Monitoring Change in the Arctic - Satellite-based Applications on Climate Change - page 123

Chapter 9
Monitoring Change in the Arctic

Jeffrey R. Key, Xuanji Wang, and Yinghui Liu

Abstract Modeling studies have shown that the Arctic is one of the most sensitive
regions on Earth to global climate change due primarily to the positive feedback
between surface temperature, surface albedo, and ice extent. Because in situ
measurements in this harsh environment are costly, satellites are a critical source
of information for monitoring and evaluating changes in the Arctic climate system.
Satellite data can be used to measure polar winds, clouds, sea ice, snow cover, and
glaciers. Applications of space-based imager and sounder data have shown that
over the last three decades, the Arctic has warmed and become cloudier in spring
and summer, but cooled and become less cloudy in winter. Arctic sea ice has
declined substantially and at a greater rate than that predicted by most climate
models. Snow cover has decreased in many areas, and vegetation growth has
increased at high latitudes. Satellite products have also been used to demonstrate
the complex feedbacks between clouds and sea ice, providing insight into the
possible future state of Arctic climate.

9.1 Introduction

The Arctic has become an area of considerable interest for studying the Earth's
changing climate (e.g., ACIA 2005 ; Overland 2009 ). Satellite observations have
shown that Northern Hemisphere sea ice extent and thickness have been decreasing
beyond the expectation of natural climate variability (Rothrock et al. 1999 ; Vinnikov
et al. 1999 ; Parkinson et al. 1999 ; Cavalieri et al. 1999 ; Maslanik et al. 2007; Kwok and