New Research Shows Global Warming Could Turn Tropics Into a Sweltering Dead Zone
9
March, 2017
New
research out of Purdue University finds
that a global warming event called the PETM made parts of the
tropics too
hot for living organisms to survive.
And though the PETM happened many millions of years ago, these new
scientific revelations are pertinent to the present day. The reason
is that human activity in the form of fossil fuel burning is now
rapidly causing the globe to heat up. And such warming, if it
continues, could well turn large sections of the tropics into a dead one.
PETM
— Warm-up Sparks Global Upheaval, Extinction
The
PETM was a big global warm up that happened 56 million years ago as
the Paleoceneepoch
passed into the Eocene.
It is numbered as one of many hothouse extinctions occurring in the
geological record. And it is generally thought to have been one of
the milder such events — especially when compared to the biosphere
wrecking ball that was the
Permian.
(NASA
tool shows that business as usual greenhouse gas emissions would
force averagemaximum
July temperatures over large sections of the world to warm to 40-45 C
[104-113 F] by the 2090s. For many regions, such a high degree of
heat is incompatible with crops and human habitability. In the deep
past, hothouse events were found, in recent research, to render large
sections of the tropics uninhabitable to most forms of life. Image
source:NASA.)
During
the PETM, global temperatures jumped by 5 degrees Celsius above an
already warm base-line over the course of about 6,000 years. And
research indicates that the resulting heat stress set
off massive wildfires, forced land animal species to move pole-ward,
and killed off a big chunk of the ocean’s bottom dwelling
foraminifera.
Parts
of the Tropical Biosphere Seem to Have Died
However,
past scientific consensus held that the tropics still managed to
support life during the PETM due to a kind of thermostat-like heat
regulation preventing the equatorial region from becoming too warm.
Temperatures were thought to have remained within a range that would
have continued to support life in this lower latitude zone. So it was
only thought that the tropics experienced die-offs during ancient and
more intense warming events like the Permain of 250 million years
ago.
The
new research by Purdue scientists calls that theory into question.
Their findings show that temperatures crossed a key threshold —
becoming too hot to support life throughout sections of the tropics
and rendering large areas uninhabitable.
Matthew
Huber, professor in the Earth, Atmospheric, and Planetary Sciences
Department at Purdue University and study co-author notes:
“The records produced in this study indicate that when the tropics warmed that last little bit, a threshold was passed and parts of the tropical biosphere seems to have died. This is the first time that we’ve found really good information, in a very detailed way, where we saw major changes in the tropics directly associated with warming past a key threshold in the past 60 million years.”
Half
of Human Population Lives and Farms in the Tropics
During
the present day, about half the human population, a good chunk of the
world’s life forms, and a considerable amount of global farming
occupies the tropics. However, according to
recent research by the Max Planck Institute,
parts of the tropical zone could be rendered basically uninhabitable
to human beings by mid Century as
the Earth heats up due to fossil fuel burning. And already, the
critical region of Equatorial Africa and the adjacent Middle East are
experiencing record droughts, water stress, and instances of hunger,
famine and related food insecurity as global temperatures rise to 1 C
or more above 1880s averages.
(Climate
zone habitability is a function of what forms of life can exist in a
given region at a given range of temperatures. Warming in the tropics
is expected to impact human habitability by mid Century. Warming,
however, is also expected to impact crop yields well into the middle
latitudes. U.S. food production is therefore likely to be negatively
impacted by rising global temperatures. Video source: Peter
Carter.)
The
serious concern is that as the world warms up — a humanitarian
crisis of unprecedented scope could emerge as whole countries become
unable to support their populations. As entire regions become too hot
to live in. And as major swaths of global farmland become
non-productive.
The
present narrative hints that human civilization can somehow adapt by
shifting farm zones northward. However, it’s worth noting that
boreal regions do not support the same highly productive soils as the
tropical and temperate zones that are now under threat due to rising
temperatures. In addition, the nations of the world have thus far
shown considerable reluctance to accepting refugee populations from
destabilized zones. And as the world heats up, desperation will only
increase as waves of refugees seek to remove themselves from what
could well become a kind of global warming produced dead zone.
The
Perdue research underscores a very real risk that we are now facing.
It shows that the tropics did not self regulate temperature in a
range conducive for life during the PETM. And these findings
reinforce present temperature and soil moisture research trends
placing human habitability and crop production under threat due to
fossil fuel based warming this Century.
(UDATED)
Links:
Hat
tip to Suzzanne
Hat
tip to Colorado Bob
Hat
tip to Andy in San Diego
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