Posted on 07/07/2003 9:09:43 AM PDT by presidio9
If your dogwoods and peony patches are looking a bit more robust than they did 20 years ago, you may have climate change to thank for much of their growth. Using two decades' worth of data on climate and vegetation, a team of scientists has taken what may be the first planet-wide look at plant activity during a time when Earth's environment underwent significant change.
The researchers found that globally, shifts in rainfall patterns, cloud cover, and warming temperatures triggered a 6 percent increase in the amount of carbon stored in trees, grass, shrubs, and flowers.
Many scientists hold that the growth in atmospheric concentrations of heat-trapping carbon-dioxide - from nearly two centuries of rapidly growing populations that burned increasing amounts of fossil fuels - is largely responsible for the earth's warming climate.
The new research adds to the body of evidence that plants can store increasing amounts of carbon from the atmosphere, but it remains unclear how long this trend will continue or whether it will significantly affect atmospheric CO2 levels.
Kyoto provisions
The 1997 Kyoto Protocols - a first step at trying to reduce emissions and so moderate the change - permits countries to use the carbon-absorbing capacity of their forests and farmlands as credits against their emissions targets. In addition, projects that increase vegetation also are seen as ways to reach national CO2 emissions targets. Thus, understanding the flow of carbon from the atmosphere to plants and back is vital to projecting future trends in atmospheric CO2 levels.
For 50 years, scientists have been measuring the growth of CO2 in the atmosphere, according to Ramakrishna Nemani, a professor in the forestry school at the University of Montana in Missoula, who led the research team. "But if you look at the record of the past two decades, the annual growth rate hasn't been going up like it had before," he says.
Other groups had forecast an increase in plant growth for a time with climate change, although rates would vary depending on region. And some smaller-scale studies had indicated that the earth was greening.
Dr. Nemani's team was interested in seeing how plant activity had changed - and where - worldwide during a 20-year period that saw two of the warmest decades ever recorded, several intense El Nino episodes, one major volcanic eruption, a 9 percent increase in atmospheric CO2 concentrations, and a 37 percent growth in human population.
The team measured how much carbon plants store after absorbing carbon dioxide through photosynthesis and returning some of it through respiration.
First, the team built maps reflecting changes in temperature, cloud cover (which affects the amount of sunlight reaching plants), and available water. Then they overlaid satellite data on net primary productivity on land and looked for relationships among these components.
Big change in the Amazon
They were stunned at the growth rates in South America's Amazon region.
"That was a big surprise," says Ranga Myneni, a botanist at Boston University and a member of the research team. Amazon rain forests accounted for nearly half the increase seen globally over the 20-year period.
The surprise was twofold. The growth rate far exceeded what most scientists expected. Many models indicated that additional growth in the tropics would be minimal, given the fairly constant temperatures from one season to the next. In addition, many researchers had held that any increased productivity in the tropics would largely be driven by a rise in atmospheric CO2 rather than changes in climate itself.
Yet the drop in tropical cloud cover during the period allowed more sunlight into places like Amazonia, Dr. Myneni says, far outpacing CO2 as a prod to growth. Likewise in other climate regions, changing Climate conditions appeared to be the dominant factor driving plant growth.
The other half of the equation
The good news for plants, which appears in Friday's edition of the journal Science, comes with caveats, Myneni cautions. Since humans collectively use about half of plants' net primary production, he says, the team's estimate of 6 percent growth over 20 years translates into a trivial 3 percent growth in material available to a growing human population.
Moreover, the 20-year period the team studied could be unusual, and hence not representative of long-term prospects for vegetation growth. And if the climate continues to warm, as many expect, plants will bump up against limits to their ability to make use of the additional water, warmth, and sunlight, just as they bump into limits on the amount of CO2 they can use. The study also doesn't answer questions about how changing climate conditions in these areas are affecting the amount of CO2 given off from plant decomposition and soil - amounts that can offset the CO2 that plants imprison in their roots, stems, and leaves.
"That's the other half of the equation" the study doesn't address, he cautions.
Post 85 says porpoise has looked at the same data as you are quoting --- and says your are wrong.
Why don't you respond to that post and show that you are not denying science.
Not true.
File this under: Things that Dan Rather will never tell you. Go HERE and look for the Oregon Petition. Far more scientists have flatly rejected the man-made global warming theory than have accepted it. There is not even agreement that temps have increased over the last 50 years and some evidence that they have in fact fallen.
Not true.
File this under: Things that Dan Rather will never tell you. Go HERE and look for the Oregon Petition. Far more scientists have flatly rejected the man-made global warming theory than have accepted it. There is not even agreement that temps have increased over the last 50 years and some evidence that they have in fact fallen.
Just echoing your comment.
No, your big point was to focus on what the Conservative position was (or should be) to the "problem" of Global Warming without discussing the science at all.
Care to try again?
Mr. Author, are you sure about that? That was a proposal, but wasn't it shot down?
Wanna try again? Global warming itself is questionable (and subject to defenitions), much less its cause. There has been a general warming trend over the last century, but there have also been cooling periods within that time. The scientific community can't even agree on a usable meaningful definition of "global warming".
Nope. See the U.S. Academy of Sciences study (not the disavowed summary).
Irony of ironies, there is some significant evidence of mans activities changing the global climate: Our output of reflective particulates was exhibiting a cooling effect, which was reduced by the Kyoto protocols. An article by Teller a few years ago gave costs for a few methods to achieve global cooling that would cost in the single-digit Billions.
Mount Pinatubo greatly increased the levels of atmospheric CO2 world-wide (though most strongly in the norther hemisphere). As predictable with an understanding of dynamic equilibrium, by January of the following year, the CO2 levels were BELOW normal levels.
Simple output of CO2 into the atmosphere is not sufficient to cause a multi-year rise in levels, as the various plants on the planet would simply convert more CO2 into more food - as they currently do to 99.84% of the atmospheric CO2/O2 cycle. It would take other events in order to elevate CO2 levels on a long-term basis.
It is pretty much universally understood that water vapor has a much stronger effect than either of these, especially at their relative incidences, but only within the last three years has any real effort been made to include the overwhelming effects of water vapor in the models...and they still haven't included layering, or the stratification of cloud layers (each type of cloud appears to have a different effect, especially when one is above another).
Why is there not a specific correlation in time between man-made greenhouse gas increases and temperature increases? As example, through the 20th Century, there is purported to have been a 1 degree rise in temperatures, while a substantial increase in CO2 levels occured. Unfortunately, for this correlation, nearly all of the rise in temperature was in the first half of the century, and the rise is CO2 was primarily during the latter, where the temperature stabilized or slightly dropped. Clearly something else was driving temperature changes to a degree that was larger than the effects of CO2.
As a portion of the carbon-cycle, the ability for plants to uptake this difference is trivial. Man could not make this change if he WANTED to - at least not yet, and without sterilizing the planet.
It is NOT a fact. It is an observation. An observation made with an instrument of undeclared uncertainty and no calibration certificate. An observation made under unstated conditions. The high was probably either above or below 92F. The only fact is that your high was your observation.
In his defense, that's not how his credibility was dissolved. We don't know how much the ocean can hold, nor how much additional life will thrive with easier access to CO2 for photosynthesis, nor do we have world-wide volumetrically accurate data for the ocean's temperature, nor data for smokers (underwater volcanic plumes). We aren't even able to definitively calculate the amount of material released from a major volcanic eruption that we can see. His argument loses it because the capacity for the ocean to hold and consume CO2 is a HUGE unknown variable, which must be known in order to even begin to determine the cause of the CO2 level change.
You are measuring the wrong thing there: The wave-action is related to the rate of CO2 transfer, not the amount that can be held in the ocean. That is partially temperature-based, and partially based on what is done with the CO2 when in the ocean, neither of which are definitively known for the oceans as a whole.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.