Study shows experiments underestimate plant responses to climate change

May 02, 2012

Experiments may dramatically underestimate how plants will respond to climate change in the future. That's the conclusion of an analysis of 50 plant studies on four continents, published this week in an advance online issue of the journal Nature, which found that shifts in the timing of flowering and leafing in plants due to global warming appear to be much greater than estimated by warming experiments.

"This suggests that predicted —including continuing advances in the start of spring across much of the globe—may be far greater than current estimates based on data from experiments," said Elizabeth Wolkovich, an ecologist at the University of British Columbia who led an interdisciplinary team of scientists that conducted the study while she was a postdoctoral fellow at the University of California, San Diego.

"These findings have extensive consequences for predictions of species diversity, ecosystem services and global models of future change," said Elsa Cleland, an assistant professor of biology at UC San Diego and senior author of the study, which involved 22 institutions in Canada, Sweden, Switzerland, the U.K. and the U.S. "Long-term records appear to be converging on a consistent average response to , but future plant and ecosystem responses to warming may be much higher than previously estimated from experimental data."

Predicting plant responses to climate change has important consequences for human water supply, pollination of crops and the overall health of ecosystems. Shifts in the timing of annual plant events—which biologists call "phenology"—are some of the most consistent and visible responses to climate change.

Long-term historical records show that many plant species have shifted their leafing and flowering earlier, in step with warming temperatures over recent decades. Because historical records are not available in most locations and climate change may produce temperatures higher than previously recorded, however, ecologists often rely on experiments that warm small field plots to estimate plant responses to temperature and project future conditions.

With support from the National Center for Ecological Analysis and Synthesis, a research center funded by the National Science Foundation, the State of California and the University of California, Santa Barbara, the scientists created new global databases of plant phenology to compare the sensitivity of plants to temperature— that is, how much plants shift their timing of leafing and flowering with warming. These were calculated from experiments and then compared to long-term monitoring records.

Wolkovich and her colleagues found that experiments underpredicted plant phenological responses to temperature by at least fourfold compared to long-term records. Long-term historical records consistently showed that leafing and flowering will advance, on average, 5 to 6 days per degree Celsius—a finding that was strikingly consistent across species and datasets.

"These results are important because we rely heavily on these experiments to predict what will happen to communities and ecosystems in the future," said Ben Cook, a climatologist at the NASA Goddard Institute for Space Studies and Columbia University, who helped bring together the research team.

Wolkovich said a number of factors could explain this discrepancy—including additional effects of climate change not mirrored by warming experiments, or specific aspects of the experimental design such as the degree of warming. But her team's analyses found that within the range of temperature increases considered, responses were not noticeably affected by the degree of warming or the number of years the study spanned. Instead, the discrepancy may be driven by exactly how researchers manipulate temperatures and how accurately they measure them.

"Researchers use a variety of methods to increase temperatures in the field—including heating cables in the soil, small greenhouse-like structures and heating above plants," explains Wolkovich. "We found that plant sensitivities to temperature vary with the design of the experiment, with above plant warming producing consistent advances in flowering."

Additionally, because the comparison was based on a metric that considered plant responses per degree Celsius of temperature change, experiments that overestimate their temperature increases could underestimate the change in leafing and flowering per degree of warming. The difference in estimated responses from experiments versus long-term records has important consequences for predictions of species diversity, ecosystem services and global models of future change.

"Continuing efforts to improve the design of warming experiments while maintaining and extending long-term historical monitoring will be critical to pinpointing the cause of the mismatch," said Wolkovich. "These efforts will yield a more accurate picture of future plant communities and ecosystems with continuing climate change."

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User comments : 14

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mememine69
2.3 / 5 (18) May 02, 2012
Climate scientists have done to science what abusive priests did for religion.
Peteri
3.9 / 5 (11) May 02, 2012
Climate scientists have done to science what abusive priests did for religion.

And you are quite obviously an ignoramus to even think that such a comparison is clever!
Vendicar_Decarian
3.5 / 5 (12) May 02, 2012
Translation: I won't believe climate science so I now distrust all science and science is to blame.

"Climate scientists have done to science what abusive priests did for religion." - MeMeTard

Sorry Tard Boy. The failure is yours.

If the universe does not mesh with your expectations, then your expectations are flawed and irrational.

gregor1
1.9 / 5 (14) May 02, 2012
Activist scientists , led by Hansen at NASA, have brought science into disrepute world wide. The advent of the Internet has seen many of these bozos, and once respected journals like Science and Nature, suffering badly from emporer's new clothes syndrome. How can we take anything from NASA seriously when so often we've often seen Hansen before us in his underwear? Science is mean't to be objective. Activist clowns with crystal ball predictions are not. At the moment the public perception puts scientists down there with used car salesmen
StarGazer2011
1.7 / 5 (12) May 02, 2012
Wow ... talk about anti-science!
The observation in the lab says warming causes a change of X.
The observation in the environment shows a change of Y.
Y>X.
Therefore there is ANOTHER FACTOR 'Z' which is causing the environmental change in addition to X such that X Z = Y!

I mean seriously how stupid can alarmists get? CO2 is their God and is responsible for all things apparently. Does it ever occur to them that there might be unknown unknowns?
Vendicar_Decarian
3.6 / 5 (12) May 02, 2012
Then why is the scientific community applauding his efforts and producing paper after paper confirming and building upon his results?

"Activist scientists , led by Hansen at NASA, have brought science into disrepute world wide." - GregorTard

"How can we take anything from NASA seriously when so often we've often seen Hansen before us in his underwear? " - GregorTard

Clearly you can't. After all NASA did fake the entire Apollo program.

Shame on them, and thank Gawad the Tards figured out their dastardly plan of Global Domination.

Curses.... Foiled Again.

Vendicar_Decarian
4.3 / 5 (11) May 02, 2012
"Therefore there is ANOTHER FACTOR 'Z' which is causing the environmental change in addition to X such that X plus Z = Y!" - StarTard

Are you sure it isn't

x * z = y

or

x plus x**Z plus sin(Z)**e = Y

No matter. Attribution studies have provided us with the causes of the observed warming along with all major feedback mechanisms, both positive and negative.

The hardest has been the effect of clouds, and the consensus view is that they appear to be weekly positive. However there is still some wiggle room for change there.

Lurker2358
4.3 / 5 (6) May 02, 2012
The hardest has been the effect of clouds, and the consensus view is that they appear to be weekly positive. However there is still some wiggle room for change there.


Man, I hope you're wrong.

If clouds cause a net positive feedback by trapping heat, then there will be nothing natural to offset the positive albedo feedback from ice loss.

I had always assumed increased convection would offset ice loss at a ration of about 3 units cloud area per 1 unit ice area.

If this is not the case, then there would appear to be nothing to prevent extreme warming once seasonal snow packs in N. America and Asia develop an increase of another 20 or 30 net annual melting days anomaly, which should happen over the next 20 to 30 years.

It would seem like clouds, especially over water, should reflect more energy in visible light than the amount of energy in infrared that they trap.
bhiestand
3.7 / 5 (3) May 03, 2012
The hardest has been the effect of clouds, and the consensus view is that they appear to be weekly positive. However there is still some wiggle room for change there.


Man, I hope you're wrong.

I hope he's wrong too. Hell, I hope climate scientists are wrong and there's really some god out there making sure we don't destroy our planet. I'm not holding my breath, though... unless I visit certain highly polluted areas.

Unfortunately, the science is probably erring on the wrong side of things. Most models seem conservative, using the lower range of estimates for the unknowns. I've seen a few TRUE doomsday scenarios over the years, calculating based on the most extreme projections, and they're frightening. I'm expecting warming and ice melt slightly faster than most models predict.
djr
4.3 / 5 (6) May 03, 2012
"At the moment the public perception puts scientists down there with used car salesmen" I think u mean that the American public who watch Fox news feel that way. Research shows that 62% of Americans agree with the scientific majority view that our climate is warming - and that this is a serious problem. http://www.brooki...rick.pdf Studies comparing views from different countries show that American's are pretty low on the scale with their concern about global warming - but seem to be taking their lead more from the politicians than the science community. http://pewresearc...oncerned Overall it seems that the antiscience gang are more of a very vocal majority than your biased comment would indicate.
Vendicar_Decarian
5 / 5 (3) May 03, 2012
NonScience nonsense in America is growing rapidly. Current polling has 13% of Americans believing that the world will end at the end of this year with the end of the Mayan Calendar, and 23% of Americans believing that the end of the world will come during their lifetime.

It is a common Conservative Mental Disease.
MarkyMark
3.7 / 5 (3) May 03, 2012
The diseases name is called Gullabillaty and Rupert Murdock Selective Amnesia.
Nartoon
not rated yet May 04, 2012
OMG! It's worse than we thought.
Moebius
3 / 5 (2) May 05, 2012
Stargazer says: Wow ... talk about anti-science!
The observation in the lab says warming causes a change of X.
The observation in the environment shows a change of Y.
Y>X.
Therefore there is ANOTHER FACTOR 'Z' which is causing the environmental change in addition to X such that X Z = Y!

I mean seriously how stupid can alarmists get? CO2 is their God and is responsible for all things apparently. Does it ever occur to them that there might be unknown unknowns?


How stupid can deniers like you be? The observation in the lab says warming causes X (melting of what used to be permanent glaciers and ice packs) and we are seeing X. Warming causes Y (increased weather fluctuations) and we are seeing Y.

The problem is human nature which is to come to a belief first and then look for evidence to support your belief and only reluctantly change your opinion if at all. More so with the right but the left isn't innocent either. It is mostly the right that is full of science disbelievers