What is the evidence for glacial shrinkage across the Himalayas?: systematic review

There has been concern in the scientific community surrounding the claim that Himalayan glaciers are shrinking at an alarming rate as a result of climate change, leading to significant impacts on the water resources of populations in the downstream basins. Despite much research, there remains no clear understanding of how glacier shrinkage varies across the region, or how it might impact downstream stakeholders. Clearly this hinders well-informed, evidence-based decision and policy making. A rigorous systematic review, to discern what is the evidence about glacier shrinkage across the Himalayas, is a major step to support policy-making in the region. This systematic review assesses the primary evidence regarding physical changes in glaciers in order to ascertain what evidence is available, whether glaciers are shrinking in mass, reducing future melt-water availability, and whether the rate of shrinkage is changing. Four main measurement types have been employed to assess such changes: terminus position, area, volume, and mass balance. Some measurements are more appropriate and indicative than others in assessing changes in glacier mass. As well as assessing the available evidence, the review provides an appraisal of current understanding and corresponding knowledge.