To be rational is to know that weather events cannot
be causally related to climate change, although exacerbation is another
issue. Yet when the news is full of record-setting fires in California
and Greece and Australia, temperature records tumbling, and typhoons
and hurricanes relentless in their intensity, one might be forgiven for
wondering.
Those who are not climate scientists can only interpret research done by others for the general public and form opinions colored by their work. That sum of work as it develops becomes more frightening by the day, with a strong fear the predictions will come true earlier than anticipated.
Now
there is new climate research on the troposphere, a region extending from the
surface of the earth to 16 km (10 miles) at the tropics and 13 km at the
poles. Researchers have studied the amplitudes of the annual cycle of
tropospheric temperatures, the highs and the lows, and how these have
changed over time. Above all, they have examined human agency.
The news, as they say, is not good. Their results, the authors state, "provide powerful and novel evidence for a statistically significant human effect on earth's climate." They call it 'anthropogenic forcing'.
As
a consequence we have "pronounced midlatitude increases in annual cycle
amplitudes in both hemispheres." These are repeated in satellite data.
It means higher tropospheric temperatures in summer and lower in winter.
Not
only is there "seasonality in some of the climate feedbacks triggered
by external forcings" (read human fingerprint), say the authors, but worse, "there are
widespread signals of seasonal changes in the distribution and abundance
of plant and animal species." In other words, we are screwing up wildlife, both plant and animal.
It is as if the air in the earth's attic is warmer in summer and colder in winter. And its air conditioner, the tropical rainforest, is on the blink. Greed for hardwoods and farmland has resulted in serious depletion.
Meanwhile, carbon-dioxide levels continue to soar, exceeding 412 ppm on May 14, 2018. The last time the earth reached a 400-ppm threshold was several million years ago.
The human footprint here is proven through the negative delta-13C
levels caused by fossil-fuel use because plants are lacking in the 13C isotope of carbon. Combining the CO2 rise with
increasing tropospheric temperature cycle amplitudes can only magnify the
problem. A new report in the Proceedings of the U.S. National Academy of Sciences lays out a scenario for a self-reinforcing feedback loop, a 'hothouse earth' at which point no human action could prevent catastrophe.
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