As climate changes, boreal forests to shift north, relinquish more carbon than expected

May 05, 2013

It's difficult to imagine how a degree or two of warming will affect a location. Will it rain less? What will happen to the area's vegetation? New Berkeley Lab research offers a way to envision a warmer future. It maps how Earth's myriad climates—and the ecosystems that depend on them—will move from one area to another as global temperatures rise.

The approach foresees big changes for one of the planet's great carbon . Boreal forests will likely shift north at a steady clip this century. Along the way, the vegetation will relinquish more trapped carbon than most current predict. The research is published online May 5 in the journal Nature Geoscience.

Boreal ecosystems encircle the planet's , covering swaths of Canada, Europe, and Russia in coniferous trees and . This vegetation stores vast amounts of carbon, keeping it out of the atmosphere where it can contribute to change.

Scientists use incredibly complex called models to predict the interactions between climate change and ecosystems such as boreal forests. These models show that boreal habitat will expand poleward in the coming decades as regions to their north become warmer and wetter. This means that boreal ecosystems are expected to store even more carbon than they do today.

But the Berkeley Lab research tells a different story. The planet's boreal forests won't expand poleward. Instead, they'll shift poleward. The difference lies in the prediction that as boreal ecosystems follow the warming climate northward, their southern boundaries will be overtaken by even warmer and drier climates better suited for grassland.

And that's a key difference. Grassland stores a lot of carbon in its soil, but it accumulates at a much slower rate than is lost from diminishing forests.

"I found that the boreal ecosystems ringing the globe will be pushed north and replaced in their current location by what's currently to their south. In some places, that will be forest, but in other places it will be grassland," says Charles Koven, a scientist in Berkeley Lab's Earth Sciences Division who conducted the research.

"Most Earth system models don't predict this, which means they overestimate the amount of carbon that high-latitude vegetation will store in the future," he adds.

Koven's results come from a new way of tracking global warming's impact on Earth's mosaic of climates. The method is based on the premise that as temperatures rise, a location's climate will be replaced by a similar but slightly warmer climate from a nearby area. The displaced climate will in turn shift to another nearby location with a slightly cooler climate. It's as if climate change forces warmer climates to flow toward cooler areas, making everywhere warmer over time.

This approach can help determine where a given climate is going to in the future, and where a given climate will come from.

Koven applied this approach to 21 climate models. He used simulations that depict a middle-of-the-road scenario, meaning the range of warming by the end of this century is 1.0°C to 2.6°C above a 1986 to 2005 baseline.

Climate models divide the planet into gridcells that cover tens or hundreds of square kilometers. In each model, Koven identified which gridcells in a warmer climate have a nearby gridcell with a similar climate in terms of average monthly temperature and precipitation. A good match, for example, is a neighboring gridcell that has similar rainfall patterns but is slightly warmer in the summer and winter.

Koven then calculated the speed at which a gridcell's climate will shift toward its matching gridcell over the next 80 years. He also investigated how this shift will transport the carbon stored in the vegetation that grows in the gridcell's climate.

In general, he found that climates move toward the poles and up mountain slopes. In parts of South America, warmer climates march westward up the Andes. In the southern latitudes, warmer climates head south.

But the most dramatic changes occur in the higher latitudes. Here, boreal ecosystems will have to race poleward in order to keep up with their climates. They'll also be encroached by warmer climates from the south. By the end of this century, a forest near Alberta, Canada will have to move 100 miles north in order to maintain its climate. And it will gain a climate that is now located 100 miles to the south.

Forests can't adapt this quickly, however, meaning that in the short-term they'll be stressed. And in the long-term they'll be forced to move north and give up their southern regions to .

Only one of the Earth system models shows this precipitous loss of carbon in southern boreal forests. Koven says that's because most models don't account for random events such as fire, drought, and insects that kill already-stressed trees. His "climate analogue" approach does account for these events because they're implicit in the spatial distribution of .

In addition, Earth system models predict carbon loss by placing vegetation at a given point, and then changing various climate properties above it.

"But this approach misses the fact that the whole forest might shift to a different place," says Koven.

Explore further: Land-restoration expert cautions: 'Nature never forgets nor forgives'

More information: Boreal carbon loss due to poleward shift in low-carbon ecosystems, DOI: 10.1038/ngeo1801

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User comments : 10

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NikFromNYC
1.5 / 5 (17) May 06, 2013
Mann scam. Defund shamelessly brazen climate FRAUD. Save science from further backlash. Utterly no CO2 era trend change is found in the vast majority of long running thermometer or tide gauge records, period, falsifying all headline claims that global warming is supported by actual facts.
deepsand
3.1 / 5 (15) May 06, 2013
Mann scam. Defund shamelessly brazen climate FRAUD. Save science from further backlash. Utterly no CO2 era trend change is found in the vast majority of long running thermometer or tide gauge records, period, falsifying all headline claims that global warming is supported by actual facts.

CLUELESS DRIVEL.
axemaster
4.6 / 5 (11) May 06, 2013
Mann scam. Defund shamelessly brazen climate FRAUD. Save science from further backlash. Utterly no CO2 era trend change is found in the vast majority of long running thermometer or tide gauge records, period, falsifying all headline claims that global warming is supported by actual facts.

Aren't you usually out drinking with your buddies about now?
deepsand
3.1 / 5 (15) May 06, 2013
Mann scam. Defund shamelessly brazen climate FRAUD. Save science from further backlash. Utterly no CO2 era trend change is found in the vast majority of long running thermometer or tide gauge records, period, falsifying all headline claims that global warming is supported by actual facts.

Aren't you usually out drinking with your buddies about now?

They decided that he was too dumb even for them, so they don't let him join them anymore.
Birger
4.4 / 5 (7) May 06, 2013
Complex issues are complex. Which is why we don't invite interns to do brain surgery, and why we let trusted researchers with decades of experience do science-y stuff.
Sometimes the research turns up unpleasant findings and denial sets in. Cancer from smoking? Bah,humbug!
antigoracle
1.4 / 5 (10) May 07, 2013
It happened in the past, within human history and we are still around. Only to the AGW Alarmist Cult is this unprecedented doom and gloom.
http://www.eoeart...e_Arctic
deepsand
2.8 / 5 (11) May 07, 2013
It happened in the past, within human history and we are still around. Only to the AGW Alarmist Cult is this unprecedented doom and gloom.
http://www.eoeart...e_Arctic

Dinosaurs also happened in the past. Doesn't mean squat to the present.

Idiot doesn't understand that current effects are not constrained to being the result of known past causes. Were that the case, we'd still be heating and cooking over the open flames of burning natural materials.

antigoracle
1 / 5 (9) May 07, 2013
It happened in the past, within human history and we are still around. Only to the AGW Alarmist Cult is this unprecedented doom and gloom.
http://www.eoeart...e_Arctic

Dinosaurs also happened in the past. Doesn't mean squat to the present.

Idiot doesn't understand that current effects are not constrained to being the result of known past causes. Were that the case, we'd still be heating and cooking over the open flames of burning natural materials.
-- deepsandTurd
What a "brilliant" argument that this AGW Alarmist turd would call scientific and the Cult would rank him 5 for.
Really, the fact that the dinosaurs dominated the earth for 165 million years means nothing to the present. The fact that you AGW Alarmist turds dominate this forum means even less.
So tell me turd what known past causes resulted in previous warming and how is it different now?
deepsand
2.8 / 5 (11) May 08, 2013
So tell me ... what known past causes resulted in previous warming ...

Since that is your claim that present causes are same as those of the past it is yours to prove.

... and how is it different now?

Asked and answered ad nauseum.
Howhot
5 / 5 (4) May 10, 2013
@Anti whose breath fumigates the room in his glory, did thus spanketh;
What a "brilliant" argument that this AGW Alarmist turd would call scientific and the Cult would rank him 5


He then adds to his fallacy, "the fact that the dinosaurs dominated the earth for 165 million years means... " which means what? Dinosaurs as a species lived 165 million year, and then suddenly where extinct? Its common belief now that a massive 5 mile wide meteor strike did them in, but the amount of CO2 released from that strike from volcanic sources, crustal oil and methane, forest fires and other sources, etc, would probably have had a huge impact on extending the extinction event globally.

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