TN, Kerala coastlines to be hit with rise in sea levels, intense heatwaves: Study

CHENNAI: The coastlines of Tamil Nadu and Kerala could face increasing environmental and socioeconomic stress over the next 15 years due to rising sea levels, prolonged heat waves, coastal erosion and saltwater intrusion, according to a new climate projections report released by Azim Premji University.

The study warns that climate change is likely to significantly affect coastal communities, fisheries, agriculture, public health and critical infrastructure unless adaptation measures are strengthened.

A new report titled, Indian Coastal Region Climate Projections 2021-2040, has projected heightened climate vulnerabilities along India’s coastline, with TN emerging as one of the states likely to experience severe impacts from rising temperatures and changing coastal conditions over the coming decades. Based on high resolution climate projections using CMIP6 models corrected for regional biases, the study provides district-level and regional assessments at a 25x25 km scale. It highlights that Tamil Nadu and Kerala are expected to witness a sharp increase in summer temperatures and the frequency of heatwave events between 2021 and 2040.

Heatwaves that currently last for 3-5 days during peak summer months could become significantly longer, extending up to 8-9 consecutive days. These prolonged periods are also expected to occur multiple times during a season, increasing the burden on vulnerable populations, particularly those dependent on outdoor occupations.

Researchers have also raised concerns over increasing wet bulb temperatures, a measure that combines heat and humidity to indicate the human body’s ability to cool itself. Higher wet bulb temperatures can increase the risk of heat stress and heat-related illnesses, especially among fisherfolk, agricultural workers, construction labourers and others engaged in outdoor work along the coast.

Tamil Nadu’s coastline (more than 906 km) has 14 districts that support a large population dependent on fisheries, agriculture, tourism and allied sectors. The report notes that rising ocean temperatures and sea levels are likely to accelerate coastal erosion and intensify the impact of storm surges during extreme weather events.

Several coastal stretches have already reported shoreline changes in recent years. The study cautions that continued sea level rise could result in the gradual loss of beaches, damage to coastal ecosystems and increased risks to infrastructure located near the shoreline. Heritage sites and tourism dependent coastal regions could also face mounting pressure from climate-related impacts.

Another major concern highlighted in the report is saltwater intrusion into freshwater aquifers. As sea levels rise and storm surges push seawater further inland, groundwater resources in coastal areas may become increasingly saline. This could affect drinking water availability and reduce the productivity of agricultural lands, posing challenges for farmers and rural communities.

Researchers have emphasised that the projections relate to the next 15 years and are based on a moderate greenhouse gas emission pathway. The findings underline the need for immediate adaptation planning rather than viewing climate risks as long term concerns.

The report recommends strengthening coastal resilience through measures such as mangrove restoration, protection of natural coastal buffers, climate resilient infrastructure and improved local level planning. It also calls for efforts to diversify livelihoods in vulnerable coastal regions and enhance preparedness for extreme weather events.

VS Chandrasekaran, former principal scientist CAR-CIBA, told DT Next, “Researchers found corals changing colour due to ocean warming, and algae being significantly affected by global warming. Chennai is relatively flat compared to Visakhapatnam and several other coastal cities. So, sea-level rise can have a greater impact on Chennai, particularly during the monsoon season. In the future, flooding may occur more frequently because rainwater may not drain efficiently into the sea.”

On declining fish populations, Chandrasekaran said the trend was real, and that coastal pollution was the primary reason for the decline, while rising sea temperatures were also a contributing factor. “Ocean warming and ocean acidification are among the most serious threats facing marine ecosystems. Many marine microorganisms may struggle to withstand these changes,” he warned. “Ocean current, which play a crucial role in regulating and maintaining global temperatures, are being significantly affected by global warming. Any disruption to them could have far reaching climatic consequences.”