Global warming...get yer beachfront property in New mexico now..

[Guest guest]

http://www.oriononline.org/pages/om/05-1om/deMenocal.html

 

AS A GROUP, CLIMATE SCIENTISTS are reluctant to claim even the

soundest projections as incontrovertible facts. The climate system is

by definition exceedingly complex, and theories must always be open

to revision as new observations become available. When I was a

graduate student we learned that the warming that defined the end of

an ice age occurred very gradually, over the course of many thousands

of years. This view of sluggish climate changes was shattered about

ten years ago when scientists discovered that the main warming events

that ended the last ice age took place within less than a decade. In

Greenland, air temperatures warmed by about fifteen degrees

centigrade within the time it takes to complete a college degree.

 

Still, most climate scientists today agree that Earth's climate is

warming and changing as a result of human activity, and that the

projected changes in coming decades will affect nearly all parts of

the globe. This combination of exceptional risk and uncertainty has

led to a lack of clear consensus among policy makers on how to

address the global warming crisis. National-level planning and

preparation for current and future climate change remain mired in

dysfunction and polarized along a scientific/political divide. There

are those who are convinced that there is a big problem and those who

would make the case that there is no problem at all. A path of least

resistance has led to a cul-de-sac of inaction.

 

 

The divide between science and policy is marked by the fundamentally

different motivations, accountability, and time frames that

characterize the players. Scientists are generally motivated by

intellectual curiosity and achievement; they are accountable mainly

to their profession; and they have open time frames in which to

produce results.

 

 

Politicians, on the other hand, are generally motivated by the need

for conflict resolution and political viability. They are accountable

to their constituents and have very restricted time frames in which

to produce results. Global warming is of far larger scope than any

single administration can address, and effective policy demands a

decades-long, committed, political response.

 

 

To complicate matters, political solutions to global warming call for

critical decisions based on imperfect observations and seemingly

nebulous risks, in contrast to problems like world hunger or AIDS,

for which the evidence and consequences are all too apparent.

Consequently, few American politicians have had the courage to take

on the issue. Given the short-term economic costs and the perceived

lifestyle changes required, addressing the problem of global warming

is a platform perfectly ill-suited to election or re-election.

 

 

 

 

WITH THE START of the Industrial Revolution, humankind began a vast

global climate experiment of which we are only now realizing the

effects. Combustion of fossil fuels, burning, and land-use changes

have led to a nearly 34 percent increase in atmospheric carbon

dioxide (CO2), reaching the highest levels in four hundred thousand

years, and a nearly 150 percent increase in methane, both greenhouse

gases that warm the planet.

 

Global Warming Trendiness

 

A study released last August by the National Academy of Sciences

projects that Los Angeles summertime temperatures could increase by

as much as 15 degrees in coming decades, putting its climate on par

with that of Death Valley.

 

The same study showed reductions in the Sierra Nevada snow pack of 73

to 90 percent, " resulting in disrupted water supplies... to the

Central Valley, " with devastating consequences for wine, milk

production, and agriculture in the region.

 

China's industrial output -- and its contribution to global warming --

has doubled in the past five years due in large part to the American

appetite for cheap goods.

 

Europe, Japan, and North America, with 15 percent of the world's

population, account for 66 percent of all carbon dioxide emissions.

The United States alone contributes 24 percent.

 

The World Health Organization estimates that global warming causes

150,000 deaths each year.

 

In the past six years, as many as 3,000 farmers in the Anantapur

region of India have committed suicide as their wells dried up and

they fell behind in debt payments.

 

At the December, 2004 U.N. summit on the Kyoto Protocol in Buenos

Aires, the U.S. delegation spent its capital trying to convince

delegates to change the phrase " global warming " to " climate

variability " in all official documents.

 

 

 

 

Over the last 150 years the Earth's surface temperatures have risen

by about 0.8 degrees centigrade, with the majority of the rise taking

place in just the last fifty years. A true though seemingly

improbable statistic is that all of the ten warmest years on record

have occurred since 1990.

 

The warming we've experienced so far may not seem like much, but it

is just the beginning of a steadily upward trend that is expected to

reach between 1.4°C and 5.8°C by the end of this century when CO2

levels will have more than doubled. The Earth hasn't seen such high

CO2 levels for over 25 million years, and it was then a very

different place: London had groves of palm trees, and crocodiles

nested in the swamps of a warm and humid Canadian arctic.

 

 

Current projections indicate that if nothing is done to slow

greenhouse gas emissions, rising global temperatures will produce a

wide range of climate impacts. Large-scale changes in rainfall

patterns and growing seasons are predicted, as are more intense and

frequent storms, typhoons, and hurricanes. Higher frequencies of

extreme weather events may also occur, with record temperatures and

high heat-index days, like the August 2003 heat wave across Europe

that claimed thousands of lives. Sea levels are predicted to continue

to rise (perhaps by as much as one meter by 2100), an especially

pernicious risk since roughly half of the world's population lives

within sixty miles of an ocean. In addition to causing the loss of

productive land in highly populated coastal regions such as

Bangladesh, rising seas would force the relocation of tens or

hundreds of millions of people and lead to a refugee crisis of

unprecedented scope.

 

 

Perhaps one of the greatest challenges to society, however, and one

often overlooked, is the likelihood of drought events more severe

than any we have experienced. The continental interiors, home to the

breadbaskets of North America and Eurasia, are projected to become

markedly drier in future decades, leading to a greater frequency of

protracted regional drought. How a modern, urbanized society of today

might respond to a period of pervasive, extended drought is yet to be

seen, but climate history may offer some lessons in at least

understanding the effects of this aspect of our climatically

uncertain future.

 

 

 

 

 

FOR ALL ITS DEVASTATION, the Dust Bowl of the 1930s -- one of the

most well-documented agricultural, economic, and social disasters in

the history of the United States -- was the result of a merely " above

average " drought. But in a rare display of unanimity the scientific

community has determined that this is not the type of drought we need

to prepare for today. Cardinal among the climate risks presented,

under numerous scenarios, by global warming, is the higher

probability of " megadroughts. " A megadrought is a very different

beast in that it persists for many decades, not just a few years, and

affects broad sectors of whole continents. Though we have no modern

instrumental records of past megadroughts, there is very good

scientific evidence that vast regions of North America witnessed

several such periods during the last millennium, with devastating

cultural consequences.

 

Paleoclimatology, the branch of science to which I belong, involves

the reconstruction of ancient climatic conditions using evidence such

as tree rings, lake and ocean sediment records, and ice cores. Our

particular corner of science affords us a different view of climate

change than that available to scientists who, for example, examine

historical (recorded) climate changes. Such records extend back only

a century or two. But by comparing paleoclimate evidence of climate

changes to archeological records of cultural changes, we have been

able to learn a great deal about the broader social impacts of

exceptionally large changes in climate.

 

The history of the Maya culture in Central America provides possibly

the best example of how an extended drought can impact a highly

developed, technologically advanced urban society. The Maya had

thrived for nearly two thousand years and their cultural achievements

were comparable in many ways to those of any modern G-8 nation. They

were accomplished astronomers, mathematicians, and urban planners.

They built large, well-engineered cities and had established trade

networks. Their society was stratified, closely governed, and

populous, with an estimated eight to fifteen million people in cities

and rural villages across Central America and the Yucatán Peninsula.

 

 

This thriving civilization collapsed at the peak of its cultural and

scientific development, between 750 and 950 a.d., and the decline

coincided precisely with a 150-year drought that gripped the region.

A paleoclimate record consisting of annually laminated sediments

revealed that the three regional waves of societal collapse

(occurring around 810, 860, and 910 a.d.) corresponded with three

decade-long extreme droughts that hit the region during this already

dry period. Many archeologists recognize the importance of social

conditions in contributing to the collapse, but the extended drought

appears to have been a primary factor in gradually reducing the

carrying capacity of the land, which already suffered from

overpopulation and overexploitation of resources.

 

 

 

THE SCIENTIFIC COMMUNITY is now very confident that much of the

warming over the past century is attributable to human activities.

Global temperatures have changed for many natural reasons, of course,

but when scientists try to account for the full record of global

temperature changes over the past several hundred years, it is

impossible to obtain a close match to the observed temperature curve

without including the effects of very recent increases in greenhouse

gas concentrations.

 

 

With global warming comes greater probabilities of " climate

surprises " -- unexpected climate changes such as megadroughts, which

would seriously challenge our ability to adapt. Wally Broecker, a

National Medal of Science awardee for his paleoclimate research and

my colleague at Columbia University, likens the climate system to an

angry beast that we're poking with a stick -- provoking something we

know to be extremely sensitive and immeasurably powerful.

 

 

Of perhaps still greater concern than megadrought, though even more

difficult to predict, is the possibility that continued global

warming may lead to changes in ocean circulation -- the giant

flywheel of global climate, and also its Achilles heel. Modern ocean

observations provide some very early indications that the initial

phases of circulation change are already underway. A team of

oceanographers at the Woods Hole Oceanographic Institution have

observed that all Nordic seas have freshened tremendously over the

last forty years, and that the salinity of the deep ocean is now

lowering as well. These changes may be signaling a shift or

disruption in ocean circulation, and if that happens, we're in for

all sorts of surprises. Atmospheric circulation is often likened to a

nimble mouse scurrying through the forest -- it responds quickly to

imposed changes. Ocean circulation, on the other hand, is more like a

giant lumbering elephant -- reluctant to alter its course but

suddenly clearing the forest when it does.

 

 

 

The kinds of climate change that could result from a shift in ocean

circulation would be as devastating to contemporary culture as the

decimating drought was to the Maya. The scenario that current climate

models show goes like this: Today, as northward-flowing warm, salty

North Atlantic Drift water is stripped of its heat by the atmosphere

each winter, it brings surface warmth to the North Atlantic, and is

partly responsible for the mild climate of northwestern Europe. In

the Nordic seas chilled surface waters sink and massive volumes of

cold, salty deep water flow southward toward the Antarctic, where

they resurface, forming a giant ocean conveyor. In some climate model

simulations of our future, after a gradual, decades-long warming and

freshening trend in the North Atlantic due to increased Arctic

warming, ice melting, and river runoff, this ocean conveyor slows

down abruptly -- within several decades. The stability of the ocean

conveyor has been likened to a light switch that flips suddenly from

the " on " to " off " position given a steady application of finger

pressure. The resulting changes in ocean temperatures would likely

lead to equally abrupt, very large, and lasting changes in land

temperature and rainfall patterns globally. A shift in the ocean

conveyor, once initiated, is essentially irreversible over a time

period of many decades to centuries, and would permanently alter the

climatic norms for some of the most densely populated and highly

developed regions of the world, multiplying the risks -- and

magnifying the effects -- of major climatic disruptions from global

warming.

 

While most climate models indicate the conveyor is responsive to

global warming, few models project a complete conveyor shutdown

within the next century. However, we do know that this scenario has

happened several times before, and scientists have a very good idea

of how large and how far-reaching the impacts can be. When the Earth

was thawing out of the last ice age about 14,500 years ago due to

gradual, periodic changes in the Earth's orbit, the melting of large

ice sheets on the continents funneled large volumes of fresh water

into the North Atlantic. Analyses of ice cores, deep-sea sediment

cores, and other geologic evidence have shown that the surge of river

runoff did in fact form a freshwater lid over the North Atlantic,

which subsequently shut down formation of deep water currents for

about a millennium between 12,800 and 11,700 years ago.

 

 

Known as the Younger Dryas event, this period marked a sudden

reversal in the warming trend, and regional temperatures plummeted.

Greenland and northern European temperatures dropped by as much as

ten to fifteen degrees centigrade within a decade. Arctic conditions

were established in the United Kingdom and Europe; icebergs reached

as far south as Portugal; Africa and parts of Asia became much drier.

The event has been detected in paleoclimate records from nearly all

regions of the globe. It took nearly a thousand years for ocean

salinities to gradually increase until the conveyor switched on

again. An equally rapid warming, completed in less than a decade,

marked the end of the Younger Dryas event and the beginning of the

current warm period, the Holocene, bringing with it the birth of

agriculture and the subsequent rise of complex urban societies.

 

 

 

IN LEARNING HOW and why past shifts in climate have occurred and what

their effects have been, paleoclimatology has made remarkable

progress in defining just how large and abrupt natural climate swings

can be and what these may mean for our global-warming future. In his

statement to a U.S. Senate committee in 2003, Richard Alley, a

leading paleoclimatologist from Pennsylvania State University,

presented a consensus view of past and present climate change that

was recently summarized in the National Academy of Sciences report

Abrupt Climate Change: Inevitable Surprises. The main points were

that climate is very sensitive to even weak forcing; that climate

changes, when they occur, tend to happen very quickly (on timescales

of years to decades); and that the present and projected greenhouse-

gas climate forcing greatly exceeds the relatively weak forcing that

caused, for example, the Dust Bowl, or even past megadroughts.

 

 

" Many current policies and practices are likely to be inadequate in a

world of rapid and unforeseen climatic changes, " said

Alley. " Identifying ways to improve these policies will be beneficial

even if abrupt climate change turns out to fit a best-case, rather

than a worst-case, scenario. Societies will have no regrets about the

new policies, because they will be good policies regardless of the

magnitude of environmental change. "

 

 

The " no-regrets " and " good policy " political solutions are still

distant dreams, however, as the U.S. government has been reluctant to

face the political dimension of the problem. In 2001, the Bush

administration abandoned the Kyoto Protocol, the first legally

binding international treaty for reducing greenhouse gas emissions.

The administration deemed it unfair (developing nations such as China

and India were exempted in the short term) and viewed it as too

costly to the U.S. economy. Yet the cost of doing nothing may be far

greater. In the state of Florida alone, the projected cost of a one-

meter rise in sea level has been estimated to exceed $300 billion (in

1991 dollars), not including future development losses for the nearly

fourteen thousand square miles of inundated real estate.

 

 

A recent European Union economic assessment concluded that Kyoto

compliance will cost the EU only about 0.1 percent of its gross

domestic product by 2010. And with less than 5 percent of the world's

population here in this country responsible for nearly 25 percent of

global fuel consumption and emissions, there can be little question

that the U.S. has a huge historical carbon debt. The current gas-

guzzling culture only deepens the international community's growing

disappointment with the lack of American leadership on the issue.

 

 

 

 

 

Even in the U.S. there is a growing recognition that the magnitude of

the changes that could ensue from global warming would very likely

challenge political stability worldwide. A report commissioned in

2002 by the Pentagon entitled Imagining the Unthinkable explored a

scenario in which continued global warming leads to the eventual

shutdown of the conveyor after 2010. The resulting changes in climate

bring about protracted megadroughts in Europe, China, and North

America. Food, water, and energy shortages create border conflicts

that are exacerbated by mass migrations. Citing historical precedent,

the authors note, " Every time there is a choice between starving or

raiding, humans raid. " Widespread famine and political chaos

eventually lead to a " world of warring states. " Many scientists

dismissed the report as overly alarmist. " Exaggerated scenarios serve

only to intensify the existing polarization over global warming, "

said Wally Broecker. " What is needed is not more words but rather a

means to shut down CO2 emissions to the atmosphere. "

 

 

IT MAY BE TOO LATE to reverse changes that have already begun, but

there is still much that can be done to minimize future increases of

greenhouse gases and to mitigate and prepare for the effects of large

climate change. Policy makers must begin serious discussion on

immediate implementation of political solutions to reduce emissions

and increase adaptive capacity. While some of the coping strategies

learned from previous shorter droughts will no doubt prove useful,

the sheer duration and intensity of a megadrought pose an entirely

new set of technological hurdles. One of the world's leading

freshwater resource experts, Dr. Peter Gleick of the Pacific

Institute, recommends that " water managers should begin a systematic

reexamination of engineering design, operating rules, contingency

plans, and water allocation policies under a wider range of climatic

conditions and extremes than has been traditionally used. For

example, the standard engineering practice of designing for the worst

case in the historical observational record may no longer be

adequate. "

 

 

Presciently, some industries are already incorporating future global

warming into their business plans. Perhaps most revealing are the

concerns of the reinsurance industry -- those who insure the

insurers -- which has been paying out an escalating number of claims

in recent years as a result of vastly increased storm-related

property damage. Between 1989 and 1994, insurers paid out more than

$67 billion in storm damage claims -- $20 billion more than was paid

out during the previous five years. Natural disaster claims in 2003

were up 36 percent from 2002, and claims from the August hurricanes

of 2004 exceeded $20 billion in Florida alone. Facing potentially

crippling future claims, the industry has been lobbying on Capitol

Hill to jump-start discussions on climate-change mitigation. In a

richly significant statement, H. R. Kaufmann, general manager of

Swiss Re, the world's second-largest reinsurer, dryly announced, " In

light of the magnitude of these losses, it would be prudent for the

property/casualty industry to act as if that theory [global warming]

is correct. Failure to act would leave the industry and its

policyholders vulnerable to truly disastrous consequences. "

 

 

 

PETER B. DEMENOCAL is an associate professor of earth and

environmental sciences at Columbia University, where he conducts

research at the Lamont-Doherty Earth Observatory. He serves on

scientific steering committees for the National Science Foundation,

American Geophysical Union, and the National Academy of Sciences.