threegenerationsleft

human activity and the destruction of the planet


Leave a comment

Growing palm oil on former farmland cuts deforestation, CO₂ and biodiversity loss

From The Conversation:

https://theconversation.com/growing-palm-oil-on-former-farmland-cuts-deforestation-co-and-biodiversity-loss-127312

Few natural products are as maligned as palm oil, the vegetable oil that’s in everything from chocolate spread to washing up liquid. On the island of Borneo, oil palm plantations have replaced nearly 40% of the native forest cover since 2000. Deforestation releases CO₂ into the atmosphere and deprives rare and endangered species with the complex habitats they need to thrive.

A new study has tried to find out if this valuable crop can be grown without destroying more forests, by converting existing pastureland into new oil palm plantations instead. Could growing more oil palm on land with already scarce wildlife be a solution to the deforestation crisis?

The oil palm tree produces two types of vegetable oil. Palm oil from the fruit is used in cooking and baking and helps feed over three billion people, mostly in Asia. The other oil comes from the palm kernel, or seed, which is used around the world to make most of our detergents, soaps and other cleaning products.

Palm oil comes from the tree’s bright red fruit and is one of the most valuable vegetable oils in the world. Eva Blue/Unsplash, CC BY-SA

The relentless increase in global demand for vegetable oil has driven the logging and draining of forests and peatland to grow soybeans in South America and oil palm in Asia. About 85% of oil palm is grown in just two countries: Indonesia and Malaysia. But other tropical countries, particularly in South America and West Africa, are establishing their own oil palm plantations. These are vast monocultures that very few species can inhabit, especially compared with the tropical forest they replace.

A drainage ditch in a recently created oil palm plantation, Sarawak, Borneo. As the peat dries, it can release large quantities of greenhouse gases into the atmosphere. Denis Murphy, Author provided

Use farms not forests

In the recent study, researchers measured how much carbon – previously locked up in trees and other vegetation – was lost to the atmosphere when either pastureland or rainforest was converted to oil palm plantation.

The good news is that turning pastureland into oil palm plantations reduced how much carbon was released by 99.7%, compared to when rainforest was converted. Another bonus of using pastureland might be that its starting biodiversity is relatively low anyway, so the plantation may actually have a greater diversity of wildlife than the previous ecosystem.

Areas of forest that have been cleared for oil palm plantations, in Bawa village, Subulusalam, Aceh, Indonesia, July 27 2019. EPA-EFE/HOTLI SIMANJUNTAK

Converting grassland ecosystems like the Llanos in South America to oil palm plantations also released less carbon than converting forests. But in this case, the researchers found there were significant losses for biodiversity. If we have to produce more palm oil, the best outcome for wildlife and the climate would be to make former pastureland the first choice for future plantations.

But would it not be better to ban palm oil altogether? Campaigns have urged consumers to switch to products that don’t contain palm oil, while some retailers have announced plans to exclude such items from their own-brand products.


Read more: Replanting oil palm may be driving a second wave of biodiversity loss


Oil palm plantations produce 73.5 million tonnes of vegetable oil from a total land area of 27 million hectares worldwide. This might seem like a large area, but the second most important vegetable oil crop, soybean, produces 56 million tonnes from 97 million hectares – more than 3.6 times the oil palm area. This means that oil palm actually uses much less land than other crops, which is one reason why it’s so popular with growers.

Scientists measure greenhouse gas emissions and sample groundwater in an oil palm plantation in Sarawak, Borneo. Denis Murphy, Author provided

So boycotting palm oil could actually increase deforestation, since alternative tropical oil crops tend to use much more land. A better approach is to ensure that all the palm oil used in food and other products has been obtained from a “sustainable” source, and not from recently logged forests.

That’s why it’s important to base our decisions on sound scientific evidence. Oil palm will continue to be a vital crop for many developing countries in the future. Using former pastureland to grow the crop could ensure the product’s development isn’t at the expense of vulnerable ecosystems. Given how bad red meat production is for the planet, a switch from cattle pasture to oil palm plantation in the tropics could well be a marked improvement.”


Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.


Leave a comment

UK aid’s commitment to tackle climate change in Africa

A UK aid package to tackle climate change across Africa has been announced by the International Development Secretary Rory Stewart during a two day visit to Kenya.

International Development Secretary Rory Stewart greets a community member in Loiyangalani, Kenya. Picture: Will Crowne/DFID

International Development Secretary Rory Stewart greets a community member in Loiyangalani, Kenya. Picture: Will Crowne/DFID

The support would help sub-Saharan African countries build resilience to climate change and develop low carbon economies.

Increasing temperatures and extreme weather across the continent are having a profound impact on the lives and livelihoods of communities.

During his visit, the Secretary of State saw first-hand what happens when we do not protect the planet, including damaged natural flood defences; arid, drought-stricken land; and wildlife, the environment and jobs put at risk. He highlighted how tackling climate change is a global problem, and taking on an issue which affects us all will also ultimately benefit the UK.

Over the next five years, the new £250 million UK aid package would ensure UK expertise and experience can help developing countries become more climate resilient and move away from fossil fuels onto cleaner energy sources.

Working in partnership with African governments, organisations and communities, this funding would be the Department for International Development’s (DFID’s) largest single direct climate investment ever in the continent.

The Secretary of State said during his visit to a drought-affected village in Marsabit County in northern Kenya (July 12):

We are facing a global climate emergency. Polluted air, rising sea levels and increasing temperatures are felt by everyone in the world.

We must all play our part to protect the environment, wildlife, vulnerable families and communities – and this includes investing in renewable energy.

I am today announcing DFID’s biggest ever single direct aid investment in climate and the environment across Africa. This builds on my ambition to double DFID’s efforts on this issue globally. Tackling climate change is of direct benefit to everyone living on this planet, including of course in the UK.

African nations are responsible for just 2 to 3% of global emissions, but the continent is set to be the worst affected by the devastating impacts of climate change. Kenya is getting warmer and its rainfall becoming more uncertain.

In the coastal town of Lamu, in southern Kenya, the International Development Secretary heard on Thursday (July 11) about the importance of mangrove conservation. These trees act as a vital natural flood defence protecting communities from storms.

However, they are among the world’s most threatened vegetation and nearly 40% of Lamu’s mangroves have already been destroyed.

The International Development Secretary also visited the UNESCO World Heritage site Lamu Old Town where he heard how UK aid will support sustainable development of the town. While there he announced an additional £10 million towards DFID’s Sustainable Urban Economic Development programme to support urban economic growth in Kenya, which is resilient to climate-related shocks and disasters.

On Friday (July 12), the International Development Secretary met with communities in northern Kenya whose lives have been hit by drought. He announced an extra £4 million UK aid commitment to help prevent malnutrition and the threat of starvation for those living off arid lands in Kenya.

The effects of a changing climate and damage to the environment can already be seen in the village of Loiyangalani, near Marsabit County. In 2017 villagers experienced the worst drought for over five years, with people and livestock threatened by death, disease and starvation.

Wildlife and biodiversity is also under threat. Globally, one million animal and plant species are threatened with extinction. During a visit to Ol Pejeta conservancy in central Kenya, he saw the last two northern white rhino on the planet; a sub-species on the edge of extinction. The combination of cattle herders searching for food for their livestock and human conflict is having an impact on the habitats of rhinos – making them more vulnerable to extinction.

UK aid is helping to preserve the environment where wildlife like rhinos live. It does this in part, by helping cattle herders in Kenya fatten up their cows to earn more from their livestock while helping to manage the land where they graze, so they are not competing so intensely for grassland with such rhinos and other endangered species.

The UK is also working with African nations to deliver an ambitious move to efficient, low carbon technologies. An estimated 600 million Africans currently do not have access to electricity, but UK aid – through its development finance arm CDC and UK private sector investment is helping to support Kenya’s renewable energy sector, by funding the development of the largest onshore wind farm in sub-Saharan Africa at Lake Turkana.

The £250 million climate programme will work across Sub-Saharan Africa, in partnership with African governments and institutions, to increase resilience and support the transition of countries to low carbon economies. The funding will also help build technical expertise across a range of sectors to support the continent to deal with the devasting impacts of climate change and help it move to clean energy sources.



24th July 2019:

International Development Secretary, Rory Stewart, resigned his post in the cabinet on learning that Boris Johnson would become the new Prime Minister.

Since posting the notes above from the Government’s website (gov.uk), an article has appeared in The Guardian warning that much of UK foreign aid is spent on fossil fuel projects, though the study covers the period from 2010.  The figure quoted is £680 million of the foreign aid budget being spent on fossil fuel projects.

Britain allocated more overseas development cash to oil and gas in the two years after signing the 2015 Paris agreement than it had in the previous five, according to the study commissioned by the Catholic development agency Cafod and carried out by the Commons international development committee. Although the UK also increased support for renewables, Cafod said the continued support for carbon-intensive energy in middle-income countries was diverting resources that should be used to help poor communities gain access to electricity from wind and solar power.



 


Leave a comment

Heatwaves, fires, floods, reef pollution and wildlife deaths affecting Australia

In an earlier blog, I have described the prolonged extreme heat that affected Australia in January.  It was followed by devastating bush fires.  In February, unprecedented floods hit Northern Queensland as double the annual rainfall fell in just 12 days, causing rivers and creeks to burst their banks.  500,000 cattle were drowned as well as much of the state’s native wildlife.  Cattle that did survive were in a poor state after being stranded in deep water and mud for days.

cattle

Queensland cattle drowned by the flood waters

Following the floods, a massive plume of polluted floodwater has hit the Great Barrier Reef, sparking a fresh threat to its fragile ecosystem. The muddy plume, which likely included nitrogen and pesticide chemicals, spread 60 kms to the outer reefs and was so large it could be seen from space. The satellite image below from the recent Queensland floods shows how far polluted runoff can reach into Reef waters.

gbrfloodpollution

Satellite image showing river flood pollution along the Australian coast south of Townsville, Queensland

Sediment and fertiliser runoff from farms is a major threat to inshore coral reefs and seagrass meadows of the Great Barrier Reef. This pollution can lead to devastating impacts to corals and seagrass ecosystems, critical habitats for threatened dugongs, turtles and many juvenile commercial fish species.

The Reef life is also being weakened by sediment and chemical pollution – right when it needs to be strong in the face of rapidly heating oceans. Its corals are still recovering from the devastating back to back bleaching events that occurred from rising ocean temperatures in 2016 and 2017. Improving the quality of water flowing from the Reef coast into the sea is critical to reduce the pressure and support its recovery.

Nutrients from fertiliser runoff are driving massive outbreaks of coral-eating Crown-of-Thorns Starfish. These starfish devour vast amounts of coral on the Reef, threatening the recovery of bleached corals.  So, the Great Barrier Reef is at risk from a number of sources.

One of the corollaries to climate change is extreme weather events and Australia has had its fair share of them this year (2019).



And, from the Times, 4th March 2019, the following:

“Residents in part of the outback have been ordered to limit their showers to three minutes a day and banned from using a washing machine more than twice a week amid the worst drought since 1900.

The seven-year lack of rain has prompted convoys of lorries to take bottled water to small towns across far-western New South Wales. Their water supply, from stagnant ponds in drying rivers, has become undrinkable.

“There’s an acute water shortage in a substantial amount of western New South Wales,” James McTavish, the state’s town water supply co-ordinator, said.”



Guardian 7th March 2019:

Ringtail possums in Victoria are dying of heat stress.  Rescuers found 127 of them at Somers Beach on the Mornington Peninsula, dying or already dead.  It is thought that the possums had become so dehydrated and desperate they had left an area of scrub and come down to the beach and attempted to drink salt water.  Some had fallen out of trees.

possums

Story at: https://www.theguardian.com/environment/2019/mar/07/falling-out-of-trees-dozens-of-dead-possums-blamed-on-extreme-heat-stress?utm_term=RWRpdG9yaWFsX0dyZWVuTGlnaHQtMTkwMzA4&utm_source=esp&utm_medium=Email&utm_campaign=GreenLight&CMP=greenlight_email



April 15th 2019

A Nature study reported on CNN website found that successive ocean heat waves are not only damaging Australia’s Great Barrier Reef, they are compromising its ability to recover, raising the risk of “widespread ecological collapse”.

The 2,300-kilometer-long (1,500 mile) reef has endured multiple large-scale “bleaching” events caused by above-average water temperatures in the last two decades, including back-to-back occurrences in 2016 and 2017.
The new study, released in the journal Nature, examined the number of adult corals which survived these two events and how many new corals they created to replenish the reef in 2018.
The answer was as bleak as it was stark: “Dead corals don’t make babies,” the study’s lead author, Terry Hughes, said in a press release.
Scientists working on the study found the loss in adult corals caused a “crash in coral replenishment” on the reef, as heat stresses brought about by warming ocean temperatures impacted the ability of coral to heal.
Coral
“The number of new corals settling on the Great Barrier Reef declined by 89% following the unprecedented loss of adult corals from global warming in 2016 and 2017,” said Hughes.
Scientists have long warned of the impact on global warming on the reef, the world’s largest reef system and the only living organism that can be seen from space. The reef, a UNESCO World Heritage Site, supports thousands of species — fish, turtles, sharks and marine mammals.
In the introduction to the report, the authors note that environmental changes caused by climate change, “are increasingly challenging the capacity of ecosystems to absorb recurrent shocks and reassemble afterwards, escalating the risk of widespread ecological collapse of (the) current ecosystem.”
The study found that one of the most dominant species of coral, Acropora, which provides “most of the three-dimensional coral habitat that support thousands of other species,” according to co-author Andrew Baird, had suffered a 93% drop in replenishment following the back-to-back bleaching events of 2016 and 2017.


May 2019:

Australia re-elects the climate change denier, Scott Morrison.

Battered by extended droughts, damaging floods, and more bushfires, Australian voters had been expected to hand a mandate to the Labour party to pursue its ambitious targets for renewable energy and carbon emissions cuts.

Instead, they rejected the opposition’s plans for tax reform and climate action, re-electing a Liberal-led center-right coalition headed by Morrison. The same coalition government last year scrapped a bipartisan national energy plan and dumped then-prime minister Malcolm Turnbull because he was viewed as anti-coal.

Prime Minister Scott Morrison once brandished a lump of coal in parliament, crying, “This is coal – don’t be afraid!”

It would appear that the Australian voting public were enticed to vote this way in order to reduce energy prices.



July 31st 2019:

Another report from Nature gives the alarming news that the climate crisis is already causing deaths and childhood stunting. The Nature report from Monash University in Melbourne, Australia, is reviewed in The Guardian and msn.

https://www.msn.com/en-gb/news/world/climate-crisis-already-causing-deaths-and-childhood-stunting-report-reveals/ar-AAF76ZS?ocid=spartandhp

The report “From Townsville to Tuvalu” pulled together scientific research from roughly 120 peer-reviewed journal articles to paint a picture of the health-related impacts of the climate emergency in Australia and the Pacific region. It stated, “Climate change is “absolutely” already causing deaths” and also predicts climate-related stunting, malnutrition and lower IQ in children within the coming decades.

It pointed to a 2018 report from the World Health Organisation, which predicted that between 2030 and 2050, global warming would cause an additional 250,000 deaths per year from heat stress, malnutrition, malaria and diarrhoea. But Misha Coleman, one of the report’s authors, stressed that deaths were already occurring:

“During the Black Saturday fires (in Victoria in 2009) for example, we know that people were directly killed by the fires, but there were nearly 400 additional deaths in those hot days from heat stress and heatstroke.”

The report found that, as well as deaths caused directly by severe weather events such as hurricanes, flooding and fires, the “more deep and insidious impact” came from the secondary impacts of climate change.

The report warned that rising global temperatures would expand the habitat of mosquitos, exposing more people to diseases including dengue, chikungunya and zika, and would cause other diseases to spread into Australia, including Nipah virus, which is spread by bats, and Q fever, which is already prevalent around Townsville.

John Thwaites, Chair of the Sustainable Development Institute of Monash University. said:

“Q fever is something that is carried by a lot of wild and domesticated animals. “As climate change degrades their habitat through fires and drought, these animals go looking for green grass and fresh water [and] they find themselves on golf courses and on retirees’ two-acre blocks.”

Coleman said the problem comes when infected animals defecate on lawns and the poo is then run over by humans with lawnmowers. “It becomes airborne and a highly transmissible toxin, that’s why it’s being described, even by the Lancet medical journal, as a bioweapon in our own backyard.”

Climate change is expected to pose particularly stark issues for childhood development, with the report citing research that shows children born to women who were pregnant while they experienced floods in Brisbane in 2011 had lower cognitive capacity (equivalent to at least 14 points on an IQ scale), smaller vocabularies and less imaginative play at the age of two.

The decreased nutritional value of staple crops as a result of higher CO2 concentration was also expected to cause stunting, anaemia and malnutrition in children, within 10 to 20 years.

See also:

https://www.theguardian.com/environment/2019/jul/31/climate-crisis-already-causing-deaths-and-childhood-stunting-report-reveals

https://www.nature.com/nclimate/articles?type=news-and-views

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)32610-2/fulltext

https://www.climaterealityproject.org/blog/how-climate-change-affecting-australia

The final article in the link above describes specifically the reality of climate change effects for Australia. It is worth reading. It shows, by means of a graph, the consequences of an upward shift in average temperature for the region:

heatw3



December 2019:

Extensive bush fires have hit Australia earlier this year, affecting much of Queensland and especially New South Wales, where the fires have been burning out of control, destroying property, as well as wildlife.  Smoke pollution has also hung over Sydney for days on end.

One big concern in all of this is the loss of many of the native koalas, killed in the fires.  Concern was already being expressed about the future viability of this species, due to habitat loss.  Now, heartbreaking film of burnt and dying koalas is being shared globally.

koala2

Reports state that:

Thousands of koalas are feared to have died in a wildfire-ravaged area north of Sydney, further diminishing Australia’s iconic marsupial, while the fire danger accelerated on Saturday in the country’s east as temperatures soared.

The mid-north coast of New South Wales was home to up to 28,000 koalas, but wildfires in the area in recent months have significantly reduced their population.

Koalas are native to Australia and are one of the country’s most beloved animals, but they have been under threat due to a loss of habitat.

Environment minister Sussan Ley said: “Up to 30% of their habitat has been destroyed.

“We’ll know more when the fires are calmed down and a proper assessment can be made.”

Images shared of koalas drinking water after being rescued from the wildfires have gone viral on social media in recent days.

koala

Ms Ley said: “I get mail from all around the world from people absolutely moved and amazed by our wildlife volunteer response and also by the habits of these curious creatures.”

About 12.35 million acres of land have burned nationwide during the current wildfire crisis, with nine people killed and more than 1,000 homes destroyed.

Fire danger in New South Wales and the Australian Capital Territory was upgraded to severe on Saturday, as high temperatures built up over the region.

Sydney’s western suburbs reached 41C, while the inner city is expected to hit 31C on Sunday before reaching 35C on Tuesday.”



 


Leave a comment

The effects of heat waves on human survivability

An article in the New Scientist (No.3161) by John Pickrell, entitled “Too hot to handle”, discusses the increasing trend of heatwaves throughout the world, as a result of climate change.

heatwave

Pickrell starts by discussing Australia, which had a heatwave in January 2017, with the hottest ever recorded temperatures in Sydney and Brisbane (Sydney had over 47 degrees). Large parts of the country had temperatures over 40 degrees C for weeks on end, as well as bush fires.  Many of the unique species of wildlife common to Australia had to be rescued from fires and heat, many of them suffering from heat exhaustion, burns, dehydration and stress.

koala

kangaroo

 

Temperatures of 50 degrees C are predicted by 2040 for Australia.

Pickrell then goes on to cite papers, which give statistics about fatalities during heatwaves, one from The Lancet which covered research by 26 institutions (including the World Health Organization).

The 2003 heatwave in France killed 70,000 people – but it would appear that the level of humidity is the crucial factor, as high levels of water in the atmosphere can reduce the body’s ability to cool down through sweating.  To sweat effectively, you must maintain your blood volume, so dehydration can cause heat stress, followed by heat stroke, multiple organ failure and possible death.  The elderly and children are at greater risk of heat stroke, as well as those on medication or with heart disease.

I came across another wordpress website, which gives a useful chart showing temperature against relative humidity and which combinations are lethal:

See: https://andthentheresphysics.wordpress.com/2017/06/24/heatwaves/

and below for the table (with acknowledgments):

nclimate_heatwaves

The black crosses in the chart above show temperature and relative humidity during events that were lethal. The blue line shows the likely boundary between lethal and non-lethal events, and the red line is a 95% probability threshold.


According to The Lancet, global warming has reduced the workforce in India by 418,000.


An interesting map of the world is given in the New Scientist article to show the probability of deadly heatwaves for three global warming scenarios: 1.5 degrees C; 2 degrees C and 4 degrees C.  This can be seen by clicking on the link below:

heatwaves data

It shows that, even with an increase in global temperature of 2 degrees, many parts of the world will become uninhabitable, through rising temperatures: North West Africa, much of the Middle East, parts of Central and South America, India, Pakistan and Bangladesh and much of Australia.  At four degrees the situation is dire throughout much of the tropical world.

The New Scientist article concludes with a list of advice on how to keep cool.


 Another academic article on a similar subject has been published in the Proceedings of the National Academy of Science USA by Sherwood and Huber in 2010 (Vol 107, (21), 9552-5) entitled “An adaptability limit to climate change due to heat stress.”  This article has been summarised in the Science & Technology section of the The Observer (10th Sept. 2017).  This article gives a chart showing which species die at particular degrees of warming above pre-industrial levels.  Amphibians will be the first to go (at 0.6 degrees+), followed by penguins, due to loss of food sources, as the krill populations dwindle. At 1.6 degrees+, the wooded tundra is lost, along with its inhabitants, moose, lynx and brown bears, followed by large African mammals, such as elephants, then rain forest dwellers (orangutans, jaguars, sloths) at 2.6 degrees+.  At a warming of 4 degrees, 70% of species would be extinct, coral reefs dead and deserts would expand across the world. The fate of humankind would be dominated by mass migration, on a scale even larger than we see today, with water resources extremely limited, as we would have to abandon most of the Earth or live underground.  The authors predict that, by 2050, temperatures will be in a range that nobody has experienced before.

It is interesting to note that the Australian town of Coober Pedy, a major site for opal mining, has already built an underground town, including hotels, for those times in the year when it is already too hot to live above ground.


2nd August 2018

Since this post was first written, time has now moved on into 2018 with heatwaves across much of the northern hemisphere (see other posts on this site for details).  Even climate sceptics are now beginning to accept that climate change is with us, with the extremes of weather which accompany it.

A piece this week in The Guardian by David Carrington deals with the issue of human survivability during heat waves.  I quote a short passage from him, in which he summarises scientific work on the issue:

The new analysis assesses the impact of climate change on the deadly combination of heat and humidity, which is measured as the “wet bulb” temperature (WBT). Once the WBT reaches 35C, the air is so hot and humid that the human body cannot cool itself by sweating and even fit people sitting in the shade die within six hours.

A WBT above 31C is classed by the US National Weather Service as “extreme danger”, with its warning stating: “If you don’t take precautions immediately, you may become seriously ill or even die.”

He then goes on to discuss which parts of the world are most at risk of high WBT temperatures.  This would appear to be the north China plain, with a population of 400 million people, most of them farmers.  The scientists who produced the data have predicted that by 2070 to 2100, this area of the world will become uninhabitable.  Other areas at risk are the Middle East, around the Gulf (particularly Dubai, Abu Dhabi, Doha and the coastal cities of Iran) and parts of South Asia (around the Indus and Ganges valleys).

For the full Guardian article, see:

https://www.theguardian.com/environment/2018/jul/31/chinas-most-populous-area-could-be-uninhabitable-by-end-of-century?utm_source=esp&utm_medium=Email&utm_campaign=Green+Light+2016&utm_term=282539&subid=2617869&CMP=EMCENVEML1631



July 2019

The UK has experienced another heatwave period this summer, with record temperatures being reached in a number of countries.  It was particularly humid in the UK, with weather forecasters predicting the humidity above 50%, a level which can prove fatal with temperatures above 25ºC, according to the graph shown above.

So its worth looking again at the relationship between WBT (wet bulb temperature) and death due to heat stress.  The following can be found in Wikipedia:

“Living organisms can survive only within a certain temperature range. When the ambient temperature is excessive, humans and many animals cool themselves below ambient by evaporative cooling (sweat in humans and horses, saliva and water in dogs and other mammals); this helps to prevent potentially fatal hyperthermia due to heat stress. The effectiveness of evaporative cooling depends upon humidity; wet-bulb temperature, or more complex calculated quantities such as Wet Bulb Globe Temperature (WBGT) which also takes account of solar radiation, give a useful indication of the degree of heat stress, and are used by several agencies as the basis for heat stress prevention guidelines.

A sustained wet-bulb temperature exceeding 35 °C (95 °F) is likely to be fatal even to fit and healthy people, unclothed in the shade next to a fan; at this temperature our bodies switch from shedding heat to the environment, to gaining heat from it. Thus 35 °C (95 °F) is the threshold beyond which the body is no longer able to adequately cool itself. A study by NOAA from 2013 concluded that heat stress will reduce labour capacity considerably under current emissions scenarios.

A 2010 study concluded that under a worst-case scenario for global warming with temperatures 12 °C (22 °F) higher than 2007, the wet-bulb temperature limit for humans could be exceeded around much of the world in future centuries. A 2015 study concluded that parts of the globe could become uninhabitable. An example of the threshold at which the human body is no longer able to cool itself and begins to overheat is a humidity level of 50% and a high heat of 46 °C (115 °F), as this would indicate a wet-bulb temperature of 35 °C (95 °F).”