Thanks to Marek Smith for this piece on carbon and forests.
Here’s more on “forests are dying”.
It’s worth reading the whole thing, plus some of the sidebars. I just quoted the part here on our favorite topic, fires’n’bugs.
Wildfires and Bugs
Stripping the bark of a tree with a hatchet, Diana L. Six, a University of Montana insect scientist, pointed out the telltale signs of infestation by pine beetles: channels drilled by the creatures as they chewed their way through the juicy part of the tree.
The tree she was pointing out was already dead. Its needles, which should have been deep green, displayed the sickly red that has become so commonplace in the mountainous West. Because the beetles had cut off the tree’s nutrients, the chlorophyll that made the needles green was breaking down, leaving only reddish compounds.
Pine beetles are a natural part of the life cycle in Western forests, but this outbreak, under way for more than a decade in some areas, is by far the most extensive ever recorded. Scientists say winter temperatures used to fall to 40 degrees below zero in the mountains every few years, killing off many beetles. “It just doesn’t happen anymore,” said a leading climate scientist from the University of Montana, Steven W. Running, who was surveying the scene with Dr. Six one recent day.
As the climate has warmed, various beetle species have marauded across the landscape, from Arizona to Alaska. The situation is worst in British Columbia, which has lost millions of trees across an area the size of Wisconsin.
The species Dr. Six was pointing out, the mountain pine beetle, has pushed farther north into Canada than ever recorded. The beetles have jumped the Rocky Mountains into Alberta, and fears are rising that they could spread across the continent as temperatures rise in coming decades. Standing on a mountain plateau south of Missoula, Dr. Six and Dr. Running pointed to the devastation the beetles had wrought in the forest around them, consisting of a high-elevation species called whitebark pine.
“We were going to try to do like an eight-year study up here. But within three years, all this has happened,” Dr. Six said sadly.
“It’s game over,” Dr. Running said.
Later, flying in a small plane over the Montana wilderness, Dr. Running said beetles were not the only problem confronting the forests of the West.
Warmer temperatures are causing mountain snowpack, on which so much of the life in the region depends, to melt earlier in most years, he said. That is causing more severe water deficits in the summer, just as the higher temperatures cause trees to need extra water to survive. The whole landscape dries out, creating the conditions for intense fires. Even if the landscape does not burn, the trees become so stressed they are easy prey for beetles.
From the plane, Dr. Running pointed out huge scars where fires had destroyed stands of trees in recent years. “Nothing can stop the wildfires when they get to this magnitude,” he said. Some of the fire scars stood adjacent to stands of lodgepole pine destroyed by beetles.
At the moment, the most severe problems in the nation’s forests are being seen in the Southwestern United States, in states like Arizona, New Mexico and Texas. The region has been so dry that huge, explosive fires consumed millions of acres of vegetation and thousands of homes and other buildings this summer.
This year’s drought came against the background of an overall warming and drying of the Southwestern climate, which scientists say helps to explain the severe effects. But the role of climate change in causing the drought itself is unclear — the more immediate cause is an intermittent weather pattern called La Niña, and research is still under way on whether that cycle is being altered or intensified by global warming, as some researchers suspect. Because of the continuing climatic change, experts say some areas that are burning this year may never return as forest — they are more likely to grow back as heat-tolerant grass or shrub lands, storing far less carbon than the forests they replace.
“A lot of ecologists like me are starting to think all these agents, like insects and fires, are just the proximate cause, and the real culprit is water stress caused by climate change,” said Robert L. Crabtree, head of a center studying the Yellowstone region. “It doesn’t really matter what kills the trees — they’re on their way out. The big question is, Are they going to regrow? If they don’t, we could very well catastrophically lose our forests.”
A couple of thoughts..
It’s interesting to me that people are predicting that trees are “on their way out”. I wonder specifically what evidence is there for this? I wonder about what I call the “pontification to data ratio” of some of these observations.
It’s also interesting when people use the term “devastation” to describe mountain pine beetle killed forests. Because “natural” cycles vs. “climate change induced” cycles look exactly the same (acres of dead trees).
4 thoughts on “NY Times on “Forests are Dying” and Carbon”
Can we truly say that the current situation is part of a “natural cycle”? In a truly “natural cycle”, (like Derek has pointed out) there is “temporal diversity” in these natural monocultures. That cycle has clearly become broken, and we have widespread forests all on the same cycle at once, unlike “nature” as presented by the preservationist crowd. It appears that some in the media are finally discovering the scope and impact of what is happening, and using that disaster mentality to sensationalize these powerful images they are capturing. Since I don’t live near those impacted areas, I’m hoping that the media coverage of current and future catastrophic wildfires and bark beetles will convince Americans that doing nothing is the wrong thing to do.
You’re right. We don’t really know what was “natural” or what might have been “natural” without the efforts of Native Americans.
We do know that even if we wanted to manage the same way they did, that houses are now in the way. So any area that has had fire management cannot be considered to be “natural.”
I was trying to make the point that the impact of “natural” events aren’t always desirable to humans, even when we know they are 100% natural (e.g., hurricanes), which, as you stated, does not fit the pine beetle example..
Here is some related science that’s in the news this week.
Productivity of Land Plants May Be Greater Than Previously Thought
ScienceDaily (Sep. 29, 2011) — The global uptake of carbon by land plants may be up to 45 per cent more than previously thought. This is the conclusion of an international team of scientists, based on the variability of heavy oxygen atoms in the carbon dioxide of the atmosphere driven by the El Niño effect. As the oxygen atoms in carbon dioxide were converted faster than expected during the El Niño years, current estimates for the uptake of carbon by plants are probably too low. These should be corrected upwards, say the researchers in the current issue of the journal Nature.
Instead of 120 petagrams of carbon, the annual global vegetation uptake probably lies between 150 and 175 petagrams of carbon. This value is a kind of gross national product for land plants and indicates how productive the biosphere of Earth is. The reworking of this so-called global primary productivity would have significant consequences for the coupled carbon cycle-climate model used in climate research to predict future climate change.
Lisa Welp of the Scripps Institution of Oceanography at the University of California in San Diego and her colleagues evaluated the data for the global isotopic composition of the greenhouse gas CO2 over the last 30 years. This analysis indicated regular fluctuations between years and a connection with the El Niño phenomenon in the Pacific. Overall, El Niño years are warmer. They are also characterised by greater precipitation in South America and less intensive monsoons in Southeast Asia. The researchers found a more rapid recovery of the isotopic ratios following the El Niño events than assumed, indicating a shorter conversion time for CO2 in the terrestrial biosphere. On the basis of these data, the authors calculate the so-called global primary productivity (GPP). They now propose correcting this in the global models from 120 to 150-175 petagrams) of carbon annually.
Since 1977 the isotopic ratios in the carbon dioxide of the atmosphere (18O/16O and 13C/12C) have been measured in order to better understand the global carbon cycle, as the exchange processes between the biosphere, the atmosphere and the oceans are reflected in these values. “We assume that the redistribution of moisture and rain in the tropics during El Niño raises the 18O/16O ratio in precipitation and plant water and then signals this to the atmospheric carbon dioxide,” explains Lisa Welp the new approach of the researchers.
“Our atmosphere is a perfect blender. Changes in its levels of trace gases — such as carbon dioxide — reflect the overall release and uptake of trace gases from all sources. So if you measure the carbon exchange of a forest ecosystem, for example, you “only” get the net exchange of all the carbon taken up by the trees for photosynthesis and all the carbon released by the trees and soil ,” writes Dr. Matthias Cuntz of the Helmholtz Centre for Environmental Research (UFZ) in his commentary in the same issue of Nature.
The gross-exchange fluxes, such as photosynthesis, are however accessible only with difficulty. “Global estimates therefore depend upon a number of assumptions. This includes, for example, how many of the CO2 molecules entering a plant are actually fixed by photosynthesis. The researchers of Lisa Welp’s team assume that around 43 per cent of all CO2 molecules entering a plant are taken up by the plant. If this were only 34%, the estimate would fall to about 120 billion tons of carbon — that is, to the currently accepted value,” for Matthias Cuntz reason of thought. In his opinion, the new findings do not completely upset the research to date. Nevertheless, they demonstrate an interesting new method for the determination of plant productivity over large areas. In future, the combination of several isotopic methods with conventional measurements represents a promising approach.
The now published study was carried out under the direction of Ralph F. Keeling, a professor of oceanography and the son of the late Charles David Keeling, after whom the so-called Keeling curve was named. This graph shows the concentration of CO2 of the volcano Mauna Loa on Hawaii since the year 1957. In the 1950s the CO2 fraction in Earth’s atmosphere was still around 315 ppm. In 2011, by comparison, it has already increased to 390 ppm. With his measurements Keeling was able to show for the first time that the concentration of the greenhouse gas increases in relation to changing land use and the combustion of fossil fuels. This new study underscores the importance of long-term measurements of the isotope 18O in the carbon dioxide of the atmosphere from the scientific point of view, as this occupies a key position between the carbon cycle and the hydrogen cycle.
Lisa R. Welp, Ralph F. Keeling, Harro A. J. Meijer, Alane F. Bollenbacher, Stephen C. Piper, Kei Yoshimura, Roger J. Francey, Colin E. Allison, Martin Wahlen. Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Niño. Nature, 2011; 477 (7366): 579 DOI: 10.1038/nature10421
Thanks, Doug! This seems like a very important finding.