text-only page produced automatically by LIFT Text Transcoder Skip all navigation and go to page contentSkip top navigation and go to directorate navigationSkip top navigation and go to page navigation
National Science Foundation Home National Science Foundation - Biological Sciences (BIO)
Biological Infrastructure (DBI)
design element
DBI Home
About DBI
Funding Opportunities
Awards
News
Events
Discoveries
Publications
Career Opportunities
Examples of Broader Impacts
Supplements & Other Opportunities
See Additional DBI Resources
View DBI Staff
BIO Organizations
Biological Infrastructure (DBI)
Environmental Biology (DEB)
Emerging Frontiers (EF)
Integrative Organismal Systems (IOS)
Molecular and Cellular Biosciences (MCB)
Proposals and Awards
Proposal and Award Policies and Procedures Guide
  Introduction
Proposal Preparation and Submission
bullet Grant Proposal Guide
  bullet Grants.gov Application Guide
Award and Administration
bullet Award and Administration Guide
Award Conditions
Other Types of Proposals
Merit Review
NSF Outreach
Policy Office
Additional DBI Resources
BIO Reports
BIO Dear Colleague Letters
Merit Review
Merit Review Broader Impacts Criterion: Representative Activities
Image Credits
Other Site Features
Special Reports
Research Overviews
Multimedia Gallery
Classroom Resources
NSF-Wide Investments

Email this pagePrint this page

Discovery
Permafrost Could Be Climate's Ticking Time Bomb

Researchers conduct fieldwork to track permafrost melting in Alaska and gain insight about the release of carbon into the atmosphere

Photo of Gregory Lehn and Matt Knhosh talking with co-principal investigator Jim McClelland.

Doctoral students Gregory Lehn and Matt Knhosh talk with co-principal investigator Jim McClelland.
Credit and Larger Version

August 5, 2009

The terrain of the North Slope of Alaska is not steep, but Andrew Jacobson still has difficulty as he hikes along the spongy tundra, which is riddled with rocks and masks multitudes of mosquitoes.

Jacobson, a professor of earth and planetary sciences at Northwestern University, extracts soil and water samples in search of clues to one of global warming's biggest ticking time bombs: the melting of permafrost.

Permafrost, or frozen ground, covers approximately 20 to 25 percent of the land-surface area in the northern hemisphere, and is estimated to contain up to 1,600 gigatons of carbon, primarily in the form of organic matter. (One gigaton is equivalent to 1 billion tons.)

By comparison, the atmosphere now contains around 850 gigatons of the element as carbon dioxide.

"Permafrost historically has served as a carbon sink, largely isolating carbon from participating in the carbon cycle," says Jacobson, whose research is funded by the National Science Foundation (NSF) and the David and Lucile Packard Foundation. "However, global warming could transform the Arctic into a new carbon source by accelerating the rate of permafrost melting. This undoubtedly would have a dramatic effect on the global carbon cycle."

Jacobson says the key concern is that permafrost carbon will oxidize to carbon dioxide as melting accelerates, causing a positive feedback to global warming. A vicious cycle is created as a warmer climate facilitates more carbon release, which in turn favors more warming.

So Jacobson and his colleagues collect river water and soil samples near NSF's Toolik Long-Term Ecological Research station, approximately 250 kilometers (km)--155 miles--north of the Arctic Circle. The Dalton Highway--built as a supply road to support the Trans-Alaska Pipeline System--provides the only access to the site.

"Planning constitutes a large part of our day--looking at maps, figuring out where to go and how to get there," he laughs. "Fieldwork is typically fraught with vehicle problems, poor roads and bad weather. One thing you can always count on is that every expedition is exciting."

While a logical first step for modeling global warming is quantifying carbon flow, unresolved complexities surrounding the Arctic carbon cycle make it difficult to create models for that element.

Jacobson and his team take a complementary approach by analyzing naturally occurring isotopes of other elements, such as calcium and strontium, which track permafrost melting and therefore provide insight into carbon release.

Initial data show that rivers and permafrost have distinctly different calcium and strontium isotope compositions.

When permafrost thaws during the summer and melts into rivers, the rivers show calcium and strontium isotope compositions that approach those for permafrost. Jacobson hypothesizes that in a warmer world, the permafrost signature in rivers will be more pronounced for longer periods of time.

Changes in the isotope composition of rivers can relate to changes in the release of carbon. So the calcium and strontium isotope composition of Arctic rivers can track the impact of warming on permafrost stability and carbon dioxide release.

"The ultimate goal is to establish a baseline to which future changes can be compared," Jacobson says. "Several years from now, we can compare real changes to model predictions and improve our understanding of how the system works."

The sampling season lasts for only a short time when permafrost thaws in the spring until it refreezes in the fall. Although he visited Alaska in May and will return in October, Jacobson has a team of colleagues and students who will conduct fieldwork throughout the season and again next year. Samples are shipped from the field to Jacobson's laboratory in Evanston, Ill., where he analyzes them in the off-season.

He received NSF funding in 2007 to acquire a multi-collector thermal ionization mass spectrometer for measuring isotopes of calcium, strontium and other elements. Northwestern currently is building a state-of-the-art "metal free" clean laboratory that will house the instrument and support Jacobson's research.

-- Amanda Morris, Northwestern University amandamo@northwestern.edu

This Behind the Scenes article was provided to LiveScience in partnership with the National Science Foundation.

Investigators
Andrew Jacobson
Thomas Douglas
James McClelland

Related Institutions/Organizations
Northwestern University
Department of Army Cold Regions Research & Engineering Lab
University of Texas at Austin

Locations
Alaska
Illinois
Texas

Related Programs
Arctic Natural Sciences
Long-Term Ecological Research (LTER)
Major Research Instrumentation Program

Related Awards
#0806643 Collaborative Research: Chemical Weathering and Organic Carbon Export From Arctic Watersheds, North Slope, AK
#0806714 Collaborative Research: Chemical Weathering and Organic Carbon Export from Arctic Watersheds, North Slope, AK
#0806827 Collaborative Research: Chemical Weathering and Organic Carbon Export from Arctic Watersheds, North Slope, Alaska
#0723151 MRI: Acquisition of Multicollector Thermal Ionization Mass Spectrometer (MC-TIMS) for Earth, Environmental, and Cross-disciplinary Research

Total Grants
$1,440,063

Related Websites
LiveScience.com: Environment: Permafrost Could Be Climate's Ticking Time Bomb: http://www.livescience.com/environment/090724-bts-permafrost.html
Andrew Jacobson's Research Web Site: /news/longurl.cfm?id=178
NSF News Release & Audio Slideshow: Arctic Tundra May Contribute to Warmer World: http://www.nsf.gov/news/news_summ.jsp?cntn_id=114865

Photo of Andrew Jacobson doing fieldwork in Alaska.
Andrew Jacobson does fieldwork in Alaska to learn how rapidly permafrost is melting.
Credit and Larger Version

Photo of Thomas A. Douglas, co-principal investigator on the project, drilling in tundra.
Thomas A. Douglas, co-principal investigator on the project, drills in tundra.
Credit and Larger Version

Photo of Andrew Jacobson and colleague hiking along a road with Alaskan pipeline in foreground.
Andrew Jacobson and a colleague hike along the Dalton Highway; Alaskan pipeline in foreground.
Credit and Larger Version



Email this pagePrint this page
Back to Top of page