BLOG | Hitting the limits: Where to go in a world that is getting too hot?

Philippus Wester, HI-AWARE Principal Investigator


Even a 1.5 degree world, as aimed for under the Paris Agreement, is projected to be too hot for the Hindu Kush Himalayan (HKH) region, leading to a warming of 2.1 degrees and a loss of one-third of glacier volume in the HKH by 2100. In a 2 degree world, the warming in the HKH could be 2.7 degrees, and glacier volume would be reduced by half. Alarmingly, projections based on current emission trends show a warming of up to 6 degrees and a loss of two-thirds of glacier volume by 2100. These changes will directly impact the lives of the quarter of a billion people living in the mountains and hills of the HKH region, as well as the 1.65 billion people living downstream.

These are just some of the highlight findings of HI-AWARE that fed into the landmark HKH Assessment Report, published by Springer in early January 2019. The HKH region, often called the Third Pole due to the largest concentration of snow and ice outside the polar regions, is the source of ten major Asian rivers, providing water and other ecosystem services to more than 1.9 billion people, equal to 25% of humanity. Stretching some 3500 km through some of the world’s wettest and driest environments, and rising eight vertical kilometres through nearly every agro-ecological zone existing on Earth, the HKH is one of the world’s greatest mountain systems: home to the world’s highest peaks, unique cultures, diverse flora and fauna, and a vast reserve of natural resources. It is also a fragile environment that is highly vulnerable to climate change. This is compounded by rapid socio-economic changes seriously threatening the livelihood systems of poor communities.

The journey of the Himalayan Adaptation, Water and Resilience (HI-AWARE) Research on Glacier and Snowpack Dependent River Basins for Improving Livelihoods consortium started exactly six years ago, in March 2013. At the time, a lot was unknown about future climate change and its impacts on the regions glaciers and livelihoods. To tackle this knowledge gap, the International Centre for Integrated Mountain Development (ICIMOD), a regional intergovernmental organization owned by the eight member countries sharing the HKH, formed a partnership together with BCAS, TERI, PARC and Wageningen Environmental Research (previously Alterra). The consortium set out to enhance the adaptive capacities and climate resilience of the poor and vulnerable women, men, and children in the mountains and plains of the glacier and snowpack-dependent river basins of the HKH, focusing on the Indus, Ganges, and Brahmaputra river basins.

With a strong focus on research and the development of robust evidence to inform climate change adaptation policies and practices in the region, HI-AWARE set ambitious goals for itself in terms of knowledge generation. These were largely met, as outlined in the HI-AWARE Highlights Report 2014-2018 and summarized in 15 HI-AWARE Briefs. Some of the most interesting findings relate to the differences between a 1.5 and a 2.0 degree world for the HKH region. While over the past years, scientific consensus has been building on the general pattern of change in the HKH region, confirming a gradual increase in temperature and a modest increase in total precipitation in the source areas of the Indus, Ganges and Brahmaputra rivers basins by the end of this century, HI-AWARE researchers made a novel contribution by studying what a 1.5 °C global temperature increase would imply for South Asian river basins.

They analyzed climate model data for changes in a range of climate change indicators over the Indus, Ganges, and Brahmaputra basins, such as temperature, changes in rainfall patterns, changes in extreme rainfall events and changes in drought and heat extremes. The findings, published in Regional Environmental Change, show that one degree of global temperature increase with respect to preindustrial levels has already been realized to date in the HKH region and that a global temperature increase of 1.5 degrees would imply a regional temperature increase of more than 2 degrees by 2100. The culprit here is the fact that mountainous areas tend to warm up much faster than low-lying lands, a process also referred to as “elevation-dependent warming”. With the Hindu Kush, Karakoram and Himalayan mountain ranges as the basins’ headwaters, this phenomenon is particularly strong for South Asia. The analysis of climate change indicators also showed that the impacts of a global warming of 1.5 degrees are significant. For example, monsoon precipitation increases by 3 to 11% and the intensity of extreme rainfall events increases by 7-11%. Also, the number of nights with very high nighttime temperature, hampering sufficient cooling of the human body, would increase by around 10% on average.

At the same time, many uncertainties remain, for example how the combination of increasing temperatures and changing precipitation patterns will lead to shifts in the timing of precipitation and runoff and in the frequency of extreme weather events like extended periods of extreme heat or high intensity precipitation. Most climate impact studies to date have focused on yearly totals and long term averages. This leaves translation of how more local and seasonal, time-specific shifts will impact people in the mountains and plains during critical moments (e.g. water shortage during sowing time), and how to adapt, still largely unexplored territory. Also very uncertain is the extent to which increasing atmospheric aerosol loading may be contributing to changes in precipitation patterns in the HKH region through effects on both cloud microphysics and on atmospheric heating and cooling.

While more research will improve decision-making, in part based on HI-AWARE’s research we now know enough to take action, and much more ambitious climate action is urgently needed. Even a 1.5 degree world will already test the limits of adaption in the HKH region, let alone a 2.0 degree world. Tackling the massive air pollution in the countries of the HKH region, which has marked negative impacts on human health and agriculture, while also amplifying global warming and accelerating glacier and snow melt, is an important priority, and will generate important mitigation co-benefits. In parallel, much more emphasis will need to be placed on bolstering transformational adaptation in the HKH, and ensuring good integration with development plans and programmes. This will require very substantial increases in funding from all sources, as part of a larger drive to achieve the Sustainable Development Goals by 2030 in the HKH region.