If a Tree Falls in the Forest...

Jan 18, 2010
Carbon models should be adapted to take into account the world’s increasing number of natural disasters and human-caused disturbances. Some models could be off by three to 10 percent, estimates PNNL researcher Ben Bond-Lamberty.

(PhysOrg.com) -- In a century of increasing forest fires, hurricanes and plagues, Dr. Ben Bond-Lamberty, a terrestrial ecologist for the Pacific Northwest National Laboratory, suggests taking a fresh look at modeling carbon's impact on the biosphere. During his presentation at the 2009 American Geophysical Union fall meeting last month, Bond-Lamberty encouraged carbon modelers to account for considerable ecosystem changes and reconsider some outdated assumptions in their constant pursuit of more accurate carbon modeling.

Bond-Lamberty roughly estimates that many models predicting global carbon input and output could be off by three to 10 percent. Carbon modeling examines what happens when plants die and carbon is released back into the atmosphere. But if more plants die than usual, such as when trees are knocked down by a hurricane or destroyed by a plague of insects, the cycle can shift.

For example, the average annual number of wildfires has increased four-fold in the Western United States, according to a Scripps Institute of Oceanography report. About twice as many Atlantic hurricanes form each year on average than did a century ago, according to the National Center for Atmospheric Research. And British Columbia, Canada, has lost at least 33 million acres of pine forest because of the unprecedented mountain pine beetle outbreak, the New York Times reported last year.

The sky is falling? Not yet, but this increase , plus human-caused disturbances like land-use changes, makes it increasingly challenging to predict the planet's cycle of carbon, the main component of climate-altering greenhouse gases.

Challenging as it is, accurately modeling the is critical when trying to understand and predict the human impact on the biosphere.

When scientists first developed carbon models in the late 1970s and early 1980s, they assumed the Earth's ecosystems would remain fairly stable. But that's increasingly not the case. Many carbon models aren't adjusted for disturbances like natural disasters, logging, and land-use changes. As a result, Ben Bond-Lamberty is actively advocating the need to update carbon modeling to further reduce uncertainties.

Over the last decade, more scientists have started adding disturbances into their carbon models, particularly regional models, but this isn't a standardized practice. Most global models don't account for such changes yet, Bond-Lamberty said. He's trying to change that.

"As world leaders consider their climate and carbon policies, scientists have a responsibility to provide them the best available data. Getting that reliable data isn't easy, but I'm confident ecosystem modelers are up for the challenge," said Bond-Lamberty.

Studies will be expanded to include ecosystem-specific carbon density values and extent wildfire records to calculate a more accurate estimate of woody debris carbon fluxes on a continental scale. Portions of Bond-Lamberty's presentation will be presented in a forthcoming review paper currently being written as part of the North American Carbon Program's Disturbance Synthesis Activity, where Bond-Lamberty writes in collaboration with Dr. Mark Harmon of Oregon State University, Dr. Rodrigo Vargas of University of California, Berkeley, and Jianwu Tang of the Marine Biological Laboratory. The paper will be submitted to the Journal of Geophysical Research.

This research was funded by the PNNL Laboratory Directed Research and Development program.

Explore further: Five anthropogenic factors that will radically alter northern forests in 50 years

More information: B.P. Bond-Lamberty, "Challenges (and annoyances) in modeling disturbance effects on terrestrial carbon cycling." Dec. 18, 2009. Presentation at 2009 AGU Conference, San Francisco, Calif.

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dachpyarvile
1 / 5 (1) Jan 18, 2010
There are a great many factors which must be taken into consideration--and not just the number of fallen trees. Until all the factors that can be taken are taken the models will never be right.

Echinoderms in the sea must be counted. Carbonate-laden fish defecation must be accounted for. Fallen trees must be accounted for.

By the same token, however, we also must count the rise of other plants and grasses in place of the trees. For instance, grasses are overall better photosynthesizers than trees.

When heavy shade of a tree is lost via natural disaster or by land-use changes, and the fallen tree then opens up the sky for the better growth of grasses and perennial plants, how does that impact the overall carbon cycle?

The models need to take all this into consideration. This article, therefore, is spot-on.
RayCherry
not rated yet Jan 18, 2010
Two articles have hit on the changing flora today. How about the forna also? How many buffalo and wild cats where replaced by how many domesticated animals? How do the different purposes of those animals affect the food supply chains, and the by-products of each effect the local ecosystems which in turn contribute to the climate?

Another article today talked about the utility of deterministic versus statistical probability modelling. How many measurements will be required for acomplete Earth model? How many dimensions does this cube have? When is enough going to be enough?

Each new dimension, each new aspect of the change that can be measured, each distraction and diversion consumes time ... quite probably the first resource we will all notice has fallen into short supply, after it is too late to slow down the clock.
dachpyarvile
3 / 5 (2) Jan 18, 2010
Fortunately, the clock has been reset--as in error of timeline and substantial error of fact on the part of the IPCC. It is the difference in years between 2035 and 2350. Even then glaciers will survive in the Himalayas and not "likely disappear" by 2035 or sooner.

There are a lot of factors that must be measured and taken into account before any hypothetical climate model can be validated. When you rush the science you get things like the Fourth IPCC Report. :)

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