Urban heat islands are a tricky problem: Jaya Dhindaw, Director, WRI India Ross Center

Jaya spoke to indianexpress.com on urban heat islands and the technology that helps monitor the same, the challenges Indian cities face in using such tech, and WRI’s work on urban heat islands and heat resilience.

Edited excerpts:

Venkatesh Kannaiah: What has been WRI’s work on ‘urban heat islands’ and how serious is the problem across Indian cities?

Jaya Dhindaw: An urban heat island occurs when a city or parts of a city experience much warmer temperatures than nearby areas. Urban heat islands result from complex interactions between built environments, natural factors, and human activities. WRI has done extensive work on urban heat islands and measuring and mapping of urban heat waves in India.

An earlier study by the United Kingdom’s Met Office assessed that the spell of record-breaking temperatures in India may occur every three years now instead of the previous time frame of about 300 years.

Around 80 per cent of the people in India have experienced heat waves in the first 15 days of summer, and research has proven that the informal sector, the lifeblood of any economy, is disproportionately affected by such urban heat stress. While it leads to illnesses, discomfort, it has a substantial impact on energy consumption, air pollution levels in cities, human productivity patterns and overall ecological impact.

We have found that urban heat islands could lead to temperature differences of up to six degrees centigrade within a given area or neighbourhood. This could change depending on the construction material used, the number of buildings around the area and the way it is built, the road materials that have been used and tree/green cover presence and density in the particular locality. Also the lack of water bodies can add to the heat effect. This six degrees figure is one data point from Mumbai, but not during the peak summer. This figure could be higher depending on season, climatic zone or urban conditions. Just imagine the heat distress if the city is recording 40 degrees centigrade of heat, and your locality or sub locality is six or more degrees higher.

And add to this the vulnerability of specific socio-economic groups, as data shows that a large number of informal settlements in India use heat-absorbent GI/metal/asbestos sheets for roofing, which could worsen the situation.

According to a 2014 Indian Institute of Science report, the ideal tree-human ratio should be seven trees for every person. The lack of trees increases the risk of exposure to higher temperatures. We have found that in Indian cities there are places with such poor density of trees as one tree for 50 people. There are some places where it could be as low as one tree for 450 people. All these contribute to worsening the urban heat islands effect.

We at WRI India work on using data tools to visualise the magnitude and extent of the problem and thereby raising awareness. We also test solutions like green infrastructure and heat-resilient designs and engage with cities to build their strategic plans with a focus on climate risks and hazards.

Venkatesh Kannaiah: Can you tell us about significant tech innovations which have led to a better weather/heat tracking in India. And how well do you compare it with other countries?

Jaya Dhindaw: In India, several tech innovations have enhanced weather and heat risk monitoring. There is the soft infrastructure of remote sensing satellites which provide valuable data for tracking weather patterns, land surface temperatures and urban heat islands. There is the hard infrastructure where sensors are deployed in cities to gather real-time data on several parameters like temperature, humidity, precipitation and air quality, all of which help in monitoring heat risks.

And now, with AI, we have developed advanced modelling techniques for weather forecasts which allow us to be prepared for heatwaves and other weather events.

India’s tech adoption in weather and heat risk monitoring is improving but may not be at par with other developed countries that have sophisticated systems due to more resources allowing them to deploy more extensive networks and achieve higher-resolution data. For example, while leading Indian cities have seven to eight India Meteorological Development weather stations on an average, a comparable city like San Francisco would have more than 100 weather monitoring stations. Our focus on weather has been more on water risk and security and hence we have more granular data on precipitation, while heat is not a consistent part of the monitoring process.

In developed economies, weather tracking is done by a variety of actors, from academic and research institutions to government bodies to the private sector. All of this rich data provides a much more nuanced understanding of scenarios.

Venkatesh Kannaiah: How simple or complex is the tech to monitor urban heat islands, and how prevalent is this tech in India to capture the nature of the problem?

Jaya Dhindaw: Depending on the level of accuracy required, tech to monitor urban heat islands can be simple or complex. For example, the basic method we use now is satellite imagery for land surface temperature. We can also use handheld infrared thermometers to measure surface temperature at a given location. These methods are frequently being used in large cities. However, smaller cities don’t have these capabilities and the nature of infra and coverage that they can deploy is usually limited.

More advanced methods would look to put in sensors across the city to monitor temperature variations at different heights and locations. This can help greatly with preparedness and mitigation but would be fairly resource intensive and difficult to scale.

Another initiative WRI is working on with Google is to develop a product to help decision makers with designing cooling systems and tracking urban heat islands. We want to go beyond merely using land surface temperature (LST) as a metric and more accurately use Albedo — the amount of energy reflected by a surface for tracking.

In big cities in India, we are getting pretty good at adopting some of the more sophisticated tech and its coverage, however, access to such tech in tier 2 and tier 3 cities remains an area of concern. There is not much capacity, or investment or planning in these places.

Venkatesh Kannaiah: Are Indian city governments using tech to track urban heat islands? Any success stories?

Jaya Dhindaw: If there is a success story in heat tracking by an Indian city, it is certainly Ahmedabad, which turned a new leaf after the heatwave of 2010 which led to deaths of more than 2,000 people. In 2012, they developed a heat action plan. This initiative included the deployment of temporary monitoring stations, satellite-based heat maps and early warning systems to identify areas vulnerable to extreme heat events. The data collected from these systems is helping inform decision-making and design interventions to mitigate the heat stress.

Now all over India, more than 24 cities and states are in the process of preparing ‘heat action’ plans demonstrating the value of using technology-driven evidence and decision-support systems to tackle urban heat issues.

Venkatesh Kannaiah: Are Indian climate tech startups working on urban heat island issues?

Jaya Dhindaw: Yes. Climate tech has attracted investments worth billions of dollars, and one must understand that it need not be on mitigating heat stress in a direct manner. Startups in the energy, building materials and mobility space are working on tech to reduce the heat stress in urban areas.

There are several startups focused on themes like nature-based solutions — greening, and improving natural infrastructure like water bodies that are coming up. There are also some that use data and predictive analytics to figure heat hotspots and suggest types of nature-based interventions that can be deployed. However, there are serious challenges in India for startups to mainstream such solutions and for governments to adopt them, as tendering and procurement procedures are cumbersome and have not caught up to on-board newer systems.

We at WRI India work on bringing stakeholders like the government, startups and funders together and through these convenings and lab engagements that enable pilots, socialise these ideas with the government and policy makers to help scale up these solutions in the city space.

Venkatesh Kannaiah: Can you tell us about tech innovations that help to mitigate urban heat islands?

Jaya Dhindaw: The tech for mitigation is around building materials like cool roofing materials, reflective building materials, different varieties of paints, apart from having vertical gardens, urban forests and green infrastructure. There is work going on in several cities of Gujarat on this issue.

Japan and China are looking at cool pavements, where they are looking at light coloured paints, special coatings etc. that reflect sunlight and can help lower surface temperatures and mitigate heat island effects. Such innovations are being studied in Pune and Delhi.

There is also innovation of running cold water through pipes all across houses and many other architectural-led innovations for heat mitigation.

We need to incorporate heat-resilient designs based on factors such as building orientation, location, materials to maximise shade, create green spaces, and promote natural ventilation which all can help mitigate urban heat island effects.

There is another important aspect of health tech that is associated with heat stress. That is the provision of customised heat stress testing and customised alerts and medication based on vulnerabilities to heat or dehydration. This is not based on generalised guidelines but on customised individual data.

Venkatesh Kannaiah: Is urban heat islands and heat waves an issue for tech to solve?

Jaya Dhindaw: Tech has a significant role to play in this issue. The role of tech is in providing data-driven insights into the nature and intensity of heat stress, providing early warning, and at the mitigation end look at the larger gamut of materials and coming up with ‘cooler’ materials. But more importantly, the urban heat islands issue is an urban design and development issue, which needs to be looked at from a bigger lens of economic policy, city management and sustainable living in cities.