From NASA:
download large image (700 KB, JPEG) acquired January 1, 2000 – December 31, 2009
download large Hemispheric Trends image (81 KB, PDF)
Conventional wisdom holds that plants should thrive when temperatures warm and the growing season lengthens under a changing climate. A 2003 study showed that plant growth indeed increased as temperatures warmed between 1982 and 1999. But when researchers at the University of Montana updated the study for the last decade, 2000–2009, they discovered that even though the decade was the warmest since instrumental recordkeeping began, plant growth slowed.
The study is significant because plants soak up carbon from the atmosphere as they grow. As growth slows, the amount of carbon plants take up slows as well, leaving more carbon in the atmosphere to contribute to climate change. It is also a warning that a warming climate could bring a decrease in food and biofuel production.
Researchers Maozheng Zhou and Steven Running published the work in Science on August 20, 2010. They used data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite to monitor plant growth and calculate the total amount of carbon plants store as they grow, a value called net primary productivity. Their results are illustrated in this image, which shows the change in the amount of carbon consumed by plants between 2000 and 2009. Green areas show where plants grew more (and consumed more carbon), and brown areas show where they grew less. The deeper the color, the stronger the trend.
In general plant growth and consequently the amount of carbon plants store increased in the Northern Hemisphere and decreased in the Southern Hemisphere. The difference, say Zhou and Running, is water. Three things limit plant growth: light, water, and temperature. In the Northern Hemisphere, warmer temperatures and a longer growing season allowed plants to grow more. But in the Southern Hemisphere, drought dominated the decade. Higher temperatures dried plants and soil, generally slowing growth. The attached graphs illustrate the direct relationship between drought and the amount of carbon plants absorbed between 2000 and 2009.
During the decade, large-scale droughts, primarily in the Southern Hemisphere, were strong enough to overwhelm increased plant growth in other places, resulting in decreased plant growth overall. While 65 percent of the Northern Hemisphere’s vegetated land had increasing growth, 70 percent of the Southern Hemisphere’s vegetated land had decreasing growth. Added together, global plant growth decreased slightly in the decade, reducing carbon uptake by an estimated 0.55 petagrams, a one percent decrease.
It is too early to tell if the recent decade marks the beginning of a longer term trend in plant growth related to long-term climate change. Climate is defined by patterns seen over longer periods of time, at least 20-30 years. In the previous 20 years (1982–1999), plant growth and the related carbon uptake increased as much as six percent. Regardless, the observed decrease in plant growth between 2000 and 2009 helps researchers better understand how plants might respond to a changing climate.
“We see this as a bit of a surprise, and potentially significant on a policy level because previous interpretations suggested that global warming might actually help plant growth around the world,” Running said. “This is a pretty serious warning that warmer temperatures are not going to endlessly improve plant growth.”
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A longer NASA feature article and videos describe the results in greater detail. (below)
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From NASA
Drought Drives Decade-Long Decline in Plant Growth
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A snapshot of Earth’s plant productivity in 2003 shows regions of increased productivity (green) and decreased productivity (red). Tracking productivity between 2000 and 2009, researchers found a global net decrease due to regional drought. Credit: NASA Goddard Space Flight Center Scientific Visualization Studio
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Interannual shifts in plant productivity (green line) fluctuated in step with shifts in atmospheric carbon dioxide (red line) between 2000 through 2009. Credit: Maosheng Zhao and Steven Running Earth has done an ecological about-face: Global plant productivity that once flourished under warming temperatures and a lengthened growing season is now on the decline, struck by the stress of drought.
NASA-funded researchers Maosheng Zhao and Steven Running, of the University of Montana in Missoula, discovered the global shift during an analysis of NASA satellite data. Compared with a six-percent increase spanning two earlier decades, the recent ten-year decline is slight — just one percent. The shift, however, could impact food security, biofuels, and the global carbon cycle.
“We see this as a bit of a surprise, and potentially significant on a policy level because previous interpretations suggested that global warming might actually help plant growth around the world,” Running said.
“These results are extraordinarily significant because they show that the global net effect of climatic warming on the productivity of terrestrial vegetation need not be positive — as was documented for the 1980’s and 1990’s,” said Diane Wickland, of NASA Headquarters and manager of NASA’s Terrestrial Ecology research program.
Conventional wisdom based on previous research held that land plant productivity was on the rise. A 2003 paper in Science led by then University of Montana scientist Ramakrishna Nemani (now at NASA Ames Research Center, Moffett Field, Calif.) showed that global terrestrial plant productivity increased as much as six percent between 1982 and 1999. That’s because for nearly two decades, temperature, solar radiation and water availability — influenced by climate change — were favorable for growth.
Setting out to update that analysis, Zhao and Running expected to see similar results as global average temperatures have continued to climb. Instead, they found that the impact of regional drought overwhelmed the positive influence of a longer growing season, driving down global plant productivity between 2000 and 2009. The team published their findings Aug. 20 in Science.
“This is a pretty serious warning that warmer temperatures are not going to endlessly improve plant growth,” Running said.
The discovery comes from an analysis of plant productivity data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, combined with growing season climate variables including temperature, solar radiation and water. The plant and climate data are factored into an algorithm that describes constraints on plant growth at different geographical locations.
For example, growth is generally limited in high latitudes by temperature and in deserts by water. But regional limitations can very in their degree of impact on growth throughout the growing season.
Zhao and Running’s analysis showed that since 2000, high-latitude northern hemisphere ecosystems have continued to benefit from warmer temperatures and a longer growing season. But that effect was offset by warming-associated drought that limited growth in the southern hemisphere, resulting in a net global loss of land productivity.
“This past decade’s net decline in terrestrial productivity illustrates that a complex interplay between temperature, rainfall, cloudiness, and carbon dioxide, probably in combination with other factors such as nutrients and land management, will determine future patterns and trends in productivity,” Wickland said.
Related Links: > Related video
This narrated video gives an overview of net primary production and the carbon cycle. High-resolution data from the Moderate Resolution Imaging Spectroradiometer, or MODIS, indicate a net decrease in NPP from 2000-2009, as compared to the previous two decades. Credit: NASA/Michelle Williams
Researchers are keen on maintaining a record of the trends into the future. For one reason, plants act as a carbon dioxide “sink,” and shifting plant productivity is linked to shifting levels of the greenhouse gas in the atmosphere. Also, stresses on plant growth could challenge food production.
“The potential that future warming would cause additional declines does not bode well for the ability of the biosphere to support multiple societal demands for agricultural production, fiber needs, and increasingly, biofuel production,” Zhao said.
“Even if the declining trend of the past decade does not continue, managing forests and croplands for multiple benefits to include food production, biofuel harvest, and carbon storage may become exceedingly challenging in light of the possible impacts of such decadal-scale changes,” Wickland said.
This is how the NASA/AGW/Gouvernment do it!
They leave a little propaganda turd in shape of an “alarming study” stinking on the floor.Then they run and hide from the most basic quality conrol questions and NEVER cleans up after themselfes.
There are som many turds on the floor now that they have problems to place new ones without steppin in old ones. Its time to call anticimex to take care of the problem!!
We’ll be alright. By next summer with the Greenland ice cap melted and replaced by thousands of square miles of grassland, an awful lot of CO2 will have been used up.
Before you bet on that you will have to be sure that there is some well mineralised soil under all that ice, that there is just the right amount of precipitation, that the temperature of the soil is just a little above freezing, that some of that CO2 is floating around over Greenland, and, absolutely vitally, that there is an abundance of ultra violet light shining down on that glorious soil. Temperature, per se, is not the vital plant growth factor. It is the combination of mineral availability, moisture, CO2 and good old sunlight that rule the roost.
Just more evidence against the use of tree rings as proxies…
-Scott
Alexander K says:
August 23, 2010 at 3:08 am
Nah … we call ’em climate scientists and watch in amazement as they scoop up grants by the armful issuing forth from a seemingly inexhaustible horn of plenty.
This study finished in 2009, this year in the southern hemisphere we have had rain, the drought is over. I have been watching our forests and grassland suffer for years, this year they have quadrupled in growth. In OZ our CSIRO are climate alarmists but have some real scientists still working for them. Some while ago they stated that our country absorbes all our emissions of CO2. The growth we have seen this year most likely sucked in all of Europes too, and a some of Chinas. Australia is blooming.
Come off it! There are less than ten independent data points in the set, with a year to year variation of order +/- 3 times the alleged trend (’04-’05 -6x, ’05-’06 +4x!). That’s not enough even to get an average value to this level, let alone a trend. Note the “how to lie with statistics” trick of suppressing the zero and plotting differences instead (and calling the differences anomalies, when there’s nothing remotely anomalous about them).
Perhaps the rate of increase has decreased because it is not slowing down at all, but not spending up in proportion the level of growth?
A one unit increase in a pool of ten units is dramatic. A one unit increase in a pool of 100 units is a marginal increase, but is still the same amount of growth.
This would be funny if it wasn’t so pathetic.
As a long distance hiker, I’ve walked in a lot of places (SoCal, New Mexico, Alaska, Canadian Rockies, Newfoundland, Florida, North Carolina, Montana – just to name a few) over the last 20 years. My only comment is that these people need to get out where the plant growth is actually happening, because it IS happening. I was in Virginia 4 days ago – and the kudzu is lusher than I’ve ever seen it before. Same story everywhere I’ve been for the last few years.
BTW – having worked for 40+ years as a science ops engineer on spacecraft remote sensing instruments like (and including) MODIS/Terra, I’d suggest that the boys need to recalibrate their data.
If one disregard the fact that this is just another calculated guesstimate of made up proxies. Why again has their been so many floods and above normal precipitation in south america this decade, reported even by NASA pretty much every time it is reported, if their conclusion is drought?
And by the way, plants need nutrients and sunlight first, moist and water second, warmth is third because it can get too hot and warmth is not really as necessary other than it not being freezing for too long.
One way to kill a plant is to derive it of sunlight for too long like when it’s too cloudy and it turns pitch black in the under growth where the kid planty grow.
Gee, I wonder if it ever occurred to the authors to compare 2000-2009 temperature anomalies in the southern and northern hemisphere. I thought even cavemen knew that that global warming is a northern hemisphere phenomenon.
So what did the authors find? Northern hemisphere plants grew better and southern hemisphere plants did not.
Conventional wisdom, it seems, wins again.
björn says:
August 23, 2010 at 12:40 am
Another proxy showing a cooling trend.
This is Lysenkoism, the theory is always right, it is nature who is behaving wrong.
Solution: Destroy real data and replace with politically corrected data.
Nice.
So having no snow on the ground isn’t vitally important to plant growth?
Ooooooooooooooookay…
Next!
Plants use less water as CO2 level rises.
How bad for plant growth would the recent southern hemisphere drought have been with pre-industrial CO2 level?
Anyone? Anyone? Bueller?
Warmer earth with higher CO2 is a godsend.
Pay attention:
http://ag.arizona.edu/pubs/natresources/az1395.pdf
Compared to plants grown at existing carbon dioxide
levels, plants “fertilized” by elevated levels of atmospheric
carbon dioxide increase their photosynthesis rates (Norby et
al. 1999, Kimball et al. 2002, Nowak et al. 2004). In addition,
carbon dioxide-fertilized plants respond with increased
biomass (dry weight), improved water use efficiency, and
an increased tolerance of low light levels.
An important consideration in relation to climate change
is that carbon dioxide fertilization raises the optimum
temperature for photosynthesis (e.g., Norby et al., 2002). It
also increases water use efficiency of plants. However, other
factors, such as deficient nitrogen or absence of moisture, can
limit plant response to increases in carbon dioxide.
Higher level of CO2 will definitely help in a drought. It won’t magically make plants require no water but it does help them use what little water there is more efficiently.
The might even lead one to think that green plants evolved over the course of billions of years where temperatures and CO2 levels were much higher than today and so that is the evironment evolution optimized them around. If one thinks that one would in fact be correct as the geologic column reveals a planet that spent most of its history in warmer with much higher atmospheric CO2.
1. If you drop the first point on the chart, the trend is flat, not down.
2. They ignored deforestation.
3. This is weather, not climate.
Do it again in 50 years.
Move along, nothing to see here.
Nasif Nahle says:
August 22, 2010 at 10:08 pm
re; C3 C4 plants
“The advantage of C3 plants over C4 plants is that C3 plants survive to cold temperatures. 20 °C is the peak temperature at which the growth of C3 plants is optimum. Below and above this temperature the growth of C3 plants unavoidably slows; even if the CO2 in the environment is abundant.”
Yabbut the temperature span around the optimum is pretty wide and both C3 and C$ respond positively to higher CO2 up to at least 2x current levels.
While C3 has an optimum temperature of 20C it doesn’t fall off the peak much at 23C which is where C4 hits its optimum.
The difference of course is, as you stated, C3 plants survive in cold that will kill a C4 plant and C4 plants will survive in heat that will kill a C3 plant.
Yet one fact that stubbornly remains is that global warming isn’t global. It’s regional with the primary beneficiary being the higher northern latitudes where for most of the year it’s too cold for even C3 plants and where early and late frosts can have a devastating effect on agriculture. The warming is happening right where we need warming to happen and it isn’t happening where we don’t need it. What’s to complain about? Global warming and rising CO2 is a wonderful thing.
In fact right around 25C
The potential that future warming would cause additional declines does not bode well for the ability of the biosphere to support multiple societal demands for agricultural production, fiber needs, and increasingly, biofuel production,” Zhao said.
First: This is the same tale for scaring kids. There is no future warming at all, but PRESENT COOLING:
http://weather.unisys.com/surface/sst_anom.html
In South America there are two main weather systems: One to the east of the Andean mountains range (altitude up to 7000 m), and other to the west of it. Cold SST means less evaporation in the pacific, but normal at the east side, so the amazon basin will not suffer any droughts. These are to be expected, as in other solar minimums, more to the south, at the argentinian “pampas” plains:
From the known argentinian geologist Miguel Gonzales, in his studies in the “Salinas del bebedero”, a salt lake in Argentina
http://www.springerlink.com/content/m11m129238u61484/
He studied a dried salt lake called “Salinas del Bebedero”, he found that this salt lake , though then surrounded by dried lands and weather, filled with water during solar
minimums, coming from the east side of the Andes mountains.
Uh, Roger P.?
Comment?
Didn’t have time to read all the comments, so this has likely already been said, but:
If the biomass had increased in the last decade, that would have been proof that global warming was proceeding apace.
But the biomas decreased in the last decade (supposedly) and so that becomes evidence that global warming will cause droughts that will eventually have dire consequences for humanity.
The first possibility adds support to the global warming hypothesis while the second assumes global warming. This leaves no possibility of the study reducing support for the global warming hypothesis, an approach likely to keep those research dollars flowing.
But if they were surprised by the reaction of biomass to a warming world, perhaps someday they’ll also be surprised by the reaction of the climate to rising CO2? Maybe both models, that of biomass production and that of the effect on climate of rising CO2 were too simplistic from the outset?
lookimng at that map in red and green.
Australias areas of green?
someone better do that map again and try and get it right!
the green areas across the middle of aus,Sth Aus and victoria, and Tasmania?
all of which have been hard hit by drought for many years.
the coastal fringes in red? when they ARE our food production areas in the main.
sheesh, give a kid a crayon and look what you get!
“During the decade, large-scale droughts, primarily in the Southern Hemisphere, were strong enough to overwhelm increased plant growth in other places, resulting in decreased plant growth overall.”
________________
Let me see if I understand. During the period, h2o was down due to drought, so things didn’t grow well. OK, what does this have to do with co2 intake being down? I don’t get it. Were the waterless plants supposed to suck in just as much co2 even it there was a drought? That doesn’t sound right? Does this mean if there’s a drought that we’re in trouble? Wasn’t that always true? I still don’t get it.
Dave Springer says:
August 23, 2010 at 7:20 am
While C3 has an optimum temperature of 20C it doesn’t fall off the peak much at 23C which is where C4 hits its optimum.
What really surprised me is that C4 plants survive at high temperatures, up to 45 °C. The production of C4 plants becomes stable at 20 °C; from there on up to 45 °C the production doesn’t increase but doesn’t decrease either. However, C3 plants offers a production line of Gaussian type, although its minimum is above than that of C4 plants. Corn, a C4 plant, would benefit from the combination “high temperature -high CO2 concentration” but up to some limits, which, according to experimentation, are ~1000 ppmV, on CO2 concentration, and 45 °C, on temperature. However, yet on this case we cannot generalize because of the many varieties of corn.
Yet one fact that stubbornly remains is that global warming isn’t global. It’s regional with the primary beneficiary being the higher northern latitudes where for most of the year it’s too cold for even C3 plants and where early and late frosts can have a devastating effect on agriculture. The warming is happening right where we need warming to happen and it isn’t happening where we don’t need it. What’s to complain about? Global warming and rising CO2 is a wonderful thing.
I agree, rising CO2 and GW are good for life, but limits exist. I consider it is another case where the axiom “The whole is greater than the sum of its parts” applies on, especially when dealing with climatology. For example, we have had a nice mild summer, regarding temperatures. 🙂
This is just another puzzle piece and nothing more. Like so many recent articles, much to do about nothing.
This is what happens when ‘researchers’ draw straight lines through stochastic data and extrapolate to answers they want to get.
The variance is as the paper states – due to lack of rain not temperature. Droughts and floods have come and gone- look at the Murray Darling Basin. But I suppose it all depends on the answer the ‘researcher’ is looking for.
Strange, the Sahel in these pictures is white or the zones bordering it are mostly red. Yet a recent study revealed a serous greening in the last decades. This study also corresponds to the increased rice production reported during recent years in the Sahel. Despite ongoing civil war food production increased.
http://news.nationalgeographic.com/news/2009/07/090731-green-sahara.html