20th Century Warmest In 1200 Years 608
gcranston writes "Research from the University of East Anglia in Norwich, U.K. shows that the 20th century was the warmest for the northern hemisphere since approximately 800AD. Historical climate data were calculated from weather 'proxies' such as tree rings, ice cores, and seashells from Europe, Asia, and North America, and attempted to address the shortcomings of earlier studies. The findings support the argument for global warming as a result of human interference rather than natural climate change."
Food for thought (Score:5, Informative)
During the 1959-2002 period, the total CO2 emissions equaled ~220 gigatons; ~14% of the atmospheric CO2 in 1959.
In 2002, Humanity pumped 7 gigatons (6975 megatons) of CO2 into the atmosphere. That is almost 4 times the emissions from 50 years ago (1952: 1795 megatons), and is more than was released from 1751-1886 (136 years: 6732 megatons).
There is a close correlation between Antarctic temperature and atmospheric concentrations of CO2. The extension of the Vostok [antarctic ice core] CO2 record shows the present-day levels of CO2 are unprecedented during the past 420 thousand years.
Cites:
Atmospheric carbon dioxide record from Mauna Loa [ornl.gov] [ornl.gov]
Global CO2 Emissions [ornl.gov] [ornl.gov]
Historical carbon dioxide record from the Vostok ice core [ornl.gov] [ornl.gov]
Earth's atmosphere [wikipedia.org] [wikipedia.org]
More junk science (Score:1, Informative)
This is like taking a one gallon sample of the stagnant pond and concluding that the only life on Earth is single celled organisms. The Earth is how old? What is the percentage of time of information available. And, how much of the surface was tested? Less than half.
I have had about all of the junk science I can stand. We need some real sceintist making real conclusions.
Re:Food for thought (Score:5, Informative)
'Antartic climate cooling and terrestrial ecosystem response' Nature 415: 517-20
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"Both satellite data and ground stations show slight cooling over the last 20 years."
'Variability and trends in ANtartic surface temperates from in situ and satellite infared measurements' Journal of CLimate, 13: 1674-96
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"Side-looking radar measurements show West Antartic ice is increasing at 26.8 gigatons/yr. Reversing the melting trend of the last 6000 years"
'Positive mass balance of the Ross Ice Streams, West Antarticia' Science 295: 476-80
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"During the last four interglacials, going back 420,000 years, the Earth was warmer than it is today."
'CLimate and atmospheric history of hte past 420,000 years from the Vostok Ice Core, Antartica' Nature 399: 429-36
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"Less Antartic ice has melted today than occured furing the last interglacial"
'Radiocarbon constrains on ice sheet advance and retreat in the Weddell Sea, Antartica' Geology 27: 179-82
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The Sahara has shrunk since 1980
'Africans go back to the land as plants reclaim the desert' New Scientist 175, 21 September 2002.
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On the other hand sea level *is* rising, as it has been for the last 6000 years since the satart of the Holocene, about 10-20 cm every 100 years.
http://www.csr.utexas.edu/gmsl/main.html [utexas.edu]
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Hell I could throw in stats and references about the decreases in tropical storm activity, but I think I've made my point enough.
Re:What would scientists think? (Score:2, Informative)
I think you mean in light of the following...
"In lieu" means instead of.
Re:No.. It doesn't show this... geeze... (Score:5, Informative)
No, it's not. Modeling climate change is far more complicated and difficult than a simpleminded approach like that. For one, it's difficult to predict the effects of aerosol and cloud formation, both of which reflect/scatter light and reduce the total incident solar energy. It's also necessary to model the CO2 harvesting charactersitics of oceans, and glacial movement as well.
I'm not saying global warming *doesn't* exist, or that it's anthropogenic, but real climatologists will tell you that saying CO2 + IR absorption = warming doesn't cut it.
Re:Food for thought (Score:1, Informative)
the present-day levels of CO2 are unprecedented during the past 420 thousand years
Good, and from this we can conclude that the present day temperature is the highest in 420 thousand years. Oh, no, that is not the case. In fact, it was significantly warmer just a few hundred years ago, and warmer again a few thousand years ago.
I don't think anyone seriously disputes the fact that it is getting warmer, but how much in relation to previous times is debatable. I also don't think anyone seriously disputes that our CO2 emissions have some impact on the global climate, but nobody can seriously say how much impact. The main problem with the global warming scare is the fact that we only started systematic measurements in the 1940s. Anything special about the 1940s? Oh yes, they were the coldes decade in a long time.
In other words, the temperature may be going up as part of a cycle, and we may have added slightly to the higher trend, but not a lot. This means that even significant reductions in CO2 emissions migt not matter much, or at all, in the bigger scheme of things. The cries for immediate action are premature and, quite frankly, a little hysterical. Not based in sound science.
No one notice that bright ball in the sky... (Score:2, Informative)
No it doesn't. Every hear of the thing that is 93,000,000 miles away called the Sun? It's causing global warming of Mars as well.
Re:Food for thought (Score:4, Informative)
Possibly the real contributor to global warming is not the warm fuzzies of CO2 but the the heat itself that is released when Carbon based fuels are burned. A coal, oil or gas burning power plant needs to waste one unit of energy for every unit of energy it delivers to the consumer, and that is with the power plant operating at close to 100% efficiency. The worse the efficiency the worse the heat waste.
Eventually, all energy generated or wasted by power plants ends up as waste heat. That waste heat raises the mean temperature of the atmosphere until the T gets high enough so that the energy radiated (proportional to T^4) back into space equals the total of the incident Solar energy and the waste heat energy.
Atmospheric scientists know that the concentration of CO2 is not high enough by itself to cause global warming, so they postulate a "trigger" or "catalyst" effect, which is unproven. Neither my theory nor theirs can explain the last hot house period that occured 1,200 years ago. Then, the CO2 was lower than it is now and there were no power plants spewing heat, so the burning of fossile fuels was not the cause. That leave other possible causes: solar output or volcanos, to name a couple.
Re:Food for thought (Score:4, Informative)
The article did not say that it was warmer than today 1200 years ago. It said the reliable historic data goes back 1200 years, and the current readings exceed it all in terms of magnitude and extremes.
Logic clew-by-four (Score:5, Informative)
Re:Food for thought (Score:3, Informative)
Except that back then "we" were much smaller. Several millions, vs. 6 billion now. Get real.
Re:No.. It doesn't show this... geeze... (Score:4, Informative)
You're completely wrong, chap. (Score:3, Informative)
YEAR | AVERAGE TEMPERATURE IN BRITAIN (deg. C)
0706 | 14
0806 | 14
0906 | 15
1006 | 14
1106 | 14
1206 | 15
1306 | 13
1406 | 15
1506 | 14
1606 | 13
1706 | 14
1806 | 17
1906 | 19
2006 | 21
Notice that even though 2006 is the hottest year of the past 1200, it in no way implies that any of the previous years were hotter, even going back over 1200 years. As shown in the data above, the earlier years could be far colder.
Re:No one notice that bright ball in the sky... (Score:3, Informative)
http://www.realclimate.org/index.php?p=192 [realclimate.org]
mars warming seems to be mainly caused by a decrease in the huge dust storms it has. These storms typically reflect sunlight. If you have a year with few storms the temp can increase by a great deal.
Re:Is this "bad"? (Score:2, Informative)
Re:Interesting... (Score:5, Informative)
From TFA Reliable records from trees and other sources go back only about 1,200 years. So no, they're NOT saying that it was as warm in 800 AD. They are saying that this is the warmest year since 800 AD and that they don't have have any reliable records before that! This is a big difference.
I know that this is Slashdot but you really should try reading the article before making inflamatory statements like "Another crackpot theory bites the dust."
Quit assuming that 800 AD was as warm as today. (Score:5, Informative)
No they didn't and no it doesn't.
1) Nothing was said about the temperature in 800 AD.
2) Nothing was said about the rate of change in temperature in 800 AD.
We didn't have the modern industrial society that is thought to be the primary cause of global warming today. They're just using the tree ring study by Esper, Cook, and Schweingruber as the end point for as far back as we can go. Check out this graph [wikipedia.org] and its explanation on the Wikipedia for more data points.
Basically, the Medieval Warm Period was still an average of 0.4 C cooler than modern times. It took about 800 years for temperatures to drop 0.4 C to the minimum before the Industrial Revolution and only 200 years since then to rise 0.8 C, an 8X difference in rate of change. Global climate does change on its own naturally, but the change since the dawn of the Industrial Age is still the fastest we've ever seen, and we have solid science that shows how it happens in the form of the greenhouse effect. What more will it take for you people to quit filtering the world for the few tenuous scraps of information that back up your preconceived notions?
Re:MOD PARENT UP (Score:3, Informative)
Re:Methodologically Flawed (Score:4, Informative)
Ad 2: Volcanos put no CFCs into the atmosphere. The only significant source of CFCs are humans.
Ad 3: Volcanos do indeed inject some chlorine into the atmosphere. However, these chlorine compunds are unstable, and the chlorine quickly reacts with water vapor to form HCl, which leaves the atmosphere via precipation. Thus, the chlorine injected into the atmosphere is again insignificant. CFCs are problematic because they are so stable.
Moreover, the connection between ozone depletion and global warming is tenous. Both are processes where human emissions change the large scale composition of the atmosphere, but they only weakly influence each other.
Re:Ingrate! (Score:4, Informative)
While these mechanisms are different, to call a 0.6C change over 100 years "rapid" is kind of silly. We really don't know shit about global climate patterns yet. I'm all for cutting back on pollution, and managing how we use our resources a lot better - I just get fired up about "global warming", when:
A) We don't know shit about "global warming", or climate change in general.
B) What we're currently measuring is nothing compared to other changes that we can see historically.
C) Politics, the media, and related funding has more to do with "global warming" than science does.
We need to do a better job protecting our environment, and reducing our footprint, as a WORLD. I just don't think blathering on like idiots about "global warming" is helping us do that. It'd be like blathering on about how spring means that all our snow will melt away - it does, on a regular basis. Like global climate change does to the ice caps and glaciers.
Re:Quit assuming that 800 AD was as warm as today. (Score:3, Informative)
There is some curious micro-structure in the warming trend of the past 200 years: http://en.wikipedia.org/wiki/Image:Instrumental_T
It appears temperatures were flat between 1860 and somewhere between 1910 and 1920, then rose sharply until somewhere around 1940 when they became flat again for 40 years, after which we have experienced another sharp increase between 1980 and the early 2000's. So rather than having had a global warming trend for the past 200 years, we appear to have had 80 years of warming where the rise in temperature has been far faster than 0.8 C/200 years.
Is anyone doing research on this structure? It is extremely pronounced. There is a temptation to dismiss this micro-structure as irrelevant sub-variation on uninteresting scales, but I don't think we know enough about climate to say that.
Anthropogenic greenhouse forcing is still unproven, although it appears pretty compelling to everyone but the anti-scientific true believers whose faith told them that this article said the earth was only as warm as it was in 800 AD. Detailed study of the decade-scale variations in recent global temperatures might produce more definitive proof regarding the major drivers of contemporary climate change, one way or the other.
Re:Logic clew-by-four (Score:4, Informative)
Global warming does not mean that every single place on the globe will get warmer at the same rate. It is an average climate change. In fact, many places will actually get colder. Here is how it works:
Because of the way the earth spins, and the distrobution of land and water, there are "climate bands" going around the globe. At the top, there is a cold one (obviously), beneath that, a "warm" band, then a cooler one, and a warm band again at the equator. This explains some of the wierd things about global climates, including how Alaska and Great Britian are at about the same latitude, but the climates are radically different.
Global warming would cause these bands to shift. At the top and bottom of the world, there would be significant warming on the ice caps, causing significant and possibly even complete melting. Below that, the "cold" bands would move and put places with previously warm and wet climates into a colder, dry zone. These areas would still be habitable, however, the ecosystems would suffer because they would have to deal with a completely new climate, either signicantly warmer, colder, wetter, or dryer than previously.
At the equator, there would also be signficant warmning, causing deserts to grow rapidly (most signifcantly the sahara, which would destroy cropland in africa, and cause even more starvation).
Also, a shift in the major air and water currents (eg the gulf stream) would create new and much more severe weather patterns all over the globe. Some claim the record number of huricanes in the last year are the result of global warming (no real evidence of this that I know of).
Lastly, Global warming is not necessarily caused by humans, or specifically by CO2 and other green house gasses. The earth undergoes periodic, unpredictable and mysterious warm and cold periods, some short, some long. The most recent was the "little ice age". Look it up. That being said, it has been well proven that CO2 absorbs heat from infrared light and releases that heat instead of reflecting it. It is also true that humanity has been dumping much more CO2 into the atmosphere than ever in earth's history. However, scientists will probably never have conclusive proof that this causes global warming, as earth's atmosphere is unimaginably complex.
Hope this is informative.
oh, good frickin' christ almighty!!!!!! (Score:4, Informative)
The residence time of water vapor in the atmosphere is very short, on theorder of a few weeks. Perturb the equlilibrium for water vapor, and within a very short time, the atmosphere returns to equilibrium. The residence time for CO2 is many, many, many orders of mgnitude longer. This means that CO2 increases can create long-term perturbatins in global atmospheric heat flow, but water vapor cant. The climate people refer to this with the pharase, "CO2 is a driver, water is a feedback."
"Possibly the real contributor to global warming is not the warm fuzzies of CO2 but the the heat itself that is released when Carbon based fuels are burned. A coal, oil or gas burning power plant needs to waste one unit of energy for every unit of energy it delivers to the consumer, and that is with the power plant operating at close to 100% efficiency. The worse the efficiency the worse the heat waste. Eventually, all energy generated or wasted by power plants ends up as waste heat. That waste heat raises the mean temperature of the atmosphere until the T gets high enough so that the energy radiated (proportional to T^4) back into space equals the total of the incident Solar energy and the waste heat energy."
That waste heat radiates VERY FAST. Ever notice how cold it gets at night? That is due to radiative heat loss. Add more heat at the surface, and the excess is very rapidly lost. You might also want to calculate the ratio of human heat release to heat input from solar irradiation; the results might show you that this argument is pretty weak.
"Atmospheric scientists know that the concentration of CO2 is not high enough by itself to cause global warming, so they postulate a "trigger" or "catalyst" effect, which is unproven. Neither my theory nor theirs can explain the last hot house period that occured 1,200 years ago. Then, the CO2 was lower than it is now and there were no power plants spewing heat, so the burning of fossile fuels was not the cause. That leave other possible causes: solar output or volcanos, to name a couple."
Your first sentence her is simply absurd. Our planet is not a ball of ice only becaus e of global warming due to CO2. The question is how much the ADDITIONAL CO2 humans are adding to the atmosphere is causing ADDITIONAL warming. And we know that effect is happening; the debates are over how much additinal warming we are/will going to experience with this much additional CO2. That discussion involves known feedback effects (not triggers) like waramer temps causing increased atmospheric water content, for example, leading to a magnification of the warming effect. BTW, this article does NOT say it was hotter 1200 years ago. That is simply as far back as their analysis goes. Other good studies show it was NOT as warm than as it is now.
Re:Ingrate! (Score:5, Informative)
You're right about Kyoto, though. The biggest problem with it is the nations that didn't jump on: China and India. Save the "developing nation" crap. Yes, they're dirt poor. They're also huge polluters because they can't afford proper scrubbing on their stacks. There's also a zillion of them, and CO2 isn't the only way to measure pollution. Think particulate matter. I hear lots of environmentalists saying that 300,000,000 Americans make more pollution than 3,000,000,000 Chinese and Indians. Then how come the skies of our cities aren't choked dark orange in midday like in China? (Yes, I've been there, I know.)
Oh, and for the record: Germany is the only European country actually reducing pollution to meet its Kyoto obligations. CO2 output is up 7% in France, 11% in Italy, and 29% in Spain (numbers from 2003 - the most recent available). They're supposed to reduce their emissions 8% by 2012. Looks like arrogant Europe is going the wrong way and should get its own house in order before jumping ugly with the U.S.
Good thing I've got Excellent karma. I'm going to need it after this one.