HISTORY OF CLIMATE SCIENCE: LESSONS UNLEARNED

Three years ago Carl Sagan and a few other scientists proposed a new theory of Armageddon. 

They called it "nuclear winter,"and their message was chilling.

The end  of  the  world,  they  said, would come not by fire during a nuclear attack but by ice afterward

After a nuclear war, the Earth would become encircled with smoke, dark, and cold. No one could  expect to survive the frost, not the innocent New Zealanders or the remotest tribes of  Africa. Even a small atomic  war  could  end  human  life , Sagan  concluded  in  the  Winter 1983-84  issue of Foreign Affairs  that  all  nuclear weapons should  be eliminated, or at least 99 percent of them.

This insight did not come from a rereading of the book of Revelation, It rested on modern physics and a very sophisticated computer program. It had the glint of hard science. 

Sagan, who is an expert on the solar system and an adviser to NASA on the Voyager space probe, may be America's most famous popularizer of science.  In  1983  several  other  scientists,  including  biologist  Paul Ehrlich  of  Stanford,  joined  Sagan  to  endorse  the view  that  nuclear weapons  were  a  threat to  the  human species, quite  apart  from the obvious threat to civilized life north of the equator.  They launched a media blitz that included heavy technical articles, political essays, and TV interviews.  It  still  reverberates  through  literature.

The message was always the same:

 scientific analysis "proves" that nuclear

weapons are useless. To employ them is

to commit global suicide. Even owning

them is dangerous because it increases

The best thing to do is to get rid of them.
This message came nine months after 
Reagan's "Star Wars" speech,  matching
his technician's dream  with a technician's 
nightmare of equal force.

The nuclear winter theorists wanted

publicity back then, and they got it.

But now the situation has changed.

The death-by-ice theory seems moribund,

riddled with problems, and of diminishing
relevance to strategic policy. The same can
be said of  Reagan's idea  of  using  space 
weapons to protect cities.

The main technical challenge to nuclear

winter comes from Stephen Schneider

and Starley Thompson, researchers at

the National Center for Atmospheric 
Research in Boulder, Colorado. They agree

with Sagan that the number of nuclear

weapons should be reduced, but they

say the integrity of atmospheric science

should not be sacrificed to make that

point. 

Schneider claims that it has been

clear for perhaps two years that Sagan's

original description of nuclear winter is

not the most accurate. But coaxing has

not brought any acknowledgment that

this is so. Sagan said recently that he

found "nothing new" in a state-of-theart

computer analysis by Schneider and

Thompson to change his view of

Armageddon.

Schneider and Thompson laid out

their doubts in a Foreign Affairs article last

summer, reporting that the chance of

human extinction after a nuclear war is

"vanishingly low," They find no risk of

a new ice age. Some open, dry areas in

the war latitudes might undergo temporary

"quick freezes," But, on average,

the temperature drop in the Northern

Hemisphere would not be worse than 12

degrees during the first week or so after

an attack.

At a private gathering of experts at the

National Academy of Sciences in January,

it became clear that this new mild

version of "nuclear autumn" is credible

and may even overstate the temperature

drop. This does not mean the climatic

impacts of war would be mild, Schneider

and Thompson say that rice and soybeans

are sensitive to small temperature

changes and that global rainfall patterns

might be disrupted. Millions (billions?)

might starve. But there would be no ice

in the tropics; that is certain. Schneider

says: "Carl's idea was brilliant. He proposed

an invasion from Mars," It just

didn't hold up under scrutiny.

The more apocalyptic version of nuclear

winter has become a part of the

anti-weapons dogma of the 1980s, As a

result, some people may be reluctant to

let it go. Others will delight in its agonies...

Although Schneider's milder scenario

has more credibility today, the technical

argument has a long way to run.

This is because the Pentagon has been

cajoled into taking nuclear winter seriously.

The Defense and Energy Departments

have increased research on nuclear winter

from around $300,000 a few years ago
to around $5.5 million now. It is embedded
in the budget. The amount is nothing like 
the $5 billion spent on the other millennial
fancy of  the 1980s, "Star Wars," and not

enough—the vested researchers  say—to

provide definitive answers to the questions

Sagan has raised.

But even without definitive answers,

it may be time to say goodbye to nuclear

winter as a policy issue. If Schneider and

Thompson are right, and atmospheric

scientists seem to think they are, the climatic

impact is just one of a dozen "secondary

effects" of nuclear war that would make 
life hardly worth living.

The main policy debate will continue to

focus on the "primary" effect: the use of

weapons. In this sense, nuclear winter

was a diversion, providing little insight

on how to cooperate on arms reductions,

an area rife with distrust.

The freeze movement may have gained

a tactical victory through the promotion

of nuclear winter. It helped get attention.

But the advantage appears to have been

short-lived. Now, as the computer termites

gnaw at the data, the structure creaks and

totters. Soon it may be gone.

Perhaps if we are lucky, 1987 will bring

the final debunking of two great science

fictions of the Reagan era: nuclear winter

and Star Wars.

Thanks to Eliot Marshall for  providing the pdf from which this was excerpted- 

Copyright 1987 , The New Republic

Some of the true believers are still  re-running the TTAPS models parameters and deny that anything much went wrong :
http://www.nature.com/nature/journal/v475/n7354/full/475037b.html?foxtrotcallback=true