From the University of California – Irvine and the “Environmentalists are never happy” department comes this amusing quandary.
The cause? Increased high-elevation plant growth fueled by climate warming
Irvine, Calif. — Freshwater runoff from the Sierra Nevada may decrease by as much as one-quarter by 2100 due to climate warming on the high slopes, according to scientists at UC Irvine and UC Merced.
Accelerated plant growth at higher elevations caused by increasing temperatures would trigger more water absorption and evaporation, accounting for the projected runoff declines, the researchers add.
A diminished river flow will only add to the burden of providing resources to the thirsty farms and homes that rely on it. The state is currently experiencing a severe drought, and some reservoirs and groundwater levels are at all-time lows.
The study findings appear this week in the early online edition of Proceedings of the National Academy of Sciences.
“Scientists have recognized for a while that something like this was possible, but no one had been able to quantify whether it could be a big effect,” said UCI professor of Earth system science Michael L. Goulden of the decreased runoff. “It’s clear that this could be a big effect of climate warming and that water managers need to recognize and plan for the possibility of increased water losses from forest evaporation.”
According to the researchers, runoff from mountain ranges is vulnerable to temperature hikes that lengthen growing seasons and result in more vegetation growth at high elevations. Snow-dominated mountain forests that are currently dormant in winter with cold temperatures have lower vegetative density and less evapotranspiration than downslope forests in the snow-rain transition zone, which have year-round growing seasons. Evapotranspiration is the combination of water evaporation from land and the loss of water through plant-leaf transpiration.
Goulden and UC Merced’s Roger C. Bales investigated the potential influence of a warming climate on evapotranspiration in the Kings River Basin in California’s Sierra Nevada and found resulting changes in the amount of freshwater mountain runoff available to serve surrounding communities.
They gauged water vapor emission rates and combined those measurements with remote sensing imagery to determine relationships among elevation, climate and evapotranspiration. According to the data, freshwater mountain runoff is highly sensitive to expanded vegetation growth.
The authors found that greater vegetation density at higher elevations in the Kings basin with the 4.1 degrees Celsius warming projected by climate models for 2100 could boost basin evapotranspiration by as much as 28 percent, with a corresponding 26 percent decrease in river flow.
Further, the relationships among evapotranspiration, temperature and vegetation density were similar across a broader area of the Sierra Nevada, suggesting that the impact of climate change on evapotranspiration and freshwater availability could be widespread.
“Most people have heard about the giant forests around Yosemite and Sequoia national parks, but these areas have not been a focus of this type of research. Understanding of Sierran hydrology has improved recently with the National Science Foundation’s Critical Zone Observatory, and data collected there allowed us to look at the problem from several perspectives,” Goulden said. “All of our analyses pointed in the same direction: An upslope expansion of forest with warming would cause a large increase in evaporative water loss and lead to reduced water availability.”
Bales is a professor of engineering and director of the Sierra Nevada Research Institute at UC Merced. The research was supported by the NSF, through the Southern Sierra Critical Zone Observatory (EAR-0725097) and a major research instrumentation grant (EAR-0619947), and by the U.S. Department of Energy’s Terrestrial Ecosystem Science program.
A diminished river flow will only add to the burden of providing resources to the thirsty farms and homes that rely on it. The state is currently experiencing a severe drought, and some reservoirs and groundwater levels are at all-time lows.
Have any of these idiots actually been up to the high altitudes in the Sierras lately? I have been in the past few weeks and have pictures from friends who were up there this weekend and recent rains have completely replenished the lakes above 10,000 feet. Also, if you are up there, where is the most moisture, where there are no plants and trees? Nope, where there are trees, there is moisture, and it retains that moisture to run into the lakes during the dry summer months and precludes rapid evaporation that otherwise happens at the high altitudes.
More stupid computer models that fly in the face of reality.
I live in the Sierras and have also been in the high country. It has been a relatively wet August in the high country, but little of it has found its way down to lower reservoirs. Every little bit helps though.
Give it time.
Aquifers take years to replenish.
So plant growth is advancing upward.
We have already seen plants encroaching on desert areas.
More CO2 allows plants to prosper in areas in which they previously could not live. More CO2 promotes more plant growth everywhere — in deserts and on the sides of mountains.
I have to laugh. Trees are now evil. We need to send in the loggers to clear cut them.
“Trees are now evil.” Not really, trees became “evil” to these charlatans long ago the minute they started carping about “sustainability”. Bio-fuel, solar panels and wind turbines are already the enemies of the forest and everything that lives there. Coal and crude are what saved US forests from complete decimation in the 1800’s.
And X degree C increase in average global temp results in X degree C increase in the Sierra Nevadas? Yeah, right!
And a change in average global temp does not result in a change in rain fall patterns.
Yeah, right!
This study has enough holes in it to contain a major modern naval battle.
“A new paper…… suggests…”?
So what is vastly important about that paper? Absolutely nothing.
There’s a new paper every day suggesting every imaginable thing.
Are all of the suggestions vastly important?
What is it you think is so important?
4.1 Degrees Celsius warming? Are they out of their minds? Where’s the evidence that this is even remotely starting to happen?
The evidence must be in the models, as it surely is not in the data!
http://www.mercurynews.com/science/ci_24993601/california-drought-past-dry-periods-have-lasted-more
“California drought: Past dry periods have lasted more than 200 years, scientists say
The two most severe megadroughts make the Dust Bowl of the 1930s look tame: a 240-year-long drought that started in 850 and, 50 years after the conclusion of that one, another that stretched at least 180 years.“.
Models say 4 degrees, my guess 0.8 maximum given current hiatus projected to continue for 20 to 30 years. This is being generous. Therefore divide the result by say 5 gives 5% increase. If we knew the margin of error for this research given it is climate and widely variable. The real answer is probably with the margin of error 100 years out.
Why do “scientist” use failed models
Reply to denniswingo
Simple, these guys spend their time in front of their computers and don’t do much fieldwork. Possibly when they did their degrees they didn’t do much fieldwork then either.
So even if they did do fieldwork now they would not understand what they would see with their own eyes.
I wonder if they took into account the increased density of trees due to the many decades of total fire suppression?
In Brisbane Australia we have had ideal weather all year.
Has this been caused by catastrophic man made global warming horror.
An energised planet?
I think you have been drinking too much Red Bull..
And pigs may fly on the upcurrents from these expanding forests.
CA has always been short of water, it is what makes CA a nice dry place to live. CA’s problem is too many people drinking the available water.
Increasing the temp a few degrees may increase the biomass accumulation rate. If so, it will sequester CO2. It will increase the water vapour content of the air and promote rainfall. If the density is great enough it will create a damp, wet microclimate that retains moisture well.
The claim about drought sounds very unlikely. Recreating forests slopes improves groundwater retention and runoff goes up because trees harvest water from fog at high elevations. Examples of this exist in Chile and the Giant Sequoia National Forest.
Trees shade the ground are reduce evaporation of rainfall. They also harvest snow as already noted above. They reduce sublimation of the snowpack. Trees are altogether good. Remove them and reduce surface water resources. This has been well known for over a century. Refer to books by Dr St. Barber Baker and Men of The Trees for additional information.
“Look, I barely passed science in high school so I don’t know much, but one thing I have learned is that climate scientists have an enormous regard to climate history. So much so that it occupies the bulk of their research.”
So much so that they are constantly rewriting it make sure it fits thier model output.
“… will only add to the burden of providing resources to the thirsty farms and homes that rely on it.”
Those farms and homes, and the people living in them, shouldn’t be there in the first place. I call this a win for global warming.
Plant growth will probably be increased by increased levels of CO2 but not by the totally absent increases in temperature. What effect this will have on rainfall or run-off is anyone’s guess.
Too much CO2, too much plant growth, cut down all the trees… No wait…
Interesting this. Whatever happens, “the models predicted it”. Sheeesh!
Jimbo: http://link.springer.com/article/10.1007/s10584-011-0298-z
Thanks for the link. If that is correct, the extra tree growth will be most welcome. I think more tree growth will be better anyway, but hopefully more people will read the two papers together.
If more trees causing a decrease in run-off is such a big problem, there’s an easy solution.
Bring back logging.
Perhaps they’d be happier if we sent in loggers to clear-cut the mountain slopes and remove all the trees. Then they could have ALL the runoff, including mudslides.
I’d like to see Jim Steele’s take on the points raised in this thread. He does know what he’s talking about!
The guys at the AMS seem a bit dramatic and unfamiliar with other established research.
http://www.mercurynews.com/science/ci_24993601/california-drought-past-dry-periods-have-lasted-more
That said, a prolonged drought will have serious consequences. My suggestion would be desalinization plants quickly.
One solution is to bulldoze the activists out of the way and build more water reservoirs. Incidentally, the rain over the Ogalla reservoir, even in TX, OK, NB etc. has been much more copious this year. Natural recharge can take a long time but perhaps we should take a leaf out of the oil and gas notebook and artificially recharge the aquifers when rain does come. Capture a lot more of it in reservoirs and the demand from aquifers is also greatly reduced. I guess we are stuck with the expense of empty-headed activists misanthropists against everything. Ironically, they can only thrive in an economy that creates the prosperity and abundance of dollars to keep them unproductive. Not a lot of this activism in 150 countries or so. If you want to know the end game of a long term successful social activist campaign against capitalism and the innovation and prosperity it creates, look at the winner of the earth day lights-out contest every year – North Korea. They have the lowest carbon and every other form of footprint in the world.
“They have the lowest carbon and every other form of footprint in the world.”
Yes comrade, DPRK is a shining example of sustainability on the march. http://eoimages.gsfc.nasa.gov/images/imagerecords/79000/79796/korea_vir_2012268_1.jpg
So now more plants are bad for the earth. Just what exactly is good for the planet?
Mother Gaia said that communism would be the best thing, (well okay, it was secondhand, a donkey told me she said it).
Simple Californy-style solution — legislate for resident arsonists to go up to the high country to burn off the excess vegetation.