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December 12, 2017
Is Climate Change Driving the Demise of the Koala?
By Arshad M. Khan
The koala is an engaging, docile, cuddly and lovable animal. It is also, tragically,
undergoing a decline in numbers. To the extent climate change and a degraded
environment are responsible, we can be blamed for not heeding the repeated
warnings of scientists and others.
Warnings to humanity are much in the news again as the latest, signed by over
15,000 scientists from 184 countries, appeared in the journal Bioscience not long ago
on November 13. But before, much before, there was an earlier one, now a quarter
The late Henry Kendall was the winner of a Nobel Prize in physics, a founding member
of the Union of Concerned Scientists, and the chairman of its governing board. He
spearheaded the effort leading to the 1992 warning signed by 1700 eminent
scientists, including then a majority of science Nobel Laureates. It appealed for the
help of the world’s peoples, its scientists, religious, industrial and business leaders.
Earlier still, there was Rachel Carson’s 1962 canary in the coal mine, The Silent
Spring, famous for its attack on pesticides like DDT.
While these warnings caution us on the degradation of our planet, there is one area
that might be implied but is not specifically mentioned: the negative impact on the
quality of our food. Noted first by Irakli Loladze, the relatively new discovery was
hypothesized in 2002.
In the parts of the world relying on a plant-based diet, people cannot easily
compensate for the loss of nutrients. The proven decline of protein, iron and zinc in
grains, potatoes and vegetables will inevitably lead to stunted growth, anemia and
This distressing and unhappy prospect is not confined to humans. Bees rely on the
goldenrod plant. It flowers late, and the protein in its pollen is vitally important for
them to build themselves up to weather the winter. Unfortunately, as scientists have
learned, the protein content in goldenrod has suffered a drastic loss of about a third
as atmospheric CO2 levels have increased. There may be other causes like
pesticides and parasitic mites but lack of nutrition has to be a major candidate.
On the other side of the world lives the harmless Koala bear. A marsupial, it is truly
unique for feeding only on eucalyptus leaves. Most unusually the female has three
vaginas, the outer two leading each to a separate uterus while the center passage is
for delivery of its young. To complement this anatomy, the male is endowed with a
Many causes are attributed to the serious drop in koala bear numbers, including
habitat destruction, road kills, bush fires and loss of genetic fitness due to inbreeding,
but also chlamydia. This STD has found a fertile field in its complicated genetic
apparatus, aided possibly by weakened immunity. In some places infection rates are
as high as 90 percent. Sadly, the little joeys pick it up suckling in their pouch.
Moreover, the infection can also leave mothers infertile.
Now a new threat has been identified leaving them on the brink. The koalas source of
all nourishment, the eucalyptus tree, has been affected by increasing CO2 levels.
The koalas rely on the mildly toxic leaves for food and water and up to now have been
able to tolerate the toxicity — they sleep up to 20 hours to work it out. But the rise in
CO2 has decreased nutrition content leaving them more poisonous. Feeding on
these, the koalas are ingesting ever more poison. Worse, the Australian drought,
blamed on global warming for its intensity, has left the leaves with reduced moisture
content. The stresses have left the koalas dying from kidney failure.
How long before they are added to the ever-increasing endangered list? Unless the
world really sits up and takes notice, we will be soon adding our pollinator bee friends
and, eventually, ourselves to that list. It is what we have in common.
Arshad M. Khan is a former professor who has, over many years, written occasionally
for the print and often for online media outlets.