The results of a USDA experiment called PHACE (Prairie Heating and CO2 Enrichment) where liquid CO2 is injected into the ground from a storage tank, then effects measure on grassland growth, shows a surprising result: increased range grass growth leading to retaining more soil moisture. I hate it when that happens. I’ll have to give them credit though, back in 2007 in the paper starting the project they theorized from models that:
Model results suggest that soil water content, plant production, soil respiration, and nutrient mineralization will increase for the high-CO treatment. Soil water content will decrease for all years, while nitrogen mineralization, soil respiration, and plant production will both decrease and increase under warming depending on yearly differences in water stress.
And the credit is, they followed through with a ground truth experiment to verify the model.
But reality turned out to be different than model output. Big surprise. More photos here From the United States Department of Agriculture – Research, Education and Economics
USDA scientists study effects of rising carbon dioxide on rangelands
Rising carbon dioxide (CO2) levels can reverse the drying effects of predicted higher temperatures on semi-arid rangelands, according to a study published today in the scientific journal Nature by a team of U.S. Department of Agriculture (USDA) and university scientists.
Warmer temperatures increase water loss to the atmosphere, leading to drier soils. In contrast, higher CO2 levels cause leaf stomatal pores to partly close, lessening the amount of water vapor that escapes and the amount of water plants draw from soil. This new study finds that CO2 does more to counterbalance warming-induced water loss than previously expected. In fact, simulations of levels of warming and CO2 predicted for later this century demonstrated no net change in soil water, and actually increased levels of plant growth for warm-season grasses.
“By combining higher temperatures with elevated CO2 levels in an experiment on actual rangeland, these researchers are developing the scientific knowledge base to help prepare managers of the world’s rangelands for what is likely to happen as climate changes in the future,” said Edward B. Knipling, administrator of the Agricultural Research Service (ARS), USDA’s principal intramural scientific research agency.
The results cover the first four years of the eight-year Prairie Heating and CO2 Enrichment (PHACE) experiment on native northern mixed grass rangeland. The study is being conducted by the ARS Rangeland Resources Research Unit (RRRU) at the High Plains Grasslands Research Station near Cheyenne, Wyo.
ARS plant physiologist Jack Morgan leads the study, which uses both CO2 pipelines and thermal infrared heaters to simulate global warming conditions predicted for the end of the century: 600 parts per million (ppm) of CO2—compared to today’s average 390 ppm—and day/night temperatures raised by 3 and 5 degrees Fahrenheit, respectively.
Based on these findings, warmer temperatures would likely play a role in changing the relative success of various grass types. “Only the warm-season grasses had their growth boosted higher by CO2 and warmer temperatures,” Morgan said. “If this leads to a competitive advantage for warm-season grasses, it may increase the challenges faced by ranchers who desire cool-season grasses for early-season forage.”
Elise Pendall and David Williams at the University of Wyoming at Laramie and Matthew Wallenstein at Colorado State University at Fort Collins also are participating in the study, which will be completed in 2013. Retired ARS soil scientist Bruce Kimball, designer of the infrared heater system, is helping conduct the study. Kimball serves as a research collaborator at the ARS U.S. Arid-Land Agricultural Research Center in Maricopa, Ariz.
Grass-dominated, dry rangelands account for approximately a third of the Earth’s land surface, providing most of the forage eaten by livestock. This research, the first of its kind on this scale for rangelands, supports the USDA priority of helping farmers and ranchers throughout the United States and the rest of the world best adapt production practices to variable climate patterns.
Morgan said more research is needed to determine how the water-savings effect applies over the long run and in other types of semi-arid rangelands as well as to croplands in semi-arid areas. “It is important to understand that CO2 only offset the direct effects of warming on soil water in this experiment, and that it is unlikely to offset more severe drought due to combined warming and reduced precipitation projected for many regions of the world,” he said.
In addition to ARS funding, the research is supported by grants from the National Science Foundation, the U.S. Department of Energy, and USDA’s National Institute of Food and Agriculture.
h/t to Bruce Hall
vboring says:
August 3, 2011 at 2:39 pm
I can’t imagine how this got published.
easy. the current meme making the rounds is that native grass ( in California, for example ) is losing to the invasive alien grass, owing to, what else…… AGW.
now this study says that this creates a new challenge. the ranchers that need cold weather grass earlier in the season are going to have chanllenges…. ergo, it is worse than we thought. so publish this new meme.
“This new study finds that CO2 does more to counterbalance warming-induced water loss than previously expected.”
That’s because scientists have been conditioned like Pavlov’s dogs to expect bad things from higher CO2 levels. This conditioning generally occurs on college and university campuses which are notorious bastions for idealistic spoiled youths and where the most sheltered of those youths move straight from being students to professors never leaving the sheltered liberal enclave where their initial indoctrination occured. In other words a few students from each graduating class are promoted from one of Pavlov’s dogs to Pavlov himself. 🙂
GoatGuy says:
August 4, 2011 at 7:00 am
DUDE! GOOD CATCH!
Using a ruler and the guy’s height at 6 feet for scale reference I measure the tank as 8 feet by 52 feet which works out to a bit under 20,000 gallons. No way in hell that’s a 50,000 gallon tank. Not even half that.
Dave Springer says:
August 4, 2011 at 4:17 pm
I also looked at this. I appears to me that it is probably a typo. Since this is an insulated and refrigerated tank, I an guessing that the takn itself is ~ 6ft dia and 40′ +/- long therefore about 10,000 gal.
Better assume 6 inches on the tank radius for insulation (12 inches on the diameter), and maybe 1/2 to 3/4 inches for the tank wall thickness.
The best of all possible worlds awaits:
Since CO2 does not actually increase temperatures, rising CO2 will improve yields, conserve water, and have no effect on rangeland grass mixtures and crop balances.
Dave;
It’s even less than that. He’s SITTING on the platform holding the tank. Take a look at the height of his knees above the ground. Or just look at the torso. For the great majority of men, sitting height (butt to top of head) is 28″. (Women is 24″).