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.
You could also "predict" that higher CO2 will cure male pattern baldness and cause women's busts to grow larger. You can predict most anything but you have to measure the change to make it supportable, and higher CO2 levels have not resulted in measured temperature increases or more severe weather events.
Even the line in this article about last year having more tornados than "ever in history" is not supportable. Until very recently, we have not had the technology to detect most of the tornados that occurred. No one knows how many tornados struck in 1702, 1802, 1902 or even as recently as 1992 before Doppler radar covered the entire country. All we had last year was the most tornados detected in a single year and that only can only be honestly measured against the handful of years when we had the ability to detect virtually every tornado.
Argumentum ad Hominem
Graphs showing this are at the link below which has this quote ---
Quote ---"Based on the analysis of entrapped air from ice cores extracted from permanent glaciers from various regions around the globe, it has been demonstrated that global warming began 18,000 years ago, accompanied by a steady rise in atmospheric carbon dioxide. What caused this phenomena is a matter of ongoing debate. Clearly, though, global warming and rising CO2 levels in Earth's atmosphere started long before the industrial revolution."
link to graphs of Vostok CO2 and Temperature
At the link for Vostok graphs, links are available for the Vostok data going back about 240,000 years. The CO2 and Temperature appear to cycle and reach a peak around every 100,000 years.
Quote from the expert ---"...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...."
Was it those nasty 1st century Romans who caused the global warming of the late middle ages? Were they emitting too much methane at their orgies? Did the Elizabethans not burn enough wood to counteract the little ice age of the 19th century? ;~))
Even with an industrial society world-wide, man-made greenhouse gases are inconsequential. Natural sources absolutly dwarf anything that man could hope to produce. Nature will do what it wants on a global scale and we are virtually powerless to control it one way or another. One minor burp of the sun, which burps very regularly when measured against the eons, can either fry us or freeze us within minutes. We have no control over the global environment. We can act on local problems but globally, we are powerless. It's arrogance to think that nature cares one way or another what we do or if we even exist. We are virtually a nothing on a global scale. Nature adjusts in ways we have little or no comprehension of.
This suggests that the current higher levels of CO2 may not necessarily be higher -- it is possible the CO2 concentration in the entrapped bubble is not exactly the same as the atmospheric CO2. (CO2 absorbed in water is at a lower concentration than the CO2 in the air in contact with the water --- the concentration difference is the driving force -- not the same as the ice, but for example).
What is needed is correlation between CO2 in the air and CO2 in the ice --- I did not see such a correlation.
Must be --- and the Vostok data seem to show that every 100,000 years there has been manmade warming ---
LOL. It was those damn Neanderthals.
How do you get 100 percent increase ?
Using your own data in post 21 gives a 36 percent increase [ 380/280 = 36 % increase].
Using the peak of 300 ppmv in 323 Kyr BP gives 27 percent increase [380/300 = 27 % increase.]
Comparisons should be based on the same temperature = 27-37 percent.
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