Sunday, 19 September, 2021

Heat Waves Now a Global Threat

Closer to Irreversible Tipping Point

Md. Abul Kalam Azad and Sirazoom Munira

Closer to Irreversible Tipping Point

Popular News

The latest Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) is a wake-up call for humanity facing an imminent risk of a grimmer future. The irrefutable evidence of the report leaves us with a reality check – taking us perilously close to an irreversible tipping point in the near term. Extreme events are only set to become more frequent since the earth has surpassed more than 1°C in average warming, leaving unprecedented changes which are mostly human-induced. This further hinders global efforts to keep the internationally agreed threshold of 1.5 degrees above the pre-industrial levels.

Frequency and intensity of extreme events on the rise 

Multiple extreme weather events are now happening at the same time. The problem is compounded by contextual realities of the ongoing Covid-19 pandemic. The recent heat wave in Canada, wild fires in California, Turkey, Italy and Greece, droughts in central Brazil and floods in China and across Europe are some of many examples of this unpredictability. The propensity and intensity of these events have also worsened. Heavy rain events that would take place once in 10 years are now 1.3 times more likely and 6.7 per cent wetter – compared with the 50 years up to 1900. Experts noted that extreme heat waves which earlier struck once-in-50-years, are now happening every decade due to global warming. If the world gets 4°C warmer with the current high-emissions trend, the heat waves would take place every one or two years. This is alarming and unless we choose an alternate course for ourselves and the next generation, consequences will only aggravate. It is crucial to urgently step up and accelerate efforts to pursue the ambitious path of the Paris Agreement with all our respective capacities.

Heat waves: Leaving no regions unharmed 

With reference to the Era of Anthropocene, the IPCC’s AR6 states that there is “high confidence” that human activities are the main drivers of more frequent or intense heat waves, glacier melting, ocean warming and acidification. Heat waves, among others, have brought about monumental financial losses, health problems, damage to infrastructure and biodiversity in recent years. It is estimated by the C40 initiative that the number of cities exposed to extreme temperatures will nearly triple over the next decade and by 2050 more than 970 cities will experience average summertime temperature highs of 35˚C. Record temperatures were observed in multiple parts of the Southwester United States in 2021, reaching a maximum of 54°c at Death Valley, California, where normal temperature during this month averages around 42°C. This year, Greece is suffering its most extreme heat wave since 1987 with temperatures set to reach 45°C – whereas, on average, the country experiences its peak temperature levels in July and August reaching mid-30°C. In 2019, an Indo-Pakistani heat wave reached a near record high temperature of 50.8°C in Churu, located in the desert region of Rajasthan, India, beating the previous highest average of 43°C. The extreme heat waves in June and July 2019 killed approximately 2,500 people in northern Europe.

Implications heat waves on certain sectors

Agriculture: The current heat situations will have severe implications on food insecurity, energy insecurity, livelihood, water quality and health – particularly impacting in poor and vulnerable regions. In April 2021, Bangladesh recorded the highest temperature in seven years as a severe heat wave struck the country. During the same period, a heat stress caused by a mix of high temperatures, low rainfall and low humidity ruined standing paddy on cropland across 36 districts, leading to enormous losses.

Labour: Heat stress affects all sectors of workers, particularly threatening the world’s 1 billion agricultural workers, among others. With the increasing trend of heat, it is predicted that by 2030, more than 2% of the total global working hours is expected to be lost per year.

Health: The World Health Organization has warned global citizens that extreme heat will have severe health implications, including dehydration, acute cerebrovascular accidents and thrombogenesis (blood clots).

Biodiversity: A new study has found the daunting reality of marine heat waves and its impact on global biodiversity. Nature Climate Change has shown in its report that heat waves in oceans are becoming recurrent. Currently – with 54% more annual heat wave days from 1987-2016 – marine heat waves have posed threats to the ocean ecosystems, which were already facing threats like over fishing, acidification, plastic pollution etc. While many of the largest thermal displacements were caused by El Niño events, marine heat waves can scatter wildlife in the oceans more than a thousand miles.

Vegetation: Increased frequency of drought, heat waves and heavy rain are not mutually exclusive and can lead to water shortages and increased stress for plants, particularly in places like Southern Africa. In Europe, the 2003 heat waves caused tree damage, increased leaf fall and turned carbon-sink landscapes into carbon-sources, releasing more carbon dioxide into the atmosphere than was absorbed. These hot and dry conditions are favourable to the start and rapid spread of forest fires, which now regularly accompany heat waves.

Roads and transportation: Heat can bring about changes in roads and transportation services and an example of that is the buckling of railways during the Melbourne heat wave in January 2009. 

Buildings and infrastructure: Research has shown that building and infrastructure under an extreme heat wave condition have implications on bodily homeostasis of people living inside. However, architectural adjustment in buildings like painting the roof with white could help reflect sunlight and reduce temperature. UN Secretary General Ban Ki-moon in a BBC interview referred to a pilot project conducting similar intervention in 2017 where more than 3,000 city rooftops in Ahmedabad, India were painted using both white lime and a special reflective coating. This "cool roofing" process was meant for reduction in the solar radiation absorption, meaning less heat being transferred inside the building.

Recommendations and way forward

The difference between 1.5°C and 2°C of warming is such that the latter case would mean a third more heat wave spell in tropical developing countries. Citing this, the Thematic Ambassador for Parliament of Climate Vulnerable Forum (CVF), Ms. Loren Legarda had noted that “bending the global warming curve to 1.5°C is a moral imperative”. Five years into that statement being made, our attempts to curb emissions are still far off from that which is required. However, countries and communities are now preparing for rising temperatures and extreme heat. With special attention on the most vulnerable communities to heat stress, every city management authority should consider its region-specific vulnerabilities. The most vulnerable during such events include infants and children, elderly communities, people with chronic conditions, low-income residents, and outdoor labourers, among others. In an attempt by several European cities to endorse focused action on extreme heat and the protection of vulnerable people, the Mayor of Athens recently announced Europe’s first Chief Heat Officer. A set of strategies to build resilience should centre around these vulnerable populations. Attempts should be made in early warning systems and raising awareness about risk factors, symptoms of heat-related illness, and when and how to seek treatment. In addition, cities can protect or modify roads, train tracks, and other infrastructure by using more resilient materials, as well as implement energy efficiency measures to reduce disruptions of city services and stress on electricity systems during heat waves. At the same time, increases in the number of and access to green spaces by integration of green roofs, cool pavements and increased vegetation and trees in national urban plans and policies can ensure mainstreaming of green infrastructure, thus helping lower urban temperatures in the long run. As such, a comprehensive heat response plan is critical that combines individual strategies into an integrated approach. Designing and adopting socio-economic developmental policies will help reduce scope for future exposure while also strengthening adaptive capacity of vulnerable communities.


Of the writers, the former is the

Special Envoy of the Climate Vulnerable Forum Presidency of the Bangladesh Government and currently serves as Commissioner at the Commission on BiodiverCities of the World Economic Forum and the latter works at

the Global Centre on Adaptation

and currently supports the CVF

Presidency of the Bangladesh

Government as Program Officer.