Off the Wire:
Geocryology important tool in global change scienceNEWARK, DE.--Geocryology, or the study of permafrost, is an increasingly important area of study in the larger field of global change science, Frederick E. Nelson, professor of geography at the University of Delaware, writes in the March 14 issue of Science magazine.
Nelson, who has undertaken extensive field studies of permafrost in the Arctic, notes in an article titled (Un)frozen in Time that geocryology got off to a rocky start in 1838 when a Russian academician told the Royal Geographical Society of London that the ground in central Siberia was frozen to a depth of more than 100 meters. The claim was met with disbelief.
It was not until the next century, after the Soviet Union had gained extensive experience with construction on frozen ground, that geocryology was developed as an integrative discipline with links to geography, geology, engineering, hydrology and ecology.
Nelson writes that geocryology emerged as an important component of climate change studies in the 1990s because the distribution, thickness, temperature and stability of permafrost are determined to a large extent by the temperature at Earths surface.
He adds that permafrost, which is defined as any subsurface materials that remain at or below freezing continuously for two or more years, plays three important roles in climate-change science. First, because it preserves a record of temperature changes at Earths surface, permafrost acts as a data archive. Precise measurements taken in deep boreholes show that permafrost temperatures have increased markedly during the latter half of the 20th century in the northernmost regions of North America and Eurasia, and Nelson writes, This trend appears to be accelerating.
Permafrost's second role is to translate the effects of climate change by impacting natural ecosystems and human infrastructure. Changes have been most dramatic in regions where permafrost is relatively thin and its geographic distribution is patchy. Extensive areas in central Alaska have experienced thaw subsidence over the past two centuries, converting birch forests to low-lying wetlands. Heated structures built on ice-rich terrain are subject to thaw-induced settlement or collapse unless specialized engineering design criteria are used.
One of the biggest challenges facing geocryologists is separating out changes induced by climate warming from those caused by localized human activities, Nelson writes. If climate warming exceeds design criteria, extensive damage to infrastructure could result. There have been many reports of thawing ice-rich permafrost causing damage to structures over the past decade. More than 300 buildings in the vicinity of Fairbanks, Alaska, have been affected by thawing permafrost, although most problems can be traced to inadequate site preparation or design flaws. Permafrost is an increasingly important consideration for planners, mortgage lenders and the real estate industry.