(1)Re: [pf] Time Cover Article on Global Warming

At 07:46 6/4/2001 +1200, Molly Williams sent to PF:
>
>http://www.time.com/time/magazine/article/0,9171,104617,00.html
>
· I sent these two posts to GreenViews-NZ a few minutes ago.

· This _part_1_ is my selection from the main article (very slightly
edited, e.g. inserting "a metre" instead of "3 feet").

· This TIME cover article contains:
  "In the short run, there's not much chance of halting global warming, not
even if every nation in the world ratifies the Kyoto Protocol tomorrow. The
treaty doesn't require reductions in carbon dioxide emissions until 2008.
By that time, a great deal of damage will already have been done. But we
can slow things down."   D.

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http://www.time.com/time/magazine/printout/0,8816,104617,00.html
  has:

Thursday, April 5, 2001 

Life In The Greenhouse 

BY MICHAEL D. LEMONICK

 ... [T]he only reliable signal that such changes [as going into and out of
ice-ages] may be in the works is a long-term shift in worldwide temperature. 

And that is precisely what's happening. A decade ago, ... evidence that the
climate was actually getting hotter was still murky.

Not anymore. As an authoritative report issued a few weeks ago by the
U.N.-sponsored Intergovernmental Panel on Climate Change makes plain, the
trend toward a warmer world has unquestionably begun. Worldwide
temperatures have already climbed more than 1 degree F over the past
century, and the 1990s were the hottest decade on record. After analyzing
data going back _at_least_ two decades on everything from air and ocean
temperatures to the spread and retreat of wildlife, the IPCC asserts that
this slow but steady warming has had an impact on no fewer than 420
physical processes and animal and plant species on all continents.
 ...

Measuring the warming that has already taken place is relatively simple;
the trick is unraveling the causes and projecting what will happen over the
next century. To do that, IPCC scientists fed a wide range of scenarios
involving varying estimates of population and economic growth, changes in
technology and other factors into computers. That process gave them about
35 estimates, ranging from 6 billion to 35 billion tons, of how much excess
carbon dioxide will enter the atmosphere. 

Then they loaded those estimates into the even larger, more powerful
computer programs that attempt to model the planet's climate. Because no
one climate model is considered definitive, they used seven different
versions, which yielded 235 independent predictions of global temperature
increase. That's where the range of 1.4 C to 5.8 C (or: 2.5 F to 10.4 F)
comes from.

The computer models were criticized in the past largely because the climate
is so complex that the limited hardware and software of even a half-decade
ago couldn't do an adequate simulation. Today's climate models, however,
are able to take into account the heat-trapping effects not just of CO2 but
also of other greenhouse gases, including methane. They can also factor in
natural variations in the sun's energy and the effect of substances like
dust from volcanic eruptions and particulate matter spewed from smokestacks. 

That is one reason the latest IPCC predictions for temperature increase are
higher than they were five years ago. 
 ...
[I]t took only a 9 F shift to end the last ice age. Even at the low end,
the changes could be problematic enough, with storms getting more frequent
and intense, droughts more pronounced, coastal areas ever more severely
eroded by rising seas, rainfall scarcer on agricultural land and ecosystems
thrown out of balance.

But if the rise is significantly larger, the result could be disastrous.
With seas rising as much as a metre (3 ft.), enormous areas of densely
populated land--coastal Florida, much of Louisiana, the Nile Delta, the
Maldives, Bangladesh--would become uninhabitable. Entire climatic zones
might shift dramatically, making central Canada look more like central
Illinois, Georgia more like Guatemala. Agriculture would be thrown into
turmoil. Hundreds of millions of people would have to migrate out of
unlivable regions.
 ...

The models still aren't perfect. One major flaw, agree critics and
champions alike, is that they don't adequately account for clouds. In a
warmer world, more water will evaporate from the oceans and presumably form
more clouds. If they are billowy cumulus clouds, they will tend to shade
the planet and slow down warming; if they are high, feathery cirrus clouds,
they will trap even more heat. 

Research by M.I.T. atmospheric scientist Richard Lindzen suggests that
warming will tend to make cirrus clouds go away. Another critic, John
Christy of the University of Alabama in Huntsville, says that while the
models reproduce the current climate in a general way, they fail to get
right the amount of warming at different levels in the atmosphere. Neither
Lindzen nor Christy (both IPCC authors) doubts, however, that humans are
influencing the climate. But they question how much--and how high
temperatures will go. Both scientists are distressed that only the most
extreme scenarios, based on huge population growth and the maximum use of
dirty fuels like coal, have made headlines.

It won't take the greatest extremes of warming to make life uncomfortable
for large numbers of people. Even slightly higher temperatures in regions
that are already drought- or flood-prone would exacerbate those conditions.
In temperate zones, warmth and increased CO2 would make some crops
flourish--at first. But beyond 3 F of warming, says Bill Easterling, a
professor of geography and agronomy at Penn State and a lead author of the
IPCC report, "there would be a dramatic turning point. U.S. crop yields
would start to decline rapidly." In the tropics, where crops are already at
the limit of their temperature range, the decrease would start right away.

Even if temperatures rise only moderately, some scientists fear, the
climate would reach a "tipping point"--a point at which even a tiny
additional increase would throw the system into violent change. If peat
bogs and Arctic permafrost warm enough to start releasing the methane
stored within them, for example, that potent greenhouse gas would suddenly
accelerate the heat-trapping process. 

By contrast, if melting ice caps dilute the salt content of the sea, major
ocean currents like the Gulf Stream could slow or even stop, and so would
their warming effects on northern regions. 
 ...
The IPCC's calculations end with the year 2100, but the warming won't.
World Bank chief scientist, Robert Watson, currently serving as IPCC chair,
points out that the CO2 entering the atmosphere today will be there for a
century. Says Watson: "If we stabilize [CO2 emissions] now, the
concentration will continue to go up for hundreds of years. Temperatures
will rise over that time."

That could be truly catastrophic. The ongoing disruption of ecosystems and
weather patterns would be bad enough. But if temperatures reach the IPCC's
worst-case levels and stay there for as long as 1,000 years, says Michael
Oppenheimer, chief scientist at Environmental Defense, vast ice sheets in
Greenland and Antarctica could melt, raising sea level more than 10 metres
(30 ft). Florida would be history, and every city on the U.S. Eastern
seaboard would be inundated.

In the short run, there's not much chance of halting global warming, not
even if every nation in the world ratifies the Kyoto Protocol tomorrow. The
treaty doesn't require reductions in carbon dioxide emissions until 2008.
By that time, a great deal of damage will already have been done. But we
can slow things down. If action today can keep the climate from eventually
reaching an unstable tipping point or can finally begin to reverse the
warming trend a century from now, the effort would hardly be futile.
Humanity embarked unknowingly on the dangerous experiment of tinkering with
the climate of our planet. Now that we know what we're doing, it would be
utterly foolish to continue.

REPORTED BY DAVID BJERKLIE, ROBERT H. BOYLE AND ANDREA DORFMAN/NEW YORK AND
DICK THOMPSON/WASHINGTON

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sent to Pos Fut by David.
(David MacClement) davd@ihug.co.nz 
http://www.geocities.com/davd.geo/index.html#top
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