Climate change: Summers could become 'too hot for humans'
Millions of people around the world could be exposed to dangerous levels of heat stress - a dangerous condition which can cause organs to shut down.
Many live in developing countries, and do jobs that expose them to potentially life threatening conditions.
These include being out in the open on farms and building sites or indoors in factories and hospitals.
Global warming will increase the chances of summer conditions that may be "too hot for humans" to work in.
When we caught up with Dr Jimmy Lee, his goggles were steamed up and there was sweat trickling off his neck.
An emergency medic, he's labouring in the stifling heat of tropical Singapore to care for patients with Covid-19.
There's no air conditioning - a deliberate choice, to prevent the virus being blown around - and he notices that he and his colleagues become "more irritable, more short with each other".
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And his personal protective equipment, essential for avoiding infection, makes things worse by creating a sweltering 'micro-climate' under the multiple layers of plastic.
"It really hits you when you first go in there," Dr Lee says, "and it's really uncomfortable over a whole shift of eight hours - it affects morale."
One danger, he realises, is that overheating can slow down their ability to do something that's vital for medical staff - make quick decisions.
Another is that they may ignore the warning signs of what's called heat stress - such as faintness and nausea - and keep on working till they collapse.
What is heat stress?
It's when the body is unable to cool down properly so its core temperature keeps rising to dangerous levels and key organs can shut down.
It happens when the main technique for getting rid of excess heat - the evaporation of sweat on the skin - can't take place because the air is too humid.
And as Dr Lee and other medics have found, the impermeable layers of personal protection equipment (PPE) - designed to keep the virus out - have the effect of preventing the sweat from evaporating.
According to Dr Rebecca Lucas, who researches physiology at the University of Birmingham, the symptoms can escalate from fainting and disorientation to cramps and failure of the guts and kidneys.
"It can become very serious as you overheat, and in all areas of the body."
How can we spot it?
A system known as the Wet Bulb Globe Temperature (WBGT) measures not only heat but also humidity and other factors to give a more realistic description of the conditions.
Back in the 1950s, the US military used it to work out guidelines for keeping soldiers safe.
When the WBGT reaches 29C, for example, the recommendation is to suspend exercise for anyone not acclimatised.
Yet that's the level Dr Lee and his colleagues are regularly experiencing at Singapore's Ng Teng Fong General Hospital.
And at the top of the scale - when the WBGT registers 32C - the US says strenuous training should stop because the risk becomes "extreme".
We, the citizens of our nation and of our Earth, are endowed with certain rights, powers, and obligations, which demand we act to preserve and protect the longer term of humanity also as Earth's other animal and biological life.
Based on abundant scientific evidence, we recognize that our global climate is rapidly warming and becoming increasingly unstable thanks to human-caused atmospheric carbon pollution primarily at this point from the burning of fossil fuels.
We also recognize that in spite of 35 years of credible scientific warnings, heating remains rising and is now at dangerous levels!
we've already seen global warming-aggravated weather, like record-breaking floods, hurricanes, and wildfires. we've witnessed the "worst in centuries" droughts and mud storms. we've experienced alternating unseasonably cold then warm winters, extreme storms, bomb cyclones, and rain bombs where weeks or months' worth of rain falls during a few hours or a couple of days.
With our own eyes, we see that something very abnormal is occurring to the previous stability of our normal weather and seasonal patterns. we've also noticed that heating connected consequences (like those just mentioned,) are getting more frequent, more severe, and are affecting larger and bigger areas!