World's vegetation is cleaning more carbon from skies

The Christian Science Monitor ^ | June 06, 2003 | Peter N. Spotts

[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.

[cinFLA]

(from Columbia U V1003 course)

There have been times on earth in the past when the CO2 concentration of the atmosphere has been both less and greater than it is today. If it has been greater, then one might ask "why are we so worried, the CO2 concentrations were greater than they are today and we still survived?" The answer to that question lies in the fact that the rate of change of CO2 in the atmosphere is faster today than at anytime in earth's history. It is this rapid increase in CO2, not necessary the final CO2 concentration that we may achieve, which is driving much of our concern. For example, because organisms (and certainly all of the human cultures on earth) have never been exposed to such rapid rates of CO2 increase, we don't know how they will respond and whether they will be able to adapt quickly enough to survive. These are the questions that science and society are struggling with today. While we know that CO2 concentrations are increasing, there have been several plans or ideas on how to control them "naturally", such as plant more trees to take up the excess CO2. Later in the lecture we will examine two of these ideas and determine if they could be real solutions to global warming.

[lepton]

And even more so when there is a biosphere to contend with as well.

I haven't heard any updates, but a while ago, I understood it was calculated that (non-human) life on earth has altered the atmospheric temperature by about 18 degrees Fahrenheit. I'd say that if there is any credence to that, it certainly applies to this question of mans influence.

[nwconservative]

For all those that think global warming is man caused;
http://www.freerepublic.com/focus/f-news/942540/posts

The biggest laugh is that majorities of scientists believe it, HOGWASH!!!! Saying a majority of social engineers believes it may be the truth.

In addition, the same majority of scientists believed we would be facing a coming ice age and that we originated from monkeys! Does that make it true?

[bruinbirdman]

Climate-Gate

Human Events Online

"Climate-Gate" is getting a lot of attention. What is the White House being accused of, exactly? Let's take a closer look:

1) The White House is denying a "scientific consensus" that global warming is occurring and that human beings, through the use of fossil fuels, are "largely" responsible.

FACTS: First, does this statement really say much? How much warming are humans responsible for? 1 degree? 3 degrees? 10 degrees? Second, media reports said the White House took out a reference to a graph showing the 20th century as the warmest on record. This graph, called the hockey stick, provides the scientific basis for the Kyoto Protocol and international climate negotiations. Is it credible? Does it command consensus? Just ask the 4,000 scientists from 106 countries who signed the Heidelberg Appeal, which includes 72 Nobel Prize winners. The appeal warns industrialized nations that no compelling scientific consensus exists to justify mandatory greenhouse gas emissions cuts. What about the Oregon Petition (http://www.oism.org/pproject/), sponsored by Dr. Frederick Seitz, former past president of the National Academy of Sciences? It has over 17,000 independently verified signatures from scientists. It reads, in part: "There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gasses is causing or will, in the foreseeable future, cause catastrophic heating of the Earth's atmosphere and disruption of the Earth's climate. Moreover, there is substantial scientific evidence that increases in atmospheric carbon dioxide produce many beneficial effects upon the natural plant and animal environments of the Earth."

Or, what about the 46 climate scientists who sent a letter, printed in the June 3 edition of Canada's National Post, to a Canadian member of Parliament, questioning the theory that mankind is responsible for global warming? According to the signatories, the Kyoto Protocol "lacks credible science." Moreover, "Many climate science experts from Canada and around the world, while still strongly supporting environmental protection, equally strongly disagree with the scientific rationale for the Kyoto Accord."

What do state climatologists say? According to a survey of state climatologists by Citizens for a Sound Economy, 58 percent surveyed said they disagreed with the claim that "the overwhelming balance of evidence and scientific opinion is that it is no longer a theory, but now fact, that global warming is for real" and with the statement that "there is ample evidence that human activities are already disrupting the global climate." Only 36 percent of the climatologists agreed with the assertion.

The National Academy of Sciences also doesn't see consensus. As it wrote in 2001: "Because of the large and still uncertain level of natural variability inherent in the climate record and the uncertainties in the time histories of various forcing agents (and particularly aerosols), a causal linkage between the buildup of greenhouse gases in the atmosphere and the observed climate changes in the 20th Century cannot be unequivocally established."

2) The hockey stick graph represents scientific consensus and is the best science on the subject of global warming.

FACTS: The hockey stick was developed by Dr. Michael Mann, of the University of Virginia, and others. Despite reporting that says the hockey stick represents "consensus," it is in fact widely disputed within the scientific community. Why?

Unlike the more comprehensive Harvard study, Mann uses only 12 sets of proxy data, drawn from the Northern Hemisphere. Mann extrapolated that data to reach the conclusion that global temperatures remained relatively stable and then dramatically increased at the beginning of the 20th century. That leads to Mann's unfounded conclusion that the 20th century has been the warmest in the last 1000 years.

How does Mann get the blade on the stick? The blade is formed by crudely grafting the surface temperature record of the 20th century onto a pre-1900 proxy tree ring record. As is widely recognized in the scientific community, two data series representing radically different variables (temperature and tree rings) cannot be grafted together credibly to create a single series. Even Mann and his coauthors admit that if the tree ring data set were removed from their climate reconstruction, the calibration and verification procedures they used would fail.

How confident is Mann of his conclusions? Does the author of the hockey stick even think the science is settled? "Our results suggest that the latter 20th century is anomalous in the context of at least the past millennium. The 1990's was the warmest decade, and 1998 the warmest year"-here's the key phrase-" at moderately high levels of confidence."

3) The White House replaced the hockey stick graph with a reference to a new study that, according to AP, was "partly sponsored by the American Petroleum Institute."

FACTS: This is the 1,000 year Harvard-Smithsonian study, which is based on 240 independently peer reviewed climate studies (http://cfa-www.harvard.edu/press/pr0310.html). Notably, it was also funded by NASA, the National Oceanic and Atmospheric Administration (within Commerce), and the Air Force Office of Scientific Research. Somehow its connection to API makes it inherently suspect. But this is a totally irrelevant issue. Why not rigorously critique the study? Where is the proof that its scientific conclusions are flawed? The study, unlike the hockey stick, relies on climate proxies from all over the globe. It found that the Medieval Warm Period (800 to 1300), a widely recognized phenomenon in the scientific literature (as is the Little Ice Age, 1300 to 1900), was actually warmer than the 20th century.

4) President Bush made a mistake by pulling the U.S. out of Kyoto.

FACTS: Dr. Tom Wigley, a senior scientist at the National Center for Atmospheric Research, found that if the Kyoto Protocol were fully implemented by all signatories, it would reduce temperatures by a mere 0.07 degrees Celsius by 2050, and 0.13 degrees Celsius by 2100. What does this mean? Such an amount is so small that ground-based thermometers cannot reliably measure it.

Dr. Richard Lindzen, an MIT scientist and member of the National Academy of Sciences, who has specialized in climate issues for over 30 years, told the Committee on Environment and Public on May 2, 2001 that there is a "definitive disconnect between Kyoto and science. Should a catastrophic scenario prove correct, Kyoto will not prevent it. If we view Kyoto as an insurance policy, it is a policy where the premium appears to exceed the potential damages, and where the coverage extends to only a small fraction of the potential damages."

Similarly, Dr. James Hansen of NASA, considered the father of global warming theory, said that Kyoto Protocol "will have little effect" on global temperature in the 21st century. In a rather stunning follow-up, Hansen said it would take 30 Kyotos – let me repeat that – 30 Kyotos to reduce warming to an acceptable level.

Mr. Catanzaro is Communications Director for the Senate Environment and Public Works Committee.

[wayne_shrugged]

The entire scientific community has reached consensus on this point. I don't think I'd even bother debating with a patzer that doesn't get that point. These threads pooh-poohing global warming are just ignorant.

Um, hello. There is evidence that the earth (in what is now the industrialized West), that we had warmer temperatures IN THE MIDDLE AGES! As far as I know, we didn't have combustion engines and reliance on the burning of fossil fuels. How do those scientists explain that?

[wayne_shrugged]

The entire scientific community has reached consensus on this point. I don't think I'd even bother debating with a patzer that doesn't get that point. These threads pooh-poohing global warming are just ignorant.

Um, hello. There is evidence that the earth (in what is now the industrialized West), that we had warmer temperatures IN THE MIDDLE AGES! As far as I know, we didn't have combustion engines and reliance on the burning of fossil fuels. How do those scientists explain that?

[Jessamine]

Ughh. I would love to learn more from both sides on this debate, but one side has a condescending ''trust me'' in two posts in a row, then ''Fact is, I refuse to engage in a battle of wits with unarmed people.''

ughh, double ughh, hurl.

[FreeTheHostages]

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.

I agree with everything you wrote, except that I ever said that wave height was the determining factor in capacity. I agree that it's not. I just noted that as I follow these things, I find it particularly interesting/surprising. So I agree with you.

[FreeTheHostages]

I disagree -- remember this isn't atmosphere CO2 overall -- there man couldn't yet make the change. This is the Vostok ice sample -- this is CO2 at the poles.

[FreeTheHostages]

well, I actually *am* responding to nice and sensible posts. I freely admit to posting such things in response to posts that begin "Dear useless idiot" etc.!

[FreeTheHostages]

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.

OK, this is going to sound like a stupid question, but: Really? I mean is there scientific consensus on THAT? Without a hint of petulance, I respectfully ask: do you have a science citation I could look at on that?

[Jessamine]

I appreciate your intent to keep our side of the political spectrum from appearing to short-sightedly deny GW for financial gain. But the other side uses the GW potential for such anti-American purposes we are only defending ourselves and our futures from luddite-ism. Check out this website/article:

http://www.techcentralstation.com/1051/envirowrapper.jsp?PID=1051-450&CID=1051-070903C

[gatex]

"... Without a hint of petulance, I respectfully ask: do you have a science citation I could look at on that?"

Without a hint of petulance, I respectfully ask: do you have a science citation I could look at on the ice data you are calling "the science"?

[FreeTheHostages]

With a hint of petulance, the Vostok ice core is accepted science. Do a google search on the word Vostok and ice -- you'll come up with lots of sources.

[gatex]

"Do a google search on the word Vostok and ice ..."

Why can't you post your good source ?

There are a lot of people on this thread -- so "do a google search" is not impressive.

You asked for a reference, so why can't you give one.

[Paradox]

There are a few of us here who are a bit less skeptical of the GW claims. I am not convinced either way, but I do agree its something we need to keep an eye on. My guess is that it will take some decades before we know with enough certainty to take steps drastic enough to seriously degrade our lifestyles, or whatever.

However, as an exercize, I would have no problem discussing various market based solutions to this problem. Lets get away from the "scientific fact" claim, and start postulating possible fixes, IN CASE we need them. How about that?

[gathersnomoss]

What about the bad science that resulted in the creation of the catalytic converter. A thirty year study has found that it's use in all cars has not as a result made any difference in our air quality.

So what is it with the market-based solutions, hmmm?

[FreeTheHostages]

My number one fix is quite simple: DO NOTHING

I say that because I believe that even if Global Warming from manmade sources were to accelerate, even IF we had hard science that was going to happen, we (1) still don't know if it will be fighting an overall cooling trend the earth might be going through (2) whether vegetation might increase and lead to an eventual deacceleration.

By the time we know all these things, it might be 100-200 years down the road, and I believe in science and progress: I think by then we'll have more cost-efficient, pollution free means of energy. Solar and wind aren't those now, but if the price of oil goes up much more and instability in the Arab world still plagues us, the market will put "clean" sources in. Maybe, like the president says, hydro. But this I know: U.S. scientists and markets will lead the way. No way we need international treaties or even government intervention, in my opinion.

[FreeTheHostages]

The truth? Because I'm more interested in talking to people who have already heard of Vostok. The "do a google search" is my polite way of saying: "Look, if you haven't even heard of Vostok, out of my way please."

[palmer]

It's positively Orwellian to sit around and say that there's not climate change going on, even as the ice caps melt.

Antarctic ice sheets are getting thicker.