A cautionary tale--the PETM
One frequently hears comments like, "Earth has had many periods of warmth far exceeding the warmth of today's climate, so we should not be surprised if the current warming of the globe is a natural phenomena". This view is especially prevalent among geologists, who take a very long view of history and are among the most skeptical scientists regarding the reality of human-caused climate change. It is true that Earth's past has had many episodes of natural global warming that we can learn from. But the greatest natural global warming episode of the past 65 million years, the Paleocene-Eocene Thermal Maximum (PETM) event of 55 million years ago, presents us with a cautionary tale of how massive releases of greenhouse gases--similar in scale to what humans are now producing--may cause extreme warming of the climate.
Earth's orbital variations--the most common form of natural global warming
The most common cause of natural global warming over time has been changes in Earth's orbit. Three oscillations in Earth's orbit with periods of 26,000, 41,000, and 100,000 years (called Milankovitch cycles) cause ice ages to be triggered when summer sunshine at 65°N reaches a minimum. The reduced sunlight over Canada, Siberia, and Scandinavia allows winter snowfall to persist through the summer, and thus accumulate and build Northern Hemisphere ice sheets. There isn't enough land in the Southern Hemisphere to allow large, land-based ice sheets to build there, so it is the growth and decay of Northern Hemisphere ice sheets that has controlled the timing of ice ages and warm inter-glacial periods over the past three million years. Earth's orbit is currently in a phase where the amount of sunlight falling at 65°N is changing very little. Thus, the primary mechanism for past natural global warming events is not to blame for the current warming. According to the "official" word on climate, the 2007 report of the U.N.'s Intergovernmental Panel on Climate Change (IPCC), the amount of sunlight falling at 65°N is expected to change little over the next 30,000 years, and "it is very unlikely that the Earth would naturally enter into another ice age for at least 30,000 years".
Pumping huge amounts of carbon into the atmosphere coincided with extreme climate warming during the PETM
Natural global warming has also occurred in the past due to changes in solar brightness, and natural emissions of natural carbon dioxide (CO2) and methane (methane is the primary component of the natural gas we use to heat our homes, is a potent greenhouse gas 20 - 25 more effective at heating the Earth than than CO2, with a lifetime of about 9 years in the atmosphere before reacting with the OH radical to form CO2). I discussed one example of natural global warming in my previous post--volcanoes have emitted enough CO2 over time to account for a large portion of Earth's natural greenhouse effect. However, volcanoes only put about 1 - 3% as much CO2 per year into the atmosphere as human activities do. What, then, does Earth's past tell us about what might happen if we dump 100 times more carbon than volcanoes do into the atmosphere, over a period of a few centuries?
The end of Earth's Paleocene era, 55 million years ago, was a time of great warmth on planet Earth. Subtropical vegetation grew in Greenland and Patagonia, and crocodiles swam off the coast of Greenland. Sea surface temperatures at the North Pole were a toasty 64°F (18°C). Tropical palm forests in northern Wyoming played host to early primates. Despite the fact that the sun put out 0.5% less energy than today (equivalent to a global temperature that would be 0.5°C cooler), there was no polar ice cap or Greenland Ice Sheet. The higher temperatures of that era were probably due to high carbon dioxide levels of 560 - 600 ppm. This is far higher than the 280 ppm seen in the 1800s, and the 383 ppm as of 2009. The continents had a different configuration due to continental drift, and this may have kept the world warmer as well.
Figure 1. Global temperature change (right scale) as inferred from oxygen-18 isotope measurements (left scale) from fossil ocean microorganisms (Zachos et al., 2001). Oxygen-18 levels in these fossils are proportional to the temperatures of the era when the fossils were formed. The Paleocene-Eocene Thermal Maximum (labeled PETM) shows a sharp upward spike in temperatures occurred. This spike is likely to be understated by a factor of 2 - 4 due to coarse sampling and averaging in this data set. For more detail, see the Wikipedia entry for the PETM.
Then, 55 million years ago, the fossil record shows that an extraordinary drop in the ratio of carbon-13 to carbon-12 occurred, indicating that a massive amount of "light" carbon with low levels of the carbon-13 isotope was emitted into the atmosphere in a very short amount of time--just 500 - 20,000 years. The most likely source of carbon-13 depleted carbon would have been methane from ocean sediments or land vegetation. If it was methane, about 1,000 - 2,000 gigatons of carbon would have had to be injected into the atmosphere, in order to account for the observed fossil deposits. For comparison, the total amount of carbon in today's atmosphere, primarily as CO2, is a factor of two or three less--about 810 gigatons. The fossil record shows that extreme climatic warming occurred nearly simultaneously with this massive release of carbon into the atmosphere. Global average temperatures rose 9°F (5°C) in a geological instant--1,000 - 10,000 years (Sluijs et al., 2007). Average sea surface temperatures at the North Pole reached 74°F (23°C). The warmth lasted 120,000 - 220,000 years before weathering of silicate rocks was able to remove the CO2 from the atmosphere and return the climate to its former state. This was the largest global warming event since the time of the dinosaurs, 65 million year ago (Moran et al., 2006). The resulting impact on Earth's climate was so severe that a new geological era was born--the Eocene. The warming event has been dubbed the Paleocene-Eocene Thermal Maximum (PETM), since it occurred at the boundary of these two eras. Ocean circulation patterns changed radically during the first 5,000 years of the PETM (Nunes and Norris, 2006), and the deep oceans became 11°F (6°C) warmer, severely depleted in oxygen, and more acidic. A mass extinction of deep ocean microorganisms resulted, though the exact reasons remain unclear. The PETM did not cause mass extinctions on land of plants and animals, but a major turnover in mammalian life occurred at that time. Many of today's major mammalian orders emerged in the wake of the PETM. The new geological era it ushered in, the Eocene, is named for the Greek goddess of the dawn (Eos), since this was the dawn of the era of large mammals.
It is extremely difficult to explain the warmth of the PETM without assuming that the huge amount of "light" carbon pumped into the atmosphere created intense warming due to the greenhouse effect. The controversial question is, how did this carbon get into the atmosphere? Did PETM happen because of the greenhouse effect from all the carbon added to the atmosphere, or did the carbon get released into the atmosphere in response to climatic warming from another cause (and boosting the warming that was already occurring?) The mystery is a difficult one to unravel, since our vision of what happened so long ago is very fuzzy. A recent high-resolution study of ocean sediments laid down in New Jersey during the PETM (Sluijs et al., 2007) argued that about half of the PETM warming occurred 1,000 - 1,500 years before the 1,000 - 2,000 gigatons of "light" carbon got injected into the atmosphere. The authors theorize that global warming due to some other cause heated up the deep oceans enough to release methane stored in the form of methane hydrate, a form of methane 'ice' that forms in cold bottom water under great pressures and is widely distributed and plentiful in sediments on the outer edges of continental margins. The methane released was the huge pulse of "light" carbon seen in the fossil record, and this methane warmed the planet even further via the greenhouse effect. The authors argued that the warming that triggered the PETM could have been due to a variation in Earth's orbit, or due to a pulse of greenhouse gases that didn't happen to be enriched in light carbon. A wide variety of other theories abound. Dickens (2004) theorizes that a volcano in the North Atlantic erupted through a huge fossil fuel deposit in overlying ocean sediments, releasing massive amounts of the stored carbon into the atmosphere. Pancost et al. 2006 found evidence that the warming of the PETM significantly increased as carbon stored on land in wetlands was released in the form of methane. Huber (2008) argued that temperatures got so hot during the PETM that a huge die-off of tropical vegetation resulted, creating vast deserts and putting thousands of gigatons of carbon dioxide into the atmosphere, further increasing temperatures.
Figure 2. Photographs of methane hydrate as nodules, veins, and laminae in sediment. Intense warming of the deep oceans during the PETM may have released huge quantities of methane gas from ocean sediments with methane hydrates in them. Image credit: United States Geological Survey.
Computer climate models fail to reproduce the PETM
A big concern about the climate models that we are using to forecast climate for the coming century is that they do a poor job of reproducing the climate of the Eocene, and, in particular, the PETM. These models fail to reproduce the high temperatures observed in the polar regions relative to the tropics during the PETM. However, in the words of climate scientists Daniel Schrag and Richard Alley in a 2004 article in Nature, "It would be a grave mistake to take these lessons from ancient climates as a reason to disregard the projections from climate models." If the observations of the climate in this far-ago era are correct, the reason that the climate models fail to correctly simulate this past climate is because the climate is more sensitive to CO2 than believed. There is a missing "feedback" causing increased warming near the pole that the models are missing. Sluijs et al. (2006) theorize that the models may be missing how hurricanes transport heat to the poles, or how polar stratospheric clouds may act to trap heat over the poles. In short, the failure of the models to correctly simulate the PETM may mean that our current estimates of the amount of global warming likely over the coming century (1.1°C - 6.4°C) are far too low. The other possibility, mentioned by Huber (2008) is that the models are correct, but the temperatures inferred for the tropics from the fossil record are in error. This wouldn't be the first time that measurements were found to be in error and the models vindicated.
Comparison with today
Since the beginning of the Industrial Revolution, humans have pumped about 500 gigatons of carbon into the atmosphere. There are about 5,000 gigatons in the planet's coal reserves, while oil and traditional natural gas deposits are hundreds of gigatons each (Rogner, 1997). Given that humans are now adding about 10 gigatons of carbon to the atmosphere each year (Global Carbon Project, 2007), we will surpass the 1,000 gigaton mark 50 years from now at current emission rates. This is at the lower end of the 1,000 - 2,000 gigatons of carbon that are estimated to have been added to the atmosphere during the PETM--the most extreme natural global warming event of the past 65 million years. Though our view of events so long ago is very fuzzy, the PETM should serve as a cautionary tale. We cannot rule out the possibility that continuation of our current rates of fossil fuel burning will lead to an extreme climatic warming event like the PETM. In particular, we need to keep a careful eye on the huge reservoirs of methane hydrate stored in marine sediments (500 - 10,000 gigatons of carbon) and stored in permafrost (7.5 - 400 gigatons). Continued warming of the planet could trigger substantial releases of these massive reservoirs of greenhouse gases, leading to a repeat of the PETM event. However, a 2008 study by the U.S. Climate Change Science Program (CCSP, 2008) concludes that there is currently no evidence that a sudden catastrophic release of methane stored in ocean sediments or in permafrost will happen over the next century. It should take at least a century for global warming to penetrate the deep oceans and permafrost regions containing these significant reservoirs of methane hydrates. The study concludes, "Catastrophic release of methane to the atmosphere appears very unlikely in the near term (e.g., this century)...Although the prospect of a catastrophic release of methane to the atmosphere as a result of anthropogenic climate change over the next century appears very unlikely based on current knowledge, many of the processes involved are still poorly understood, and developing a better predictive capability requires further work. On a longer time scale, methane release from hydrate reservoir is likely to be a major influence in global warming over the next 1,000 to 100,000 years". So, the bottom line is: don't expect global warming to be able to cause huge releases of methane hydrates in the coming century, such as may have occurred during PETM. But it is wise to ponder that a release of greenhouse gases similar in magnitude to what we are doing now coincided with the most extreme global warming event of the last 65 million years. We should not be surprised if our human greenhouse gas emissions cause a similar massive climate perturbation over the next 1,000 years, leading the dawn of a new geological era--the Anthropocene.
For more information
The best resource I found while researching this was a December 2008 report from the U.S. Climate Change Science Program (CCSP), titled, Abrupt Climate Change. Chapter 5, "Potential for Abrupt Changes in Atmospheric Methane" [1.3 Mb] was the relevant chapter.
References
Archer, D., 2007, "Methane hydrate stability and anthropogenic climate change", Biogeosciences, 4, 521544,.
Dickens, G.R., 2004, "Hydrocarbon-driven warming", Nature 42, 429, pp513-515, 3 June 2004.
Huber, M., 2008, "A Hotter Greenhouse?", Science 321, no. 5887, pp. 353-354, DOI: 10.1126/science.1161170
Moran, et al., 2006, "The Cenozoic palaeoenvironment of the Arctic Ocean", Nature 441, 601-605 (1 June 2006) | doi:10.1038/nature04800.
Nunes, F. and R.D. Norris, 2006, "Abrupt reversal in ocean overturning during the Paleocene/Eocene warm period", Nature 439 (7072): 603. doi:10.1038/nature04386
Pancost, R.D., et al., 2006, "Increased terrestrial methane cycling at the Palaeocene-Eocene thermal maximum", Nature 449, 332-335 (20 September 2007) | doi:10.1038/nature06012
Rogner, H.-H, 1997, "An assessment of world hydrocarbon resources", Annu. Rev. Energy Environ., 22, 217-262.
Sluijs, A., et al., 2006, "Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum", Nature 441, 610-613 (1 June 2006) | doi:10.1038/nature04668
U.S. Climate Change Science Program (CCSP), 2008: Abrupt Climate Change. A report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research [Clark, P.U., A.J. Weaver (coordinating lead authors), E. Brook, E.R. Cook, T.L. Delworth, and K. Steffen (chapter lead authors)]. U.S. Geological Survey, Reston, VA, 459 pp.
Zachos, J. C., U. Rohl, S.A. Schellenberg, A. Sluijs, D.A. Hodell, D.C. Kelly, E. Thomas, M. Nicolo, I. Raffi, L.J. Lourens, H. McCarren, and D. Kroon, 2005, "Rapid Acidification of the Ocean During the Paleocene-Eocene Thermal Maximum", Science, 308, 1611-1615
Portlight.org relief walk in Destin, FL a big success
Over the weekend, the portlight.org disaster relief charity ran a highly successful relief walk in Destin, FL, to raise money for the disaster relief. The theme of this walk was to raise relief money not only for people, but for pets as well, with 25% of the money raised intended for taking care of pets injured or abandoned during disasters. As detailed in the portlight.org blog, the pet theme was a great way to raise money, and about $5000 was raised. The other relief walks this year raised $1500 in New Orleans and $542 in Kissimmee. Many more walks are planned this year, with the next one being this weekend (May 2) in Summerville, SC. Portlight also helped out with disaster relief operations for the South Carolina fires yesterday.
Jeff Masters
Reader Comments
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Get off your bash Obama campaign... read and learn something instead.
Q Do masks provide protection against swine flu?
A Yes, but probably not to the person wearing them. They help stop the virus being expelled from the mouth and nose when coughing or sneezing, but are much less effective at protecting the wearer from a virus picked up on the hands or circulating in the air. Wearing a mask thus becomes a public-spirited act.
It is questionable if the mask helps even. I read something about it yesterday.
Back to the tropics - what does the latest GFS run show? I'm at work and do not have access to the models.
To help chronicle events after Ike,I was writing a notebook of sorts to help keep things straight chronogilically with the insurance company and city. I think I will go back and see if I can put together a detailed one page hurricane kit guideline for those who risk potential destruction/loss of dwelling type events. Thinking back, I do not think I ever saw one list that captured more than maybe 40% of the items that were really useful after the storm for keeping yourself alive and cleaning out your house.
I have ordered Germs Make Me Sick! from Amazon. Thanks again, Surfmom.
Folks, there were plenty available - both new and old, as well as
other books for getting teaching children how to avoid germs
Stay in Canada please.........LOL
And gives no protection if you slip under the mask to rub your itchy nose.
Money better spent on soap, bleach and pocket size hand sanitizers.
CDC Link
The more recent illnesses and the reported death suggest that a pattern of more severe illness associated with this virus may be emerging in the U.S. Most people will not have immunity to this new virus and, as it continues to spread, more cases, more hospitalizations and more deaths are expected in the coming days and weeks.
virus will pass through the mask easy...as well as touch "the bugger", itch your ear, rub your eye... Bada Bing! Do your best to have a strong immune system.
I think Patrap posted the original link.. he might have it still.
So would you like to to work on the Border Patrol. What protection do they have? I don't think they will be caring bleach and soap in there pockets........SORRY!
Umm the same as every policeman/fireman or any other public servant?
Read your own links..... there are more cases in New York then the rest of the US... how many Border patrol agents do they have???
Don't panic, but don't take this lightly either. Be ready to hunker down if needed. Get the stuff you need in place so you don't have to fight the panic stricken masses if it is found in you locality. Kinda like plywood sales when a storm is off shore. Fever meds and pain aids are some that get overlooked. I would add something with electrolytes also. If you don't get exposed to it, you don't get sick. Just my take
Then you read this type of stuff from a few days ago.
Link
ADDENDUM: This does not mean, that I do not take this flu seriously. Nor does it mean, that I do not realize that Border Guards have a tough job. But ineffective methods that mislead folks into thinking they have protected themselves are dangerous/
ADDENDUM #2 Of course, this virus could mutate!
NO!! I just got a lawyer to go against them with the lemon law....crap!
Wrong info....A sneeze or a cough from an infected person may infect many as a virus can be air transmitted for a short period of time. Your statement is not correct....I live in the Medical world my friend.
Geophysicist John Goff has studied some of the slim barrier islands running parallel to the Texas coast – including Galveston Island. He said those islands were badly damaged in September of 2008 by Hurricane Ike, which made landfall near the city of Galveston.
John Goff: There was a tremendous loss of sand, and sand is the critical component to maintaining the health of the system.
Goff mapped the seafloor between barrier islands, before and after Hurricane Ike. He said the most erosion occurred when the hurricane subsided, as water rushed out of an overflowing Galveston Bay, back into the Gulf of Mexico.
John Goff: The back surge is very important. That, we found, was a very, very strong force. It moved a lot of sediment and eroded a lot of the sand. Those sands are critical to maintaining the beach barrier system. And without it, once you reduce it, it’s very hard to get it back.
Published on Thursday, April 30, 2009
By Steven Knipp
steve@caymannetnews.com
In an effort to gauge Government’s level of readiness for the 2009 hurricane season, all departments are reviewing continuity of operations plans that will be put to the test during a national exercise scheduled for Tuesday, 5 May.
According to Hazard Management of Cayman Islands (HMCI) Communications Officer Simon Boxall, all Government entities are mandated to prepare and review plans that address a range of impacts posed by a hurricane.
The national exercise is designed to provide officials with an opportunity to rehearse their roles at various stages of activation.
The exercise is designed to promote inter-agency coordination and assess control capabilities in an emergency crisis.
You should not let anyone cough or sneeze on you. Ever. Distance to the infected person matters. (Most of us have an inborn discomfort with those who invade our personal space - could this be a protective mechanism....hmm) A sneeze can be pretty expulsive, I will grant you that. Coughing would not project near as far. I have no problem with anyone wearing a mask. However, the mask will NOT protect them from this virus if they do not keep hands clean (hand sanitizer) and keep their hands off their face. (ADDED) A mask does not mean that these guards do not need a way to sanitize their hands and equipment. Do they not have guard houses with facilities? If so, they need to wipe door knobs etc with bleach
Would be better off if the infected person wore the mask.
Archive products for Hurricane Ike
No i agree with everything you just stated here. Yes you are correct most virsus will march through a surgical mask. But, it will give some form of protection as does the other stuff above that you mentioned. IT'S JUST SOME FORM OF PROTECTION AND NOT A COMPLETE PROTECTANT.
: )
Two more states confirmed.
I'll bet Orca ordered up a batch of Tamiflu for the Canucks :)
using masks to ward off viruses is like putting masking tape on your windows during a hurricane. sure, it makes it look like your protected, but in reality offers very little.
did you blame bush for not closing us post offices during the anthrax scare during his administration? probably not, but bashing obama is just fine because hes a democrat.
Well said orca!!!I got lotsa respect for ya Tampa,But you've got to start watching something other than Glenn Beck or that other "fella",shawn hannity(doesn't even deserve his name capitalized)!!!!!...their making you start to act funny again,lol....
I don't care who is the sitting President. If Bush had made this choice would would have disagreed also. LOL.....LOve the way some try to really use Politics as there own Agenda...WOW! I hated many of Bush's Policies and I'm hating many of Obama's. Sorry if i just stated something that was already published that you did not want to read because you love the President.
J/K
404:forbidden!!!
Yep, the good funny one was forbidden. Oh well, just trying to ineptly bring some humor to the situation. Be well all, I am heading to antartica :) Salt mine time, end of month stuff.
Okay?
I am a proud Manic Depressant ! L8R
We also forgot you were one apparently
Excellent points, and our so-called free trade policies have led us to these kind of things with off-shoring and outsourcing. The policies are hardly "free" and mostly stacked against the US.
- TS, no worries about the Obama heat. Anyone that says anything against "The Messiah" gets bashed. The thing is, this country's been going to heck in a handbasket for a long time - about 50 years or so. Or, you could also say that it's been eventually headed in that direction since the adoption of the Federal Reserve in 1913. We really can't blame BaRockStar because most of this just fell in his inept lap, and the truth is, his liberal agenda for borrowing and spending is just adding insult to injury. They're all inept, everyone of them. They always think the solution is to throw money at a problem - lol, money we don't have, money we borrow and can't repay. Eventually, that capacity to borrow also runs out; then, well, the proverbial crap will really hit the fan! It's only a matter of time, but probably sooner than any of us expect.
LOL. I guess it's going to take a CAT 5 hitting Miami or NOLA to rid the blogs of this mess. Oh, but wait, that wouldn't do it either, would it? Y'all have fun bashing each other! Have a good day!
...meanwhile in a hospital not too far away
One "ting" this wont become,is a Chat room.
Though some try to spin it as one,..there is a Chat feature ,and wu-mail for bickering and Ping Pong postings of Baseball,Dow quotes and whatever.
Folks can easily make their OWN blog entries on matters of the Heart,aka,Politic's,Sports,or Catastrophic Bird Strikes,.. all day.
Thank you, Pat, but I don't need you to tell me what and where to post. You don't own the blog and you're not the police either. Heck, I like you just fine, but you're just as bad with all the goofy pictures and subliminal messages, too. You do your part I can assure you! Having said that, I'm out.
Y'all try to play nice and get along! Geeeesh!
PARALLEL UNIVERSE: Galveston's Learning from Cuba About Hurricanes -- Finally!
Galveston was severely battered last September by Hurricane Ike and there was much criticism about the lack of evacuation procedures on the barrier island. Lyda Ann Thomas, with her distinctive Texas drawl, became familiar to viewers of Houston television coverage of the storm -- including the present writer wondering if Ike would strike his new hometown of Port Lavaca, about 100 miles down the Gulf coast. It didn't get to us, although many people in Port Lavaca evacuated and plywood became the exterior decor of choice for homes and businesses.
The Chronicle wrote that "With little more than a month before the advent of the 2009 hurricane season, the mayor has visited with some of the most practiced - and successful - managers of storm preparedness in the world."
Invest 96W
94W
Cheers AussieStorm
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