Using satellite observations to investigate 'greening' trends across Canada and Alaska

September 05, 2005

Recent research results from scientists at the Woods Hole Research Center suggest that 'greening' has begun to decline in the high latitude forested areas of North America. The work, which represents an important advance by incorporating the full extent of the latest satellite observational record to document unique vegetation responses to climatic warming, and then projecting those trends forward in time, is now being extended to circumpolar forests. The research will be highlighted in upcoming issues of Proceedings of the National Academy of Sciences (PNAS) and in Geophysical Research Letters.

Generally, satellite observations of plant growth across the high latitudes of North America -- in Canada and Alaska -- indicate that tundra vegetation experienced an increase in both peak photosynthesis and growing season length, whereas forests experienced a decline in photosynthetic activity between 1981 and 2003. Climatic warming occurred across the entire region, but the change in the forest response indicates that long-term changes may not be predictable from initial, short-term observations. Fire disturbance has also increased with the warming but does not explain the decline in forest photosynthetic activity.

According to Scott Goetz, a senior scientist with the Center, "We believe this is some of the first evidence that high latitude forests may be in decline following an initial growth spurt associated with warming. The reasons for this decline are not certain, but related work points to increased drying as a likely cause. The observed warming and drying are consistent with climate model predictions for the region."

More specifically, Center researchers analyzed trends in a time series of photosynthetic activity across boreal North America over 22 years, from 1981 to 2003. Nearly 15 percent of the region displayed significant trends, of which just over half involved temperature-related increases in growing season, length and photosynthetic intensity, mostly in tundra. In contrast, forest areas unaffected by fire during the study period declined in photosynthetic activity and showed no systematic change in growing season length. Stochastic (random) changes across the time series were predominantly associated with a frequent and increasing fire regime. These trends have implications for the direction of feedbacks to the climate system and emphasize the importance of longer-term synoptic observations of arctic and boreal biomes.

According to Andrew Bunn, a postdoctoral fellow at the Center, "These studies are important because they describe how vast areas of forest are changing and how those changes are related to climate. They are supported by a variety of field studies from other researchers that show rapid changes in vegetation in response to climate variability."
-end-
The National Oceanic and Atmospheric Association funded this research.

The Woods Hole Research Center is dedicated to science, education, and public policy for a habitable Earth. We seek to conserve and sustain the planet's vegetation, soils, water, and climate by clarifying and communicating their interacting functions in support of human well-being and by promoting practical approaches to their management in the human interest. The Center has projects "on the ground" in the Amazon, the Arctic, Africa, Russia, Alaska, Canada, New England, and the Mid-Atlantic -- as well as integrative efforts at continental to global scale -- working in collaboration with a wide variety of partners ranging from local NGOs, research centers, and enterprises to national governments and the United Nations.

Woods Hole Research Center

Related Climate Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Climate Insights 2020: Climate opinions unchanged by pandemic, but increasingly entrenched
A new survey provides a snapshot of American opinion on climate change as the nation's public health, economy, and social identity are put to the test.

Climate action goes digital
More transparent and accessible to everyone: information and communication technologies bring opportunities for transforming traditional climate diplomacy.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

How aerosols affect our climate
Greenhouse gases may get more attention, but aerosols -- from car exhaust to volcanic eruptions -- also have a major impact on the Earth's climate.

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

How trees could save the climate
Around 0.9 billion hectares of land worldwide would be suitable for reforestation, which could ultimately capture two thirds of human-made carbon emissions.

Climate undermined by lobbying
For all the evidence that the benefits of reducing greenhouse gases outweigh the costs of regulation, disturbingly few domestic climate change policies have been enacted around the world so far.

Climate education for kids increases climate concerns for parents
A new study from North Carolina State University finds that educating children about climate change increases their parents' concerns about climate change.

Read More: Climate News and Climate Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.