Pakistan’s southern province of Sindh has been sweltering under 52°C heat in recent days. Not in the news however is that wet-bulb temperatures in the region – a more accurate indicator of risk to human health that accounts for heat and humidity – passed a key danger threshold of 30°C.  

Climate change is increasing the risk of deadly humid heat in developing countries like Pakistan, Mexico and India, and without international support to adapt, vulnerable communities could face catastrophe.  

What is wet-bulb temperature? 

Wet-bulb temperature is an important scientific heat stress metric that accounts for both heat and humidity. When it’s both hot and humid, sweating – the body’s main way of cooling – becomes less effective as there’s too much moisture in the air. This can limit our ability to maintain a core temperature of 37°C – something we all must do to survive. 

A recent study suggests that wet-bulb temperatures beyond 30°C pose severe risks to human health, but the hard physiological limit comes at prolonged exposure (about 6-8 hours) to wet-bulb temperatures of 35°C. At this point, people can experience heat strokes, organ failure, and in extreme cases, even death. 

Climate change and deadly heat 

Globally, around 30% of people are exposed to lethal humid heat. This could reach as much as 50% by 2100 due to global warming. To date, the climate has warmed around 1.3°C as a result of human activity, primarily due to the burning of fossil fuels. And along with the extra heat, with every 1°C rise the air can hold up to 7% more moisture. 

A comprehensive evaluation of global weather station data reveals that the frequency of extreme humid heat has more than doubled since 1979, with several wet-bulb exceedances of 31-33°C. Another recent study predicts a surge in the frequency and geographic spread of extreme heat events, even at 1.5°C warming.   

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What this shows is that the humid tropics including monsoon belts are all careening towards the 35°C threshold, which is very worrying for countries like Pakistan. The city of Jacobabad has already breached 35°C wet bulb temperatures many times. More areas of the country are likely to be exposed to such life-threatening conditions more often due to climate change.   

At 1.5°C of warming, much of South Asia, large parts Sahelian Africa, inland Latin America and northern Australia could be subject to at least one day per year of lethal heat. If the world gets to 3°C, this exposure explodes, covering most of South Asia, large parts of Eastern China and Southeast Asia, much of central and west Africa, most of Latin America and Australia and significant parts of the southeastern USA and the Gulf of Mexico.  

Areas of the world that will experience at least one day of deadly heat per year at different levels of warming   

Source: ScienceAdvances 

 Even at 1.5°C of warming, there will be high exposure to lethal heat in large regions where billions presently live. This terrible threat to human life calls for urgent action to limit warming and help at risk communities adapt.  

Adapting to hard limits 

 While 35°C can prove deadly, one study suggests a 32°C wet-bulb threshold as the hard limit for labour. More realistic, human-centred models found this overly optimistic, as direct exposure and other vulnerability factors were ignored. Vulnerable groups including unskilled labourers would be most at risk of losing their income.  

In densely populated urban centres, lethal humid heat is not just a future projection but a current reality. This calls for urgent adaptation measures which integrate the risk of deadly heat into urban planning, public health, early-warning systems and emergency response.  

Investments in green spaces, heat-resilient buildings and urban cooling are vital adaptation strategies. Community initiatives like awareness campaigns, indigenous cooling strategies and local heat action plans are also essential. Households could consider investing in cooling technologies or migrating – options mostly available to the wealthy.  

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As climate change makes lethal humid heat a growing threat in some of the world’s most populous areas, more attention must be paid to understanding its risks – especially in vulnerable regions with huge data gaps. This demands a multidimensional response that combines scientific research, policymaking and community engagement.  

The potential scale and level of risk to human life also reinforces the importance of ensuring that the Paris Agreement’s 1.5°C global warming limit is met. To do this, we need to halve emissions by 2030. Countries should therefore strengthen their 2030 emissions targets in line with the warming limit as they prepare equally ambitious 2035 targets in updated NDCs. 

The Pakistan heatwave is a terrible reminder of this often-underestimated threat. We must act now to limit warming while we adapt to the growing danger of deadly heat if we are to avoid potentially wide-reaching tragedies in the future.  

The post Developing countries need support adapting to deadly heat appeared first on Climate Home News.

If “massive” is the word for the heatwave losses we experienced here in Pakistan, I struggle to find an appropriate one for the losses incurred from the ongoing monsoon floods. “Colossal”, “mammoth” and “gigantic” don’t do justice to what we are witnessing.

Before now, 2010 marked the year with the worst flooding in Pakistan’s history, directly affecting an estimated 14-20 million people, and killed over 1700. Nearly 1.1 million homes were damaged or destroyed, causing $9.7 billion in damages in 46 of the country’s 135 districts.

This year’s monsoon season is not over yet and the scale of destruction from the flooding is already expected to be far higher than 2010. One third of the country is suffering from floods: 30 million people.

The critical difference between the two is that the 2010 flood was mainly a riverine flood originating from the north of the country, providing a considerable lag time for regions downstream to take evacuation measures.

This time the deluge is caused by torrential rains which began in mid-June, seeing flooding outside areas that are usually prepared for such events. This is compounded by the no-less devastating riverine flooding, which has already caused the collapse of two dams in the north of the country.

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As of 29 August, Pakistan’s national disaster risk management authority estimates over 1,100 casualties. Over one million homes have so far been damaged or destroyed, 800,000 livestock have been killed, 3500 km of roads have been damaged and 162 bridges have collapsed. The economic damages are likely to go well above the $9.7 billion in damages from the 2010 floods.

Pakistan is at its nadir of political stability. Thirteen political parties joined forces to oust the Pakistan Tehreek-i-Insaf (PTI) government earlier this year, after which PTI resigned from the national assembly. PTI, however, remains in power at the provincial level and is ruling over 75% of the country’s population. In a recently-called all parties conference, PTI was not even invited, a reflection of the political bitterness, even during the time of worst flooding of country’s history.

One doesn’t need to think hard to understand how this would affect the relief activities carried out in the provinces where PTI is in power. This aspect is important to highlight because in May, the Pakistan Meteorological Department forecast a more than average rainfall in the country, warning of flash floods. But because of the political scenario, this information fell on deaf ears, including the country’s media.

To make the situation worse, Pakistan’s economy is also crippled. Pakistan was kneeling before the IMF to revive a bail-out package, including a disbursement of about $1.1 billion, to save the country from going bankrupt, funds which were released by IMF in the days after the flooding started.

With estimates of $10 billion in economic losses from the 2010 floods, a larger scale of devastation would lead to even higher level of losses.

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The record-breaking heatwave in March-April this year which gripped large parts of the country, and now the worst flooding in history, are back-to-back calamities which present a classic case of what we call “loss and damage” in climate circles. Loss and damage is the loss of lives, land and infrastructure from climate impacts that cannot be recovered, nor adapted to.

A recent climate attribution study has concluded that climate change has made a 2022 heatwave across India and Pakistan 30 times more likely compared to a world without climate change. It is too early to state unequivocally (as additional studies will be conducted once the monsoon is over) but climate scientists believe that climate change will most likely have had a role in increasing the intensity of the present flooding. It certainly fits with the models and predictions of climate change driving more intense monsoons.

Flood affected people stand in a long line with utensils to get food distributed by Pakistani Army troops in a flood-hit area in Rajanpur, district of Punjab, Pakistan, Saturday 27 August 2022 (AP Photo/Asim Tanveer)

For a long time now, developing countries have been asking for a separate finance facility for loss and damage in the international climate negotiations under the UNFCCC.

So far, there has been resistance from the developed world to talk about the costs of loss and damage. At Cop26 in Glasgow last year a finance facility could not be agreed, despite a push from developing countries, and only a formal dialogue on loss and damage made it into the final outcome of the negotiations.

Loss and damage is likely to be a hot topic during Cop27 negotiations in Egypt this year. In the wake of this year’s record-breaking climate catastrophes it has already witnessed, it would make sense that Pakistan, as the chair of the largest group of developing countries – the G77 plus China – could make a strong case to push developed countries to agree on the establishment of a loss and damage finance facility.

This flooding must also be a wakeup call for the global community to speed up its efforts towards climate action. Pakistan emits less than 1% of global greenhouse emissions, but it is bearing a massive burden from climate change. And the large majority of the people affected are the poorest of the poor.

The devastation faced by Pakistan now is a mere precursor of what we may see at higher levels of warming. Even at the Paris Agreement’s 1.5C warming limit, some of the impact of climate extremes will go beyond the tolerable limits of human and natural systems.

As the world continues on its go-slow in getting out of fossil fuels and decarbonising the global economy, the losses and damage will continue to mount, and countries like Pakistan – and those others suffering damage they cannot pay for – need financial support.

Dr Fahad Saeed is a climate impacts scientist at Climate Analytics, based in Islamabad. This article was originally published on Climate Analytics’ blog.

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