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20th Century Warmest In 1200 Years
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."
It's "Global Climate Change",
The findings of this study are hopelessly flawed in that they conflict with the principle that only the scientific positions of the campaign contributors to the ruling party in the United States are in any way valid. Please take your actual science with its actual testing and actual methods of deduction elsewhere, as we've got Italian sports cars, mansions, and private jets to buy.
This sig, aah-ah, is comin' like a ghost-sig...
It's the Bush Administration's gift to the world -- lower heating bills and summer vacations all year round!
If this is the warmest in so many years, then back then it was hotter that what we have now.
I am defenseless. Use your button. Mod me down with all of your hatred.
There has been a 19.4% increase in the mean annual concentration of CO2 in the atmosphere from 1959 to 2004.
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]
Global CO2 Emissions [ornl.gov]
Historical carbon dioxide record from the Vostok ice core [ornl.gov]
Earth's atmosphere [wikipedia.org]
Let's take a pool on exactly how many posts this story will receive from partisans claiming that because the earth has been this warm in the past (the 800s) through natural causes, the earth either is not unusually warm now, or if it is warm now it must be because of natural causes--
not realizing that (1) the thing that makes manmade global climate change distinguishable from natural global climate fluctuations is not how warm the earth has become, but how quickly and consistently the earth has warmed since the industrial revolution;
and (2) the problem with manmade global climate change is not how warm the earth is now, but how warm it will become if this consistent, quick rise continues...
What's your guess? 10? 40? 100?
Fact is, we're looking at a ~2000 year snapshot of an incredibly comlex system that's a few billion years old.
I'm not saying that there isn't claimte change -- of course there is. I'm also not saying that man doesn't affect it -- of course we do. But what I'm saying is that we don't know how we are affecting it. Maybe the "Little Ice-Age" ended because of man. Perhaps we saved ourselves from freezing to death by creating a cozy CO2 blanket?
My 2c...
Help me out here. If it was warmer in 800 AD, what 'human interferance' caused the global warming in the 9th century?
Vikings in SUVs, duh.
Quidquid latine dictum sit, altum sonatur.
And, in a few years, when melting arctic and Greenland ice has disrupted the Atlantic Conveyor, northern europe, including Great Britain and Scandanavia, will be much, much colder.
The article doesn't say what happened in the 8th century, just that tree rings don't reliably go back any farther. They must be using only specific species of trees, though, because there there are several species of living trees that are much, much older. Do their rings not reflect temperature, too?
The article contains almost no technical data, but it does say there have been been conflicting results:
"In 2003, a team led by researchers from the Harvard-Smithsonian Center for Astrophysics announced that it believed the 20th century wasn't the warmest, nor the one with the most extreme weather of the past 1,000 years.
"But this research has been criticized for its selection of the indicators used to estimate historic temperatures, among other problems."
The article doesn't say what indicators the Harvard-Smithsonian group used, just that they think their indicators are better.
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.
The warming of the globe as a whole will cause some locations to actually cool down, as air and water currents re-route.
This does not change the fact that the globe as a whole is warming.
(And frankly it is irrelevent whether humans are to blame or not. It is warming, which is going to cause climate change. Are we ready for it? If not, we may want to try to stop it (or at least slow it down).
I doubt we are.)
'Sensible' is a curse word.
Earth is way overdue for a magnetic field reversal. They have an average interval of 1/4 million years and it has been 3/4 million already since the last one. Some say it is beginning with the loss of a magnetic pole in certain places in the southern hemisphere. It could be the cause of the ozone layer loss because as the field weakens it radius at the poles grows. When the field is strong the field meets at the poles in a tight radius.
Here are some cool sims from Los Alamos National Laboratory.
As we lose protection more radiation gets through and mother earth gets a temperature. I'm not saying that 100 years of intense burning hasn't contributed but this seems to be an ignored fact that may be contributing in a large manner.
I first heard of this from watching a NOVA program. Here is the NOVA site on earths magnetic fields with some animations.
Ok, now where did I put the SPF 10,000?
Gizmos Gagets For Ninjas
You need to be modded "-1 Has Stick In Ass."
Warning: Apple/Nintendo fangirl. Likes her electronics cute & cuddly. May be rabid.
I'm going insane here -- everyone is saying "how does this prove anything if it was warmer in 800AD?" THAT'S NOT WHAT THE ARTICLE SAYS! "Warmest in 1200 years" does NOT implicitly mean it was warmer 1200 years ago, people -- read the article, we CAN ONLY TEST BACK 1200 years using ice cores, trees, etc.... it was COLDER 1200 years ago, that's what the article says... and as for the folks who mentioned the Little Ice Age, etc. -- yes, they mention that too (and the Medieval Warm Period from 890 to 1170), but both eras were not CONTINUOUSLY warm or cool, but were PUNCTUATED by hot and cold SPELLS... The concern of global warming is that the CONTINUOUS temperature is changing. I will concede that without data before 800AD, the study is looking at a pretty small sample of time, and that there are so many factors in such a hugely complex weather system to take into consideration, so I have no problem at all with those arguments, just with the fact that the majority of people here seem to be good at quickly sorting through text looking for keywords (such as "since 800AD") without actually COMPREHENDING what they are reading.... /rant.
That's an important point. Calling the phenomenon Global Warming is perhaps misleading. Some places will get warmer, others colder. Some will be wetter, some dryer. Dumping more energy into a chaotic system like the climate means more extreme climates, not necessarily warmer ones.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
I thought yesterday Slashdot told me there was no such thing as time. So 1200 years ago is actually now. I'm so confused.
Big ones, small ones, some as big as yer 'ead!
Give 'em a twist, a flick o' the wrist...
Here is some commentary on this article from the Junk Science people:
http://www.junkscience.com/feb06/NotCO2.htm
I find their opposing views are sometimes interesting.
If the data they considered stops 1200 years ago then it can be correct that this was the warmest century in those 1200 years *and* it was colder before that. Similarly, if this was the hottest January on record that doesn't mean the hottest January ever.
Not necessarily:
Assume we are looking at n time intervals numbered 1, 2, ..., n. If the maximum observed temperature was in interval n, we can assert that this interval was the warmest of the last n intervals.
Now consider interval 0. If this interval is warmer than n, the strongest assertion we can make is that the recent interval is the warmest of the last n. If the recent interval is warmer than 0, we could make a stronger assertion. However, the validity of 'warmest of the last n remains.
In effect, you are assuming that the researchers made the strongest possible assertion. Another alternative is that they were only able to measure a certain number of intervals.
Clouds can also have a blanketing effect as well as a reflective effect. Also, H2O is a greenhouse gas, adding still more complexity to the problem. Add in the natural variability of solar influx, changes in the reflectivity of the surface due to deforestation, changing ice cover, urbanization, etc and it becomes even more complex. Frankly, I'd rather model supernova explosions, they're a lot simpler.
So here we are again, another long rant from two sides of an argument where those arguing are not in possesion of most of the facts.
It always amazes me that these two sides will get into bitter feuds over this subject and no one seems to want to put it in any context. For me what it comes down to is this: we can spend a lot of money, time, and research trying to find out if we are a contributing factor to global warming, only to discover it may be too late, or we can spend even more money, time, and research trying to change the way we interact with the atmosphere. And in the end if those who claim that global warming is impacted by humans are right and we listened to them then we are on our way to fixing it and have a cleaner environment for the future. If they are wrong and we listened to them we still have a cleaner environment and we might just find that all those chemicals we were pumping into the atmosphere had other effects which would then be limited. If, on the other hand we don't listen to them and they are right then we have to learn to live in a new world climate and deal with the vast ammounts of crap we have been pumping into the atmosphere for centuries.
What it comes down to, for me, is this: do we want to risk the global climate on this? Is it worth the piece of mind to know that what happens is out of our control instead of our fault?
On a more serious note, there are people that think global warming is good. Receding ice caps leave minerals in the ocean that encourage sea life and will help feed the world's population. Receding glaciers will open up valuable, fertile ground that hasn't been farmed for nearly a thousand years. And the increase in temperature will raise the humidity world wide, perhaps turning the Sahara desert into the rain forest it used to be, and expanding the world's rainforests to new latitudes.
I could also see a future when there is no freezing winter, it's jus a year-round summer like on the tropical islands. Maybe then we won't be losing so many homeless to the random snowstorms of today.
I often wonder what the world would be like if every year the north and south poles melted. Would the entire world turn into a humid tropical paradise?
The radical sect of Islam would either see you dead or "reverted" to Islam.
So could you please refute his argument with, oh, I don't know, data?
You better watch out, there may be dogs about . .
They're saying that it was every bit as warm in 800 A.D. then? That kinda discounts their theory that modern man is causing global warming then doesn't it?.
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 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?
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
Hey, making inflamatory statements without having any idea what we're talking about is all some of us have!!
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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.
Stephan
"Except for the fact that water vapor is SEVEN TIMES the green house gas that CO2 is, and it is present in the atmosphere in MUCH MUCH higher concentrations. Over all, water vapor contributes 280,000 time more to the greenhouse effect than CO2, and it's been doing it for ages, long before CO2 rose 25% to a measley 375 parts per million."
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.