The Biggest Control Knob: CO2 in Earth's Climate History
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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Inner core breaking apart as excepted during a landfalling system.
Tropical cyclones and climate change
Progress Article:
Tropical Cyclones and Climate Change
Supplemental Material
There are some interesting conclusions and followup.
Paleotempestology !
Paleotempestology Resource Center
07.17.09
NASA's Lunar Reconnaissance Orbiter, or LRO, has returned its first imagery of the Apollo moon landing sites. The pictures show the Apollo missions' lunar module descent stages sitting on the moon's surface, as long shadows from a low sun angle make the modules' locations evident.
The Lunar Reconnaissance Orbiter Camera, or LROC, was able to image five of the six Apollo sites, with the remaining Apollo 12 site expected to be photographed in the coming weeks.
The satellite reached lunar orbit June 23 and captured the Apollo sites between July 11 and 15. Though it had been expected that LRO would be able to resolve the remnants of the Apollo mission, these first images came before the spacecraft reached its final mapping orbit. Future LROC images from these sites will have two to three times greater resolution.
this show a lot of storms going to out sea
Pat, that's an interesting link with some great images,thanks.
LoL, here is something I posted on my blog earlier. Quite an interesting item from 30 years ago. It should play in series. It is not intended to be controversial, just interesting :)
BTW, it was a short lived series, but quite good.......
James Burke : Connections, Episode 1, "The Trigger Effect", 1 of 5 (CC)
Future LROC images from these sites will have two to three times greater resolution.
I look forward to that.
is there one for the atlantic and caribbean
and in loop format
A Lady Called Camille came calling to Mississippi and Se La.
Department of Agriculture
A Lady Called Camille
AVA11983VNB1 - 1971
The video documents the devastation caused by Hurricane Camille and the suffering caused thousands of people. It shows that while hundreds of lives were lost to the hurricane, thousands were saved due to emergency plans, trained rescue teams, and help from the forces of government.
I have not seen it yet
But I didn't say it because Press beat me to it... lol
Don't ask too hard or you may get more than you need.
...everyone knows this was all done on a Hollywood soundstage...
...and that climate change is a giant hoax...
...jeez...
WE NEED LOTS IT IS DRY MY DOOR SWIPE FINGER AND DUST AND SLAT WILL COME OFF LIKE DUST IN VACUME CLEANER
just hang in there.
avoid salty food.
not seeing much of it now.
Tropical Cyclone Advice
TROPICAL CYCLONE PAUL, CATEGORY 1 (11U)
11:00 AM CST March 28 2010
=================================
At 9:30 am CST, Tropical Cyclone Paul, Category 1 (995 hPa) located at 13.1S 136.5E or 90 kms north of Alyangula and 105 kms south southwest of Nhulunbuy has 10 minutes sustained winds of 40 knots with gusts of 55 knots. The cyclone is reported as moving south at 3 knots.
Gale Force Winds
=================
90 NM from the center
Dvorak Intensity: T3.0/3.0/D1.5/24HRS
The cyclone is expected to intensify slightly before it moves inland between CAPE SHIELD and ALYANGULA on Monday.
GALES with gusts to 110 kilometres per hour are currently being experienced between and NHULUNBUY and PORT ROPER, including GROOTE EYLANDT. GALES may extend west to MILINGIMBI and MANINGRIDA late Monday if the system takes a more northerly track.
A STORM TIDE is expected between CAPE SHIELD and PORT ROPER. Tides are likely to rise significantly above the normal high tide, with DAMAGING WAVES and DANGEROUS FLOODING today and Monday.
HEAVY RAIN may lead to localised flooding and significant stream rises in the Arnhem and Roper-McArthur Districts today and Monday.
Cyclone Watches/Warnings
=========================
A Cyclone WARNING continues for coastal and island communities from Milingimbi to Port Roper, including Nhulunbuy and Groote Eylandt.
A Cyclone WATCH continues for coastal and island communities from Maningrida to Milingimbi.
Forecast and Intensity
=======================
12 HRS: 13.4S 136.3E - 45 knots (CAT 1)
24 HRS: 13.4S 136.0E - 45 knots (CAT 1)
48 HRS: 13.3S 135.3E - 30 knots (Tropical Low)
72 HRS: 13.7S 135.2E - 30 kntos (Tropical Low)
Additional Information
========================
The tropical low has shown strong signs of intensification overnight as it moved slowly south along the eastern coast of Arnhem Land. A comma shaped area of cold cloud evolved into a CDO with well-developed bands in the eastern semicircle. Position based on a well-defined LLCC and partial eye wall developing on radar. Reassessment of Dvorak yielded FT=3.0 at 2100UTC, based on DT=3.0 from 0.7 curved band wrap. TC Paul was named at 0000UTC.
The broadscale environment remains favourable for further intensification, with low vertical wind shear and good outflow to the south and north of the system. The cyclone is forecast to stall and drift slowly west under the influence of a building mid-level ridge to the south. Intensity is forecast to increase slightly during the next 24 hours while TC Paul remains near the coast, then weaken below cyclone intensity as it moves inland on Monday. In the longer term, an amplifying upper trough is expected to move the system over Gulf of Carpentaria waters where it may reintensify into cyclone later in the week.
Looks like a new system emerging off Brazil.
Based upon the latest climate model data, expect El Nino to really weaken later in April and going into May.
That "Climategate" incident disproves nothing about climate science. It may have a shadowy history but that doesn't mean its conclusions are false. The emails show no evidence of fraud.
By the way, research shows that (American) people become more Liberal as they age. :P
El Nino has already become a shadow of its former self.
I love Dr. Master's climate change posts for one.
On Antartic sea ice this has been established to be caused by the ozone hole. Remember the ozone hole from the 1970's? Nobody believed the scientists back then either and then in the 80's it just sort of showed up in spades. Fortunately folks stopped arguing and the free world, led by Lady Thatcher and Ronald Reagan, came to its senses and ratified the Montreal Protocol.
Yes, we have had a climate related international treaty signed by this country already UNDER REAGAN AND A REPUBLICAN SENATE!
The history of climate change science per se can be traced to calculations of Arrhenius about the dawn of the 20'th century.
Now, for those who don't like the hockey stick neither do I (Dr. McIntyre is correct, at least about the statistics).
This bickering is stopping the US for doing what it needs to do to ensure a sustainable energy future.
Has been happening since the earth formed and will continue until the earth is gone.
We still have an El Nino in effect, albeit getting progressively weaker. My response was just when I expect it to transition into a neutral ENSO to weak La Nina. Yet another potentially ominous sign for the upcoming hurricane season.
LOL Press. Life is a dastardly hoax. Death too.
What is the hurricane in your avatar? Its pretty far south
It's a comma. Don't pray too hard.
We got off easy last year. But that's what's made drought conditions in the Caribbean. Everything was torn up with shear.
anyway, goodnight chet.
It appears that there could be another severe weather threat overnight Sunday and into Monday morning across South Florida as the front being dragged by this storm system coming across the Southeast moves into the region and the upper level jet shifts over the area. Most models agree that there will be sufficient instability with CAPE (Convective Available Potential Energy) values around 1500 to 2000 J/Kg and moisture content rising to around 1.75 inches. This could lead to a heavy rain threat and strong winds. At this time, I don't expect a tornado threat, although in an ideal situation at the right time, an isolated one could develop.
Just looking at long range models, you should be getting better rain chances in a few weeks as moisture continues to build and more energy comes across the Caribbean. I know what you mean though. The Caribbean has been uncharacteristically dry and has been suffering from drought for a while now.
TROPICAL CYCLONE ADVICE NUMBER 11
Issued by the BUREAU OF METEOROLOGY, DARWIN
at 11:00 am CST Sunday 28 March 2010
A Cyclone WARNING continues for coastal and island communities from Milingimbi
to Port Roper, including Nhulunbuy and Groote Eylandt.
A Cyclone WATCH continues for coastal and island communities from Maningrida to
Milingimbi.
At 9:30 am CST Tropical Cyclone Paul, Category 1 was estimated to be 90
kilometres north of Alyangula and 105 kilometres south southwest of Nhulunbuy,
moving south at 6 kilometres per hour parallel to the coast.
The cyclone is expected to intensify slightly before it moves inland between
CAPE SHIELD and ALYANGULA on Monday.
GALES with gusts to 110 kilometres per hour are currently being experienced
between and NHULUNBUY and PORT ROPER, including GROOTE EYLANDT. GALES may extend
west to MILINGIMBI and MANINGRIDA late Monday if the system takes a more
northerly track.
A STORM TIDE is expected between CAPE SHIELD and PORT ROPER. Tides are likely to
rise significantly above the normal high tide, with DAMAGING WAVES and DANGEROUS
FLOODING today and Monday.
HEAVY RAIN may lead to localised flooding and significant stream rises in the
Arnhem and Roper-McArthur Districts today and Monday.
Details of Tropical Cyclone Paul at 9:30 am CST:
.Centre located near...... 13.1 degrees South 136.5 degrees East
.Location accuracy........ within 30 kilometres
.Recent movement.......... towards the south at 6 kilometres per hour
.Wind gusts near centre... 100 kilometres per hour
.Severity category........ 1
.Central pressure......... 995 hectoPascals
The next advice will be issued by 2:00 pm CST Sunday 28 March.
Does that storm SE of South America (just came off shore) look tropical to anyone else, or is it just me??
Ivan
2004
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