Existing models do predict an increase in extreme rainfall events as observed in historical records, but these cannot be attributed to human-induced climate change, explains Arpita Mondal, assistant professor at the Indian Institute of Technology-Mumbai. “One of the major reasons behind this gap is because India does not have its own climate models,” she tells SciDev.Net.
M.N. Rajeevan, secretary in India’s ministry for earth sciences, tells SciDev.Net that by the end of 2016 India will have the computational power to make its own climate assessment model, allowing the country to participate in next assessment of the UN’s Inter-governmental Panel on Climate Change (IPCC).
According to Mondal, an author of a paper on the gap published in the Journal of Hydrology in September 2015, what is problematic is that the trends of extreme rainfall events projected by model simulations over the last 100 years do not match trends in observed rainfall events. She and her co-researchers used global climate model simulations based on data from natural as well as anthropogenic emissions under different eras for their study. Rainfall predictions from the models were compared with the rainfall data spatially aggregated from 1,800 rain gauges scattered across the country by the India Meteorological Department using sophisticated mathematical tools.
In particular, the team looked at very heavy rainfall received in a single day against that in a five-day span, which is most likely to cause floods and found a need for fine-tuning climate models to simulate hydro-climatic variables at the South Asia regional level. “Human knowledge about the climate system is still inadequate and we need to take account of as many factors as possible,” Mondal says.
India’s Earth System Model (ESM), developed by the Indian Institute of Tropical Meteorology (IITM) and slated for use with IPCC assessments this year, has already shown more than 90 per cent agreement with observed results, according to findings published in the Bulletin of American Meteorological Society in August 2015. The IPCC mandates that every country tries to quantify how human activities are influencing climate.
“The ESM will help to create projections of the future monsoon climate and its uncertainties and will be useful for understanding observed changes in the climate caused by natural and man-made effects," P. Swapna, a scientist at the IITM tells SciDev.Net.
This piece was produced by SciDev.Net’s South Asia desk.