Global Warming™, Global Cooling... All Part of a Natural and On-going Cycle
Rewriting Glacial History In Pacific North America
Edmonton AB, Jan 10, 2006 [All emph. add.]
Glacier fluctuations are sensitive indicators of past climate change, yet little is known about glacier activity in Pacific North America during the first millennium A.D.
Alberto Reyes, a PhD student in the Department of Earth and Atmospheric Sciences [at the University of Alberta], and his research team have found evidence for a regionally-extensive glacier expansion in the first millennium AD, suggesting that climate during the last several thousand years may have been even more variable than previously thought.
The research appears in the journal Geology. [...]
Most of the evidence they found was in the form of buried soils and logs covered by glacial sediments. "In some cases, entire forest stands were buried by sediments and their trunks sheared off by advancing ice," said Reyes. [...]
Samples were then sent off for radiocarbon dating and when the results came back, the researchers were able to tell a story about when each individual glacier was expanding. Reyes had earlier noted the first millennium AD glacier advance at the glacier he was studying for his master's thesis, which jumped out because it was not thought that glaciers in the region were expanding at that time.
After poring over old data and early results of new research, the team found that many other glaciers had advanced during that period. "If only one or two glaciers are advancing at any particular time it is not really significant," said Reyes. "But when many glaciers across a wide region are advancing with some degree of synchronicity, there is likely something going on with regional climate that causes the glaciers to advance."
Reyes was surprised that the regional nature of this first millennium AD glacier advance remained unrecognized for so long. He suspects some of the earlier reports that hinted at the existence of an advance stayed under the radar because they did not fit into the established chronology of past glacier activity.The glacier data reported by Reyes and colleagues, together with other clues of past climate, support an emerging idea that climate in the North Pacific region has cycled from warmer to colder intervals several times over the last 10,000 years.
Edmonton AB, Jan 10, 2006 [All emph. add.]
Glacier fluctuations are sensitive indicators of past climate change, yet little is known about glacier activity in Pacific North America during the first millennium A.D.
Alberto Reyes, a PhD student in the Department of Earth and Atmospheric Sciences [at the University of Alberta], and his research team have found evidence for a regionally-extensive glacier expansion in the first millennium AD, suggesting that climate during the last several thousand years may have been even more variable than previously thought.
The research appears in the journal Geology. [...]
Most of the evidence they found was in the form of buried soils and logs covered by glacial sediments. "In some cases, entire forest stands were buried by sediments and their trunks sheared off by advancing ice," said Reyes. [...]
Samples were then sent off for radiocarbon dating and when the results came back, the researchers were able to tell a story about when each individual glacier was expanding. Reyes had earlier noted the first millennium AD glacier advance at the glacier he was studying for his master's thesis, which jumped out because it was not thought that glaciers in the region were expanding at that time.
After poring over old data and early results of new research, the team found that many other glaciers had advanced during that period. "If only one or two glaciers are advancing at any particular time it is not really significant," said Reyes. "But when many glaciers across a wide region are advancing with some degree of synchronicity, there is likely something going on with regional climate that causes the glaciers to advance."
Reyes was surprised that the regional nature of this first millennium AD glacier advance remained unrecognized for so long. He suspects some of the earlier reports that hinted at the existence of an advance stayed under the radar because they did not fit into the established chronology of past glacier activity.The glacier data reported by Reyes and colleagues, together with other clues of past climate, support an emerging idea that climate in the North Pacific region has cycled from warmer to colder intervals several times over the last 10,000 years.
posted by Oroborous at 12:24 AM
7 Comments:
See Reid Bryson, 'Climates of Hunger" (if you can find it) and Emanuel Le Roy Ledurie's book on European glaciers, whose title I have forgotten.
After a while, these revelations stop surprising anybody who's been paying attention.
Bryson, at least, wrote about cooling and drying in western North America in the latter centuries of the first millenium. And that was 30 years ago.
Intellicast has a meteorologist who writes extensively, and reasonably technically, on this subject.
These articles from Dr. Dewpoint are an excellent hysteria corrective.
Cool, thx.
I caught a bit of a TV interview the other day with MIT's resident Chicken Little, Kerry Emmanuel, who has tabulated hurricanes for the past 35 years and 'discovered' that warming has caused them to double in intensity and size, worldwide.
'35' is the key fact here. What he means is that he used records as far back as satellites take him.
It might be that hurricanes are smaller and less intense than they were 70 years ago, but Emmanuel has no idea, because a good fraction of the world's hurricanes arise and die in the eastern tropical Pacific, an area where almost no humans ever go.
Until satellite surveys, such hurricanes were never observed unless one swerved north to Hawaii or made it as far west as the Marianas.
When the satellite records become available, the 'number' of Pacific hurricanes jumps by a factor of 2 or 3.
If I know this way out on the edge of the known world -- I got it by interviewing Neil Frank, who used to be director of the National Hurricane Center, after Katrina -- then it becomes really, really difficult to accept the fundamental intellectual honesty of people like Emmanuel.
Just so.
I don't know if there is a sustained warming trend occurring or not, but I'm very skeptical that we have enough data, and knowledge of how the system works, to say that humans are having a significant effect, much less CAUSING the warming.
We know that before there were enough humans to matter, the Earth warmed and cooled, for whatever reasons - volcanoes, sunspots, solar flares, ocean salinity...
I'd like to see some ten-year projections made, and found to be accurate, before I'll believe that humans have a good grasp and model of climatology.
Harry:
Funny you should mention that 35 yr thing.
The Atlantic, being far smaller than the Pacific, is proportionately better known.
Who knows if the Pacific has a cyclone cycle, but the Atlantic has a 30-ish year hurricane cycle.
Which was at its ebb with the first weather satellites.
Another thing about hurricanes. They are giant heat engines, taking very warm air from the surface and hurling it up a half dozen miles.
That means hurricanes pump heat to where it can more easily radiate into space.
And one other thing. CO2 preferentially blocks emission of infrared from the earth's surface back into space. But CO2 isn't a one-way filter. It also preferentially blocks the infrared part of the sun's spectrum.
The delta is what matters. Do the climate models take that into account?
And one other one other thing. Ceteris paribus, the earth's climate would get warmer simply by operating machines. Where does that affect show up in the models?
I find it plausible that human activity is having an effect on climate, but as Oroborous points out we really can't point to a conclusive model. And how can you possibly control for the other variables that the article points out to get a definitive answer?
The upshot is that if our activity is having an effect, well then that's how it has to be. We'll just have to adapt to whatever changes we cause. Giving the "all stop" order to economic activity is not an option. Whatever changes we make to mitigate our impact will have to be evolutionary, and cannot be at the expense of economic growth or productivity.
Post a Comment
<< Home