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https://thebulletin.org/2024/08/desertification-was-supposed-to-be-the-greatest-environmental-challenge-of-our-time-why-are-experts-now-worried-about-greening/>
"Southeast Australia has been getting hotter and drier. Droughts have
lengthened, and temperatures regularly soar above 95 degrees F (35 degrees C).
Bush fires abound. But somehow, its woodlands keep growing. One of the more
extreme and volatile ecosystems on the planet is defying meteorology and
becoming greener.
And Australia is far from alone. From Africa’s Sahel to arid western India, and
the deserts of northern China to southern Africa, the story is the same.
“Greening is happening in most of the drylands globally, despite increasing
aridity,” says Jason Evans, a water-cycle researcher at the Climate Change
Research Centre of the University of New South Wales in Sydney, Australia.
What is going on? The primary reason, most recent studies conclude, is the
50-percent rise in carbon dioxide concentrations in the atmosphere since
preindustrial times. This increased CO₂ is not just driving climate change, but
also fast-tracking photosynthesis in plants. By allowing them to use scarce
water more efficiently, the CO₂-rich air fertilizes vegetation growth in even
some of the driest places.
As we pump yet more CO₂ into the air, arid-land greening seems set to continue,
according to two recent modeling studies. But ecologists warn that, despite
appearances, going green may have downsides for arid ecosystems and for the
people who depend on them. Desert plants and animals will often lose out, and
the extra vegetation may soak up scarce water supplies.
Drylands cover roughly 40 percent of the planet’s land surface. The deserts at
their core are surrounded by wide expanses of savanna grass, dry woodlands, and
sometimes irrigated fields. They are home to more than a third of the world’s
population and are among the most biodiverse ecosystems in the world, according
to the International Union for Conservation of Nature, the international
organization for conservation scientists.
Over the past half-century, most drylands have been experiencing a decline in
rainfall, along with higher temperatures and greater rates of evaporation. Many
have also been degraded by poor farming practices and overgrazing of livestock.
Climate scientists and ecologists alike have until recently presumed that this
combination of growing meteorological aridity and pressure from human
activities would lead to less vegetation. They have routinely warned of
widespread desertification, which U.N. officials have called “the greatest
environmental challenge of our time.”
Yet in most drylands, this anticipated desertification has not happened. Rather
than shriveling and dying, vegetation is usually growing faster and expanding
its terrain, while deserts are retreating. This, researchers of the world’s
carbon and water cycles say, is largely due to the extra CO₂ in the
atmosphere."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
