Skip to comments.The Cooling World (Blast From The Past Archived Newsweek Article Warning About "Global Cooling")
Posted on 10/02/2003 10:21:17 AM PDT by presidio9
There are ominous signs that the Earths weather patterns have begun to change dramatically and that these changes may portend a drastic decline in food production with serious political implications for just about every nation on Earth. The drop in food output could begin quite soon, perhaps only 10 years from now. The regions destined to feel its impact are the great wheat-producing lands of Canada and the U.S.S.R. in the North, along with a number of marginally self-sufficient tropical areas parts of India, Pakistan, Bangladesh, Indochina and Indonesia where the growing season is dependent upon the rains brought by the monsoon.
The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it. In England, farmers have seen their growing season decline by about two weeks since 1950, with a resultant overall loss in grain production estimated at up to 100,000 tons annually. During the same time, the average temperature around the equator has risen by a fraction of a degree a fraction that in some areas can mean drought and desolation. Last April, in the most devastating outbreak of tornadoes ever recorded, 148 twisters killed more than 300 people and caused half a billion dollars' worth of damage in 13 U.S. states.
To scientists, these seemingly disparate incidents represent the advance signs of fundamental changes in the world's weather. Meteorologists disagree about the cause and extent of the trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century. If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic. A major climatic change would force economic and social adjustments on a worldwide scale, warns a recent report by the National Academy of Sciences, because the global patterns of food production and population that have evolved are implicitly dependent on the climate of the present century.
A survey completed last year by Dr. Murray Mitchell of the National Oceanic and Atmospheric Administration reveals a drop of half a degree in average ground temperatures in the Northern Hemisphere between 1945 and 1968. According to George Kukla of Columbia University, satellite photos indicated a sudden, large increase in Northern Hemisphere snow cover in the winter of 1971-72. And a study released last month by two NOAA scientists notes that the amount of sunshine reaching the ground in the continental U.S. diminished by 1.3% between 1964 and 1972.
To the layman, the relatively small changes in temperature and sunshine can be highly misleading. Reid Bryson of the University of Wisconsin points out that the Earths average temperature during the great Ice Ages was only about seven degrees lower than during its warmest eras and that the present decline has taken the planet about a sixth of the way toward the Ice Age average. Others regard the cooling as a reversion to the little ice age conditions that brought bitter winters to much of Europe and northern America between 1600 and 1900 years when the Thames used to freeze so solidly that Londoners roasted oxen on the ice and when iceboats sailed the Hudson River almost as far south as New York City.
Just what causes the onset of major and minor ice ages remains a mystery. Our knowledge of the mechanisms of climatic change is at least as fragmentary as our data, concedes the National Academy of Sciences report. Not only are the basic scientific questions largely unanswered, but in many cases we do not yet know enough to pose the key questions.
Meteorologists think that they can forecast the short-term results of the return to the norm of the last century. They begin by noting the slight drop in overall temperature that produces large numbers of pressure centers in the upper atmosphere. These break up the smooth flow of westerly winds over temperate areas. The stagnant air produced in this way causes an increase in extremes of local weather such as droughts, floods, extended dry spells, long freezes, delayed monsoons and even local temperature increases all of which have a direct impact on food supplies.
The worlds food-producing system, warns Dr. James D. McQuigg of NOAAs Center for Climatic and Environmental Assessment, is much more sensitive to the weather variable than it was even five years ago. Furthermore, the growth of world population and creation of new national boundaries make it impossible for starving peoples to migrate from their devastated fields, as they did during past famines.
Climatologists are pessimistic that political leaders will take any positive action to compensate for the climatic change, or even to allay its effects. They concede that some of the more spectacular solutions proposed, such as melting the Arctic ice cap by covering it with black soot or diverting arctic rivers, might create problems far greater than those they solve. But the scientists see few signs that government leaders anywhere are even prepared to take the simple measures of stockpiling food or of introducing the variables of climatic uncertainty into economic projections of future food supplies. The longer the planners delay, the more difficult will they find it to cope with climatic change once the results become grim reality.
Reprinted from Financial Post - Canada, Jun 21, 2000
But since you brought up the Vostok ice core, I just have to show some interesting data plots from it:
Comment: the ice core shows that over the past 400,000 years, atmospheric CO2 concentrations varied between an upper bound of ~290 ppm and a lower bound of ~190 ppm. Climate scientists are real interested in determining what determined those bounds. Atmospheric CO2 concentration is currently at ~370 ppm -- 80 ppm higher than that upper bound! But there is a lag time in the climate system. So the problem facing the climate science community is; what is the rapid increase in atmospheric CO2 concentration, out of the 400,000 year bounds, going to cause?
Here's the other plot (at the far right edge you can see how high current atmospheric CO2 concentrations are):
Comment: this shows that CO2 and temperature have been linked over the past 400,000 years. Most studies show that the warming was driven by other factors and that CO2 concentration responded to warming or cooling. The problem facing climate scientists now is that the CO2 rise is occurring in a nominally "stable" temperature regime, so it will be a forcing factor for climate change. How much the change will be, and how fast, is very uncertain.
This is the type of data I'd like to discuss with ancient_geezer. I just need some time to prepare a full treatment.
It may not be as troubling as at first look, if we consider that the current 370 CO2 is only 22 percent higher that the highest 304 from Vostok ( as I recall from the table of data) (close to this on graph).
We don't know the accuracy of CO2 and Temperature data from 300,000 years ago. I suspect +/- 22 percent accuracy of the data would be very good. The ~304 years ago may have actually been ~370.
In fact, a couple of the web references state that the CO2 concentrations lag the temperature data by 1000 to 4000 years. This means that we need to learn much more.
But it all is very interesting.
Those cycles are fascinating. I am glad to see these threads.
CO2 concentrations are not calculated from proxies; they are directly measured from bubbles trapped in the ice, and therefore are probably quite accurate. The temperature is determined from stable oxygen isotope ratios and is more uncertain.
But here is an interesting statement ---"Because air bubbles do not close at the surface of the ice sheet but only near the firn-ice transition (that is, at ~90 m below the surface at Vostok), the air extracted from the ice is younger than the surrounding ice (Barnola et al. 1991). Using semiempirical models of densification applied to past Vostok climate conditions, Barnola et al. (1991) reported that the age difference between air and ice may be ~6000 years during the coldest periods instead of ~4000 years, as previously assumed."
I need to ponder this statement. Have any thoughts on this?
This is further down in the link ---"According to Barnola et al. (1991) and Petit et al. (1999) these measurements indicate that, at the beginning of the deglaciations, the CO2 increase either was in phase or lagged by less than ~1000 years with respect to the Antarctic temperature, whereas it clearly lagged behind the temperature at the onset of the glaciations. "
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