By Amy Kirbyshire for ODI.

Cities are already home to more than half the world’s population. It is estimated that, by 2050, they will be home to between 2 and 3 billion more. Many cities are in areas prone to flooding, storms, heat waves and other hazards that, in many places, are becoming more frequent and severe because of climate change. Positively, more and more cities are taking steps to address these risks, but current efforts are patchy, only scratching the surface.

As the 23rd Conference of Parties (COP23) takes place in Bonn this week, there is an urgent need to tackle climate risk on a larger scale; to benefit more cities and more people. So far, scale has been a key challenge for realising international climate and risk reduction ambitions. Here, I draw lessons from urban heat action planning in India, which has expanded rapidly in just four years.

Advancing heat action in India

Heat waves are underestimated and underreported as a disaster event but in India they are the second most deadly natural hazard, after floods. Heat has direct impacts on both human health and the built environment. It also has knock on effects for livelihoods and on local and national economies.

Last month, the Lancet Countdown report on health and climate change highlighted rising heat risk as a widespread and dangerous threat to human health. However, heatwaves are predictable hazards and preventable disasters. After a deadly heatwave in 2010 that killed an estimated 1,344 people in Ahmedabad, a partnership between the Ahmedabad Municipal Corporation, Natural Resources Defence Council, the Indian Institute of Public Health-Gandhinagar and others led to the development and implementation in 2013 of South Asia’s first Heat Action Plan. These efforts are already paying off.

According to Dr. Dileep Mavalankar, Director of the Indian Institute of Public Health Gandhinagar, Public Health Foundation of India (PHFI-IIPHG ), ‘During the devastating 2015 heatwave that left 2,300 dead across the country, fewer than 20 heat-related deaths were reported in Ahmedabad. That is impressive in a city that’s home to over 7 million people.

Success can be contagious

Following Ahmedabad’s example, across India, 30 cities and 11 states have now released, or are developing, their own Heat Action Plan. Over half of the cities are new this year[i]. A new Climate and Development Knowledge Network(CDKN) guide examines the Heat Action Planning process in Indian cities and identifies the following key drivers of this scaling-up:

Igniting a spark of political leadership

Leadership is vital, but it can come from different places and have many triggers. Leadership here is coming from city and state authorities, from health and disaster authorities, and from the Indian Meteorological Department. The source of leadership shapes heat action planning in each city. In each case clear, accessible evidence of the seriousness of the problem coupled – crucially – with examples of successful, replicable, affordable action being taken by other progressive cities has acted as the trigger; whether delivered directly by a research consortium (as in Ahmedabad) or through outreach and the substantial media coverage this issue has received. Rapid and visible benefits from implementation of a first phase of practical, affordable solutions helped to galvanise political will to take action further, within the city and beyond.

Partnerships and lesson-sharing

Vertical partnerships between city, state and national level agencies, and horizontal lesson-sharing between cities, are crucial to scaling up climate action. In this case, city-to-city learning exchanges, where participants worked together through a City Resilience Toolkit and its ‘how-to’ manual, helped to share knowledge and to increase cities’ level of ambition. New partnerships between the national and local Indian Meteorological Department offices – providing forecasts and developing heat thresholds for cities – have helped kick-start action in cities that had not been involved in the initial exchanges. As word spread, the Toolkit has proved a valuable resource these cities can use to develop Heat Action Plans independently.

Starting small, thinking big

Cities do not need to have grand, perfect plans to respond to climate risk. Building on experience elsewhere, starting small with cheap, easily implemented actions help risk management plans to move off the page and into practice. By embracing a process of experimentation, evaluation and ‘learning by doing’ cities can then deepen and expand implementation, and learn to be as effective as possible year-on-year in response to local conditions and change over time. By taking an incremental approach and building ambition, cities can turn small beginnings into much greater success.

City-led initiatives such as this cannot meet the scale of the climate risk challenge alone; they must be complemented by national policies and programmes. However, this experience from India highlights the potential for bottom-up, city-led action to have wider impact, and builds on evidence from other programmes. Given the massive investments that will be made in the urban built environment in the coming decades, it is vital that cities around the world join this transition toward resilient, lower-carbon, development pathways.