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Rising Temperatures Reducing Ability of Plants to Absorb Carbon, Study Warns
Research shows warming over past decade caused droughts that reduced number of plants available to soak up carbon dioxide
Rising temperatures in the past decade have reduced the ability of the world's plants to soak up carbon from the atmosphere, scientists said today.
Droughts have wiped out plants that would have absorbed the carbon equivalent of all the man-made greenhouse gas emissions from the UK every year. Photograph: Patrick Pleul/EPA Large-scale
droughts have wiped out plants that would have otherwise absorbed an
amount of carbon equivalent to Britain's annual man-made greenhouse gas
emissions.
Scientists measure the amount of atmospheric carbon dioxide absorbed by plants and turned into biomass as a quantity known as the net primary production. NPP increased from 1982 to 1999 as temperatures rose and there was more solar radiation.
But the period from 2000 to 2009 reverses that trend – surprising some scientists. Maosheng Zhao and Steven Running of the University of Montana estimate that there has been a global reduction in NPP of 0.55 gigatonnes (Gt). In comparison, the UK's contribution to annual worldwide carbon dioxide emissions was 0.56Gt in 2007, while global aviation industry made up around 0.88Gt (3%) of the world total of 29.3Gt that year, according to UN data.
The researchers used data from the moderate resolution imaging spectroradiometer (Modis) on board Nasa's Terra satellite, combined with global climate data to measure the change in global NPP over the past decade.
"The past decade has been the warmest since instrumental measurements began, which could imply continued increases in NPP," wrote Zhao and Running in the journal Science.
But instead of helping plants grow, these rising temperatures instead caused droughts and water stresses, particularly in the southern hemisphere and in rainforests, which contain most of the world's plant biomass. The growth there has been curtailed by lack of water and increased respiration, which returns carbon to the atmosphere. These problems counteracted any increases in NPP seen at the high latitudes and elevations in the northern hemisphere.
Reduced plant matter not only reduces the world's natural ability to manage carbon dioxide in the atmosphere but could also lead to problems with growing more crops to feed rising populations or make sustainable biofuels.
"Under a changing climate, severe regional droughts have become more frequent, a trend expected to continue for the foreseeable future," said the researchers. "The warming-associated heat and drought not only decrease NPP, but also may trigger many more ecosystem disturbances, releasing carbon to the atmosphere. Reduced NPP potentially threatens global food security and future biofuel production and weakens the terrestrial carbon sink."
The researchers conclude that further monitoring will be needed to confirm whether the decrease in NPP they have observed in the past decade is an anomaly or whether it signals a turning point to a future decline in the world's ability to sequester carbon dioxide.
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19 Comments so far
Show AllOne more feedback loop.
The decaying matter also releases CO2 or methane.
But saving humans and hundreds of thousands of other species - in a mass extinction catastrophe that will have impacts extending the rest of the time the earth capable of supporting life (600-900 MY), is bad for the economy - as the trolls that come here inform us.
"Saving humans", who have brought on these problems to the planet by their sheer numbers, is like saying we need to save a certain virus. Humans are THE REASON for the problems. If "you" don't make the choice to have less children, the planet will make it for you in the very near future.
Just a little info for those who didn't major in botany: plants respire at nighttime: this is when they "burn energy" that they've created (sugars) via photosynthesis during the daylight hours.
Here's the rub: in temperate zones, where the temperature dips significantly at night, plants are able to store their sugars as starch--which is how grain production fueled human evolution in the fertile crescent and how N. America and Europe and Russia (and a long time ago, ancient Rome) were able to feed their armies and grow their power base.
Respiration is temperature-dependent: at higher temperatures, plants respire more, leaving less sugar for storage as starch. This is an important but rarely mentioned consequence of global climate change: our staple crops (worldwide) will become less "productive" in terms of food calories due to this effect--while at the same time becoming less vigorous in growth due to water stress.
This is a positive feedback loop: its effects will significantly increase as climate change continues--to a degree that will likely surprise most of humanity. Our planet will soon be incapable of supporting the current and projected human population at the very fundamental level of raw calories.
The only upshot will be that the HFCS (high-fructose corn syrup) industry will be brought to its knees. The rest of us are in deep doo-doo.
Thanks for the technical imput as it applies to cereal crops.
More than anything, I have noticed that even when daytime highs are average or below, the early morning low temperature is almost always above normal.
ASK: Thank you for the information. If you are a specialist in botany, I'd like to ask you this: will the greater extremes of temperature figure into the harvest cycle itself?
Here's what I mean. I live in North Florida. I moved up this way in l986. I was shocked during my first winter (in Florida!) to experience temperatures occasionally below the freezing point. My concept of Florida ran along the lines of a perpetual day at the beach.
Last winter we had MANY such nights, and temperatures in the 20's became fairly routine. (I know because I felt like a Keystone Cop rushing out to wrap plants, and then upwrap them, only to repeat the ritual over and over again.)
Now we are having the hottest summer I can recall. Temperatures climbed to the 90's in June and have stayed there consistently. The heat factor is impossible. Luckily, we've had much rain.
With a more dramatic winter quickly turning to a longer summer, the cycles of nature, inclusive of the life of plants, appear to be radically altering. I would presume this would have major impacts on anticipated harvests.
My peach tree only produced one peach this summer, and my fig tree: zilch. The apple tree is struggling and the extreme cold killed the citrus.
If you have time, I'd appreciate your feedback. Thank you.
At least you dealt with the REAL issue.
we're getting our just deserts...
right; we've had the entree, main course and now we're on the dessert...........
there's nothing after that except coffee and mints............
Ashes to Ashes,
Carbon to Carbon.
Let me get this straight: the Guardian says that the last decade has been the warmest on record but the BBC says "For the last 11 years we have not observed any increase in global temperatures." [http://news.bbc.co.uk/2/hi/science/nature/8299079.stm] Which are we to believe? It seems to me that the issue is not settled, much less a consensus.
Of course Common Dreams does not try to give a balanced account - they favor one side only. I wonder if they do that with other items of interest. Hmm, non-objectivity in reporting. I wonder about that too. Makes me suggest they are not a good source of information.
jerrymat"Which are we to believe?" Why not believe them both? It's perfectly possible for the last decade to be the warmest on record, but not have experienced any temperature increase during that decade. If your grasp of statistics is that bad, why are you selling it's conclusions to the rest of us?
But, honestly, your BBC article is a year old, and so is its conclusion. Oh, what a difference a year makes!
"Which are we to believe? It seems to me that the issue is not settled, much less a consensus."
These two mass media articles, especially the BBC's, are written in a conversational style that isn't intended to convey hard information but rather to provoke thought/discussion. You might arrive at this same conclusion if you had looked into the Wikipedia article on Global warming and saw the Global Temperatures plot there at the top, generated from public data complied at NASA.
The BBC article is barely coherent, and quite deceiving if you ask me. It starts off with the claim that "For the last 11 years we have not observed any increase in global temperatures." But it does not even try to back up that statement in the following content, rather it drifts around on other points without ever tying them to the statement. This is a serious defect if the goal were to enlighten the people. This seems not to be the BBC's goal.
The BBC ultimately concludes that advocates expect some noise in the temperature data and a long term upward trend while skeptics prefer to ignore the long term trend and focus on the noise, rather hysterically in my opinion.
The Guardian article says "The past decade has been the warmest since instrumental measurements began" which is easily verified by looking at the NASA plot. The plot's yearly average actually shows four or five years in the past decade at or above the 1998 temp. it does seem that the Guardian article is easier to connect with reality than the BBC article, if you believe the NASA data is accurate.
It isn't too surprising that the BBC would lean toward disinformation while the Guardian leans toward the truth. The BBC has long been in the corner of Big Business with the anti-social agenda to keep the people confused and dependent.
Maybe you can cultivate some skepticism for the agenda of the Big Business lobby to make it easier for you to find the truth.
"Of course Common Dreams does not try to give a balanced account - they favor one side only."
Maybe CD published the Guardian article instead of the BBC article because the Guardian tends to lean toward the truth, so the reader is left with a more coherent mind full of information to make sound decisions in the civic sphere.
Look at all the effort required for the people to decode and read between the lines of confusing media reports such as that one of the BBC.
If you're interested in the real global temperature levels, there are three sources which release data at about the same time each year. That's NASA's GISS, NOAA and the Hadley Center at the University of East Anglia. Before you raise the "Climategate" bogeyman, the CRU has been cleared by a third investigation. The score is CRU 3, Climategate 0. Phil Jones is back at work and all that's happened is a lot of wasted time. To sum it up, the past decade has been the hottest since records have been kept.
You're right. Ideology trumps everything. Climate change is happening. But people are doing a knee-jerk, which will have far more dangerous implications for the future.
For the ideological fanatics on here, let me say one thing: I support an immediate and absolute cessation of foreign countries selling oil and other forms of energy to the USA. That should result in an immediately drop of US CO2 output by 75%. Perhaps even 90%. American Enviro-extremists scream at the top of your lungs against oil, but without it, they'd have no economy at all. I WISH the world would stop selling Oil and Natural Gas and Electricity and Coal to the US.
I have one hundred ten acres in the Ozarks that I devote to natural forest and prairie. Natural prairie sequesters large amounts of carbon. I prohibit hunting on that land as well to create a secure environment for animal life. The wooded land is primarily oak and hickory. A great many useful medicinal plants grow there, part of which are harvested to make natural tinctures and salves. There are two ponds and a spring on the property as well. It is increasingly a very healthy and diverse place. Mountain Lyons have returned to the area and black bears have been reported nearby. I still long to again hear the call of the Bob White and Whip-or-will. Hopefully they will return too. I am hopeful that a healthy balance endures here. The extended heat wave did stress the plants but adequate rains helped to sustain them. I'm hopeful.
totally cool.
Stone: Thank you for being a caretaker of the sacred. May you soon hear the call of the Whip-or-will. I love to hear the owls in my region. I hoot back fairly impressively to the delight of my grandson, and the potential shock of a male companion.
Less than 5% of humanity think they are entitled to 25% of the world's daily output of oil. I support an immediate and complete worldwide halt of all oil and energy sales to the United States of America, in order to save the planet.
Look science is really easy. There have been more clouds and less sunlight for the past decade, so of course plants won't grow as well as when there is more sunlight. Claims that the last ten years have been warmer have no scientific basis and should be discarded. The facts are 1 there has been less sunspot activity and this promotes more cloud cover because fewer cosmic particles are being swept away by the sunspot induced solar wind. More clouds means less sunlight so less energy available for plant growth.
Plants can't grow if there is less sunlight and that is plainly the case for the past decade. Consider the leaked email about the travesty of the decline ( in temperature) which couldn't be explained by the Climatologists.
Science should be more vigorous about wild claims that have no basis in fact and can be explained by well known science. The idea that the slight rise in temperature has caused the problem is laughable.
Selwyn Firth B.Sc., M.A.Sc. chemical engineer