Posted on 06/24/2002 2:29:56 PM PDT by cogitator
The Greening Of The North: Real, And Caused By Climate Change
Twenty years of satellite observations have indicated a "greening" trend in northern regions of the northern hemisphere (boreal regions). Scientists at Max Planck Institute for Biogeochemistry (MPI-BGC) in Jena, Potsdam Institute for Climate Impact Research (PIK), Lund University, Boston University and the Le Laboratoire des Sciences du Climat et l'Environnement (LSCE), Paris, have developed an advanced global ecosystem model showing that the trend is just as would be expected due to the warming climate (Science 31st May 2002).
Some years ago Ranga Myneni and his colleagues at Boston University published a paper in Nature apparently showing a "greening trend" in the boreal regions. The finding was based on satellite observations, and many scientists were sceptical about it because of problems of instrumental "drift" that could possibly make any observed long-term trend unreliable.
The Boston team, however, persisted in their efforts to re-analyze the data, taking into account all possible anomalies. The trend would not go away, and it has become clearer with time as new data have come in.
A possible cause was always obvious: weather station records from the North have reported a steady warming (by about 0.4 degree per decade), which is now generally attributed to the increasing greenhouse effect. Warming in the North might be expected to produce "greening".
However, it was not trivial to connect the weather station data to the satellite data to find out whether there was a quantitative correlation between the two trends. Although computer-based numerical models of the physical climate have been used for three decades to analyze the possible consequences of increasing greenhouse gas concentrations, comparable global models of ecosystem dynamics are a much more recent development.
Now, a major activity of the Global Ecology research group at MPI-BGC, under the leadership of Prof. Colin Prentice, is the ongoing development of a leading global terrestrial ecosystem model. The model is called LPJ, after the three research groups (led by Prof. Colin Prentice at MPI-BGC, Prof. Wolfgang Cramer at PIK; and Prof. Martin Sykes at Lund University) that participate in the model development consortium.
The basic idea of the model is to integrate current knowledge in separate fields (plant physiology and biophysics, terrestrial ecology and hydrology), to simulate the interaction of processes with different time constants (minutes to years), and to use all possible sources of information - including satellite observations - to evaluate and refine the model.
The new results, published in Science on 31 May 2002, are the product of a co-operation between the LPJ and Boston teams - spearheaded by Dr Wolfgang Lucht, a young scientist at PIK with close links to the remote sensing community - in which month by month climate observations from across the entire boreal zone were used to drive the LPJ model. It was found that the expected changes in leaf area index during each growing season and (most importantly) from season to season, based on climate data, fitted remarkably well to the satellite data.
Two decades of satellite observations showed that spring has advanced by about a week, and summer maximum leaf cover has increased as well. The model results showed that these trends correspond quantitatively to what should be expected, based on the warming that has occurred. The only plausible explanation for this agreement between two fully independent sources of information is that the remotely sensed trend is real, and that it was caused by the changing climate.
With a model such as LPJ, it is also possible to perform sensitivity tests to isolate the key factor causing a given effect. It was found that the trend was caused entirely by temperature. It was not caused by physiological effects of increasing carbon dioxide concentration on plant growth (which are likely to be much more important in warm climates than in cold climates), or by the increasing rain- and snowfall that has accompanied the increase in temperature.
One major event temporarily interrupted the trend: the 1991 eruption of Mount Pinatubo in the Philippines, whose fallout of volcanic aerosol produced a 0.5 to 1 degree average cooling - as well as spectacular sunsets! - in northern high latitudes during 1992-3.
Again, satellite data had already shown an interruption to the greening trend. And once again many scientists were sceptical because the volcanic aerosol itself affects the performance of the space-borne instruments. But in this case too the LPJ model results showed the same thing as the satellite observations - a short-lived dip in the trend, which was promptly resumed after the volcanic dust had settled.
The Pinatubo eruption had another effect too, which greatly surprised carbon cycle scientists when it occurred: The rate of increase of carbon dioxide in the atmosphere suddenly slowed down for two years.
A full explanation for this (which probably involves temperate and tropical regions as well) has not yet been found. It was possible to engage the LSCE team, which has been using advanced mathematical tools to analyze the small variations in carbon dioxide concentration that are observed between different measurement stations across the globe, in order to infer the changing patterns of regional sources and sinks of carbon dioxide on land and at sea. Their results showed that during the "Pinatubo years" the land at high latitudes was taking up a great deal more carbon dioxide than usual.
The LPJ model results showed exactly the same thing. Even though the growing season was shortened and photosynthesis reduced, the cooler growing season meant slower decomposition of organic matter in the soil. This was the dominant effect of cooling for the net carbon exchange of the land in high latitudes, and it contributed to the slowing of the carbon dioxide growth rate at a global scale.
These results represent a "coming of age" for ecosystem modelling. They clearly demonstrate the value of collaboration between observational and theoretical communities (which has often been deficient in global change research).
Much ecosystem modelling up to now has been aimed at forecasting the impacts of future climate change, but in this aspect models show large differences. Thus, models need better evaluation, and the only way to do this is by making systematic comparisons between model predictions and observations referring to the present and past.
The results have implications beyond academia. We have shown that the biosphere is indeed changing, due to a climate change that most likely is a direct consequence of human activities (principally in the industrialized countries).
The warming and "greening" of high latitudes, if they continue, will have mixed effects from the point of view of the societies involved. The potential for forestry and agriculture in northern Canada and Siberia will improve, but Arctic ecosystems and species, and the indigenous cultures that depend on them, will be threatened by the invasion of plant and animal species from the south.
It doesn't say that anywhere. All it says is that the observed climate change is "most likely" due to human activities.
We have shown that the biosphere is indeed changing, due to a climate change that most likely is a direct consequence of human activities (principally in the industrialized countries).
There is absolutely no evidence in the article as posted that the change is "most likely" a direct consequence of human activites in the industrialized countries. This is pure propaganda/unfounded speculation. There is no discussion of possible causes; just a remarkable leap to pin the blame on humans activity in "industrialized countries."
The biosphere is in a constant state of change and the possible causes are many and varied. The article ignores mountains of real evidence that biosphere change is caused by long-term natural processes unrelated to human activity. The work of these computer modelers cries for objective peer review as well.
Though they're impressive, they aren't widespread enough. However, the black soot aerosols they produce is likely to be of importance, but you need hundreds of thousands of cooking fires (as in India) or poorly-controlled industrial pollution (as in China) to have a substantial impact.
Your statement above is entirely correct. The implication of human activities comes from other sources.
The wildfire/green house gas connection must be a taboo subject, I'm having trouble finding hard facts about it. My best estimation from searching many websites is that one acre of forest wildfire generates very roughly the equivalent of 200 cars worth of CO2 driven for one year. If America has 1,000,000 acres of wildfires this year, that possibly exceeds the total CO2 output from all automobiles combined. That's a fairly significant source of CO2. Why is there no mention of this anywhere? I find this curious.
All of it due to the very practices advocated by the environmentalists. Seems quiet the past few days as far as agitation by the environmentalist groups. Once the fires have cooled, they will come out of their hobbit holes and treat us all to their continued rant, no change.
Excerpt: "The hypothesis we are testing in this interdisciplinary science investigation is that the interannual variations in the fire regime in the boreal forest are responsible for a significant portion of the interannual variations in the seasonal amplitude of the atmospheric CO2 record at high northern latitudes."
Biomass Burning and the Production of Greenhouse Gases
Table 6 is vital. It summarizes the total CO2 released from biomass burning annually as 3546 Teragrams carbon per year. (3.5 petagrams? I always forget what comes after tera-).
Table 8 puts biomass burning at 40% of all CO2 emissions, which are 8700 teragrams.
I also found was U.S. fossil fuel production of CO2 in 1999 (EPA site) at 6746 Teragrams, a little under twice as much as total global CO2 emissions from biomass burning. That would make the U.S. responsible for 77% of global CO2 emissions, and I know that isn't right!
So let's see what else the EPA says:
http://www.epa.gov/globalwarming/emissions/national/co2.html (National Carbon Dioxide Emissions)
Says nothing about "natural" biomass burning!
Argh.
Here's an interesting press release from 1997:
GOVERNMENT INDIFFERENCE FUELS INDONESIAN FOREST FIRE DISASTER
Excerpt: "[1] Up to a million hectares of forest are burning in Indonesia (mainly Kalimantan and Sumatra), releasing 220-290 million tonnes of CO2 (for reference, this amount is equivalent to 50 percent of the UK's annual CO2 emissions.) The fire is also threatening over 1 million hectares of peat forest, and an additional 20 million tonnes of CO2 could be released if just the top ten centimetres of peat were to burn."
So here again we see that forest fires are a substantial source of CO2 to the atmosphere. Now I wonder: why aren't they counted as significant? One answer that I saw in passing is that much biomass burning (not specifically forest fires) is considered not to be a net source of CO2 to the atmosphere if crops are re-grown, because plant growth is a CO2 sink. This probably doesn't apply to major forest fires.
I found a nice diagram here:
Understanding the Global Carbon Cycle
It's Figure 2 in a frame that I can't grab from. The units are in petagrams: I had to check the fossil fuel flux number to be sure. Now here's the key: the net flux to the atmosphere from land for "bacterial respiration" is 60 petagrams. Bacterial respiration of organic matter adds CO2 to the atmosphere the same way that burning organic matter does. So based on the numbers found, that would mean that biomass burning is about 6% of the CO2 released by bacterial respiration, which is in approximate balance with the CO2 taken out of the atmosphere by primary production (photosynthesis).
Whew. So my unanswered question is: when the carbon cycle modelers do their thing, do they just figure biomass burning is another form of bacterial respiration, since the effect on organic matter is the same and the delivery of CO2 to the atmosphere is the same? My guess is that the answer to that question is yes. But I don't really know.
Also, interesting they would use petagrams sometimes rather than tons in their data. Makes bigger numbers. Like measuring produced oil in barrels and spilled oil in gallons. Makes one immediately suspect the motives.
Perhaps, but the reasons could be more mundane. Gigatons is the same as petagrams, and some of the older sites that discuss global warming using gigatons. But gigatons risks confusing metric tons (which it represents) with short tons. Petagrams is clearer.
Perhaps then you could explain to the listeners why India and China were excluded from the Kyoto accord that the liberals have waved in front of our faces since Mr. Bush's election?
The useless Kyoto Protocol's emphasis is on CO2 emissions. The exclusion of India and China was a political decision because the Kyoto Protocol ostensibly addressed current greenhouse gas producers, and India and China weren't considered major at the time, though there potential growth in emissions was obvious. The significance of black soot aerosols to global warming has only recently been recognized. Because black soot emissions are also hazardous to health (particularly large particle emissions from fires and industrial pollution), the idea of getting China and India to cooperate more on global warming issues by controlling black soot has been offered on the dual basis of climate and health benefits.
So essentially it was a political/economic decision rather than being based on environmental issues?
Therefore President Bush's decision to disregard this issue is not an environmental decision.
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