Wet-bulb temperature – and why we need to address it
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Article Type
Sustainability Soapbox
Topics
Responsible Investing, Opinion
Published
October 02, 2024
Read time
4 mins
Author
Aegon AM Responsible Investment Specialists
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The University of Sydney recently launched a world-first study which aims to better understand at what point heat becomes deadly. Scientists have proposed that the critical ‘wet-bulb temperature’ for humans – the point at which a healthy person could survive for only six hours – sits at 35C. More precisely, this particular measure means the air temperature is 35C and the humidity is 100 per cent. At 100% humidity, the air is so full of moisture that sweat will struggle to evaporate, you can’t cool down and your core temperature begins to rise to dangerous levels.

 

The university is testing the accuracy of this proposition by placing individuals in climate chambers and subjecting them to various extreme conditions nearing the 35C threshold. They are discovering that the upper wet-bulb temperature limit of 35C could be much lower when the limitations of human physiology are considered – as low as 21.9C. 

 

Of course, the reality of daily life for many of us is not being sedentary in a climate chamber (as in the study carried out by the University of Sydney). We tend to move through air-conditioned environments over the course of an average day. This is not the reality, however, for the less fortunate. With heat waves becoming more frequent, intense, and longer-lasting, it is leading to increased mortality rates, especially among vulnerable populations like the elderly and those with pre-existing health conditions.

 

At the same time, worker productivity declines in extreme heat, particularly for outdoor jobs, leading to higher operational costs and absenteeism. Businesses may therefore need to invest in cooling systems or adjust work schedules to protect employee health. Energy companies face a dual challenge: heightened demand for cooling during heatwaves strains electrical grids, while extreme temperatures can impact the efficiency of power generation and distribution systems.

 

Equivalent full-time jobs and GDP lost to heat stress, global and by country income group, 1995 and projections for 2030

Source: ILO estimates based on data from the ILOSTAT database and from the HadGEM2 and GFDL-ESM2M climate models (using as input the RCP2.6 climate change pathway, which envisages a global average temperature rise of 1.5°C by the end of the century).  https://www.ilo.org/

 

 

How are sustainable investors addressing wet-bulb temperature and its impact on humanity?

 

Investors should be aware of strengthening workplace heat regulation and the EU Sustainability Reporting Standards (ESRS) requirements to disclose on health and safety issues. Where heat stress is identified as a material issue, companies are required to disclose related impacts on the workforce including their supply chain, along with plans to reduce and mitigate negative impacts. 

 

We encourage companies to assess the impact of heat stress on both their own operations and their supply chains, and also whether local regulations are sufficient in protecting against material impacts. 

 

As global temperatures continue to rise, understanding wet bulb temperature is crucial for both individual well-being and economic stability. It’s imperative that we adapt to these changing conditions while collectively working towards reducing greenhouse gas emissions. The challenges posed by increasing temperatures highlight the urgent need for comprehensive climate action and resilience planning across all sectors of society.

 

 

Note: the term ‘wet-bulb temperature’ refers to a specific measurement. If you wrap a wet cloth around a thermometer bulb, the evaporating water from the cloth will cause the thermometer to cool down. As humidity increases, less water can evaporate and the cooling effect diminishes. At 100% humidity, wet bulb temperature equals the air temperature and no further evaporative cooling can occur.

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Aegon AM Responsible Investment Specialists
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