Posted on 01/06/2003 10:48:27 AM PST by cogitator
Scientists discover global warming linked to increase in tropopause height over past two decades
LIVERMORE, Calif. -- Researchers at the Lawrence Livermore National Laboratory have discovered another fingerprint of human effects on global climate.
Recent research has shown that increases in the height of the tropopause over the past two decades are directly linked to ozone depletion and increased greenhouse gases.
The tropopause is the transition zone between the lowest layer of the atmosphere -- the turbulently-mixed troposphere -- and the more stable stratosphere. The tropopause lies roughly 10 miles above the Earth's surface at the equator and five miles above the poles. To date, no scientist has examined whether observed changes in tropopause height are in accord with projections from climate model greenhouse warming experiments.
The comparison was made by Livermore scientists Benjamin Santer, James Boyle, Krishna AchutaRao, Charles Doutriaux and Karl Taylor, along with researchers from the National Center for Atmospheric Research, NASA Goddard Institute for Space Studies, the Max-Planck Institute for Meteorology and the Institut for Physik der Atmosphere in Germany. Their findings are reported in the today's (Jan. 3) online edition of the Journal of Geophysical Research-Atmospheres.
This research undercuts claims by greenhouse skeptics that no warming has occurred during the last two decades. Such claims are based on satellite measurements of temperatures in the troposphere, which show little or no warming since the beginning of the satellite record in 1979.
"Weather balloons and weather forecast models show that there's been a pronounced increase in the height of the global tropopause over the last two decades," Santer said. "Our best understanding is that this increase is due to two factors: warming of troposphere, which is caused by increasing greenhouse gases, and cooling of the stratosphere, which is mainly caused by depletion of stratospheric ozone. Tropopause height changes give us independent evidence of the reality of recent warming of the troposphere."
The Livermore research supports the bottom-line conclusion of the 2001 Intergovernmental Panel on Climate Change (IPCC), which states that, "most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."
Earlier research showed that changes in the Earth's surface temperature, ocean heat content, and Northern Hemisphere sea ice cover are other indicators of human effects on climate change.
"The climate system is telling us a consistent story -- that humans have had a significant effect on it," Santer said. "We're seeing detailed correspondence between computer climate models and observations, and this correspondence is in a number of different climate variables. Tropopause height is the latest piece of the climate-change puzzle."
To support the research, Livermore scientists examined tropopause height changes in climate-change experiments using two different computer climate models. Both models showed similar decadal-scale increases in the tropopause height in response to changes in human-caused climate forcings. The patterns of tropopause height change were similar in models and so-called 'reanalysis' products (a combination of actual observations and results from a weather forecast model).
The model experiments focused on both manmade climate forcings, such as changes in well-mixed greenhouse gases, stratospheric and tropospheric ozone, and on natural forcings, such as changes in volcanic aerosols. The forces have varying effects on atmospheric temperature, that in turn affect tropopause height, the report concludes.
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.
It would make sense to observe an increase in troposheric temperature followed by an increase in height/mass and say that the latter was a reaction to the former. However, there is quite definitely no such observation.
Which led to a number of books published about the coming ice age. The more recent rise in temperature has led to many books published about global warming.
I don't know the exact statistics, but there seems to be a strong correlation.
"This research undercuts claims by greenhouse skeptics that no warming has occurred during the last two decades. Such claims are based on satellite measurements of temperatures in the troposphere, which show little or no warming since the beginning of the satellite record in 1979.
"Weather balloons and weather forecast models show that there's been a pronounced increase in the height of the global tropopause over the last two decades," Santer said. "Our best understanding is that this increase is due to two factors: warming of troposphere, which is caused by increasing greenhouse gases, and cooling of the stratosphere, which is mainly caused by depletion of stratospheric ozone. Tropopause height changes give us independent evidence of the reality of recent warming of the troposphere."
The first paragraph says "there is no evidence of warming in the troposphere". The second says that the increased size in the tropopause is due to two factors, one of which is "warming of troposphere".
Do you see what kind of crap this article is? If there is no evidence that there is warming of the troposphere then how can you say that the warming of the troposphere causes the increase in size of the tropopause?
If anything, this same evidence - no warming of the troposphere - disproves the hypothesis.
As near as I can tell from this almost unintelligible summary, this is just another computer-model masturbation by some guys with too much beer and not enough grant money.
"..seems like..." is not the correct operative word. We KNOW that the last time the planet was warmer than it is now, it was a period of great beneficence to most kinds of life (especially human). The "Medieval Optimum" period WITHIN RECORDED HISTORY was warmer than now, and the historical and archealogical record all indicate that it was a "boom" period for humanity.
The "global warmers" are just looking for another lever to overturn our liberties and institute more CONTROLS over our lives.
Explains those hot and cold spells.
"Recent research has shown that increases in the height of the tropopause over the past two decades are directly linked to ozone depletion and increased greenhouse gases."
The research says nothing of the sort. They use false information (that there is warming in the troposphere which even the article states is false) and make an unjustified assumption (that man-made activitis caused both the warming of the troposphere (which is false)and the increase in size of the tropopause (which is unknown)) to fit a pre-conceived idea that some political document that has been said to be false by even some of the author's of it is true.
GIGO!
If there was no warming of the troposphere, there would be no change in the height of the tropopause. Analyses of Microwave Sounding Unit (MSU) data to derive tropospheric temperatures have heretofore not shown an increasing tropospheric temperature trend. However, that picture is changing, according to abstracts of papers from two different groups that will be presented at the February American Meteorological Society meeting. These analyses, which include one by the Marshall Space Flight Center/University of Huntsville group that performed prior widely-quoted MSU tropospheric temperature analyses, DO show a warming of the troposphere. The increase in tropopause height is consistent with these analyses.
The implication that the authors of the study under discussion may have wished to avoid was that the prior analyses of tropospheric temperature were in error. I guess he'll wait for the researchers themselves to provide the update at the AMS meeting in February.
If the temperature rise in the next century doesn't exceed 2 C globally, the effects are likely to remain minimal, but they will be noticeable. In a second reply to you I will direct you to a thread where I expand on this topic.
Short answer: 330-520 meters at all stations.
Yeah--that's the ticket! It's...it's tropopause height, not temperature, that is a measure of "global warming!"
Where have I heard that before?
If the &$!@&$# planet froze over, they'd find a correlation between the length of porcupine quills and "global warming."
That's the ticket!
--Boris
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