Key new ingredient in climate model refines global predictions
October 9, 2009For the first time, climate scientists from across the country have successfully incorporated the nitrogen cycle into global simulations for climate change, questioning previous assumptions regarding carbon feedback and potentially helping to refine model forecasts about global warming.
The results of the experiment at the Department of Energy's Oak Ridge National Laboratory and at the National Center for Atmospheric Research are published in the current issue of Biogeosciences. They illustrate the complexity of climate modeling by demonstrating how natural processes still have a strong effect on the carbon cycle and climate simulations. In this case, scientists found that the rate of climate change over the next century could be higher than previously anticipated when the requirement of plant nutrients are included in the climate model.
ORNL's Peter Thornton, lead author of the paper, describes the inclusion of these processes as a necessary step to improve the accuracy of climate change assessments.
"We've shown that if all of the global modeling groups were to include some kind of nutrient dynamics, the range of model predictions would shrink because of the constraining effects of the carbon nutrient limitations, even though it's a more complex model."
To date, climate models ignored the nutrient requirements for new vegetation growth, assuming that all plants on earth had access to as much "plant food" as they needed. But by taking the natural demand for nutrients into account, the authors have shown that the stimulation of plant growth over the coming century may be two to three times smaller than previously predicted. Since less growth implies less CO2 absorbed by vegetation, the CO2 concentrations in the atmosphere are expected to increase.
However, this reduction in growth is partially offset by another effect on the nitrogen cycle: an increase in the availability of nutrients resulting from an accelerated rate of decomposition - the rotting of dead plants and other organic matter - that occurs with a rise in temperature.
Combining these two effects, the authors discovered that the increased availability of nutrients from more rapid decomposition did not counterbalance the reduced level of plant growth calculated by natural nutrient limitations; therefore less new growth and higher atmospheric CO2 concentrations are expected.
The study's author list, which consists of scientists from eight different institutions around the U.S. including ORNL, the National Center for Atmospheric Research, the National Oceanic and Atmospheric Administration Earth System Research Laboratory, and several research universities, exemplifies the broad expertise required to engage in the multidisciplinary field that is global climate modeling.
"In order to do these experiments in the climate system model, expertise is needed in the nitrogen cycle, but there is also a need for climate modeling expertise, the ocean has to be involved properly, the atmospheric chemistry . . . and then there are a lot of observations that have been used to parameterize the model," said Thornton, who works in ORNL's Environmental Sciences Division.
"The biggest challenge has been bridging this multidisciplinary gap and demonstrating to the very broad range of climate scientists who range everywhere from cloud dynamicists to deep ocean circulation specialists that [incorporating the nitrogen cycle] is a worthwhile and useful approach."
The ability to handle the increase in complexities of these models was facilitated by the capabilities of ORNL's Leadership Computing Facility, which currently houses the world's fastest supercomputer for civilian research. Jim Hack, director of the National Center for Computational Sciences, emphasizes that Thornton and his team were not limited by computational resources in the construction of his model. "It's one of the laboratory competencies, so we want to make sure we enable leadership science," he said.
This breakthrough is one more step toward a more realistic prediction for the future of the earth's climate. Nevertheless, potentially significant processes and dynamics are still missing from the simulations. Thornton also stresses the importance of long-term observation so scientists can better understand and model these processes.
A 15-year study of the role nitrogen plays in plant nutrition at Harvard Forest was an important observational source used to test their mathematical representation of the nitrogen cycle--a long experiment by any standards, but still an experiment that, according to Thornton, could improve the accuracy of the simulation if conducted even longer.
Other shortcomings of climate simulations include the disregard of changing vegetation patterns due to human land use and potential shifts in types of vegetation that might occur under a changing climate, although both topics are the focus of ongoing studies.
Source: Oak Ridge National Laboratory (news : web)
Dec 11, 2007 |
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"expertise is needed in the nitrogen cycle"
You all better work a little harder cloaking the BS cycle. You're too transparent. By the way, "global warming" is over.
Stick to Rush. You can't handle this.
Yes, and why is that? Thinka about it. They never say how much worse. I've read at least 50 "It's worse than we thought" articles. Is it 5% worse?....10%? With the multiplying effects, in 10 years, we'll all be freezing on a gigantic chunk of dry ice(solid CO2). Let me know when and which models accurately predict future temperatures. Meanwhile, go back to your comic books.
Heisman, is that you?
The N-cycle is nevertheless interesting. This opens up the discussion on the subject where a rise in CO2 was intuitively assumed to increase the rate of plant growth thus countering the adverse effects. But since such growth also depends on the availability of many other nutrients, this article draws attention to the fact that those cycles are also vastly variable and can't be taken for granted.
Such as a widening tropical belt and the pushing northward of sub-tropical and temperate latitudes, which would be associated with a warming planet? Oh, and let's no forget longer growing seasons. What would all this do to plant biomass and diversity, and therefore CO2 uptake? Yes, it would increase it. Might wanna get that all nailed down before anymore sweeping generalizations regarding the N-cycle and how you've revolutionized the still completely inadequate climate modeling thing.
Ah....and who would the trolls be?
There is good science and there is adgenda corrupted, dogma directed BS that is called science. "No dissenters allowed" is not science.
Those 2 sentences above speak volumes about where the science of climate modeling really stands. It's unrealistic and significant processes and dynamics are missing.
1) It isn't "getting colder". The last decade averaged warmer than the previous decade. http://www.realcl...g-pause/
2) Don't conflate weather and climate. Weather is short term. Climate is long term. And long term doesn't mean 1 day, 1 month or even 1 year - it means AT LEAST 10 years.
3) You don't measure climate trends by cherry picking two annual data points and drawing a line between them.
Let's say I make a model that is accurate to a 90% level of confidence. If I improve it to 91% it is 'more realistic' - but that in no way implies that my old model was NOT realistic.
Don't use rhetorical tricks to try and score points you can't score with actual scientific evidence.
CO2 is the primary plant food. Doubling CO2 in general would create about 50% more plant growth. To say that growth would be "two to three times smaller" is a strange way to phrase it. Logically, it means growth increase will be only 1/2 to 1/3 of previous predictions. Such a massive reduction is simply not believable. BTW, there have been thousands of plant growth experiments proving that CO2 is a powerful growth stimulant.
the resulting climate change will make it harder for non-tech savy countries to adapt to hostile living conditions.
this is by far the cheapest way for the west to take over the entire world. pull out of iraq and afghanistan and attack the ice caps.
Unfortunately, any answer they give that isn't consistent with our pre-established conclusions is dismissed because it must be flawed or biased.
Perhaps with a much better understanding of the past, we can begin to understand the mechanics of climate and climate change. Until we can produce models that actually accurately predict at least some small aspect, we are all shooting in the dark.
2) None of the computer models can track historical climate changes so there is no reason to think they can predict future climate changes (and this decade has proven that.)
3) realclimate.org is a biased site. Mann is one of the founders and is still trying to justify the shoddy work he did on his "hockey-stick". If I were to propose sites with differing opinions I could list icecap.us, climatesci.org, wattsupwiththat.com, noconsensus.wordpress.com, or climatescienceinternational.org.
The 10 year averages for the last century plus are shown in this chart: http://tamino.fil...mp;h=362
As you can see, their is NO plateau currently and the trend has been monotonically UP for the last 50+ years. Don't confuse yearly data with the 10 year running average.
I am agreeing with you but call it 'GW' in this context, not AGW.
Isn't adding 'created by man' redundant, in this case? Doesn't anthropogenic already mean 'created by man'? Regardless, your points are well taken.
I can't wait to see the 10 year average from 1999 to 2009. In case you aren't aware, the increases stopped in 1998, just before your chart data stops.
Nice try. But no prize for you.
The chart already includes the data through the end of 2008.