8 Scientific American, October 2020LETTERS
[email protected]CALCULATING CATASTROPHE
“What Should Carbon Cost?” by Gilbert E.
Metcalf, is unsuccessful in answering the
question of how to calculate the most ap-
propriate carbon tax rate. The uncertain-
ties are too great. And probable impacts
of climate change are beyond the scale of
usual economic analyses. The use of inte-
grated assessment models (IAMs) to cal-
culate climate damage is like employing
Newtonian physics to analyze phenome-
na far outside its range of applicability.
Metcalf states that “the richer future
generations are compared to us, the less
we should feel compelled to incur costs
now to make them better off. That leans
toward a high discount rate.” But it is quite
possible that future generations will be
poorer than us as a result of the climate
change that is already baked into current
atmospheric carbon dioxide—and because
perpetual economic growth is not sustain-
able. If so, ethical and economic consider-
ations suggest a negative discount rate.
Further, Metcalf mentions “low-proba-
bility, high-damage” catastrophes such as
runaway heating caused by thawing perma-
frost. There is much uncertainty about such
events. But “uncertainty” is different from
“low probability.” Their probability may be
high with the surprising six-degree-Celsius
increase in economist William D. Nord-
haus’s cited analysis—three times the limit
recommended by climate scientists.
Dick Walton Billings, Mont.
METCALF REPLIES: Economist Frank
Ramsey’s rule states that the richer future
generations are, the higher the discount
rate. Walton is correct that the poorer they
are, the lower that rate should be. But
2,000 years of history suggest our best es-
timate is of rising economic well-being go-
ing forward. As for permafrost melting,
the probability may be high if we fail to
reduce emissions, but the ultimate dam-
ages after accounting for unforeseen feed-
backs still involve considerable uncer-
tainty. The larger point, however, is that
the possibility of catastrophes compli-
cates measuring the social cost of carbon.DEATH ON THE BRAIN
In “Tales of the Dying Brain,” Christof Koch
describes near-death and out-of-body ex-
periences in humans. He does not mention
nonhuman animals, however.
Many animal species, vertebrate and in-
vertebrate, exhibit a temporary deathlike
state called thanatosis, or tonic immobili-
ty, when confronted or physically touched
by predators. Physically, vertebrates exhib-
it reduced respiratory rate, bradycardia
and hypotension. Recovery takes at least
minutes after the threat is removed.
Does tonic immobility relate to human
near-death experiences?
Bernd Esche via e-mailKoch’s article reminded me of a comment
by a Baptist minister who had attended
many bedside deaths. He related the sto-
ry of one individual who, on his deathbed,
saw glimpses of heaven and called out,
“They are all there,” naming deceased
members of his family. When the minister
was asked about this near-death experi-
ence, his response surprised and pleasedme. He said he believed that such an ex-
perience of heaven was whatever the dy-
ing person believed heaven would be.
Jean Howard via e-mailKOCH REPLIES: In response to Esche: the
possibility of animals having near-death
experiences (albeit shorn of their cultural
context) during thanatosis is fascinating.
Death feigning may indeed trigger such a
state. The methodological challenge would
be to train animals to subsequently report
something about their internal condi-
tion—say, by pressing levers or some oth-
er simple motor behavior—in a way ac-
cessible to an external, trained observer.
Howard reports a wise comment by a
Baptist minister. To me, this astute obser-
vation—that people from different faiths
and cultures experience their own idio-
syncratic heaven and hell—argues against
the hypothesis that near-death experienc-
es reveal a single, universal truth about
the hereafter. Instead everyone seems to be
granted a very different vision of an after-
life that is formed by their own expecta-
tions and upbringing.UNHEEDED WARNING
Ben Santer does a very good overview of
our nation’s current president in “Failure
to Lead” [Forum]. He does leave out one
very important occurrence, however: Don-
ald Trump’s trade adviser circulated a
memo, dated January 29, 2020, that
warned the West Wing that the coronavi-
rus was coming and would be a pandem-
ic. Of course, history is rife with moments
in which disasters would have been less-
ened or stopped if leaders had listened to
their subordinates.
Ralph Kundtz, Jr. Akron, OhioCOVID-19 ANTIBODIES
In “The Vaccine Quest,” Charles Schmidt
describes the new DNA and RNA tech-
niques being pursued for a speedy vaccine
for the novel coronavirus SARS-CoV-2. The
article left me with a nagging question
about possible side effects: With these
methods, once your cells make virus anti-
gens, do they not display them on their
surface—akin to waving a red cape at a
bull? Could a vaccine thus cause your an-
tibodies to savage your own cells?
I cannot help but think of the 1966 sci-June 2020“ History is rife with
moments in which
disasters would have
been lessened or
stopped if leaders
had listened to their
subordinates.”
ralph kundtz, jr. akron, ohio© 2020 Scientific American