October 12th, 2014
The high mountains of Asia, including the Karakoram, Himalayas, and Tibetan Plateau, combine to form a region of perplexing hydroclimate changes. Glaciers in the Karakoram region have exhibited mass stability or even expansion, contrasting with glacial mass loss across the nearby Himalayas and Tibetan Plateau. This suggests that different regional snowfall or temperature signals might be detected in the Karakoram region. However, the remote location, complex terrain, and multi-country fabric of high-mountain Asia have made it difficult to maintain longer-term monitoring systems of the meteorological components that can influence glacial change.
The authors explore this region in-depth using a high-resolution climate model (GFDL-CM2.5), and help explain why this region experiences statistically neutral, but positive snowfall changes while other high elevation zones in the region exhibit statistically significant snowfall loss under greenhouse gas forcing. This study shows that differences in the seasonal cycle and seasonality of climate change signals are driving the climate change response.
A set of experiments from 1861-2100, compared with the latest available observing systems, allowed the authors to focus on how these mountains exhibit distinct seasonal cycles and resulting climate change signatures. The Karakoram seasonal cycle, dominated by non-monsoonal winter precipitation, uniquely protects it from reductions in annual snowfall under climate warming over the twenty-first century. The simulations in this study show that climate signals are detectable only with long and continuous records, and at specific elevations. These results provide a meteorological mechanism for regional differences in glacier response to climate warming.
The Karakoram glaciers were a source of controversy when mistakenly reported in the Intergovernmental Panel on Climate Change (IPCC) Forth Assessment Report to be receding faster than in any other part of the world and to have a high likelihood of disappearing by 2035. This paper explores the component of glacial accumulation (snowfall) to show that the Karakoram exhibits a different sign than the rest of the Himalaya. It provides evidence for fundamental differences in the meteorological forcings of these regions and helps explain why the Karakoram is unique. Moreover, snowmelt and glacial melt in the region provide water supply for industry and hydropower and can also cause extreme flooding. Understanding the region’s hydroclimate is required to provide necessary infrastructure for climate change adaptation.