IPCC’s AR6 and Future of South Asia

Monirul Q. Mirza

Monirul Q. Mirza and Ajaya Dixit

The Intergovernmental Panel on Climate Change (IPCC) 6 the Assessment Report (AR6) on climate change science asserts that human actions are the reasons for climate change and that it will make weather events more erratic, abrupt and extreme.  In this write-up we have critically examined relevance of the IPCC AR6 findings and possible implications for the South Asian Region, the abode for approximately 1.85 billion people. In other words, one in every five-world population lives here. The region is characterized by differential climatic zones from the Himalayas to the coasts of the Bay of Bengal, Arabian Sea, and the Indian Ocean. Extreme weather events-heavy precipitation, heatwaves, droughts, cyclonic storms and coastal inundation, forest fire, etc. occur frequently in the region. These events lead to floods and droughts and regularly inflict heavy wounds to the life and livelihoods of the vulnerable population, ecosystems, and the  conomies. Approximately 81 percent of the population, are exposed to at least one form of natural hazard and live-in places with insufficient resources to cope with and recover from the impacts of catastrophic events.

Ajaya Dixit

Monsoon dominates life, livelihoods, and agriculture in South Asia. The evolution of cropping season and cropping pattern took place around onset and departure of monsoon which vary from year to year. The amount of precipitation also varies temporally and spatially. The spatial variation in precipitation amount occurs from the east to west. Hills and mountains have effect on the amount of precipitation but there are exceptions. Another important aspect of the monsoon is “break monsoon phase” In this phase the monsoon trough shifts close to the Himalayan foothills and stays there for two to three days leading to high rainfall around the trough while there is sharp decline in rainfall south of the trough, northeast India, and parts of the southern peninsula. The IPCC AR6 expresses high confidence in increase in mean precipitation and intensification of monsoon extremes over India and South Asia for both 1.5 o C and 2 o C global mean temperature rise. In general, for each degree rise in temperature, precipitation could increase by 6-7% due to availability of higher amount of moisture. AR6, however, does not address “break monsoon” issue under future climate change.

The intensification of heavy precipitation has major implications for South Asia. A large part of the region is vulnerable to floods that bring destruction to agriculture, infrastructure, industry and people with enormous impacts on poor marginal farmers and agriculture labour force. Not only frequent floods push people in the borderline of poverty to below it, they also affect GDP. An extreme flood could inundate 70% of Bangladesh for up to 68 days. 

Historical records show, Bangladesh’s GDP growth had suffered significantly during extreme flood years. In the mountainous regions of Nepal, Bhutan, India and  Bangladesh, heavy precipitation triggers landslides resulting in destruction and deaths.

With climate change, there is a high probability of  increased episodes of landslides and loss of human lives in the future. Urban flooding has already become a serious problem in the South Asian cities especially in the large ones. Flooding in Chennai, Karachi, Dhaka and Mumbai are annually in the news headlines. Presently more and more people are moving to urban areas and it is likely that by 2030, 55% of the population in Asia will live in cities, and urban areas will become hotspot of air pollution, floods and increased heat. The projected heavy precipitation as highlighted by the IPCC AR6 could translate into extreme urban floods unless proper flood risk management measures are put in place. The social and economic cost of urban flood will increase significantly.

Droughts and heatwaves are very common hazards in South Asia. Two third of India is chronically and frequently drought prone. Large parts of Pakistan in the south-west and east are moderately to severely vulnerable to drought. Considerable area of Bangladesh in the north-west and south is prone to very severe to severe droughts. As most of the agriculture land is still rain-fed, crop and livestock agriculture suffer greatly during a prolonged drought that could lead to food insecurity. In 1979, a prolonged drought had pushed Bangladesh almost on the brink of a famine. In a recently released report, the UN has estimated that impact of severe droughts on India’s GDP to be about 2-5%. 

The plains of South Asia are hot in summer, heatwaves are common and a significant number of people die from this extreme hazard. Although IPCC AR6 is in low  agreement on agricultural and ecological drought in South Asia in the future, extreme heatwaves for a prolonged period would increase irrigation water demand as evaporation increases. 

Heatwaves and humid heat stress would cause serious health problems for the elderly and child population. Agriculture labour force exposed to outdoor weather will suffer.

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.

Ajaya Dixit is Senior Advisor of Kathmandu based ISET Nepal.