Extreme Heat and Humidity can be deadly for human life. - Seeker's Thoughts

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Extreme Heat and Humidity can be deadly for human life.

Do you ever give a thought to the increasing heat when you step outside, and notice the humidity around? Or do you think that it can be a cause of migration and which may further arise the conflict among communities?
Can you ever relate this to the condition of life and death? if not- this article brings eye opening facts for you. 

A combination of heat and humidity so extreme that it’s unendurable isn’t just a problem for the future. Those conditions are already here.

A new study identifies thousands of previously rare unprecedented bouts of extreme heat and humidity that are taking place now across the world in Asia, Africa, Australia, South America, and North America.

Climate scientists have previously warned that a lethal combination of heat and humidity will make currently inhabited parts of the planet uninhabitable for months at a time in decades to come. New research finds that the future is now.

The study published in the journal science advances – extremely humid heat that is more intense than American has experienced – approaching a crucial immovable human survivability limit has more than doubled in frequency in some coastal subtropical regions of the world since 1979.

The researchers found that conditions briefly crossed into the danger zone – a combines heat and humidity, or “wet bulb temperature,” of 35 degrees Celsius – on 14 occasions, according to 40 years of hourly data. 

Reading of 33 degree Celsius have come 80 times and 31 degree Celsius occurred about 1,000 times reaching beyond the Middle East and southern Asia.

The Persian Gulf along with parts of Pakistan, dozens of extreme events have occurred. Along the U.S Gulf Coast, including New Orleans and Biloxi, Mississippi is already susceptible to novel severe events.

According to the associate research professor Radley Horton at Columbia University – when heat and humidity produce a wet-bulb temperature of 35 degree Celsius, the body passes a “survivability threshold.

What is survivability threshold?
 Its theoretically the point when humidity and heat prevent skin from being able to cool off by sweating, causing the body to overheat, potentially fatally.

Conceptually, this is a really powerful scary idea. It’s the notion that the combination of heat and humidity could be so extreme that a perfectly fit person, sitting in the shade, not moving at all, an endless supply of water, either unclothed or wearing perfect clothes for sweating would not thermodynamically, be able to sweat fast enough to avoid overheating and getting heatstroke.

Previous research shows that even if a person is in peak physical condition, when the heat index hits 132 F, or 32 degree Celsius on the wet bulb then outdoor activates become impossible.
The study found that wet-bulb readings close to or topping 30 Degree Celsius have doubled since 1979 around the world.

There were around 1,000 readings of 31Degree Celsius, something that was believed to be a rare occurrence. A reading of 33 degree C thought to hardly exist, actually occurred around 80 times.
In July 2019, a heatwave saw heat indexes approaching 115F in the US.
The highest recorded temperature was 122F in Baltimore, Maryland during another heatwave last August. 

The conditions led to at least six deaths: four in Maryland, an air-conditioning technician in Phoenix, Arizona, and former NFL player, Mitch Petrus, who died in Arkansas while working outside his parents’ store. 

Events were canceled across the country including the NYC triathlon for the first time.
In the US, around 90 per cent of households have air-conditioning. High-humidity heat waves in Russia and Europe, where far fewer people have air conditioning, have killed tens of thousands, the study found.
Previously worked on a 2017 paper projecting that such conditions would not take hold until later in the century.
We may be closer to a real tipping point on this than we think.
In wealthy countries, AC can provide some respite from the extreme humidity and heat but if the conditions are seen more frequently, it could force people indoors for longer periods of time. 

The economic effects of extended periods of time indoors, during the coronavirus lock-downs, are being felt acutely around the world.
In the developing world, increased heat and humidity will have life-threatening implications. It’s hard to avoid extreme heat when your livelihood depends on outdoor work and there is a lack of electricity, let alone air conditioning.
Extreme heat may make regions uninhabitable and lead to the migration of many communities.

The temperature shift coming in the next 50 years is greater than humans, livestock and crops have experienced in 6,000 years.
Unless mass-migration becomes the norm, a third of the human population will find itself living in Sahara-like conditions by 2070 if climate pollution continues at current rates. The researchers writing in PNAS found “a strong tension” between where people are expected to live and the climate conditions they have lived in for millennia.
Simultaneous high humidity and temperature are an example of what scientists call a “compound event,” when multiple things go haywire. It’s an intuitive concept, particularly at a moment when many millions of people are heading into summer heat, hurricane and wildfire seasons under the cloud of a pandemic.

Steven Sherwood, a climatologist at Australia’s University of New South Wales, said: “These measurements imply that some areas of Earth are much closer than expected to attaining sustained intolerable heat. It was previously believed we had a much larger margin of safety.”
According to the Kristina Dahl, a climatologist at the Union of Concerned Scientists, some areas may already be seeing conditions worse than the study suggests, because weather stations do not necessarily pick up hot spots in dense, concrete-heavy city neighborhoods. 

Cities have been installing “green alleys” made of materials that absorb heat more readily than concrete and asphalt and painting roofs white to reflect the sun.
The phenomenon is only now being recognized because prior studies focused on averages of heat and humidity measured over large areas and periods of several hours. In the new study, researchers zoned in on hourly data from 7,877 individual weather stations, allowing them to be more localized and exact.

Extreme heat and humidity episodes greatly impacted coastlines where evaporating seawater provides abundant moisture to be sucked up by hot air, the study noted.

How humidity occurs?

Humidity tells you the moisture content of the atmosphere, or how much water vapor there is in the air. When the humidity is high it feels oppressive outside because sweat doesn't evaporate and provide cooling. 

When the humidity is low, you feel cooler but your skin dries out and you get dehydrated more easily because more moisture is being evaporated from your body. The same thing applies to crops in high and low humidity. 

A high water vapor content is necessary to produce clouds and precipitation. Relative humidity and dew point are the two main ways to describe humidity. 

Relative Humidity
The relative humidity is given as a percentage and tells you how close the air is to being saturated. If the relative humidity is 100%, the air is saturated. 

If the relative humidity is 50%, the air contains half the water vapor required for it to be saturated. If the amount of water vapor in the air increases, the relative humidity increases, and vice versa. 
However, relative humidity is dependent on air temperature, too. If the water vapor content stays the same and the temperature drops, the relative humidity increases.

 If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn’t require as much moisture to become saturated as warmer air. 
If you pay attention to the weather in the summer, you’ll notice that the relative humidity is actually higher in the morning than in the afternoon. This is because the cooler morning air is closer to saturation than the hot afternoon air, even with the same amount of water vapor. Surprisingly, there is no significant difference in daily average relative humidity between summer and winter. 

Since warm air is less dense than cold air, there is more room for water vapor in warm summer air as compared with cold winter air.

Dew Point

Dew point is a better indicator of humidity than relative humidity because it is not a percentage dependent on temperature. 

The dew point is the temperature to which the air would have to be cooled to become saturated. Below the dew point, water will condense out of the air onto surfaces. In the early morning, grass surfaces will be coated with water if the night-time temperature has dropped below the dew point. When humidity is high, the dew point temperature is only a few degrees below, or equal to, air temperature. 

In dry places, like deserts of the southwest, air temperature can be 50 or 60 degrees above the dew point. Generally, the dew point is a more reliable indicator of humidity than relative humidity because the dew point is not affected by a change in air temperature and doesn’t fluctuate much throughout the day.
Some facts
§  In a normal year, approximately 175 Americans die from extreme heat. Young children, elderly people, and those who are sick or overweight are more likely to become victims.

§  Between 1936 and 1975, nearly 20,000 people succumbed to the effects of heat and solar radiation.

§  Because men sweat more than women, men are more susceptible to heat illness because they become more quickly dehydrated.

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