Posted on 04/03/2003 10:49:50 PM PST by farmfriend
20th Century Climate Not So Hot
Cambridge, MA - A review of more than 200 climate studies led by researchers at the Harvard-Smithsonian Center for Astrophysics has determined that the 20th century is neither the warmest century nor the century with the most extreme weather of the past 1000 years. The review also confirmed that the Medieval Warm Period of 800 to 1300 A.D. and the Little Ice Age of 1300 to 1900 A.D. were worldwide phenomena not limited to the European and North American continents. While 20th century temperatures are much higher than in the Little Ice Age period, many parts of the world show the medieval warmth to be greater than that of the 20th century.
Smithsonian astronomers Willie Soon and Sallie Baliunas, with co-authors Craig Idso and Sherwood Idso (Center for the Study of Carbon Dioxide and Global Change) and David Legates (Center for Climatic Research, University of Delaware), compiled and examined results from more than 240 research papers published by thousands of researchers over the past four decades. Their report, covering a multitude of geophysical and biological climate indicators, provides a detailed look at climate changes that occurred in different regions around the world over the last 1000 years.
"Many true research advances in reconstructing ancient climates have occurred over the past two decades," Soon says, "so we felt it was time to pull together a large sample of recent studies from the last 5-10 years and look for patterns of variability and change. In fact, clear patterns did emerge showing that regions worldwide experienced the highs of the Medieval Warm Period and lows of the Little Ice Age, and that 20th century temperatures are generally cooler than during the medieval warmth."
Soon and his colleagues concluded that the 20th century is neither the warmest century over the last 1000 years, nor is it the most extreme. Their findings about the pattern of historical climate variations will help make computer climate models simulate both natural and man-made changes more accurately, and lead to better climate forecasts especially on local and regional levels. This is especially true in simulations on timescales ranging from several decades to a century.
Historical Cold, Warm Periods Verified
Studying climate change is challenging for a number of reasons, not the least of which is the bewildering variety of climate indicators - all sensitive to different climatic variables, and each operating on slightly overlapping yet distinct scales of space and time. For example, tree ring studies can yield yearly records of temperature and precipitation trends, while glacier ice cores record those variables over longer time scales of several decades to a century.
Soon, Baliunas and colleagues analyzed numerous climate indicators including: borehole data; cultural data; glacier advances or retreats; geomorphology; isotopic analysis from lake sediments or ice cores, tree or peat celluloses (carbohydrates), corals, stalagmite or biological fossils; net ice accumulation rate, including dust or chemical counts; lake fossils and sediments; river sediments; melt layers in ice cores; phenological (recurring natural phenomena in relation to climate) and paleontological fossils; pollen; seafloor sediments; luminescent analysis; tree ring growth, including either ring width or maximum late-wood density; and shifting tree line positions plus tree stumps in lakes, marshes and streams.
"Like forensic detectives, we assembled these series of clues in order to answer a specific question about local and regional climate change: Is there evidence for notable climatic anomalies during particular time periods over the past 1000 years?" Soon says. "The cumulative evidence showed that such anomalies did exist."
The worldwide range of climate records confirmed two significant climate periods in the last thousand years, the Little Ice Age and the Medieval Warm Period. The climatic notion of a Little Ice Age interval from 1300 to1900 A.D. and a Medieval Warm Period from 800 to 1300 A.D. appears to be rather well-confirmed and wide-spread, despite some differences from one region to another as measured by other climatic variables like precipitation, drought cycles, or glacier advances and retreats.
"For a long time, researchers have possessed anecdotal evidence supporting the existence of these climate extremes," Baliunas says. "For example, the Vikings established colonies in Greenland at the beginning of the second millennium that died out several hundred years later when the climate turned colder. And in England, vineyards had flourished during the medieval warmth. Now, we have an accumulation of objective data to back up these cultural indicators."
The different indicators provided clear evidence for a warm period in the Middle Ages. Tree ring summer temperatures showed a warm interval from 950 A.D. to 1100 A.D. in the northern high latitude zones, which corresponds to the "Medieval Warm Period." Another database of tree growth from 14 different locations over 30-70 degrees north latitude showed a similar early warm period. Many parts of the world show the medieval warmth to be greater than that of the 20th century.
The study - funded by NASA, the Air Force Office of Scientific Research, the National Oceanic and Atmospheric Administration, and the American Petroleum Institute - will be published in the Energy and Environment journal. A shorter paper by Soon and Baliunas appeared in the January 31, 2003 issue of the Climate Research journal.
NOTE TO EDITORS: Photos of key climate indicators are available online at http://cfa-www.harvard.edu/press/pr0310image.html
Headquartered in Cambridge, Massachusetts, the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists organized into six research divisions study the origin, evolution, and ultimate fate of the universe.
For more information, contact:
David Aguilar, Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
Phone: 617-495-7462 Fax: 617-495-7468
daguilar@cfa.harvard.edu
Christine Lafon
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
Phone: 617-495-7463, Fax: 617-495-7016
clafon@cfa.harvard.edu
Stay Safe !
I wonder if the temperature differentials might explain the additional clothing (jackets) for men and heavy dresses for women.
So9
Maine Weather Stick
New Englanders have used this natural barometer to predict the highs and lows of weather for years. Mounted outside a window, the sprig will point up indicating fair weather and when foul weather approaches, it points down. Since it is actually cut from Maine's abundant Balsam fir trees, the sizes will vary, but generally the sprig is about a foot long and the base is around 2-1/4" tall x 3/8" wide with a pre-drilled hole for nailing.
Essex, who studies the underlying mathematics, physics and computation of complex dynamic processes, raises some very fundamental scientific issues with regard to global warming. Take, for instance, the "average global temperature," which is the primary statistic offered as evidence of global warming. The problem with this statistic is that it has no physical meaning. Temperature is not a thermodynamic variable that lends itself to statistical analysis, nor does it measure a physical quantity.
Also, global average temperatures are strongly tied to CO2 levels, and we have a significant impact on those both by producing CO2 and clearing vegetation that had previously absorbed it.
100 years ago, the Sierra Nevada range had 20 trees per acre. They now support an overgrowth of 300 trees per acre. Recent studies have also revealed that the "clearing of the rain forests" is not happening. 90 to 95% of them are still there.
The climate change debate appears to be rapidly reaching its end. New credible scientific evidence has demonstrated very strong correlations of solar and orbital variability with climate change. Advances in correlation of proxy information with natural processes of climate change, and better understanding of climate history, trends, and rates of change, have all merged to provide a much clearer picture of climate change than has been available before.
Carbon Dioxide is NOT a pollutant, plants must have it to grow, and for the majority, the more the better. Linkage to increased warming is far from proven, and is most likely Econut FUD.
The Global Warming hysteria is an irrational, unscientific hoax, and anyone from which it spews has zero credibility.
Don't take my word for it, educate yourself.
Is it just me or is the 21st Century trending towards a colder climate than the late 20th ?
Based on my recollections the 100+ degree sumer days around Dallas have been trending down for the last 5 years.
I think last year we had approximately 3 days above 100
2001 : 7 days
2000 : 14 days
1999 : 25 days
1998 : 30+ days
1980 : 100+ days over 100 degrees.
We have had 3 snow/ice days this year (2 last year, none the year before)
Just seems to me that Texas is coming down from the "Hell" climate into something a lot more pleasant.
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