Coastal areas in South Asia are threatened by the very factors that make them thrive. The four megacities of Karachi, Mumbai, Kolkata, and Dhaka are home to almost 70 million people, most of whom have migrated there in the last 50 years due to trade and economic opportunities. Among the densest human habitations on the planet, the concentration of people, economic activity, and location combine to make these cities particularly vulnerable to climate change impacts.
Many impacts are slow such as sea level rise, the growing urban heat island effect, and coastal erosion, while others are episodic such as cyclones and extreme tidal events. This means the threats are often either ignored due to their ubiquity or not factored in until the threat of natural disaster looms up suddenly.
As the climate crisis deepens, the risk of cascading disasters – of one set of problems leading to others – grows. As sea levels rising claim more land from coastal communities, the people living in these areas risk being forced into denser population areas, increasing the urban heat island effect. And hotter conditions limit the ability to work with negative health impacts for individuals and lowered productivity for the region.
Such types of maladaptation – dealing with the impacts of climate change in ways which makes communities more vulnerable – are a serious risk unless governments and policymakers take a coordinated and considered response to climate adaptation.
South Asia’s coastal communities are extremely vulnerable to flooding and sea level rise. Source: Reuters.
The need to prepare coastal cities
Preparing coastal cities is a crucial aspect of the global response to climate change. With huge economic potential and large populations, they have the means to power the adaptation and innovation needed to deal with the cumulative impacts. But much of the current expansion and investment in South Asian coastal cities is short-term, ad hoc, and under-resourced. Unless key lessons are learned and internalized, the region risks creating long-term risk factors for people and economies.
The Intergovernmental Panel on Climate Change (IPCC)’s Sixth Assessment Report has a cross-chapter on cities and settlements by the sea. It lists possible responses as: ‘avoidance (i.e., disincentivising developments in high-risk areas), hard and soft protection, accommodation, advance (i.e., building up and out to sea) and retreat (i.e., landward movement of people and development)’.
It also emphasizes some of these responses will reach their limits before 2100, but – depending on what adaptation methods are put in place by when – the space for these responses will expand or shrink. The clock is already ticking and, as the report notes, sea level rise ‘is relentless on a human timescale’ so the need to act is paramount.
Around 80 per cent of major South Asian cities are exposed to flooding, and the actions they choose now will determine the future for generations. Short-term solutions, such as building dikes which may soon be overtopped, or accommodating the intrusion of sea water in a way that leads to salinity of soil, may expend critical resources while leaving them even more vulnerable in the future.
The governance and administrative adaptation to the new and changing reality is more important than the specific solutions being advocated.
Risks and vulnerabilities
The risks to cities depend on their geography. Karachi, Dhaka, and Kolkata are on coastal deltas but Mumbai is on an estuary. However, the broad category of threats to coastal areas in South Asia can be summarized as extreme heat, greater and more frequent floods, more frequent storms and cyclones, as well as sea level rise, and the accompanying salinization.
The socio-economic characteristics of cities also matter, as they intersect with other vulnerabilities. All the cities of South Asia are classified as low income with a per capita income below $10,000. Poor residents are disproportionately affected by flooding as the most flood-prone areas are often the most affordable.
Some estimates say flooding alone could cost the region up to $215 billion every year by 2030, with the number of climate migrants reaching 40 million by 2050. This is an immense economic challenge for a region still reeling from the impacts of the COVID-19 pandemic and rising inflation while still investing in sustainable development and growth.
Some estimates say flooding alone could cost the region up to $215 billion every year by 2030, with the number of climate migrants reaching 40 million by 2050
Deltaic and estuary cities are particularly vulnerable to pluvial flooding – when excess rainfall overwhelms the drainage and absorption capacity of an area. As rainfall patterns become more erratic, leading to short bursts of heavier rain, the risks of pluvial flooding increase. This is a danger in South Asian cities, which already suffer from poor water and drainage infrastructure, especially if they have limited resources to improve their drainage capacity.
Mumbai’s drainage systems were designed for 25mm of rain per hour more than a century ago. In 2017, parts of the city received more than 300 mm of rain in one hour, although this pales in comparison to more than 900 mm of rain per hour which deluged parts of Mumbai in 2005. These problems had, to a degree, been anticipated as a plan to overhaul the city’s drainage system had been proposed in 1993 but was not implemented because of a lack of funds.
Other governance factors also increase the risk. Dhaka’s drains are plagued with discarded plastic while building encroachment along its canals limits their ability to carry water. Karachi also suffers from clogged drains with massive resources needed to separate the water and sewerage systems so excess water can flow out from the city.
Governance plays a significant role in sea level rise too. Both Kolkata and Dhaka are facing sea level rise, but one factor often ignored is the lower level of sediment reaching the deltas. With hydropower dams and barrages constructed upstream along the Ganga and the Brahmaputra, the amount of sediment reaching the deltas has fallen sharply and dramatically increased the effects of sea level rise and erosion.
More powerful cyclones also present a substantial risk to coastal cities in South Asia. Although research is in its early stages, climate models suggest a five per cent increase in the intensity and wind speeds of tropical cyclones if global temperatures increase by two degrees above pre-industrial era levels. Sea level rise will contribute to the damage cyclones cause as the possibility of greater flooding increases.
How can coastal communities shore up against climate change?
Preparing for a complex set of disasters requires a more proactive approach than has been taken so far. Many of the standard responses to climate change impacts have been prevention and protection-based such as building sea walls and dikes.
Coastal polders – areas surrounded by dikes on all sides – combined with substantial investment in early warning systems and cyclone shelters have been a key part of Bangladesh’s successful strategy to deal with cyclones, rising sea levels, and encroaching salinity. These have led to both greater agricultural production and improved safety from cyclones – casualty rates from cyclones are 100 times lower than five decades ago.
The challenge with physical infrastructure alone is it can be overwhelmed. A sea wall or dike can always be overtopped by a large enough wave or storm. The IPCC estimates that under most scenarios coastal cities and settlements will reach the limit of their ability to deal with climate change impacts by 2100.
These types of hard interventions are also expensive and provide no defence against fluvial flooding – when the water level in a river or stream overflows onto land. The creation of polders has also not been able to deal with areas of persistent extreme poverty along the coast.
Lastly, hard infrastructure solutions lock the areas in to specific development pathways for a long time, attracting construction and investment around the area where they are built, creating a concentration of assets and people which will be more at risk if the protection offered is overtaken by extreme events.
Nature-based and grey-green solutions
‘Grey-green’ and nature-based solutions can offer a more cost-effective way to manage risk. The preservation and expansion of mangroves has helped to stabilize Bangladesh’s coastline while providing significant benefits for the communities living nearby. At Pichavaram, in the Indian state of Tamil Nadu, the effectiveness of mangroves in buffering the area from the 2004 tsunami led to a renewed appreciation of their potential and led the government and local communities to expand their plantation.
Dense mangrove forest in Pichavaram reduced the impact of the 2004 tsunami.
In theory this is an easily implementable solution, as the region’s coastal cities have large natural ecosystems which provide a long list of ecosystem services to the urban areas. Unfortunately, as the example of the decline of the East Kolkata Wetlands – a Ramsar site, and one that treats 750 million litres of wastewater daily – shows, these areas are often not valued by the state and face increasing encroachments.
Other nature-based solutions include the preservation and promotion of climate-resilient agriculture. In particular, as sea level rise and storm surges increase, the adoption of salt-tolerant crops in affected areas of India and Bangladesh provides hope to farmers whose livelihoods are under threat. But there is a limit to how much salinity even these plants can tolerate.
Lastly, the creation of urban forests in depleted green areas in major cities offers both relief for citizens and a way to undercut rising temperatures and the urban heat island effect. Wetlands, increasingly facing encroachment and often undervalued for their ecosystem services, can also be restored, as has been done with Talangama Lake in Colombo.
Preserving Colombo’s wetlands provides significant economic and human savings
Colombo is Sri Lanka’s key financial centre and generates almost half of the country’s GDP. But it is extremely vulnerable to heavy rainfall, storm surges and other climate risks due to its coastal location.
In 2012, the Government of Sri Lanka and the World Bank’s Global Facility for Disaster Reduction and Recovery carried out a comprehensive technical study to assess the benefits the city’s wetlands could bring.
It found these urban wetlands could not only alleviate economic concerns – estimates suggest Colombo could lose one per cent of GDP per year due to flooding – but also bring significant well-being benefits to 2.5 million of the city’s residents by ‘operating as natural air conditioners, water and air purifiers, carbon sinks, agricultural havens and safe harbours for biodiversity’.
Grey-green solutions – a mix of technical interventions supporting nature-based solutions – offer another set of approaches. In Bangladesh a World Bank study proposed dredging a channel to allow better water flow, and using the sediment at erosion hotspots as well as using a combination of embankments and mangroves, so the two support each other.
Scaling up local-level solutions
When designing solutions, it is important not to overlook the lived realities of coastal dwellers with their own experience of adapting to changing environmental conditions. Traditional community innovations are often cost-effective, environmentally-friendly, and sustainable.
Bandalling are bamboo-made structures used for centuries in Bangladesh to protect riverbanks from erosion, increase navigability, and recover land. And Baira is a technique to build floating agricultural beds which has been used to reduce the adverse impacts of waterlogging.
Prolonged waterlogging of agricultural land – when water is unable to drain away – has led to huge losses in productivity and increasing poverty in Bangladesh. But if scaled and financed, baira could be an effective adaptation strategy to ensure greater food security, local employment, and better management of water drainage systems across South Asia.
Farmers in Bangladesh are reviving the practice of Baira, using rafts to create unique floating farms. Source: Hindustan Times
Other low-cost community innovations include geobags (sand-filled geotextile bags) as a cheap and sustainable method of river bank reinforcement, and filtration technology powered by renewable energy to convert flood water into clean drinking water. A recent report by Arup and the World Economic Forum (WEF) found that nature-based infrastructure delivers 28 per cent more added value than ‘grey’ alternatives. These are fundamental tools to anticipate and reduce climate risk and secure coastal livelihoods.
Preparation is key
Although building protective infrastructure, whether man-made or nature-based, is important, early warning systems are also vital to building resilience. In the 1970s, Bangladesh had two coastal radars to gauge weather but today it has a comprehensive set of systems supported by communication technology and a network of millions of volunteers who get the message out to the public.
This has played a key role in helping Bangladesh respond to disasters, particularly cyclones. One of its outstanding features is the strong presence of women in the volunteer force who can communicate with women from poorer and more traditional communities on the risks they face. This has brought down the disparity in casualties between women to men from 14:1 to 1:1.
Teach a Girl to Swim campaign
Drowning is ’a serious and neglected public health threat’ worldwide, according to the World Health Organization. In South Asia, the prevalence of flooding and water-related disasters exacerbates the danger. In Bangladesh, 19,000 people die by drowning each year and 14,000 of them are children. Drowning accounts for 43 per cent of all deaths in children aged 1-4.
Floods present a particular problem for women in the region, who are often not taught basic swim safety skills. Combined with frequent segregation and distinctive vulnerabilities they face, this can lead to a real fear of water for many women and girls, such as many of the refugees in Cox’s Bazar in Bangladesh – which as well as one of the world’s largest refugee settlements is one of the longest uninterrupted sand beaches.
The Teach a Girl to Swim (TAGS) campaign works with local NGOs to provide basic swimming and water safety lessons to women and girls – a locally appropriate, cost-effective, and simple solution which helps women and girls feel confident in the water and therefore hopefully avert the worst outcomes in the event of disaster. Further resilience can be built by embedding water safety practices and standards into national adaptation plans and disaster risk reduction strategies.
At the global level the UN Early Warnings for All initiative, announced at the recently concluded COP27 climate summit and spearheaded by the World Meteorological Organization (WMO) offers a template for better information to support resilience in coastal cities. At the regional level, the India Meteorological Department with the support of the WMO is to provide the data for a South Asia Flash Flood Guidance system for India, Nepal, Bhutan, Bangladesh, and Sri Lanka.
Climate resilience is not something fixed by technical solutions alone. In South Asian cities, choices around infrastructure are intensely political decisions since they are about the allocation of scarce resources. Even something as seemingly innocuous as clearing storm drains in a city such as Karachi can be a polarizing issue if it is perceived in the context of a strategy which marginalizes poor communities while ignoring the ecologically destructive practices of rich inhabitants.
The involvement of a wide range of actors is important to secure the buy-in needed for projects to succeed. It also opens the way for local knowledge which may include adaptation techniques that can be modified and incorporated within strategies to deal with the impacts of climate change.
For example, the raised stilt houses which are a form of traditional architecture in Assam offer low-cost adaptable technology for existing flood-prone areas, or areas which may becoming increasingly so with climate change.
Sponge city initiative
‘Sponge cities’ are urban areas designed to absorb rain and prevent flooding by reducing reliance on hard infrastructure such as pipes, dams, and channels, and increasing investment in green infrastructure such as inner-city gardens, improved river drainage, and plant-edged pavements to improve rainwater absorption and runoff.
The term originated in Hyderabad when city authorities collected storm water to offset water demand during the planting season. China launched the Sponge City Initiative in 2014 and has involved 30 cities to date. Notably, Chennai, Mumbai, and Kochi are all developing sponge city roadmaps to tackle urban flooding and increase resilience to drought.
This is an important opportunity to upgrade infrastructure, increase biodiversity, and more meaningfully engage citizens in city life.
Successfully building climate-resilient cities requires important and tough decisions on issues such as zoning which limits what type of buildings are allowed where. But given the scale of urbanization taking place across South Asia, the pressures and profits from the real estate sector are immense, and regulations are regularly flouted.
One way to a more fruitful conversation may be to approach the issue through finance, as the scale of investment needed to make South Asian cities climate-resilient is daunting. The funds needed for adaptation measures are beyond the reach of local governments – although these do have multiple financial levers such as public procurement at their disposal.
Climate finance commitments from the international community will continue to increase. The acceptance of the need for finance to address the loss and damage associated with climate change was a historic achievement for climate-vulnerable countries at COP27, and the Kunming-Montreal Global Biodiversity Framework has committed to $200 billion per year for biodiversity-related funding – but will likely still fall significantly short of what is required.
The acceptance of the need for finance to address the loss and damage associated with climate change was a historic achievement for climate-vulnerable countries at COP27
Public funds, either from taxes or from grants from developed countries, will always be stretched in multiple, sometimes conflicting, directions. This leaves the private sector, which is often criticized for short-term thinking, so it is a challenge for municipal, provincial, and federal governments – as well as activists and academics – to convince investors that building a climate-resilient city is a better investment than a climate-vulnerable one.
Cities do have the option of issuing green bonds for such types of investments, which would force them to clarify the rules over zoning and planning, creating greater transparency and forcing consultations. And given the greater instability of weather patterns and the risk of heavy losses, cities could seek insurance for potential damages. But this would require them to provide data to help the insurers set appropriate premiums.
Such an exercise, and an insurance company’s decision on whether to take the risk and at what cost, would be a clear market signal of how well-prepared a city is to manage the impacts of climate change. The World Bank’s country diagnostic reports offer some insight but the reporting has to be much more detailed at provincial or municipal levels.
Regional cooperation is another route to raise finance for climate adaptation. Since most of the countries in South Asia have a low per capita GDP, this may not lead to immediate or large investments. But it does offer a system for countries at similar levels of development and with geographically similar environments to learn the most efficient and cost-effective ways to create resilience.
The South Asian Association for Regional Cooperation (SAARC) and the Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation (BIMSTEC) were created as regional instruments to tackle climate risks but action remains slow and ineffective due to political stand-offs and inadequate financial and human resources.
Smaller nations such as Bangladesh, Bhutan, Nepal, the Maldives, and Sri Lanka have pursued bilateral cooperation or non-governmental pathways, leading to the establishment of the Asian Disaster Preparedness Centre to strengthen regional and national disaster risk management.
In all these approaches, local actors particularly at the municipal level who directly respond to climate threats and shape adaptation measures must play a larger role in planning the future of South Asia. This is especially true if there is to be less focus on top-down mega projects and more on networks of locally-led projects which are risk-informed, as emphasized by the recent launch in Dhaka of the Global Hub on Locally-Led Adaptation which aims to shift power to local actors to lead and meaningfully implement solutions to climate change
The size, economic power and increasing political heft of the megacities in South Asia means successful adaptors will have a transformational impact on the region. But to respond to escalating and complex crises they must break free from the inertia of the existing governance paradigm.
A resilient future requires innovative approaches from a technical point of view, but also in decision-making, cooperation, and finance. If achieved, South Asia can lead the way in implementing localized and region-specific adaptive responses to flooding and other climate impacts – and in doing so provide a platform to build resilience at scale.