Global population hit by extreme drought set to double

The drought affecting the Cerro Lake, allegedly polluted by chemical disposals from a tannery located on its banks, is visible on October 19, 2020, in Limpio, 25 km northeast of Asuncion, Paraguay. (Photo by Norberto DUARTE / AFP)


by Marlowe HOOD
Agence France Presse

PARIS, France (AFP) — Available freshwater is on track to decline sharply across two-thirds of Earth’s land surface toward the end of the century mostly due to climate change, with the number of people exposed to extreme drought doubling, researchers have reported.

Even under a scenario of moderate decline in greenhouse gas emissions, land area scorched by extreme to exceptional drought conditions increases from three to seven percent, while the population at risk jumps from 230 million to about 500 million, they reported Monday in Nature Climate Change.

Projected shortfalls of water were “especially alarming” in Amazon River basin, Australia, southern Africa, the Mediterranean region, and parts of the United States, lead author Yadu Pokhrel of Michigan State University told AFP.

Globally, one in 12 people could face severe water shortages every year by 2100, compared to an average of about one in 33 at the end of the 20th century.

Yemenis fill their jerrycans carried by donkeys, with water from a cistern at a make-shift camp for the internally displaced, in the northern Hajjah province, on June 7, 2020, amid a severe shortage of water. (Photo by ESSA AHMED / AFP)

“These declines in water storage and increases in future droughts are primarily driven by climate change, not land-water management activities such as irrigation and groundwater pumping,” Pokhrel said.

Humanity has been stalked by the deadly spectre of drought long before carbon emissions from burning fossil fuel caused global warming.

But observational data on Earth and from satellites has left no doubt that climate change is boosting their duration and intensity.

The possible consequences came sharply into view when reservoirs supplying Cape Town, South Africa — a city of 3.7 million — ran dry in early 2018 after a multi-year drought, giving rise to the term “Day Zero” when water runs out.

A picture taken on August 28, 2019, in the Western Cape Province near Swellendam shows sheep grazing in a field. – Drought, climate change, economic downturn, security issues in rural areas, and uncertainty about the future of land reform in South Africa, are making agriculture in South Africa an increasingly challenging environment. (Photo by RODGER BOSCH / AFP)

Global warming to date — just over one degree Celsius since the mid-19th century — enhances the likelihood of such droughts around Cape Town by a factor of three, earlier research has shown.

– GRACE satellite data –
Allowing temperatures to increase another degree to 2C above pre-industrial levels would triple the risk again.

Mexico City is currently facing a water crisis, and California has been coping with a lack of rain for most of the last decade.

THOREAU, NEW MEXICO – JUNE 06: A dried out lake stands near the Navajo Nation town of Thoreau on June 06, 2019 in Thoreau, New Mexico. Due to disputed water rights and other factors, up to 40 percent of Navajo Nation households dont have clean running water and are forced to rely on weekly and daily visits to water pumps. The problem for the Navajo Nation, a population of over 200,000 and the largest federally-recognized sovereign tribe in the U.S., is so significant that generations of families have never experienced indoor plumbing. Rising temperatures associated with global warming have worsened drought conditions on their lands over recent decades. The reservation consists of a 27,000-square-mile area of desert and high plains in New Mexico, southern Utah and Arizona. The Navajo Water Project, a nonprofit from the water advocacy group Dig Deep, has been working on Navajo lands in New Mexico since 2013 funding a mobile water delivery truck and digging and installing water tanks to individual homes. Spencer Platt/Getty Images/AFP

“There are growing concerns that many regions of the world will face water crises like these in the coming decades,” Pokhrel and colleague Farshid Felfelani said in a commentary published in The Conversation.

Pokhrel and an international team of two dozen hydrologists and engineers calculated for the first time the future impact of climate change on so-called terrestrial water storage (TWS), which is the total of all water stored or available on land.

Earlier projections of drought and changes in water availability have been based mostly on river flows, and only provide a partial picture.

“Understanding the risks ahead requires looking at the entire landscape of terrestrial water storage — not just rivers, but also water stored in soils, groundwater, snowpack, forest canopies, wetlands, lakes and reservoirs,” Pokhrel explained.

The researchers used a basket of hydrological models along with terrestrial water storage data from NASA’s twin Gravity Recovery and Climate Experiment (GRACE) satellites, which operated for 15 years up to 2017.

To assess the impact of climate change, the scientists ran the data through two climate scenarios from the UN’s Intergovernmental Panel on Climate Change (IPCC).

This handout picture obtained from the European Space Agency (ESA) on August 7, 2018 shows a view taken by German astronaut and geophysicist Alexander Gerst, showing drought affected areas across Germany and Central-Europe as seen from the International Space Station on August 6, 2018. (Photo by Alexander GERST / EUROPEAN SPACE AGENCY / AFP) 

One assumes that humanity ratchets down CO2 and methane emissions enough to cap global warming below two degrees Celsius, in line with the 2015 Paris Agreement. The other assumes a slower reduction in carbon pollution.

Under the first, more optimistic scenario, moderate to severe droughts increase to mid-century and then stabilise. Very extreme water-shortage droughts, however, continue to escalate in frequency.

Under the second scenario, known as RCP6.0, “people living under extreme and exceptional droughts could more than double by 2100, increasing from three percent in the recent past to eight percent,” said Pokhrel.

© Agence France-Presse