søndag den 13. januar 2008
torsdag den 10. januar 2008
January 3, 2008NORTH ATLANTIC WARMING TIED TO NATURAL VARIABILITY; BUT BLOBAL WARMING MAY BE AT PLAY ELSEWHEREA Duke University-led analysis of available records shows that while the North Atlantic Ocean's surface waters warmed in the 50 years between 1950 and 2000, the change was not uniform. In fact, the subpolar regions cooled at the same time that subtropical and tropical waters warmed.
This striking pattern can be explained largely by the influence of a natural and cyclical wind circulation pattern called the North Atlantic Oscillation (NAO), wrote authors of a study published Thursday, Jan. 3, in Science Express, the online edition of the journal Science.
Winds that power the NAO are driven by atmospheric pressure differences between areas around Iceland and the Azores. "The winds have a tremendous impact on the underlying ocean," said Susan Lozier, a professor of physical oceanography at Duke's Nicholas School of the Environment and Earth Sciences who is the study's first author.
Other studies cited in the Science Express report suggest human-caused global warming may be affecting recent ocean heating trends. But Lozier and her coauthors found their data can't support that view for the North Atlantic. "It is premature to conclusively attribute these regional patterns of heat gain to greenhouse warming," they wrote.
"The take-home message is that the NAO produces strong natural variability," said Lozier in an interview. "The simplistic view of global warming is that everything forward in time will warm uniformly. But this very strong natural variability is superimposed on human-caused warming. So researchers will need to unravel that natural variability to get at the part humans are responsible for."
In research supported by the National Science Foundation in the United States and the Natural Environment Research Council in the United Kingdom, her international team analyzed 50 years of North Atlantic temperature records collected at the National Oceanic Data Center in Washington, D.C.
To piece together the mechanisms involved in the observed changes, their analysis employed an ocean circulation model that predicts how winds, evaporation, precipitation and the exchange of heat with the atmosphere influences the North Atlantic's heat content over time. They also compared those computer predictions to real observations "to test the model's skill," the authors wrote.
Her group's analysis showed that water in the sub-polar ocean – roughly between 45 degrees North latitude and the Arctic Circle – became cooler as the water directly exchanged heat with the air above it.
By contrast, NOA-driven winds served to "pile up" sun-warmed waters in parts of the subtropical and tropical North Atlantic south of 45 degrees, Lozier said. That retained and distributed heat at the surface while pushing underlying cooler water further down.
The group's computer model predicted warmer sea surfaces in the tropics and subtropics and colder readings within the sub-polar zone whenever the NAO is in an elevated state of activity. Such a high NAO has been the case during the years 1980 to 2000, the scientists reported.
"We suggest that the large-scale, decadal changes...associated with the NAO are primarily responsible for the ocean heat content changes in the North Atlantic over the past 50 years," the authors concluded.
However, the researchers also noted that this study should not be viewed in isolation. Given reported heat content gains in other oceans basins, and rising air temperatures, the authors surmised that other parts of the world's ocean systems may have taken up the excess heat produced by global warming.
"But in the North Atlantic, any anthropogenic (human-caused) warming would presently be masked by such strong natural variability," they wrote.##
[edit] The wager
Simon had Ehrlich choose five of several commodity metals. Ehrlich chose 5 metals: copper, chromium, nickel, tin, and tungsten. Simon bet that their prices would go down. Ehrlich bet they would go up.
"The face-off occurred in the pages of Social Science Quarterly, where Simon challenged Ehrlich to put his money where his mouth was. In response to Ehrlich's published claim that "If I were a gambler, I would take even money that England will not exist in the year 2000" - a proposition Simon regarded as too silly to bother with - Simon countered with "a public offer to stake US$10,000 ... on my belief that the cost of non-government-controlled raw materials (including grain and oil) will not rise in the long run.
You could name your own terms: select any raw material you wanted - copper, tin, whatever - and select any date in the future, "any date more than a year away," and Simon would bet that the commodity's price on that date would be lower than what it was at the time of the wager." ... Ehrlich and his colleagues picked five metals that they thought would undergo big price rises: chromium, copper, nickel, tin, and tungsten. Then, on paper, they bought $200 worth of each, for a total bet of $1,000, using the prices on September 29, 1980, as an index. They designated September 29, 1990, 10 years hence, as the payoff date. If the inflation-adjusted prices of the various metals rose in the interim, Simon would pay Ehrlich the combined difference; if the prices fell, Ehrlich et al. would pay Simon. ... Between 1980 and 1990, the world's population grew by more than 800 million, the largest increase in one decade in all of history. But by September 1990, without a single exception, the price of each of Ehrlich's selected metals had fallen, and in some cases had dropped through the floor. Chrome, which had sold for $3.90 a pound in 1980, was down to $3.70 in 1990. Tin, which was $8.72 a pound in 1980, was down to $3.88 a decade later. [1]
As a result, in October 1990, Paul Ehrlich mailed Julian Simon a check for $576.07 to settle the wager in Simon's favor.
[edit] Analysis of why Ehrlich lost
According to Paul Ehrlich's website: "In 1980, Julian Simon repeatedly challenged environmental scientists to bet against him on trends in prices of commodities, asserting that humanity would never run out of anything.... Paul and the other scientists knew that the five metals in the proposed wager were not critical indicators and said so at the time.... They emphasized that the depletion of so-called renewable resources--environmental resources such as soils, forests, species diversity, and groundwater--is much more indicative of the deteriorating state of society's life-support systems....Nonetheless, after consulting with many colleagues, Paul and Berkeley physicists John Harte and John Holdren accepted Simon's challenge in late 1980..."[1]
It's not clear if Ehrlich consulted with economists. If he had, the flaw in using commodity prices as the best way to understand biophysical limits might have become obvious. Many economists understand the principle of substitution and the dynamic influence of technology with respect to commodity prices. For example, in the absence of any new technologies, copper prices would indeed be expected to increase as growing economies demanded more copper to meet the needs of expanding communications networks and plumbing infrastructure. Technological changes mitigated much of this expected demand as fiber optics replaced copper wire networks and various plastics replaced the once ubiquitous copper pipes throughout the construction industry.
Julian Simon won because the price of three of the five metals went down in absolute terms and all five of the metals fell in price in inflation-adjusted terms,[1][2] with both tin and tungsten falling by more than half. So, per the terms of the wager, Ehrlich paid Simon the difference in price between the same quantity of metals in 1980 and 1990 (which was $576.07). The prices of all five metals increased between 1950 and 1975, but Ehrlich believes three of the five went down during the 1980s because of the price of oil doubling in 1979, and because of a worldwide recession in the early 1980s.
Yet, it is significant that, according to an article in Wired:
All of [Ehrlich's] grim predictions had been decisively overturned by events. Ehrlich was wrong about higher natural resource prices, about "famines of unbelievable proportions" occurring by 1975, about "hundreds of millions of people starving to death" in the 1970s and '80s, about the world "entering a genuine age of scarcity." In 1990, for his having promoted "greater public understanding of environmental problems," Ehrlich received a MacArthur Foundation Genius Award."
[Simon] always found it somewhat peculiar that neither the Science piece nor his public wager with Ehrlich nor anything else that he did, said, or wrote seemed to make much of a dent on the world at large. For some reason he could never comprehend, people were inclined to believe the very worst about anything and everything; they were immune to contrary evidence just as if they'd been medically vaccinated against the force of fact. Furthermore, there seemed to be a bizarre reverse-Cassandra effect operating in the universe: whereas the mythical Cassandra spoke the awful truth and was not believed, these days "experts" spoke awful falsehoods, and they were believed. Repeatedly being wrong actually seemed to be an advantage, conferring some sort of puzzling magic glow upon the speaker."[3]
Exponential population growth cannot continue indefinitely for any species, whether it exists as microbes in a petri dish, wild salmon at sea, caribou in the taiga, or a global human society. However, world population is no longer growing exponentially; it has been decelerating for the last half century or so, and UN projections show that it may actually decline after 2040.[4][5]
Simon offered to raise the wager to $20,000 and to use any resources at any time that Ehrlich preferred. Ehrlich countered with a challenge to bet that temperatures would increase in the future.[1] The two were unable to reach an agreement on the terms of a second wager.
Inflation-adjusted price movements of the commodities in the wager between Simon and Ehrlich may be seen in the larger 1950-2002 context in the following chart. Prices were generally rising from 1960 up until 1978, and generally falling thereafter.
[edit] Aftermath
The price of raw and other natural commodities such as oil, gold, and uranium have risen substantially in recent years, due to increased demand from China, India, and other industrializing countries. However, this short term price increase is not contrary to Simon's cornucopian theory.
"More people, and increased income, cause resources to become more scarce in the short run. Heightened scarcity causes prices to rise. The higher prices present opportunity, and prompt inventors and entrepreneurs to search for solutions. Many fail in the search, at cost to themselves. But in a free society, solutions are eventually found. And in the long run the new developments leave us better off than if the problems had not arisen. That is, prices eventually become lower than before the increased scarcity occurred."
[2]
[edit] The proposed second wager
Understanding that Simon wanted to bet again, Ehrlich and climatologist Stephen Schneider counter-offered, challenging Simon to bet on 15 current trends, betting $1000 that each will get worse (as in the previous wager) over a ten year future period.[3]
The trends they bet would continue to worsen were:
The three years 2002-2004 will on average be warmer than 1992-1994.
There will be more carbon dioxide in the atmosphere in 2004 than in 1994.
There will be more nitrous oxide in the atmosphere in 2004 than 1994.
The concentration of ozone in the lower atmosphere (the troposphere) will be greater than in 1994.
Emissions of the air pollutant sulfur dioxide in Asia will be significantly greater in 2004 than in 1994.
There will be less fertile cropland per person in 2004 than in 1994.
There will be less agricultural soil per person in 2004 than 1994.
There will be on average less rice and wheat grown per person in 2002-2004 than in 1992-1994.
In developing nations there will be less firewood available per person in 2004 than in 1994.
The remaining area of virgin tropical moist forests will be significantly smaller in 2004 than in 1994.
The oceanic fisheries harvest per person will continue its downward trend and thus in 2004 will be smaller than in 1994.
There will be fewer plant and animal species still extant in 2004 than in 1994.
More people will die of AIDS in 2004 than in 1994.
Between 1994 and 2004, sperm cell counts of human males will continue to decline and reproductive disorders will continue to increase.
The gap in wealth between the richest 10% of humanity and the poorest 10% will be greater in 2004 than in 1994.
Simon declined the bet, and used the following analogy to explain why he did so:
"Let me characterize their [Ehrlich and Schneider's] offer as follows. I predict, and this is for real, that the average performances in the next Olympics will be better than those in the last Olympics. On average, the performances have gotten better, Olympics to Olympics, for a variety of reasons. What Ehrlich and others says is that they don't want to bet on athletic performances, they want to bet on the conditions of the track, or the weather, or the officials, or any other such indirect measure."
Simon's thesis is that humanity's life-style will continue to improve, and several of the points of Ehrlich's second bet may increase for wholly benign reasons. For instance, the prediction of less agricultural soil per capita is a trend that Simon observed in The Ultimate Resource which Simon attributed to long-term rises in agricultural productivity.
Scott Armstrong challenged Al Gore to a climate-related bet in 2007, focussed on year-to-year variation in temperatures [4], but not betting on longer term changes in global average temperatures. [5]
Simon had Ehrlich choose five of several commodity metals. Ehrlich chose 5 metals: copper, chromium, nickel, tin, and tungsten. Simon bet that their prices would go down. Ehrlich bet they would go up.
"The face-off occurred in the pages of Social Science Quarterly, where Simon challenged Ehrlich to put his money where his mouth was. In response to Ehrlich's published claim that "If I were a gambler, I would take even money that England will not exist in the year 2000" - a proposition Simon regarded as too silly to bother with - Simon countered with "a public offer to stake US$10,000 ... on my belief that the cost of non-government-controlled raw materials (including grain and oil) will not rise in the long run.
You could name your own terms: select any raw material you wanted - copper, tin, whatever - and select any date in the future, "any date more than a year away," and Simon would bet that the commodity's price on that date would be lower than what it was at the time of the wager." ... Ehrlich and his colleagues picked five metals that they thought would undergo big price rises: chromium, copper, nickel, tin, and tungsten. Then, on paper, they bought $200 worth of each, for a total bet of $1,000, using the prices on September 29, 1980, as an index. They designated September 29, 1990, 10 years hence, as the payoff date. If the inflation-adjusted prices of the various metals rose in the interim, Simon would pay Ehrlich the combined difference; if the prices fell, Ehrlich et al. would pay Simon. ... Between 1980 and 1990, the world's population grew by more than 800 million, the largest increase in one decade in all of history. But by September 1990, without a single exception, the price of each of Ehrlich's selected metals had fallen, and in some cases had dropped through the floor. Chrome, which had sold for $3.90 a pound in 1980, was down to $3.70 in 1990. Tin, which was $8.72 a pound in 1980, was down to $3.88 a decade later. [1]
As a result, in October 1990, Paul Ehrlich mailed Julian Simon a check for $576.07 to settle the wager in Simon's favor.
[edit] Analysis of why Ehrlich lost
According to Paul Ehrlich's website: "In 1980, Julian Simon repeatedly challenged environmental scientists to bet against him on trends in prices of commodities, asserting that humanity would never run out of anything.... Paul and the other scientists knew that the five metals in the proposed wager were not critical indicators and said so at the time.... They emphasized that the depletion of so-called renewable resources--environmental resources such as soils, forests, species diversity, and groundwater--is much more indicative of the deteriorating state of society's life-support systems....Nonetheless, after consulting with many colleagues, Paul and Berkeley physicists John Harte and John Holdren accepted Simon's challenge in late 1980..."[1]
It's not clear if Ehrlich consulted with economists. If he had, the flaw in using commodity prices as the best way to understand biophysical limits might have become obvious. Many economists understand the principle of substitution and the dynamic influence of technology with respect to commodity prices. For example, in the absence of any new technologies, copper prices would indeed be expected to increase as growing economies demanded more copper to meet the needs of expanding communications networks and plumbing infrastructure. Technological changes mitigated much of this expected demand as fiber optics replaced copper wire networks and various plastics replaced the once ubiquitous copper pipes throughout the construction industry.
Julian Simon won because the price of three of the five metals went down in absolute terms and all five of the metals fell in price in inflation-adjusted terms,[1][2] with both tin and tungsten falling by more than half. So, per the terms of the wager, Ehrlich paid Simon the difference in price between the same quantity of metals in 1980 and 1990 (which was $576.07). The prices of all five metals increased between 1950 and 1975, but Ehrlich believes three of the five went down during the 1980s because of the price of oil doubling in 1979, and because of a worldwide recession in the early 1980s.
Yet, it is significant that, according to an article in Wired:
All of [Ehrlich's] grim predictions had been decisively overturned by events. Ehrlich was wrong about higher natural resource prices, about "famines of unbelievable proportions" occurring by 1975, about "hundreds of millions of people starving to death" in the 1970s and '80s, about the world "entering a genuine age of scarcity." In 1990, for his having promoted "greater public understanding of environmental problems," Ehrlich received a MacArthur Foundation Genius Award."
[Simon] always found it somewhat peculiar that neither the Science piece nor his public wager with Ehrlich nor anything else that he did, said, or wrote seemed to make much of a dent on the world at large. For some reason he could never comprehend, people were inclined to believe the very worst about anything and everything; they were immune to contrary evidence just as if they'd been medically vaccinated against the force of fact. Furthermore, there seemed to be a bizarre reverse-Cassandra effect operating in the universe: whereas the mythical Cassandra spoke the awful truth and was not believed, these days "experts" spoke awful falsehoods, and they were believed. Repeatedly being wrong actually seemed to be an advantage, conferring some sort of puzzling magic glow upon the speaker."[3]
Exponential population growth cannot continue indefinitely for any species, whether it exists as microbes in a petri dish, wild salmon at sea, caribou in the taiga, or a global human society. However, world population is no longer growing exponentially; it has been decelerating for the last half century or so, and UN projections show that it may actually decline after 2040.[4][5]
Simon offered to raise the wager to $20,000 and to use any resources at any time that Ehrlich preferred. Ehrlich countered with a challenge to bet that temperatures would increase in the future.[1] The two were unable to reach an agreement on the terms of a second wager.
Inflation-adjusted price movements of the commodities in the wager between Simon and Ehrlich may be seen in the larger 1950-2002 context in the following chart. Prices were generally rising from 1960 up until 1978, and generally falling thereafter.
[edit] Aftermath
The price of raw and other natural commodities such as oil, gold, and uranium have risen substantially in recent years, due to increased demand from China, India, and other industrializing countries. However, this short term price increase is not contrary to Simon's cornucopian theory.
"More people, and increased income, cause resources to become more scarce in the short run. Heightened scarcity causes prices to rise. The higher prices present opportunity, and prompt inventors and entrepreneurs to search for solutions. Many fail in the search, at cost to themselves. But in a free society, solutions are eventually found. And in the long run the new developments leave us better off than if the problems had not arisen. That is, prices eventually become lower than before the increased scarcity occurred."
[2]
[edit] The proposed second wager
Understanding that Simon wanted to bet again, Ehrlich and climatologist Stephen Schneider counter-offered, challenging Simon to bet on 15 current trends, betting $1000 that each will get worse (as in the previous wager) over a ten year future period.[3]
The trends they bet would continue to worsen were:
The three years 2002-2004 will on average be warmer than 1992-1994.
There will be more carbon dioxide in the atmosphere in 2004 than in 1994.
There will be more nitrous oxide in the atmosphere in 2004 than 1994.
The concentration of ozone in the lower atmosphere (the troposphere) will be greater than in 1994.
Emissions of the air pollutant sulfur dioxide in Asia will be significantly greater in 2004 than in 1994.
There will be less fertile cropland per person in 2004 than in 1994.
There will be less agricultural soil per person in 2004 than 1994.
There will be on average less rice and wheat grown per person in 2002-2004 than in 1992-1994.
In developing nations there will be less firewood available per person in 2004 than in 1994.
The remaining area of virgin tropical moist forests will be significantly smaller in 2004 than in 1994.
The oceanic fisheries harvest per person will continue its downward trend and thus in 2004 will be smaller than in 1994.
There will be fewer plant and animal species still extant in 2004 than in 1994.
More people will die of AIDS in 2004 than in 1994.
Between 1994 and 2004, sperm cell counts of human males will continue to decline and reproductive disorders will continue to increase.
The gap in wealth between the richest 10% of humanity and the poorest 10% will be greater in 2004 than in 1994.
Simon declined the bet, and used the following analogy to explain why he did so:
"Let me characterize their [Ehrlich and Schneider's] offer as follows. I predict, and this is for real, that the average performances in the next Olympics will be better than those in the last Olympics. On average, the performances have gotten better, Olympics to Olympics, for a variety of reasons. What Ehrlich and others says is that they don't want to bet on athletic performances, they want to bet on the conditions of the track, or the weather, or the officials, or any other such indirect measure."
Simon's thesis is that humanity's life-style will continue to improve, and several of the points of Ehrlich's second bet may increase for wholly benign reasons. For instance, the prediction of less agricultural soil per capita is a trend that Simon observed in The Ultimate Resource which Simon attributed to long-term rises in agricultural productivity.
Scott Armstrong challenged Al Gore to a climate-related bet in 2007, focussed on year-to-year variation in temperatures [4], but not betting on longer term changes in global average temperatures. [5]
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