Ned Potter is the science correspondent for ABC's "World News with Charles Gibson." He has reported on such topics as space exploration, the human genome and climate change.
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Rain and Climate
July 23, 2007 4:07 PM
It's been raining, unusually hard, in several parts of the world--England, China, India, and parts of the U.S.--and, quite by coincidence, there is a paper coming in this Thursday's edition of the journal Nature, reporting that, "for the first time, climate scientists have clearly detected the human fingerprint on changing global precipitation patterns over the last century."
That phrase comes from the lead authors at Environment Canada, who worked with other scientists in Britain, Japan and the U.S. They compared rainfall patterns since 1925 with the changes that fourteen different computer models of the climate said ought to have happened, and found that in large parts of the world, they match pretty well.
"We show," they write in the Nature paper, "that anthropogenic forcing [i.e., changes caused by human activity] has had a detectable influence on observed changes in average precipitation within latitudinal bands, and that these changes cannot be explained by internal climate variability or natural forcing."
They found much of the Northern Hemisphere and the southern tropics getting wetter over time, and some tropical regions just north of the Equator--notably the Sahel region in Africa--getting drier.
The abstract of the paper is HERE. The full paper is not online without a subscription, but Nature does have a news piece of its own HERE.
"This is a very important paper," says climate researcher Myles Allen of Oxford, in the Nature news piece. "It identifies the fingerprint of human influence."
There are some important caveats to remember:
--The rainfall records used in the paper are only on land (records at sea, before weather satellites, are spotty), so about two thirds of the planet cannot be measured.
--Weather is not climate, so it's dangerous to say the bad rains today are necessarily connected with global changes.
--Could there be other factors at play? Yes, of course, but this paper found the best match between actual rainfall and the computer models came when the models accounted for "anthropogenic" factors--the increase in greenhouse gases such as carbon dioxide.
There's been a lot of discussion over whether variations in the Sun's intensity could explain the warming of the last 20 years. To that end, there's now a paper in Proceedings of the Royal Society, by a pair of British and Swiss scientists, saying that if anything, "all the trends in the Sun that could have had an influence on the Earth's climate have been in the opposite direction to that required to explain the observed rise in glboal mean temperatures." The full paper is HERE.
Climate is always politically contentious. Thoughts welcomed.
July 23, 2007 | Permalink | Share | User Comments (46)
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Hmmm. But even the forecasters get it right once in a while, with or without valid science to back them up. Just because a forecast or prediction based on some scientific understanding may not be correct all the time, is that any justification for ignoring it completely, especially if it is related to the potential death of our species and the entire planet due to global warming? It just doesn't make sense. I don't care if you're liberal or conservative, if the weather report says it's going to rain buckets tomorrow, you're going to take an umbrella with you, aren't you? And when it doesn't rain, what happens? You sigh in relief and thank the heanevs for another nice day. Why then do people take such a polarized view on global warming when the rationale behind it is exactly the same? Whether you believe the science or not, wouldn't it be better to err on the side of caution and do something about it now when we still have a chance to correct things instead of waiting until the damage and devastation is potentially irreversible, and we all die? Frankly, anyone who chooses to do nothing about their carbon footprint given all of the SCIENCE regarding our excessive pollution on this planet is just being selfish, greedy and LAZY, which just happens to typify the entire so-called Conservative agenda these days. Expend the least amount of effort possible to make the most amount of money at the expense of others that are less fortunate than ourselves. Come on, people. It's time to wake up. Stop thinking about yourself for once and do something to contribute to the greater good of humanity, no matter what your political bias is. This kind of change has to come from EVERYONE, not just the poor or the rich, who we've seen throughout history don't like to do anything unless they're sufficiently motivated, which usually requires the use of guns or guillotines.
Posted by: voiceofreason | Jul 23, 2007 6:09:55 PM
1. Natural processes (the 10,000 year output cycle of the sun) are causing the oceans to warm and release more of their carbon dioxide into the atmosphere.
2. This natural process causes Al Gore to hyperventalate, thus releasing mass quantities of carbon dioxide into the atmosphere, and to provide a ruse for his "carbon-credits" idiot tax on the unsuspecting population.
3. Plants and trees utilize this extra carbon dioxide as plant food, and grow much more rapidly that before.
Posted by: One_American | Jul 23, 2007 6:26:22 PM
Yes this is great, another scientist who draws a conclusion then finds data to support their argument.
How many times does science have to change their thinking over the years before people stop accepting science at face value. The climate change is nothing new, and doesn't have anything to do with "our footprint."
Posted by: joe | Jul 23, 2007 6:55:16 PM
As soon as Al Gore decides what the temperature the earth should be he should let us know. The only thing certain about the earth is that is a dynamic process constantly changing and evolving. There is no correct temperature for the earth. It is a constantly moving target and no matter what Al Gore or the U. N. says we cannot effect the weather. We should of course use less stuff in all facets of our lives, however, even if we do, the earth will continue to heat and cool at it's own pace no matter what we do. Sun spots and volcanoes have much more effect than man will ever have on the earths temperature.
Posted by: Casey | Jul 23, 2007 6:56:05 PM
The are only two reasons why anthropogenic global warming is "contentious:" special interest investment in the causes, and a massive public ignorance of science (amply demonstrated in messages posted here... the guy who says, I'm not a scientist but I think really takes the prize).
Many good articles and links on related issues--by real scientists--there is no reason anyone for anyone to remain ignorant on these issues.
Posted by: W. R. Johnson | Jul 23, 2007 7:16:59 PM
To all the naysayers that debunk science with their own patholigical rationale based on faith, lack of understanding or a propensity for believing propaganda generated by the status quo that wants to do nothing to solve the world's problems that were created by them in the first place, I have only one thing to say to you:
Learn to swim!
For the sake of humanity and the future of this planet I can only hope all you naysayers live on the coast.
Posted by: voiceofreason | Jul 23, 2007 7:24:44 PM
holli - At first glance your synopsis seems oversimplified, but I think in fact that you are right on the money. The earth is currently overpopulated and it has gotten to the point where mother nature can no longer counter what we are doing to the planet. Everyone thinks that aids, the bird flu, and other epidemics are a human tragedy, and they definitely are, but they may in fact thin out enough of us to bring us back in balance with what nature intends.
Posted by: Tom | Jul 23, 2007 8:25:30 PM
Wow! According to these computer models, no humans live in the southern hemisphere! AND rain =global warming? These models are SO scientific, who KNEW?? I guess by global warming they just mean the free, democratic societies. Would it be too much to ask ANY of these geniuses when it will actually show up in reality? Like because of global warming, will we have a reduction in the number of people who freeze to death in winter? Of course not, that does not appear on their computer! How about, since hurricanes only happen during warming, what happens when there are none?? Cooling?? Now that science is reported only when it fits a political agenda, forget any objectivity there either. People who can't tell us the temperature in 10 days claim they can tell us what it will be in 10,000 days. Amazing! Oh, and W.R. Johnson, everyone I know who lives on the coast has told me the water level has not changed in all the time they have lived there, which is a very long time in some cases.
Posted by: Johann | Jul 23, 2007 8:43:25 PM
I planned ahead I live in Colorado at 5400 ft. Let the ice melt.
Posted by: tony | Jul 23, 2007 8:46:08 PM
You're right off the money and nature hardly requires your representation. Everything is fine the way it is. It rains, earth gets warmer, then colder - whatever. Even the craziest hippie liberal intuitively knows that humans have no measurable impact on global climate....as they didn't during the last few hundred ice ages. The whole human caused global warming fad is a fragile group of theories that will NEVER hold up to any serious scientific scrutiny. We've known for decades that ice cores are not a reliable way to measure atmospheric CO2 and yet there it is, the center piece of their whole mess.....even though we also know there is no consistent relationship between even those phony ice core CO2 levels and global temperature. The climate has never been constant and the earth is 4.5 billion years old. We don't matter a bit - get over it.
Posted by: cheesetopping69 | Jul 23, 2007 8:49:40 PM
THERE IS NO CONSENSUS. I've met climatologists who are very skeptical about the global warming hype but they're not being heard. Seems the media has no interest in talking to them.
Spare yourselves the embarrassment this will eventually cause and don't fall for the nonsense. After all, there used to be lots of folks who absolutely insisted that the world was flat.
Man has always had delusions of grandeur. This just one more example.
Posted by: debunkerdude | Jul 23, 2007 10:53:44 PM
Are they predicting the past or the future? Why can't they get the hurricane forecast right for a particular year, just six months out? They have known a lot more about hurricanes for a longer time, than they do global warming.
Even if humans are having this effect, the point is, how does anyone know what the Earth's reaction will be, exactly? Some of these scientists are making statements about conditions decades from now. Why in the World then, can't they get the weather forecast right a few days from now? They can't even predict a cold front developing more than a few days out.
Posted by: SteveS | Jul 23, 2007 11:05:02 PM
man's total impact on global warming and greenhouse gasses contributes less than 3%. Even if man stopped using fossil fuels altogether, the climate would continue to warm at the same rate.
Posted by: Steve | Jul 23, 2007 11:11:48 PM
Global warming and cooling trends have been going on forever, including a mini ice-age only 300 years ago. Accurate temperature recording dates back a mere 118 years, pretty small on a planet that is billions of years old. What is more ignorant...man thinking he is impacting the global weather patterns or man thinking he can influence them?
Posted by: Bill | Jul 23, 2007 11:15:02 PM
Global warming is happening. It is a natural cyclical event. Man's impact on this cyclical change is miniscule. Global warming has been hyped by poor countries seeking influence over rich ones. Political hacks like Gore and self important meteorologists use global warming as a tool to line their own pockets and project their influence. Don't buy into the hype, research things for yourself.
Posted by: J. Seinfeld | Jul 23, 2007 11:19:31 PM
It is interesting to note that it appears only globar warming attracts the ignorant and vociferous opinions of the uneducated hacks, who "dispute" the long established facts in weather science, at a knowledge level of a badly trained monkey.
Why don't these people congregate on physics sites, loudly proclaiming impossibility of electrons being both here and there at the same time and ridiculing probabily functions?
It is a mystery.
Posted by: Dimitry | Jul 23, 2007 11:38:44 PM
Are we to respect scientists anymore or not? They constantly ascribe to global warming any condition that is not like yesterday. We have had horrific floods and droughts before and they had better soon show real evidence or the world will turn them off because we all know most of them are on the take financially for all their doom forcasts.
Posted by: rockychance | Jul 23, 2007 11:49:34 PM
==Even if man stopped using fossil fuels altogether, the climate would continue to warm at the same rate.==
Right. The amount of man-made CO2 in the atmosphere is so high, the warming cycle will continue long after we are gone from this planet.
Posted by: Dimitry | Jul 23, 2007 11:53:35 PM
==They constantly ascribe to global warming any condition that is not like yesterday.==
That's a lie pal. Scientists who publish in peer-reviewed journals (unlike, say, Michael Creiton) never do that. They calculate a significance level of a statistical effect, based on volumes of data extending back decades and sometimes centuries.
What the climate models are predicting is the global warming accentuating the DIFFERENCES in regional climates. Coastal areas getting wetter, inland areas drier. That may be way too complicated concept though, judging by the many comments on this blog.
==We have had horrific floods and droughts before and they had better soon show real evidence or the world will turn them off because we all know most of them are on the take financially for all their doom forcasts.==
The ones that are on the take are a couple of "scientists" (out of many hundreds), who have been specifically funded by the oil companies to publish contrary "studies" disputing everything and anything in order to confuse the semi-illiterate public into thinking there is "scientific controversy" over globa warming.
Posted by: Dimitry | Jul 24, 2007 12:01:34 AM
Ray Irani, the CEO of Occidental Petroleum, would call this article complete hogwash. And since he made over $400 million last year, he knows what he's talking about.
Posted by: wilder5121 | Jul 24, 2007 12:29:03 AM
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