Part-2
Coastal areas of South Asia especially the eastern coast of India and the coast of Bangladesh are highly prone to cyclonic hazards. In the Bay of Bengal, tropical cyclones are four times more likely to form than in the Arabian Sea. This is owing to the Bay of Bengal’s higher average sea surface temperatures and proximity to the Northwest Pacific basin. From 1970-2000, hundreds of thousands of people perished in the recurring cyclones in the South Asia’s coasts. In recent years, the cyclone related damages especially the loss of lives has significantly reduced due to efficient advanced forecasting and pre-cyclone evacuations. Coastal areas in South Asia inhabit approximately 40% of the population and economic activities are on the rise. IPCC’s AR6 projects that with increased rise in average temperature, the proportion of strong tropical cyclones, peak wind speeds, and high precipitation will bring more people and assets of coastal areas at increased risk in the future.
Rising sea-level will become a significant threat to the deltaic zones of South Asia. In 2013, IPCC’s AR5 WGII had identified the GBM (Ganges, Brahmaputra and Meghna) mega-delta would be one of the most vulnerable deltas in the world to future warming and sea-level rise. The AR5 report noted that “Most large deltas in Asia are sinking (as a result of groundwater withdrawal, floodplain engineering, and trapping of sediments by dams) much faster than global sea-level is rising.” The AR6 had similarly indicated with high confidence the compound effects of climate change such as land subsidence, and human factors will lead to higher flood levels and prolonged inundation in the Mekong Delta and other Asian coasts.
In South Asia, the other vulnerable deltas are the Indus in Pakistan, the Krishna, the Godavari, Brahmani and Mahanadi in Central India. Some of them are sinking fast and will simultaneously face the threat of rising sea level. Research shows that Asia’s relative sea level rise is faster than the world average. For example, according to a research published in Nature Geoscience in 2009, the GBM delta’s annual relative sea level rise is estimated to be between 8 and 18 millimetres (mm) as against ~1.7 mm global rise. For very low to very high greenhouse gas emissions scenario, respectively IPCC AR6 has projected mean sea level rise by the end the current century to be 0.28-0.55 m to 0.63-1.01 m.
Regardless of the magnitude of future sea-level rise scenarios, the deltas of South Asia will continue to remain vulnerable. With sea level rise and warming of climate frequently bringing more heavy rainfall, inundation and flooding will be compounded in the coastal areas. The possible combined impacts include increased coastal inundation, flooding, erosion, salinity intrusion, infrastructure, and agriculture losses. These changes will lead to high population displacement from coastal areas.
Himalayas are the sources of the mighty rivers like, the Ganges, Brahmaputra and Indus. While in terms of annual contribution of snow and glacier melts to runoff of these rivers is low, spring melt is important for summer season and survival of the riverine ecosystems. As per IPCC AR6, higher temperatures in the future in the Himalayas and the Tibetan region, will result in increased glacier melt rates, considerable glacier loss, and a reduction in summer runoff. Glacier melt runoff will increase until the mid-century, after which it would likely decline owing to glacier mass loss (medium confidence). Any reduction in river flows would likely generate tensions among the riparian states that share transboundary rivers. AR6 has put high confidence that climate change will lead to creation of many glacial lakes in the Himalaya-Karakoram region and high mountains of South Asia will face greater risks of glacier lake outburst floods (GLOF) threatening life, livelihoods and infrastructure in the downstream locations of a GLOF.
IPCC’s AR6 has confirmed that rising greenhouse gases (GHGs) on our planet’s atmosphere will have widespread impact globally as well as in South Asia. In the above discussions we have sketched these increasing risks across South Asian countries, the people, sectors and infrastructure. These new external layers of impacts impinge on South Asia’s social-political landscape already facing poverty, interstate disputes and conflicts. Continued emission of GHGs would also alter dynamics of regional climate with impacts exacerbating the existing social, economic and political challenges.
Avoiding climate change induced catastrophe requires immediate transitioning to a greener future globally to first stabilize and then bring the emission curve down. In the meantime, the countries of South Asia while pursuing rapid decarbonizing goals must also individually and collectively work together to establish social support mechanism to help marginal and low-income families stay resilient in face of more climate-change induced disruptions.
(Monirul Q. Mirza is an Adjunct Professor at University of Toronto Scarborough, Canada and an IPCC Author, and Ajaya Dixit is Senior Advisor of Kathmandu based
ISET Nepal).
— Concluded.
