Amplified greenhouse effect shaping North into South

Mar 10, 2013
Advancing Treeline in to Tundra. Finnmark in Norway. Credit: Dr. Hans Tommervik of NINA, Norway

An international team of 21 authors from 17 institutions in seven countries has just published a study in the journal Nature Climate Change showing that, as the cover of snow and ice in the northern latitudes has diminished in recent years, the temperature over the northern land mass has increased at different rates during the four seasons, causing a reduction in temperature and vegetation seasonality in this area. In other words, the temperature and vegetation at northern latitudes increasingly resembles those found several degrees of latitude farther south as recently as 30 years ago.

The NASA-funded study, based on newly improved ground and satellite data sets, examines critically the relationship between changes in temperature and vegetation productivity in northern latitudes.

On the amplified greenhouse effect, Prof. Ranga Myneni, Department of Earth and Environment, Boston University and lead co-author says "A greenhouse effect initiated by increased atmospheric concentration of heat-trapping gasses—such as water vapor, carbon dioxide and methane—causes the Earth's surface and nearby air to warm. The warming reduces the extent of polar sea ice and snow cover on the large land mass that surrounds the Arctic ocean, thereby increasing the amount of solar energy absorbed by the no longer energy-reflecting surface. This sets in motion a cycle of positive reinforcement between warming and loss of sea ice and snow cover, thus amplifying the base greenhouse effect."

"The amplified warming in the circumpolar area roughly above the Canada-USA border is reducing temperature seasonality over time because the colder seasons are warming more rapidly than the summer," says Liang Xu, a Boston University doctoral student and lead co-author of the study.

Of the 10 million square miles (26 million square kilometers) of northern vegetated lands, 34 to 41 percent showed increases in plant growth (green and blue), 3 to 5 percent showed decreases in plant growth (orange and red), and 51 to 62 percent showed no changes (yellow) over the past 30 years. Satellite data in this visualization are from the AVHRR and MODIS instruments, which contribute to a vegetation index that allows researchers to track changes in plant growth over large areas. Credit: NASA's Goddard Space Flight Center Scientific Visualization Studio

"As a result of the enhanced warming over a longer ground-thaw season, the total amount of heat available for plant growth in these northern latitudes is increasing. This created during the past 30 years large patches of vigorously productive vegetation, totaling more than a third of the northern landscape—over 9 million km2, which is roughly about the area of the USA— resembling the vegetation that occurs further to the south," says Dr. Compton Tucker, Senior Scientist, NASA's Goddard Space Flight Center, Greenbelt, Maryland.

The authors measured seasonality changes using latitude as a yardstick. They first defined reference latitudinal profiles for the quantities being observed and then quantified changes in them over time as shifts along these profiles.

"Arctic plant growth during the early-1980s reference period equaled that of lands north of 64 degrees north. Today, just 30 years later, it equals that of lands above 57 degrees north—a reduction in vegetation seasonality of about seven degrees south in latitude," says co-author Prof. Terry Chapin, Professor Emeritus, University of Alaska, Fairbanks. "This manner of analyses suggested a decline in temperature and vegetation seasonality of about four to seven degrees of latitude during the past 30 years," says co-author Eugenie Euskirchen, Research Professor, University of Alaska, Fairbanks.

"The reduction of vegetation seasonality, resulting in increased greenness in the Arctic, is visible on the ground as an increasing abundance of tall shrubs and tree incursions in several locations all over the circumpolar Arctic," says co-author Terry Callaghan, Professor, Royal Swedish Academy of Sciences and the University of Sheffield, UK. He notes that the greening in the adjacent Boreal areas is much less conspicuous in North America than in Eurasia.

A key finding of this study is an accelerating greening rate in the Arctic and a decelerating rate in the boreal region, despite a nearly constant rate of temperature seasonality diminishment in these regions over the past 30 years. "This may portend a decoupling between growing season warmth and vegetation productivity in some parts of the North as the ramifications of amplified greenhouse effect—including permafrost thawing, frequent forest fires, outbreak of pest infestations, and summertime droughts—come in to play," says co-author Hans Tømmervik, Senior Researcher, Norwegian Institute for Nature Research, Tromsø, Norway.

According to the authors, the future does indeed look troubling: Based on analysis of 17 state-of-the-art climate model simulations, diminishment of temperature seasonality in these regions could be more than 20 degrees in latitude by the end of this century relative to the 1951-1980 reference period. The projected temperature seasonality decline by these models for the 2001-2010 decade is actually less than the observed decline. "Since we don't know the actual trajectory of atmospheric concentration of various agents capable of forcing a change in climate, long-term projections should be interpreted cautiously," says co-author Bruce Anderson, Professor of Earth and Environment at Boston University.

"These changes will affect local residents through changes in provisioning ecosystem services such as timber and traditional foods," says Research Professor Bruce Forbes, University of Lapland, Rovaniemi, Finland. They will also impact the global community through changes in regulatory ecosystem services relating to emissions of greenhouse gases. "The soils in the northern land mass potentially can release significant amounts of greenhouse gases which are currently locked up in the permanently frozen ground. Any large-scale deep-thawing of these soils has the potential to further amplify the greenhouse effect," says co-author Philippe Ciais, Associate Director, Laboratory of Climate and Environmental Science, Paris, France.

"The way of life of many organisms on Earth is tightly linked to seasonal changes in temperature and availability of food, and all food on land comes first from plants," says Dr. Scott Goetz, Deputy Director and Senior Scientist, Woods Hole Research Center, Falmouth, USA. "Think of migration of birds to the Arctic in the summer and hibernation of bears in the winter: Any significant alterations to temperature and vegetation seasonality are likely to impact life not only in the north but elsewhere in ways that we do not yet know."

Explore further: Scientists may be cracking mystery of big 1872 earthquake

More information: "Temperature and vegetation seasonality diminishment over northern lands", DOI: 10.1038/NCLIMATE1836

Related Stories

Deforestation causes cooling, study shows

Nov 16, 2011

Deforestation, considered by scientists to contribute significantly to global warming, has been shown by a Yale-led team to actually cool the local climate in northern latitudes, according to a paper published today in Nature.

New study illustrates shifting biomes in Alaska

Feb 21, 2011

A new study released today in the EarlyView of Ecology Letters addresses forest productivity trends in Alaska, highlighting a shift in biomes caused by a warming climate. The findings, conducted by scientists at the Woods ...

Climate change's impact on Arctic regions by 2099: study

Mar 14, 2011

(PhysOrg.com) -- Imagine the vast, empty tundra in Alaska and Canada giving way to trees, shrubs and plants typical of more southerly climates. Imagine similar changes in large parts of Eastern Europe, northern ...

Peat and forests save permafrost from melting

Sep 13, 2007

Permafrost may be buffered against the impacts of climate change by peat and vegetation present in the northern regions, according to a study by McMaster researchers.

Recommended for you

Volcano in south Japan erupts, disrupting flights

3 hours ago

A volcano in southern Japan is blasting out chunks of magma in the first such eruption in 22 years, causing flight cancellations and prompting warnings to stay away from its crater.

Questions of continental crust

22 hours ago

Geological processes shape the planet Earth and are in many ways essential to our planet's habitability for life. One important geological process is plate tectonics – the drifting, colliding and general ...

User comments : 17

Adjust slider to filter visible comments by rank

Display comments: newest first

deatopmg
1.5 / 5 (17) Mar 10, 2013
This is great news.
LarryD
1.8 / 5 (12) Mar 10, 2013
Now there is a journal 'Nature Climate Change'?
schwarz
4.4 / 5 (13) Mar 10, 2013

Yes, deathtopmg, this is great news indeed:

"This may portend a decoupling between growing season warmth and vegetation productivity in some parts of the North as the ramifications of amplified greenhouse effect—including permafrost thawing, frequent forest fires, outbreak of pest infestations, and summertime droughts—come in to play," says co-author Hans Tømmervik, Senior Researcher, Norwegian Institute for Nature Research, Tromsø, Norway. "

Forest fires in the north! Yay! I can hardly wait!
kochevnik
3.3 / 5 (12) Mar 10, 2013
This is great news.
Great if you enjoy the kissing bug. One bite and a parasite slowly eats away your heart until nothing remains, and you fall over dead from "natural causes." Eighteen million latinos have it and it kills more than AIDS. Now it is endemic in America because capitalists chopped down the native habitats of the kissing bug, forcing it north. It has already adapted to areas infested with conservative mormons such as Arizona
Sean_W
2.6 / 5 (11) Mar 11, 2013
So when Dr. James Hansen and Reto Ruedy of NASA GISS say
"The five-year mean global temperature has been flat for the last decade, which we interpret as a combination of natural variability and a slow down in the growth rate of net climate forcing."
They are lying deniers who can't accept that the warming is accelerating. http://www.columb...2012.pdf
MarkyMark
5 / 5 (4) Mar 11, 2013
This is great news.
Great if you enjoy the kissing bug. One bite and a parasite slowly eats away your heart until nothing remains, and you fall over dead from "natural causes." Eighteen million latinos have it and it kills more than AIDS. Now it is endemic in America because capitalists chopped down the native habitats of the kissing bug, forcing it north. It has already adapted to areas infested with conservative mormons such as Arizona

Dont worry now that its effecting proper countries it should get a better focus from medical researchers.
gmurphy
5 / 5 (5) Mar 11, 2013
CO2 concentration rose at least 45 PPM since 1982 despite all this extra vegetation coming online, predictions that increased vegetation growth would balance CO2 increase are clearly incorrect...but we knew that anyway.
Birger
5 / 5 (10) Mar 11, 2013
Um, all this is only news to Americans, since most of them live south of the "circumpolar area roughly above the Canada-USA border"
Up here in Scandinavia, we already have very noticeable changes of vegetation and insect fauna*. Ticks were unheard of in my home town a generation ago. Now dog owners must examine them almost every day. Winter comes later and spring comes earlier.
*Which is why OUR conservatives take climate change seriously.
Anda
4 / 5 (8) Mar 11, 2013
Agree Birger. Here in the south of europe warming has been evident for everyone too in the past years.
This winter instead of the usual 3 cold months we had barely 15 "typical winter" days.
No denial in Europe, it's evident for everyone.
VendicarE
4 / 5 (8) Mar 11, 2013
Which shows how mainstream and well established the science is.

"Now there is a journal 'Nature Climate Change'?" - LarryD

Meanwhile the denialists can barely make it to quack "journals" that publish articles that also publish articles the sun is a giant ball of Iron.

Bahahahahahah......
Maggnus
4.3 / 5 (6) Mar 11, 2013
Same here in Canada Anda and Birger. We are also seeing a lot of noticable changes in vegetation and insects, including the incursion of some that have never before been a problem this far north.
antigoracle
1 / 5 (7) Mar 22, 2013
The North has been becoming the South since the end of the last ice age. I did not need millions in tax-payers dollars to conclude that.
Maggnus
3.9 / 5 (7) Mar 22, 2013
The North has been becoming the South since the end of the last ice age. I did not need millions in tax-payers dollars to conclude that.


I KNOW! All dem MILLIONS all being SPENT for STUFF! All CONCLUDING an all dat! Making north SOUTH an stuff!

You don't have the capacity to "conclude" anything.
VendicarE
4.2 / 5 (6) Mar 22, 2013
Until recently, global temperatures have been on a slow decline since the end of the last ice age. Those temperatures have now spiked upward due to a CO2 enhanced greenhouse effect.

"The North has been becoming the South since the end of the last ice age" - antigorical

One wonders how many Republican Stupid Pills antigorical has taken today.
antigoracle
1 / 5 (5) Mar 23, 2013
And the North will become the North again.
http://www.woodfo...01/trend
deepsand
2.2 / 5 (9) Mar 23, 2013
And the North will become the North again.
http://www.woodfo...01/trend

More cherry-picking.

Hadcrut also shows the following.

http://www.woodfo...80/trend

http://www.woodfo...60/trend
antigoracle
1 / 5 (4) Mar 24, 2013
The North has been becoming the South since the end of the last ice age. I did not need millions in tax-payers dollars to conclude that.


I KNOW! All dem MILLIONS all being SPENT for STUFF! All CONCLUDING an all dat! Making north SOUTH an stuff!

You don't have the capacity to "conclude" anything.

Oh, but I have long, and accurately, concluded you are a ReTurd.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.