Wet Bulb Temperatures

The social media and the internet is awash with climate change warnings and doomsday scenario predictions. But the heat wave phenomenon already at play shows the worsening climate change impacts have already arrived.

Across the globe, torrential unseasonal rains and flooding in Europe have caught the attention of a horrified populace experiencing the blow back effects of a warming planet. David Attenbourgh’s Breaking Barriers documentary talks about how the world has already left a geologically stable age of Holocene where temperatures never varied more than a degree or two, helping humans to invent agriculture and civilization that’s the bedrock of the current human soceity. Instead, we now live in Anthropocene where humans are the primary drivers of changes to climate and ecosystems.

Which brings us to the question – what are wet bulb temperatures? They are the temperatures at which the human body starts experiencing what’s known as heat toxicity as it can no longer cool down or regulate internal temperatures by sweating. These temperatures result in the human organs to gradually break down starting with the gut. The important point to note here is not just the excessive heat but also excessive humidity in the atmosphere which prevents the body from sweating.

This is already happening around the world in the US, western Canada, Pakistan and India.  A “wet bulb” temperature of 35 degrees Celsius (95 degrees Fahrenheit) — which factors both heat and relative humidity — can be fatal after a few hours, even assuming mitigating factors such as sufficient drinking water and shade from the sun.

Wet bulb temperatures are measured by a thermometer wrapped in a water-moistened cloth. The drier and less humid the air is, the faster the water will evaporate. The faster water evaporates, the lower the thermometer’s temperature will be relative to air temperature.

Living organisms can survive only within a certain temperature range. When the atmospheric temperature is excessive, mammals and most of the other animals cool themselves by evaporative cooling which helps to prevent hyperthermia due to heat stress. The effectiveness of evaporative cooling depends upon humidity; the warming planet is guzzling excessive moisture due to the associated heat waves thereby leading to high levels of humidity in the atmosphere.

Climate experts view containing climate change temperatures to within 1.5c of Holocene temperatures to avoid global wet bulb temperatures.

Which begs the question – if you are in a city or an urban landscape which is expected to suffer from wet bulb temperatures – what can you do to protect yourself and your family?

For starters, ensure your roofs and the outer wall surface of your houses or apartments are painted in white or lighter colours to reduce heat absorbtion. Dehumidifiers are another critically important tech apart from air conditioners. Plenty of water and fluid intake and sheltering from sun inside your air conditioned or dehumidified homes are the best tools that you have. Ironically, air conditioners are listed among the top contributors to global warming but they do help in escaping the worst after effects of the wet bulb phenomena.