("just one night") vs. Duke, yes?
Member Since: August 19, 2008 Posts: 32 Comments: 1918
Jeff,the El Nino supplies the fuel for the storms and the -NAO brings them up the coast,and strenghtens them.Enough already,some people up here are still under water.
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That must be why storms like Bill last year pulled north and turned away from the east coast...
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That looks like a recurvature type set-up StormW
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Quoting Levi32:
Give it a rest... I'd rather talk tropics today. I already told you I find every debate beneficial and welcome challenges to what I post. That's the only way I'm going to get better.

greeted with a big :D
Member Since: July 31, 2008 Posts: 0 Comments: 1320
Quoting NEwxguy:
GM,bloggers,turning cold up here,can't complain its been so nice this month,but next week looks like another flooding event for us,somebody ticked off mother nature up here.

Sorry NE. My bribery money ran out for mother nature, I used it up last hurricane season... won't get more until June 1, for more anti-cane bribery.
Member Since: August 3, 2008 Posts: 16 Comments: 5890
GM,bloggers,turning cold up here,can't complain its been so nice this month,but next week looks like another flooding event for us,somebody ticked off mother nature up here.
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Quoting StormW:

Looks like El Nino is fading..
Member Since: August 3, 2008 Posts: 16 Comments: 5890

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.