Category: extreme heat

Half a billion people may face heat of 56°C by 2100

Half a billion people may face heat of 56°C by 2100

By Tim Radford

Take today’s heat, apply mathematical logic and consider a murderously hot future, 56°C by 2100, for hundreds of millions.

LONDON, 29 March, 2021 − Many millions of people − among them some of the world’s poorest − will be exposed to potentially lethal temperatures on a routine basis. At worst, the mercury could reach 56°C by 2100.

Even if the world keeps its most ambitious promise and contains global heating to no more than 1.5°C above the global average normal for most of human history, the future looks distinctly menacing.

And if the world doesn’t quite get there, and annual average temperatures − already 1°C above the historic norm − rise to 2°C, then vast numbers of people in South Asia will find themselves exposed to deadly conditions at least three times as often.

As the researchers make this sober warning in one journal, researchers on the same day in yet another journal make a simple prediction about the cost of ignoring such warnings altogether, to go on burning ever more fossil fuels and destroying ever more tracts of the natural world.

If this happens, then people in the Middle East and North Africa will be hit by a new category of thermal menace: the arrival of super-extreme and ultra-extreme heatwaves.

Target far exceeded

Which means that by the end of this century, more than half a billion people could be exposed to temperatures as high as 56°C, not just for days, but for weeks. The hottest temperature so far ever recorded on Earth was 54°C, in Death Valley, California in 2020.

In 2015, almost all of the world’s nations met in Paris and vowed to contain global heating by the century’s end to “well below” a maximum of 2°C. In fact, the less explicit intention was to contain the mercury’s rise to no higher than 1.5°C.

So much for the vow: the latest evidence is that, on the basis of the national declared intentions so far, global temperatures will rise far higher than the 2°C target. And summer − defined as the hottest 25% of the year − could by the century’s end last almost six months.

A new computational study in Geophysical Research Letters warns that the 1.5°C target could be passed by 2040, in just two decades. And with higher average temperatures over longer periods, there will inevitably be higher than average extremes of temperature, more often, for longer periods, and over wider ranges.

“The need for adaptation over South Asia is today, not in the future. It’s not a choice any more.”

The outcome could be devastating for the countries of South Asia − India and Pakistan, Sri Lanka, Bangladesh and Burma among them − as the thermometer rises and the humidity increases. Researchers have warned for years that at a certain level of heat and humidity − meteorologists call it the “wet bulb” temperature − humans cannot labour productively.

That level is 32°C. At a wet bulb temperature of 35°C, humans cannot expect to survive for long. Some parts of the region have already felt such temperatures with a global average rise of just over 1°C: in 2015, at least 3500 people in Pakistan and India died from causes directly related to extreme heat.

At 1.5°C the consequences could be significantly worse, and at 2°C, the scientists say, the hazard will have been amplified by a factor of 2.7: almost threefold. South Asia could later this century be home to more than two billion people: of the working population, 60% are now engaged in agricultural labour out of doors, and many millions live in crowded cities and in severe poverty. The region should prepare itself for a dangerously hot future.

“The future looks bad for South Asia,” said Moetasim Ashfaq, of the US Oak Ridge National Laboratory, one of the authors, “but the worst can be avoided by containing warming to as low as possible. The need for adaptation over South Asia is today, not in the future. It’s not a choice any more.”

That heat extremes are potentially lethal, that the people of South Asia are potentially at risk, and that an enormous proportion of the planet’s population will be exposed to dangerously high temperatures is not in dispute: the questions now are about the degree of danger, and its extent.

Ultra-extreme heat

Once again, the statisticians have been at work, and the answer in the journal Climate and Atmospheric Science is: it will be much worse, over a vaster region and for a very large number of people in the Middle East and North Africa.

Their calculations suggest that temperatures could reach as high as 56°C, and even more than 60° C in sweltering cities. Such heat extremes could endure for weeks.

So within the lifetimes of those alive today, about half the region’s population − that is, about 600 million people − could face extreme temperatures of around 56°C by 2100 every summer.

The researchers put their message with unusual forthrightness in the headline: “Business-as-usual will lead to super- and ultra-extreme heatwaves in the Middle East and North Africa.” − Climate News Network


This article was originally posted on The Climate News network.
Cover photo by Sarah Lachise on Unsplash
Europe has grown drier over the last two millennia

Europe has grown drier over the last two millennia

By Tim Radford

Global heating may be to blame for the fact that Europe has grown drier over the last 2,000 years to a new high in 2015.

LONDON, 17 March, 2021 − Europe has grown drier, an outcome shown by the continent’s last five summers, which have been marked by drought that has no parallel in the last two millennia.

Researchers studied two kinds of evidence delivered by 27,000 measurements taken from 21 living oak trees and 126 samples from ancient beams and rafters, to piece together a precise picture of the climate of Germany, Switzerland and the Czech Republic over the last 2,110 years.

They report, after 2015, that drought conditions intensified suddenly, in ways that were beyond anything over that entire 2000-year tract of time. And, they add, “this hydroclimatic anomaly is probably caused by anthropogenic warming.”

Europe is also getting hotter. In 2003, 2015 and 2018 it was hit by severe summer heat waves and spells of drought that damaged plantations, crops and vines; the damage from drought was intensified by more virulent attacks from pathogens, insect outbreaks and tree death.

“Extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole”

In the baking summer of 2003, an estimated 70,000 people died because of extremes of heat. And, the researchers say, “a further increase in the frequency and severity of heat waves under projected global warming implies a multitude of harmful direct and indirect impacts on human health.”

In other words, things are bad now and are likely to get worse, according to a report by 17 British, European and Canadian researchers in the journal Nature Geoscience.

Dendrochronologists can and do routinely build up a picture of bygone temperatures by measuring the growth rings in trees: enough old living trees, and reliable knowledge about the felling of oaks for chateaux, cathedrals, sailing ships, fortresses and stockades can help pinpoint seasonal change on an annual basis.

But trees are also living chronicles of changes in carbon and oxygen isotope ratios − tiny atomic variations in the plant’s biochemistry − which provide evidence of rainfall and therefore a more precise picture of any growing season.

Wandering jet stream

The trees delivered mute evidence of very wet summers in 200, 720 and 1100 AD, and very dry summers in the years 40, 590, 950 and 1510 of the Common Era. But overall the big picture emerged: for the years 75 BC to 2018, Europe has slowly been getting drier.

Even so, the evidence from 2015 to 2018 shows that drought conditions in the area from which the trees were taken far exceeds anything in the previous centuries. The mostly likely explanation is the impact of ever-rising temperatures, driven by ever-higher greenhouse gas emissions from the ever-more profligate combustion of fossil fuels.

These temperatures are now considered high enough to affect the course of the stratospheric jet stream in ways that alter the long-term pattern of temperature and rainfall that defines a region’s climate.

“Climate change does not mean it will get drier everywhere,” said Ulf Büntgen, who holds research posts in the University of Cambridge, UK and the Czech Republic and Switzerland. “Some places may get wetter or colder, but extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole.” − Climate News Network


This article was originally posted on the Climate News Network.
Cover image by US Embassy, Paris (public domain), via Wikimedia Commons
Wild flowers and bees contend with climate heat

Wild flowers and bees contend with climate heat

By Tim Radford

Many alpine flowers could soon fade out. Some bees may be buzzing off. The wild things are victims of climate heat.

LONDON, 9 February, 2021 − Thanks to climate heat, this could be the last farewell to mossy saxifrage, to alpine wormwood and mignonette-leafed bittercress. With them could go plants most people could hardly name: dwarf cudweed, alpine stonecrop, mossy cyphel, cobweb houseleek and two kinds of hawkweed. All of them are mountain-dwellers, hardy little plants that depend for their existence on alpine glaciers.

And almost everywhere in the world, high-altitude rivers of ice are in retreat. Global heating, climate change and human disturbance alter both the conditions for growth and the rich variety of life.

In the same week that one team of researchers listed the alpine flowers threatened with extinction, another team of scientists assembled an inventory of observations of wild bees, to find that a quarter of the world’s 20,000 bee species have not been recorded in the last 25 years.

Bees and flowers are interdependent: they evolved together and would perish together. But climate change threatens to take a selective toll on a range of alpine plants − beloved of gardeners but also important in liqueurs and medicines − as glaciers retreat in the mountainous regions.

These little flowers are to be found variously in the Sierra Nevada in Spain, the Apennines in Italy, along the spine of the Alps in Switzerland and Austria, and even in the highlands of Scotland.

And one day, according to a new study in the journal Frontiers in Ecology and Evolution, many or all of them could be locally extinct.

“Something is happening to the bees, and something needs to be done … The next step is prodding policymakers into action while we still have time. The bees cannot wait”

The wildflowers listed in the first two sentences − Saxifraga bryoidesArtemisia genipiCardamine resedifoliaLeucanthemopsis alpinaGnaphalium supinumSedum alpestreMinuartia sedoidesSempervivum arachnoideumHieracium staticifolium and H. glanduliferum − could all go, and another suite of alpine opportunists could take advantage of their living space.

Californian researchers report that they looked at 117 plant species and matched them with geological evidence from four glaciers in the Italian Alps, and then used computational systems to calculate how plant communities have changed over the last five thousand years, and what might happen as the glaciers continue to retreat.

They found that as the glaciers disappear, more than one in five of their sample alpines could also vanish. The loss of that 22% however could be to the benefit of around 29% of the surveyed species, among them the snow gentian, Gentiana nivalis and the dwarf yellow cinquefoil Potentialla aurea. Some alpines would probably not be affected: among them alpine lovage or Ligusticum mutellina and Pedicularis kerneri, a variety of lousewort.

The authors make no mention of one alpine almost everybody in the world could name: Leontopodium nivale or edelweiss. But what happens to even the most insignificant wild plants matters to everybody.

“Plants are the primary producers at the basis of the food web that sustained our lives and economies, and biodiversity is the key to healthy ecosystems − biodiversity also represents an inestimable cultural value that needs to be properly supported,” said Gianalberto Losapio, a biologist at Stanford University in the US.

Growing interest

Meanwhile in Argentina researchers decided to take advantage of citizen science to check on some of the flower world’s biggest fans, the wild bees. There has been huge concern about observed decline in insect abundance, as wild ecosystems are colonised by humans and global average temperatures rise to change the world’s weather systems.

But over the same decades, there has also been a dramatic increase in informed interest in the wild things, among gardeners, bird-watchers and butterfly lovers, and an exponential rise in records available to an international network of databases called the Global Biodiversity Information Facility.

And, say researchers in the journal One Earth, as global records soar, the number of bee species listed in those records has gone down. Around 25% fewer species were recorded between 2006 and 2015 than were listed in the 1990s.

Wild bees have a role in the pollination of about 85% of the world’s food crops. Without the bees, many wild flowers could not replicate.

“It’s not exactly a bee cataclysm yet, but what we can say is that wild bees are not exactly thriving,” said Eduardo Zattara, a biodiversity researcher at CONICET-Universidad Nacional del Comahue.

“Something is happening to the bees, and something needs to be done. We cannot wait until we have absolute certainty because we rarely get there in the natural sciences. The next step is prodding policymakers into action while we still have time. The bees cannot wait.” − Climate News Network


This article was originally posted on The Climate News Network.
Cover photo by Dirk Beyer, via Wikimedia Commons
One hundred thousand deaths in a year: Europe tops mortality league for extreme heat

One hundred thousand deaths in a year: Europe tops mortality league for extreme heat

By Will Bugler

Whilst the rising death toll from the COVID-19 pandemic continues to dominate the front pages, a new study highlights the growing risk from another deadly phenomenon: extreme heat. The research, published in The Lancet medical journal, shows that Europeans have the highest mortality rate from heatwaves, combined with the highest number of premature deaths caused by air pollution.

Like COVID, this poses a particular threat to older people and those with underlying health conditions. In 2018, the EU recorded 104,000 heat-related deaths amongst older people, over one third of the global total. The year saw unprecedented heat across the continent, with northern Scandinavia experiencing temperatures over 5˚C warmer than the 1981-2010 average.

“Climate change induced shocks are claiming lives, damaging health and disrupting livelihoods in all parts of the world right now. That means that no continent, country or community remains untouched,” said Ian Hamilton, executive director of the Lancet Countdown.

A trend set to continue

Taking steps now to prepare for hotter temperatures is vital in order to minimise the risks to vulnerable populations. According to the European Environment Agency (EEA), Europe is warming faster than the global average, with a mean annual temperature over European land areas in the last decade 1.7 to 1.9 °C warmer than during the pre-industrial period.

“The four warmest years in Europe since instrumental records began were 2014, 2015, 2018 and 2019. Many parts of Europe experienced an exceptional heat wave in June and July 2019, during which many all-time national temperature records were broken.” Notes the EEA.

This trend will continue in the coming decades. Projections from the EURO-CORDEX initiative suggest that temperatures across European land areas will continue to increase throughout this century at a higher rate than the global average. Land temperatures in different European regions are projected to increase further by 1.4 to 4.2 °C under the RCP4.5 scenario (by 2071-2100, compared to 1971-2000).

A systemic approach

As the Lancet study shows, rising temperatures pose a direct threat to human health, especially when considered alongside other issues such as air pollution. However, gradual increases in average temperatures and extreme heatwaves will have far reaching implications for countries around the world. Infrastructure failure, agricultural production, water availability, workforce productivity and wildfire frequency are just a few examples of how temperature rises will impact our lives.

As COVID-19 has shown, it is often the most vulnerable in society that bear the greatest burden. “The COVID-19 pandemic has thrown a spotlight on the current ability of healthcare and wider health systems to cope with the sorts of future health shocks that climate change may generate,” said Professor Hugh Montgomery, Lancet Countdown co-chair and an intensive care doctor, based at University College London.

The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises is available here.


Can SE Asian workers take the heat? Researchers tackle rising temperatures

Can SE Asian workers take the heat? Researchers tackle rising temperatures

By Rina Chandran

BANGKOK, Jan 13 (Thomson Reuters Foundation) – The effects rising heat has on vulnerable workers in Southeast Asia is the focus of a new study that also aims to find out what employers and authorities can do to reduce the impact of soaring temperatures in cities.

The three-year study, led by the National University of Singapore (NUS), will examine how heat stress impacts outdoor and indoor workers, including women in Singapore, Hanoi and Phnom Penh, said Jason Lee, the lead researcher.

The project, titled Heat-Safe, views heat as a “complex socio-environmental problem” that affects workers not just in the workplace, but also in public spaces and at home, resulting in lasting mental stress and other health concerns, said Lee.

“The assumption is that only outdoor workers are affected, but factory workers also face heat stress – and in Southeast Asia these are mostly women in garment factories,” said Lee, a research associate professor at NUS.

“The study is all the more relevant now, when we have seen the disproportionate impact of COVID-19 on migrant workers who make up the bulk of construction and shipyard workers in Singapore, and garment workers in other countries,” he said.

Heat-related deaths are soaring around the world, and higher temperatures resulted in 302 billion working hours lost globally in 2019 compared with 199 billion in 2000, according to a recent study in The Lancet medical journal.

A 2019 report by the International Labour Organization forecast that an increase in heat stress would lead to productivity losses equivalent to 80 million full-time jobs in 2030.

Besides monitoring hourly heat levels in select workplaces in the three Southeast Asian cities, Heat-Safe will also evaluate psychological strain on workers and the impact on fertility and birth rates among women workers, Lee said.

The study, backed by the Singapore government, will also examine home conditions of workers, he told the Thomson Reuters Foundation on Wednesday.

“If they are unable to rest comfortably at home, that affects their vulnerability,” said Lee, a thermal physiologist who has studied the effects of heat on the armed forces.

While the study launched on Oct. 1, travel restrictions and curbs on movement because of the coronavirus have posed challenges, but researchers are now gearing up for easing restrictions and the warmer months ahead, Lee said.

More governments are recognising the growing health and economic threats to their workforce from scorching temperatures, exacerbated in many cases by high humidity.

A study published in November on the impact of heat stress on workers in Australia said that current health and safety laws are inadequate, and that employers prioritise productivity over workers’ health.

People whose jobs are “less secure” – including temporary, on-demand and migrant workers – are at greater risk, said the study by the University of Technology Sydney.

“Questions of social justice are deeply embedded in climate change and rising temperatures,” it said.

In Singapore, more than three-quarters of total coronavirus cases were linked to crowded dormitories that house more than 300,000 foreign workers, leading the government to pledge to improve their living conditions.

Elsewhere in the region, migrant workers have been dumped or persecuted during the coronavirus pandemic.

“I’d like to think there is greater pressure now on governments and employers to take action to better protect vulnerable workers,” said Lee.

“It is time we paid attention to the working and living conditions of these workers.”


Read the original story here.
Earth is now committed to a 2°C hotter future

Earth is now committed to a 2°C hotter future

By Tim Radford

LONDON, 12 January, 2021 − We Earthlings are now unmistakably on our way to the global climate we promised barely six years ago we’d never reach − a 2°C hotter future.

Some time this year, thanks to fossil fuel combustion and the destruction of natural ecosystems, the levels of carbon dioxide in the planetary atmosphere will be half as high again as the average for most of human history. That is, they will be more than half-way to doubling.

And the warming already driven by this extra charge of greenhouse gas has reached new heights: 2020, according to one calculation, shares with 2016 the grim accolade of the hottest year in history, at the end of the hottest decade since systematic records began.

A third study warns that yet more warming is now inevitable: the greenhouse gases already released must take average planetary temperatures from the present rise of more than 1°C to beyond 2°C − the limit that 195 nations vowed not to exceed when they met in Paris in 2015.

All three studies are simply progress reports on climate change itself. It is more than a century since scientists began to link carbon dioxide levels in the atmosphere with planetary temperatures, and more than 50 years since researchers began systematically monitoring atmospheric CO2 at an observatory in Hawaii, and since the first warnings that rising greenhouse gas levels could precipitate potentially catastrophic climate change.

“Our results suggest we have most likely already emitted enough carbon to exceed 2°C”

And this year, says the British Met Office, the ratio will creep up by more than 2 parts per million on last year. That will take the average to beyond 417 ppm for a number of weeks this northern hemisphere spring. And that will be 50% higher than the 278 ppm that was the norm at the close of the 18th century, when humans began to exploit coal, oil and gas as global sources of energy.

“The human-caused build-up of CO2 in the atmosphere is accelerating,” said Richard Betts, of the Met Office. “It took over 200 years for levels to increase by 25%, but now, just 30 years later, we are approaching a 50% increase.”

The last six years have all been in the hottest six years ever recorded, European scientists say in their calculations of the planetary pecking order of annual temperatures. It was 0.6°C warmer than the average for the years 1981-2010. And it is fully 1.25°C above the average for 1850 to 1900.

Europe in particular felt the heat: an average of 1.6° higher than the average for 1981 to 2010. And in the Arctic and in Siberia, temperatures were up to 6°C above the average for the same period.

“It is no surprise that the last decade was the warmest on record, and is yet another reminder of the urgency of ambitious emissions reductions to prevent adverse climate impacts in the future,” said Carlo Buontempo, who directs Europe’s Copernicus Climate Change Service.

Delay possible

Carbon dioxide is durable: it stays in the air, and each year’s emissions are added to those of the previous year. To keep the planet’s average temperature to a rise of no more than 1.5°C  the ideal of the Paris Accord in 2015 − then nations must bring global emissions to zero within the next 30 years. In fact the limit of 2°C explicit in the Accord must now, and inevitably, be exceeded at some point: there is already enough greenhouse gas in the mix to guarantee that. The big question is: when.

Chinese and US researchers report in Nature Climate Change that they looked more closely at the pattern of changes in the planet’s surface temperatures, and the impact of low-level clouds that normally reflect heat back into space. And they see regions that have yet to warm, but must do so sooner or later to raise average global temperatures to levels so far not accounted for.

“The important thing to realise is that this has not happened − it is not in the historical record,” said Chen Zhou of Nanjing University, the lead author. “After accounting for this effect, the estimated future warming based on the historical record would be much higher than previous estimates.”

And his co-author Andrew Dessler, of Texas A&M University, said: “The bad news is that our results suggest we have most likely already emitted enough carbon to exceed 2C.”

But this could be delayed by urgent action. “If we can get emissions to net zero soon, it may take centuries to exceed 2°C.” − Climate News Network


This article was originally published on the Climate News Network.
Cover Image: By Chris JL, via ClimateVisuals
Central Asia risks becoming a hyperarid desert in the near future

Central Asia risks becoming a hyperarid desert in the near future

By Natasha Barbolini

Around 34 million years ago, sudden climate change caused ecological breakdown in Central Asia. This ancient event, triggered by rapid drops in temperature and atmospheric carbon dioxide, permanently affected biological diversity in the region. Large areas of Mongolia, (geographic) Tibet and north-western China suddenly became hyperarid deserts with little vegetation cover – and stayed that way for almost 20 million years.

This was a surprising finding of new research I carried out with colleagues from across Europe and China, in which we reconstructed the past 43 million years of evolutionary history for the steppe, semi-desert and desert ecosystems of Central Asia (the biogeographical and political conceptions of “Central Asia” differ and we use the former: our research area is shown below).

Many scientists had previously thought that this region was forested for much of that time and only grew drier later on, culminating today in massive, exceptionally arid Asian deserts such as the Gobi and Taklimakan.

image showing a map, some plants and a cross section of some mountains and a desert
The modern Central Asian steppe-desert (A), characteristic plant families (B), and an altitudinal profile illustrating vegetation belts of the steppe subtypes (C). Science Advances 2020; 6: eabb8227

We found that fossil pollen combined with mammal fossils, geological and climatic evidence – all preserved inside ancient rocks – told a different tale. Ancient “wet” steppe-deserts that received enough precipitation to maintain high biodiversity already existed during the late Eocene (40 to 34 million years ago), but suddenly became much colder and drier over an event called the Eocene‒Oligocene Transition (EOT).

Scientists already knew that global climate cooling in this period caused the formation of a permanent Antarctic ice-sheet, but what happened on different continents is less clear. Our new study found that the lowlands of Central Asia became hyperarid deserts with little vegetation cover. The lack of food resources meant that larger animals were mainly replaced by small mammals like rodents, rabbits and hares.

Three bits of fossilised pollen viewed under a microscope
Scanning electron microscope (SEM) images of fossil pollen used to reconstruct the ancient ecosystems of Central Asia. Scale bars represent 5 micrometres (0.005 mm). Carina Hoorn and Fang Han, Author provided

This hyperaridity lasted for millions of years afterwards, and plants only recovered when the climate became temporarily wetter around 15 million years ago. But now, the major species were small, non-woody herbs, not the salt and drought- tolerant shrubs that had dominated before the ecological collapse. Despite large parts of Central Asia being very dry today, these shrubs (Nitraria and Ephedra) never again recovered their position of ecological prominence. We still don’t fully understand why, but it shows that populations can be permanently altered by sudden environmental changes even if widespread extinctions don’t occur.

This finding is particularly relevant today, because atmospheric carbon dioxide levels and climate are again changing rapidly. Given what we now know about the Asian steppe-desert’s climatic and ecological history, it is unlikely that these ecosystems will ever recover their present biological diversity if forced into a new state.

History repeats itself

The modern steppe-desert is the largest ecoregion of its kind in the world, hosting a lot more biodiversity than you might expect. Dry-adapted grasses and herbs support an array of wildlife, many of which are endemics (native to, and living only in, that region). These unique flora and fauna have evolved partly as a result of immense geological and climatic diversity: today Central Asia is home to some of the oldest deserts known, as well as the highest mountains outside of the Himalayas.

Flat grassy land with snowy mountains in the background
Meadow steppes in the Qilian Mountains of northern China, surrounded by alpine steppe and tundra. Topographic growth in the Tibetan region over many millions of years has created new high-elevation ecosystems for cold-tolerant biota to thrive. Xiaoming Wang / imaggeo.egu.eu, CC BY-ND

Ancient climate change and geological forces have shaped the steppe-desert through time. The collision of India with Asia, formation of the Tibetan Plateau and uplift of the Himalaya, Altai and Hangay mountain ranges created extreme altitudinal variation, as well as distinct rain shadows of dry land on the downwind side. This generated a mosaic of habitats, and in turn, an astonishing number of species who call the region home.

But now the steppe-desert’s biodiversity is under severe threat from human-induced climate change and land degradation. Growing seas of sand are claiming native steppes, imposing desertification at unprecedented rates. Evidence from the past shows us that this is a sign of impending ecosystem breakdown – and it will cause irreversible changes and loss of biodiversity if allowed to continue.

Claimed by the desert

Desertification in Asia has major implications for humans too. It now threatens almost half a billion people, many of whom are finding it increasingly difficult to make a living in communities dominated by agriculture. Crops are ravaged by drought, livestock are losing grazing pastures, and deserts are growing towards the cities.

Large sand dunes
Sand sea of the Taklimakan Desert. Similarly hyperarid deserts may have spread across Central Asia in the past as a result of rapid climate change. Matthias Alberti / imaggeo.egu.eu

Model predictions from the Intergovernmental Panel on Climate Change (IPCC) and recent climate records show that interior Asia is fast becoming one of the hottest and driest places on the planet. Major predicted changes include highly reduced vegetation cover and rapid, severe species losses, along with more unreliable rainfall and high dust emissions generated by widespread desertification and erosion.

This new hyperarid desert ecosystem phase would resemble the inhospitable, barren landscapes that spread 34 million years ago. Lessons from the past make it clear that current human-induced global changes must be urgently halted in order to preserve the Asian steppe, which has now become one of the world’s most endangered habitats.


This article was originally posted on The Conversation.
Cover photo by Wolfgang Hasselmann on Unsplash.

Drought and heat together menace American West

Drought and heat together menace American West

By Tim Radford

Climate change really is a burning issue. Simultaneous drought and heat are increasingly likely for more of the American West.

LONDON, 13 October, 2020 − The American West is about to get hotter. It is also about to get drier. To make things worse, extremes of heat and of drought will happen more often at the same time.

And to compound the damage, such simultaneous assaults are likely to extend over larger areas and become more intense and more frequent, thanks to climate change driven by profligate use of fossil fuels and other human decisions.

This is not a prediction based on computer simulations of the future. It is already happening, and the story can be traced − according to the journal Science Advances − in the narrative of hot spells and dry weather over the entire contiguous United States for the last 122 years.

Not only have combined hot and dry episodes increased in frequency, they have also grown in size in geographic terms. Where once they happened in confined localities, they now extend over whole regions, such as the entire West Coast, and parts too of the Northeast and the Southeast.

Another Dust Bowl?

“Dry-hot events can cause large fires. Add wind and a source of ignition, and this results in ‘megafires’ like the 2020 fires across the west coast of the United States. Drought and record-breaking heatwaves, coupled with a storm that brought strong winds and 12,000 lightning events in a span of 72 hours, caused more than 500 wildfires,” said Mohammad Reza Alizadeh, of McGill University in Canada, who led the research.

Heat extremes can be damaging or even devastating. So can drought. When the two coincide, their compound impact can be tragic. The study also suggested that in some way such double jeopardy events could be self-propagating: they could spread downwind, seriously bad news for the American West and other areas at risk.

Long before any fears of the climate emergency, the US Midwest was scarred by drought, and in the 1930s Oklahoma and Kansas in particular became a “Dust Bowl” and inspired the classic novel The Grapes of Wrath by the American writer John Steinbeck.

“We observed that concurrent dry and hot events of similar intensity are becoming more frequent,” said Mojtaba Sadegh, an engineer at Boise State University in Idaho, and the senior author.

“Our results point to an urgent need to take action to enhance resilience to compound hot and dry events”

“The difference is that, in the 1930s, lack of precipitation led to the local atmosphere becoming hotter, whereas in recent decades increased temperatures are driving aridity. The triggering mechanism for compound dry-hot events is changing from lack of precipitation to excess heat.”

The warning of worse to come coincides with news that California’s fires have become so bad that they warrant a new classification: the “gigafire”, with so much smoke emitted from the combined fires of California and Oregon that fumes have been detected in New York, in northern Europe, and far into the Pacific.

Researchers have repeatedly warned of the double hazard of heat and drought and the combined impact on the US, as a consequence of climate change driven by greenhouse gas emissions from power station chimneys and automobile exhausts, as well as destruction of the natural wilderness.

“This research raises an alarm about increasing frequency and intensity of compound hot and dry events,” said Dr Sadegh. “Three such events between 2011-2013 in the US caused $60bn (£46bn) in damages. Our results point to an urgent need to take action to enhance resilience to compound hot and dry events.” − Climate News Network


Cover photo by Madu Shesharam on Unsplash.
First ever climate assessment for India region projects intense heat and extreme rainfall

First ever climate assessment for India region projects intense heat and extreme rainfall

By Will Bugler

The first ever regional climate assessment for the India region, to be published later this month, suggests that India must prepare for a hooter climate, characterised by extreme heat and floods. The scientific study projects that  by the end of the century, the average temperature in India will rise by around 4.5˚C, heat waves will 3-4 times more frequent, sea levels will rise by 30 cm and the intensity of tropical cyclones will increase substantially.

The study will be an open access release on July 1st. It looks in detail at the impact of climate change on the regional monsoon, the Indian Ocean and the Himalayas. It also examines the regional climate change projections based on the climate models used by the IPCC Fifth Assessment Report (AR5) and national climate change modelling studies.

The study provides a more detailed assessment of the regional impacts of climate change compared with the global IPCC Assessment reports which are typically published every 6-7 years. The study will provide a detailed analysis of future climate effects over the Indian subcontinent, especially relating to the Indian monsoon and other locally significant climatic phenomena.

Click here to read the report.


Cover photo by Mike Sangma on Unsplash.
3 billion people may face Saharan heat levels by 2070

3 billion people may face Saharan heat levels by 2070

By Tim Radford

If humans go on burning ever more fossil fuels to put ever higher concentrations of greenhouse gases into the atmosphere, then one third of the world’s population may face – within 50 years – heat levels that could be all but intolerable.

By 2070, 19% of the land area of the planet, home to 3.5 billion people, could be faced with a mean annual temperature of 29°C. That is, although there would be seasons in which temperatures fell well below this average, these would be followed by summers in which the thermometer went much higher.

Right now, only 0.8% of the land surface of the planet experiences such a mean annual temperature, and most of this space is located in the Saharan desert region of North Africa. But population growth – already highest in the poorest and hottest parts of the globe – and the projected increases in planetary average temperatures will expand this danger zone to almost one fifth of the planet’s land area, to embrace a third of the world’s people.

The conclusion – published in the Proceedings of the National Academy of Sciences – sounds like a dramatic advance on repeated warnings that planetary average temperatures could be 3°C above the long-term average for almost all of human history. But it may not be.

One important difference is that climate science forecasts tend to describe the entire planet. But almost three fourths of the planet is ocean, which is warming much more slowly than the land surfaces. Another is that climate forecasts predict average change for a sphere with a circumference of 40,000 kms. And the third factor is that such predictions do not specifically address where humans choose to live.

“Our computations show that each degree of warming above present levels corresponds to roughly one billion people falling outside of the climate niche”

Xu Chi of Nanjing University in China and his European co-authors started from the premise that humans – like all animal species – have a preferred climate niche. They looked back through 6000 years of the history of civilisation and concluded that most of humankind flourished within a climate space between annual averages of 11°C and 15°C. A much smaller number of people lived in places where the average temperature was between 20°C and 25°C.

And they found that – although civilisations rose and fell, whole peoples disappeared, wars, plagues and famines struck, and entire populations migrated to or invaded other homes – nearly all of humankind continued to prefer to live in land zones at between 11°C and 15°C.

“This strikingly constant climate niche likely represents fundamental constraints on what humans need to survive and thrive,” said Marten Scheffer of Wageningen University in the Netherlands.

But in the next 50 years, the average temperature experienced by an average human is expected to rise by 7.5°C. And because population growth is highest in the already hottest regions, these temperature rises will affect more and more people.

Warnings mount

By 2070 this total could reach 3.5bn people, across 19% of the planet’s land surface, many of them exposed to temperatures and climate conditions that right now would be considered difficult to survive.

In just the last six or seven weeks, climate scientists have warned that rising temperatures present a direct threat to the natural ecosystems on which human civilisation depends; that the number of days that US farmworkers will find dangerously hot will almost double; that potentially lethal combinations of heat and humidity trailed as a future hazard may already have arrived, in limited locations for brief periods; that some will find more heat brings more extremes of rainfall, while other regions will become increasingly arid; and that South Asia, in particular, is at increasing hazard from ever more extreme temperatures and choking pollution, thanks to global climate change.

But the latest attempt to look at the big picture trumps all of these already bleak findings. As usual, other climate researchers will question their assumptions and challenge their conclusions, but the authors are fairly sure of their ground.

“We were frankly blown away by our initial results,” said Dr Xu. “As our findings were striking, we took an extra year to carefully check all assumptions and computations. We also decided to publish all data and computer codes for transparency and to facilitate follow-up work by others.

“The results are as important to China as they are to any other nation. Clearly we will need a global approach to safeguard our children against the potentially enormous social tensions the projected change could invoke.”

Range of pressures

This also raises issues already repeatedly raised by climate forecasters: the people most threatened by climate change are already among the world’s poorest. So there will be pressure to migrate. And there will be potential for conflict.

What will happen in the next 50 years under circumstances in which governments go on authorising fossil fuel consumption is difficult to predict with any certainty. Communities will to a certain extent adapt. Economic development could help contain some of the challenges. And governments could decide to act.

“The good news is that these impacts can be greatly reduced if humanity succeeds in curbing global warming,” said Tim Lenton, of Exeter University in the UK.

“Our computations show that each degree of warming above present levels corresponds to roughly one billion people falling outside of the climate niche.”


This article was originally posted on the Climate News Network.
Cover photo by Tomáš Malík on Unsplash