As June draws to a close, eyes are turning to the latter half of the year – and with it, the monsoon and hurricane seasons that can prove vital or devastating for many of the world’s coastal communities. Now, climate change stands to disrupt hitherto more predictable weather patterns like the monsoon season, throwing those communities into dangerous uncertainty. A coalition of researchers from 13 different institutions collaborated to investigate possible futures for monsoon regions using HPC.

Monsoon season is a decisive element of the economy in the major monsoon regions (which include countries like India and Pakistan), where heavily populated areas receive around two-thirds of their annual precipitation during the season. For those regions, economic sectors like agriculture and even energy production can depend heavily on the timely arrival of the monsoon season.

The researchers set out to examine whether climate change would affect the timeliness of future monsoon seasons. To do this, they used the regional climate model RegCM4, developed by the International Centre for Theoretical Physics.

“This is the first time that a regional climate model has been used to provide a global view of changes in monsoons,” said Oak Ridge National Laboratory (ORNL) climate scientist Moetasim Ashfaq, lead author of the research, in an interview with ORNL. “It took a great deal of time and effort to compile and analyze such high-profile, high-resolution data, and these detailed simulations would not have been possible without a significant international collaboration.”

The simulations spanned nine monsoon regions in five continents using a grid at a relatively fine 16-mile resolution, analyzing how monsoon behavior in the regions would change under both the RCP8.5 (business as usual) emissions scenario and the RCP2.6 (aggressive mitigation policies) emissions scenario. The researchers turned to HPC to complete these simulations; at ORNL, for instance, which handled the simulations for the South Asian monsoon region, researchers used the Eos system. Eos is a Cray XC30 cluster with Intel Xeon E5-2670 CPUs, 736 nodes and 64 GB of memory per node. 

The researchers’ results highlighted the urgency of the climate crisis for vulnerable monsoon regions.

“The RCP8.5 simulations reveal robust delays in the start of rainy seasons that ripple through many aspects of everyday life in these regions,” Ashfaq said. “For example, a monsoon that usually starts in the first week of June in South Asia and West Africa may be delayed as long as 15 to 20 days or even an entire month over parts of these regions by the end of the 21st century.”

These delays may sound trivial on paper, a shorter monsoon season would likely include more intense rains and longer dry periods in the rest of the year, worsening the prevalence of floods, droughts, wildfires and more.

However, all hope is not lost, as long as the world acts to limit emissions.

“If emissions are reduced based on RCP2.6 out to the year 2100, the simulations show that the long, damaging shifts in monsoon behaviors can mostly be avoided,” Ashfaq said. “If you look at the best-case scenario, we do still see changes, but they are insignificantly different from the typical year-to-year variation in regional monsoons that communities are already accustomed to.”

To read ORNL’s article discussing this research, click here.