The New York Review of Books  [Printer-friendly version]
June 13, 2006

THE THREAT TO THE PLANET

By Jim Hansen

Al Gore
Al Gore by David Levine

The Weather Makers: How Man Is Changing the Climate and What It Means
for Life on Earth
by Tim Flannery

Atlantic Monthly Press, 357 pp., $24.00
Field Notes from a Catastrophe: Man, Nature, and Climate Change
by Elizabeth Kolbert

Bloomsbury, 210 pp., $22.95
An Inconvenient Truth: The Planetary Emergency of Global Warming and
What We Can Do About It
by Al Gore

Melcher Media/Rodale, 325 pp., $21.95 (paper)
An Inconvenient Truth
a film directed by Davis Guggenheim

Jim Hansen is Director of the NASA Goddard Institute for Space Studies
and Adjunct Professor of Earth and Environmental Sciences at Columbia
University's Earth Institute. His opinions are expressed here, he
writes, "as personal views under the protection of the First Amendment
of the United States Constitution."

1.

Animals are on the run. Plants are migrating too. The Earth's
creatures, save for one species, do not have thermostats in their
living rooms that they can adjust for an optimum environment. Animals
and plants are adapted to specific climate zones, and they can survive
only when they are in those zones. Indeed, scientists often define
climate zones by the vegetation and animal life that they support.
Gardeners and bird watchers are well aware of this, and their
handbooks contain maps of the zones in which a tree or flower can
survive and the range of each bird species.

Those maps will have to be redrawn. Most people, mainly aware of
larger day-to-day fluctuations in the weather, barely notice that
climate, the average weather, is changing. In the 1980s I started to
use colored dice that I hoped would help people understand global
warming at an early stage. Of the six sides of the dice only two sides
were red, or hot, representing the probability of having an unusually
warm season during the years between 1951 and 1980. By the first
decade of the twenty-first century, four sides were red. Just such an
increase in the frequency of unusually warm seasons, in fact, has
occurred. But most people -- who have other things on their minds and
can use thermostats -- have taken little notice.

Animals have no choice, since their survival is at stake. Recently
after appearing on television to discuss climate change, I received an
e-mail from a man in northeast Arkansas: "I enjoyed your report on
Sixty Minutes and commend your strength. I would like to tell you of
an observation I have made. It is the armadillo. I had not seen one of
these animals my entire life, until the last ten years. I drive the
same forty-mile trip on the same road every day and have slowly
watched these critters advance further north every year and they are
not stopping. Every year they move several miles."

Armadillos appear to be pretty tough. Their mobility suggests that
they have a good chance to keep up with the movement of their climate
zone, and to be one of the surviving species. Of course, as they reach
the city limits of St. Louis and Chicago, they may not be welcome. And
their ingenuity may be taxed as they seek ways to ford rivers and
multiple-lane highways. Problems are greater for other species, as Tim
Flannery, a well-known Australian mammalogist and conservationist,
makes clear in The Weather Makers. Ecosystems are based on
interdependencies -- between, for example, flower and pollinator,
hunter
and hunted, grazers and plant life -- so the less mobile species have
an
impact on the survival of others. Of course climate fluctuated in the
past, yet species adapted and flourished. But now the rate of climate
change driven by human activity is reaching a level that dwarfs
natural rates of change. And barriers created by human beings, such as
urban sprawl and homogeneous agricultural fields, block many migration
routes. If climate change is too great, natural barriers, such as
coastlines, spell doom for some species.

Studies of more than one thousand species of plants, animals, and
insects, including butterfly ranges charted by members of the public,
found an average migration rate toward the North and South Poles of
about four miles per decade in the second half of the twentieth
century. That is not fast enough. During the past thirty years the
lines marking the regions in which a given average temperature
prevails ("isotherms") have been moving poleward at a rate of about
thirty-five miles per decade. That is the size of a county in Iowa.
Each decade the range of a given species is moving one row of counties
northward.

As long as the total movement of isotherms toward the poles is much
smaller than the size of the habitat, or the ranges in which the
animals live, the effect on species is limited. But now the movement
is inexorably toward the poles and totals more than a hundred miles
over the past several decades. If emissions of greenhouse gases
continue to increase at the current rate -- "business as usual" --
then the
rate of isotherm movement will double in this century to at least
seventy miles per decade. If we continue on this path, a large
fraction of the species on Earth, as many as 50 percent or more, may
become extinct.

The species most at risk are those in polar climates and the
biologically diverse slopes of alpine regions. Polar animals, in
effect, will be pushed off the planet. Alpine species will be pushed
toward higher altitudes, and toward smaller, rockier areas with
thinner air; thus, in effect, they will also be pushed off the planet.
A few such species, such as polar bears, no doubt will be "rescued" by
human beings, but survival in zoos or managed animal reserves will be
small consolation to bears or nature lovers.

In the Earth's history, during periods when average global
temperatures increased by as much as ten degrees Fahrenheit, there
have been several "mass extinctions," when between 50 and 90 percent
of the species on Earth disappeared forever. In each case, life
survived and new species developed over hundreds of thousands of
years. The most recent of these mass extinctions defines the boundary,
55 million years ago, between the Paleocene and Eocene epochs. The
evolutionary turmoil associated with that climate change gave rise to
a host of modern mammals, from rodents to primates, which appear in
fossil records for the first time in the early Eocene.

If human beings follow a business-as-usual course, continuing to
exploit fossil fuel resources without reducing carbon emissions or
capturing and sequestering them before they warm the atmosphere, the
eventual effects on climate and life may be comparable to those at the
time of mass extinctions. Life will survive, but it will do so on a
transformed planet. For all foreseeable human generations, it will be
a far more desolate world than the one in which civilization developed
and flourished during the past several thousand years.

2.

The greatest threat of climate change for human beings, I believe,
lies in the potential destabilization of the massive ice sheets in
Greenland and Antarctica. As with the extinction of species, the
disintegration of ice sheets is irreversible for practical purposes.
Our children, grandchildren, and many more generations will bear the
consequences of choices that we make in the next few years.

The level of the sea throughout the globe is a reflection primarily of
changes in the volume of ice sheets and thus of changes of global
temperature. When the planet cools, ice sheets grow on continents and
the sea level falls. Conversely, when the Earth warms, ice melts and
the sea level rises. In Field Notes from a Catastrophe, Elizabeth
Kolbert reports on the work of researchers trying to understand the
acceleration of melting, and in his new book and film An Inconvenient
Truth, Al Gore graphically illustrates possible effects of a rising
sea level on Florida and other locations.

Ice sheets waxed and waned as the Earth cooled and warmed over the
past 500,000 years. During the coldest ice ages, the Earth's average
temperature was about ten degrees Fahrenheit colder than today. So
much water was locked in the largest ice sheet, more than a mile thick
and covering most of Canada and northern parts of the United States,
that the sea level was 400 feet lower than today. The warmest
interglacial periods were about two degrees Fahrenheit warmer than
today and the sea level was as much as sixteen feet higher.

Future rise in the sea level will depend, dramatically, on the
increase in greenhouse gases, which will largely determine the amount
of global warming. As described in the books under review, sunlight
enters the atmosphere and warms the Earth, and then is sent back into
space as heat radiation. Greenhouse gases trap this heat in the
atmosphere and thereby warm the Earth's surface as we are warmed when
blankets are piled on our bed. Carbon dioxide (CO2), produced mainly
by burning fossil fuels (coal, oil, and gas), is the most important
greenhouse gas made by human beings. Methane (CH4), which is "natural
gas" that escapes to the atmosphere from coal mines, oil wells, rice
paddies, landfills, and animal feedlots, is also an important
greenhouse gas. Other significant warming agents are ground-level
ozone and black soot, which arise mainly from incomplete combustion of
fossil fuels and biofuels.

In order to arrive at an effective policy we can project two different
scenarios concerning climate change. In the business-as-usual
scenario, annual emissions of CO2 continue to increase at the current
rate for at least fifty years, as do non-CO2 warming agents including
methane, ozone, and black soot. In the alternative scenario, CO2
emissions level off this decade, slowly decline for a few decades, and
by mid-century decrease rapidly, aided by new technologies.

The business-as-usual scenario yields an increase of about five
degrees Fahrenheit of global warming during this century, while the
alternative scenario yields an increase of less than two degrees
Fahrenheit during the same period. Warming can be predicted accurately
based on knowledge of how Earth responded to similar levels of
greenhouse gases in the past. (By drilling into glaciers to analyze
air bubbles trapped under layers of snow, scientists can measure the
levels of each gas in the atmosphere hundreds of thousands of years
ago. By comparing the concentrations of different isotopes of oxygen
in these air bubbles, they can measure the average temperature of past
centuries.) Climate models by themselves yield similar answers.
However, the evidence from the Earth's history provides a more precise
and sensitive measure, and we know that the real world accurately
included the effects of all feedback processes, such as changes of
clouds and water vapor, that have an effect on temperature.

How much will sea level rise with five degrees of global warming? Here
too, our best information comes from the Earth's history. The last
time that the Earth was five degrees warmer was three million years
ago, when sea level was about eighty feet higher.

Eighty feet! In that case, the United States would lose most East
Coast cities: Boston, New York, Philadelphia, Washington, and Miami;
indeed, practically the entire state of Florida would be under water.
Fifty million people in the US live below that sea level. Other places
would fare worse. China would have 250 million displaced persons.
Bangladesh would produce 120 million refugees, practically the entire
nation. India would lose the land of 150 million people.

A rise in sea level, necessarily, begins slowly. Massive ice sheets
must be softened and weakened before rapid disintegration and melting
occurs and the sea level rises. It may require as much as a few
centuries to produce most of the long-term response. But the inertia
of ice sheets is not our ally against the effects of global warming.
The Earth's history reveals cases in which sea level, once ice sheets
began to collapse, rose one meter (1.1 yards) every twenty years for
centuries. That would be a calamity for hundreds of cities around the
world, most of them far larger than New Orleans. Devastation from a
rising sea occurs as the result of local storms which can be expected
to cause repeated retreats from transitory shorelines and rebuilding
away from them.

Satellite images and other data have revealed the initial response of
ice sheets to global warming. The area on Greenland in which summer
melting of ice took place increased more than 50 percent during the
last twenty-five years. Meltwater descends through crevasses to the
ice sheet base, where it provides lubrication that increases the
movement of the ice sheet and the discharge of giant icebergs into the
ocean. The volume of icebergs from Greenland has doubled in the last
ten years. Seismic stations reveal a shocking increase in "icequakes"
on Greenland, caused by a portion of an ice sheet lurching forward and
grinding to a halt. The annual number of these icequakes registering
4.6 or greater on the Richter scale doubled from 7 in 1993 to 14 in
the late 1990s; it doubled again by 2005. A satellite that measures
minute changes in Earth's gravitational field found the mass of
Greenland to have decreased by 50 cubic miles of ice in 2005. West
Antarctica's mass decreased by a similar amount.

The effect of this loss of ice on the global sea level is small, so
far, but it is accelerating. The likelihood of the sudden collapse of
ice sheets increases as global warming continues. For example, wet ice
is darker, absorbing more sunlight, which increases the melting rate
of the ice. Also, the warming ocean melts the offshore accumulations
of ice -- "ice shelves" -- that form a barrier between the ice sheets
and
the ocean. As the ice shelves melt, more icebergs are discharged from
the ice sheets into the ocean. And as the ice sheet discharges more
icebergs into the ocean and loses mass, its surface sinks to a lower
level where the temperature is warmer, causing it to melt faster.

The business-as-usual scenario, with five degrees Fahrenheit global
warming and ten degrees Fahrenheit at the ice sheets, certainly would
cause the disintegration of ice sheets. The only question is when the
collapse of these sheets would begin. The business-as-usual scenario,
which could lead to an eventual sea level rise of eighty feet, with
twenty feet or more per century, could produce global chaos, leaving
fewer resources with which to mitigate the change in climate. The
alternative scenario, with global warming under two degrees
Fahrenheit, still produces a significant rise in the sea level, but
its slower rate, probably less than a few feet per century, would
allow time to develop strategies that would adapt to, and mitigate,
the rise in the sea level.

3.

Both the Department of Energy and some fossil fuel companies insist
that continued growth of fossil fuel use and of CO2 emissions are
facts that cannot be altered to any great extent. Their prophecies
become self-fulfilling, with the help of government subsidies and
intensive efforts by special interest groups to prevent the public
from becoming well-informed.

In reality, an alternative scenario is possible and makes sense for
other reasons, especially in the US, which has become an importer of
energy, hemorrhaging wealth to foreign nations in order to pay for it.
In response to oil shortages and price rises in the 1970s, the US
slowed its growth in energy use mainly by requiring an increase from
thirteen to twenty-four miles per gallon in the standard of auto
efficiency. Economic growth was decoupled from growth in the use of
fossil fuels and the gains in efficiency were felt worldwide. Global
growth of CO2 emissions slowed from more than 4 percent each year to
between 1 and 2 percent growth each year.

This slower growth rate in fossil fuel use was maintained despite
lower energy prices. The US is still only half as efficient in its use
of energy as Western Europe, i.e., the US emits twice as much CO2 to
produce a unit of GNP, partly because Europe encourages efficiency by
fossil fuel taxes. China and India, using older technologies, are less
energy-efficient than the US and have a higher rate of CO2 emissions.

Available technologies would allow great improvement of energy
efficiency, even in Europe. Economists agree that the potential could
be achieved most effectively by a tax on carbon emissions, although
strong political leadership would be needed to persuasively explain
the case for such a tax to the public. The tax could be revenue-
neutral, i.e., it could also provide for tax credits or tax decreases
for the public generally, leaving government revenue unchanged; and it
should be introduced gradually. The consumer who makes a special
effort to save energy could gain, benefiting from the tax credit or
decrease while buying less fuel; the well-to-do consumer who insisted
on having three Hummers would pay for his own excesses.

Achieving a decline in CO2 emissions faces two major obstacles: the
huge number of vehicles that are inefficient in their use of fuel and
the continuing CO2 emissions from power plants. Auto makers oppose
efficiency standards and prominently advertise their heaviest and most
powerful vehicles, which yield the greatest short-term profits. Coal
companies want new coal-fired power plants to be built soon, thus
assuring long-term profits.

The California legislature has passed a regulation requiring a 30
percent reduction in automobile greenhouse gas emissions by 2016. If
adopted nationwide, this regulation would save more than $150 billion
annually in oil imports. In thirty-five years it would save seven
times the amount of oil estimated by the US Geological Services to
exist in the Arctic National Wildlife Refuge. By fighting it in court,
automakers and the Bush administra-tion have stymied the California
law, which many other states stand ready to adopt. Further reductions
of emissions would be possible by means of technologies now being
developed. For example, new hybrid cars with larger batteries and the
ability to plug into wall outlets will soon be available; and cars
whose bodies are made of a lightweight carbon composite would get
better mileage.

If power plants are to achieve the goals of the alternative scenario,
construction of new coal-fired power plants should be delayed until
the technology needed to capture and sequester their CO2 emissions is
available. In the interim, new electricity requirements should be met
by the use of renewable energies such as wind power as well as by
nuclear power and other sources that do not produce CO2. Much could be
done to limit emissions by improving the standards of fuel efficiency
in buildings, lighting, and appliances. Such improvements are entirely
possible, but strong leadership would be required to bring them about.
The most effective action, as I have indicated, would be a slowly
increasing carbon tax, which could be revenue-neutral or would cover a
portion of the costs of mitigating climate change.

The alternative scenario I have been referring to has been designed to
be consistent with the Kyoto Protocol, i.e., with a world in which
emissions from developed countries would decrease slowly early in this
century and the developing countries would get help to adopt "clean"
energy technologies that would limit the growth of their emissions.
Delays in that approach -- especially US refusal both to participate
in
Kyoto and to improve vehicle and power plant efficiencies -- and the
rapid growth in the use of dirty technologies have resulted in an
increase of 2 percent per year in global CO2 emissions during the past
ten years. If such growth continues for another decade, emissions in
2015 will be 35 percent greater than they were in 2000, making it
impractical to achieve results close to the alternative scenario.

The situation is critical, because of the clear difference between the
two scenarios I have projected. Further global warming can be kept
within limits (under two degrees Fahrenheit) only by means of
simultaneous slowdown of CO2 emissions and absolute reduction of the
principal non-CO2agents of global warming, particularly emissions of
methane gas. Such methane emissions are not only the second-largest
human contribution to climate change but also the main cause of an
increase in ozone -- the third-largest human-produced greenhouse gas
-- in
the troposphere, the lowest part of the Earth's atmosphere. Practical
methods can be used to reduce human sources of methane emission, for
example, at coal mines, landfills, and waste management facilities.
However, the question is whether these reductions will be overwhelmed
by the release of frozen methane hydrates -- the ice-like crystals in
which large deposits of methane are trapped -- if permafrost melts.

If both the slowdown in CO2 emissions and reductions in non-CO2
emissions called for by the alternative scenario are achieved, release
of "frozen methane" should be moderate, judging from prior
interglacial periods that were warmer than today by one or two degrees
Fahrenheit. But if CO2 emissions are not limited and further warming
reaches three or four degrees Fahrenheit, all bets are off. Indeed,
there is evidence that greater warming could release substantial
amounts of methane in the Arctic. Much of the ten-degree Fahrenheit
global warming that caused mass extinctions, such as the one at the
Paleocene-Eocene boundary, appears to have been caused by release of
"frozen methane." Those releases of methane may have taken place over
centuries or millennia, but release of even a significant fraction of
the methane during this century could accelerate global warming,
preventing achievement of the alternative scenario and possibly
causing ice sheet disintegration and further long-term methane release
that are out of our control.

Any responsible assessment of environmental impact must conclude that
further global warming exceeding two degrees Fahrenheit will be
dangerous. Yet because of the global warming already bound to take
place as a result of the continuing long-term effects of greenhouse
gases and the energy systems now in use, the two-degree Fahrenheit
limit will be exceeded unless a change in direction can begin during
the current decade. Unless this fact is widely communicated, and
decision-makers are responsive, it will soon be impossible to avoid
climate change with far-ranging undesirable consequences. We have
reached a critical tipping point.

4.

The public can act as our planet's keeper, as has been shown in the
past. The first human-made atmospheric crisis emerged in 1974, when
the chemists Sherry Rowland and Mario Molina reported that
chlorofluorocarbons (CFCs) might destroy the stratospheric ozone layer
that protects animal and plant life from the sun's harmful ultraviolet
rays. How narrowly we escaped disaster was not realized until years
later.

CFC appeared to be a marvelous inert chemical, one so useful as an
aerosol propellant, fire suppressor, and refrigerant fluid that CFC
production increased 10 percent per year for decades. If this
business-as-usual growth of CFCs had continued just one more decade,
the stratospheric ozone layer would have been severely depleted over
the entire planet and CFCs themselves would have caused a larger
greenhouse effect than CO2.

Instead, the press and television reported Rowland and Molina's
warning widely. The public, responding to the warnings of
environmental groups, boycotted frivolous use of CFCs as propellants
for hair spray and deodorant, and chose non-CFC products instead. The
annual growth of CFC usage plummeted immediately from 10 percent to
zero. Thus no new facilities to produce CFCs were built. The principal
CFC manufacturer, after first questioning the scientific evidence,
developed alternative chemicals. When the use of CFCs for
refrigeration began to increase and a voluntary phaseout of CFCs for
that purpose proved ineffective, the US and European governments took
the lead in negotiating the Montreal Protocol to control the
production of CFCs. Developing countries were allowed to increase the
use of CFCs for a decade and they were given financial assistance to
construct alternative chemical plants. The result is that the use of
CFCs is now decreasing, the ozone layer was damaged but not destroyed,
and it will soon be recovering.

Why are the same scientists and political forces that succeeded in
controlling the threat to the ozone layer now failing miserably to
deal with the global warming crisis? Though we depend on fossil fuels
far more than we ever did on CFCs, there is plenty of blame to go
around. Scientists present the facts about climate change clinically,
failing to stress that business-as-usual will transform the planet.
The press and television, despite an overwhelming scientific consensus
concerning global warming, give equal time to fringe "contrarians"
supported by the fossil fuel industry. Special interest groups mount
effective disinformation campaigns to sow doubt about the reality of
global warming. The government appears to be strongly influenced by
special interests, or otherwise confused and distracted, and it has
failed to provide leadership. The public is understandably confused or
uninterested.

I used to spread the blame uniformly until, when I was about to appear
on public television, the producer informed me that the program "must"
also include a "contrarian" who would take issue with claims of global
warming. Presenting such a view, he told me, was a common practice in
commercial television as well as radio and newspapers. Supporters of
public TV or advertisers, with their own special interests, require
"balance" as a price for their continued financial support. Gore's
book reveals that while more than half of the recent newspaper
articles on climate change have given equal weight to such contrarian
views, virtually none of the scientific articles in peer-reviewed
journals have questioned the consensus that emissions from human
activities cause global warming. As a result, even when the scientific
evidence is clear, technical nit-picking by contrarians leaves the
public with the false impression that there is still great scientific
uncertainty about the reality and causes of climate change.

The executive and legislative branches of the US government seek
excuses to justify their inaction. The President, despite conclusive
reports from the Intergovernmental Panel on Climate Change and the
National Academy of Sciences, welcomes contrary advice from Michael
Crichton, a science fiction writer. Senator James Inhofe, chairman of
the Committee on Environment and Public Works, describes global
warming as "the greatest hoax ever perpetrated on the American people"
and has used aggressive tactics, including a lawsuit to suppress a
federally funded report on climate change, to threaten and intimidate
scientists.

Policies favoring the short-term profits of energy companies and other
special interests are cast by many politicians as being in the best
economic interests of the country. They take no account of the
mounting costs of environmental damage and of the future costs of
maintaining the supply of fossil fuels. Leaders with a long-term
vision would place greater value on developing more efficient energy
technology and sources of clean energy. Rather than subsidizing fossil
fuels, the government should provide incentives for fossil-fuel
companies to develop other kinds of energy.

Who will pay for the tragic effects of a warming climate? Not the
political leaders and business executives I have mentioned. If we pass
the crucial point and tragedies caused by climate change begin to
unfold, history will judge harshly the scientists, reporters, special
interests, and politicians who failed to protect the planet. But our
children will pay the consequences.

The US has heavy legal and moral responsibilities for what is now
happening. Of all the CO2 emissions produced from fossil fuels so far,
we are responsible for almost 30 percent, an amount much larger than
that of the next-closest countries, China and Russia, each less than 8
percent. Yet our responsibility and liability may run higher than
those numbers suggest. The US cannot validly claim to be ignorant of
the consequences. When nations must abandon large parts of their land
because of rising seas, what will our liability be? And will our
children, as adults in the world, carry a burden of guilt, as Germans
carried after World War II, however unfair inherited blame may be?

The responsibility of the US goes beyond its disproportionate share of
the world's emissions. By refusing to participate in the Kyoto
Protocol, we delayed its implementation and weakened its
effectiveness, thus undermining the attempt of the international
community to slow down the emissions of developed countries in a way
consistent with the alternative scenario. If the US had accepted the
Kyoto Protocol, it would have been possible to reduce the growing
emissions of China and India through the Protocol's Clean Development
Mechanism, by which the developed countries could offset their own
continuing emissions by investing in projects to reduce emissions in
the developing countries. This would have eased the way to later full
participation by China and India, as occurred with the Montreal
Protocol. The US was right to object to quotas in the Kyoto Protocol
that were unfair to the US; but an appropriate response would have
been to negotiate revised quotas, since US political and technology
leadership are essential for dealing with climate change.

It is not too late. The US hesitated to enter other conflicts in which
the future was at stake. But enter we did, earning gratitude in the
end, not condemnation. Such an outcome is still feasible in the case
of global warming, but just barely.

As explained above, we have at most ten years -- not ten years to
decide
upon action, but ten years to alter fundamentally the trajectory of
global greenhouse emissions. Our previous decade of inaction has made
the task more difficult, since emissions in the developing world are
accelerating. To achieve the alternative scenario will require prompt
gains in energy efficiencies so that the supply of conventional fossil
fuels can be sustained until advanced technologies can be developed.
If instead we follow an energy-intensive path of squeezing liquid
fuels from tar sands, shale oil, and heavy oil, and do so without
capturing and sequestering CO2 emissions, climate disasters will
become unavoidable.

5.

When I recently met Larry King, he said, "Nobody cares about fifty
years from now." Maybe so. But climate change is already evident. And
if we stay on the business-as-usual course, disastrous effects are no
further from us than we are from the Elvis era. Is it possible for a
single book on global warming to convince the public, as Rachel
Carson's Silent Spring did for the dangers of DDT? Bill McKibben's
excellent book The End of Nature is usually acknowledged as having
been the most effective so far, but perhaps what is needed is a range
of books dealing with different aspects of the global warming story.

Elizabeth Kolbert's Field Notes, based on a series of articles she
wrote for The New Yorker, is illuminating and sobering, a good book to
start with. The reader is introduced to some of the world's leading
climate researchers who explain the dangers in reasonably nontechnical
language but without sacrificing scientific accuracy. The book
includes fascinating accounts of how climate changes affected the
planet in the past, and how such changes are occurring in different
parts of the world right now. If Field Notes leaves the reader
yearning for more experience in the field, I suggest Thin Ice by Mark
Bowen, which captures the heroic work of Lonnie Thompson in extracting
unique information on climate change from some of the most forbidding
and spectacular places on the planet.[1]

Tim Flannery's The Weather Makers puts needed emphasis on the effects
of human-made climate change on other life on the planet. Flannery is
a remarkable scientist, having discovered and described dozens of
mammals in New Guinea, yet he writes for a general audience with
passion and clarity. He considers changes in climate that correspond
to what I have defined as the business-as-usual and alternative
scenarios. Flannery estimates that when we take account of other
stresses on species imposed by human beings, the alternative scenario
will lead to the eventual extinction of 20 percent of today's species,
while continuing with business-as-usual will cause 60 percent to
become extinct. Some colleagues will object that he extrapolates from
meager data, but estimates are needed and Flannery is as qualified as
anyone to make them. Fossil records of mass extinctions support
Flannery's shocking estimate of the potential for climate change to
extinguish life.

Flannery concludes, as I have, that we have only a short time to
address global warming before it runs out of control. However, his
call for people to reduce their CO2 emissions, while appropriate,
oversimplifies and diverts attention from the essential requirement:
government leadership. Without such leadership and comprehensive
economic policies, conservation of energy by individuals merely
reduces demands for fuel, thus lowering prices and ultimately
promoting the wasteful use of energy. I was glad to see that in a
recent article in these pages, he wrote that an effective fossil
energy policy should include a tax on carbon emissions.[2]

A good energy policy, economists agree, is not difficult to define.
Fuel taxes should encourage conservation, but with rebates to
taxpayers so that the government revenue from the tax does not
increase. The taxpayer can use his rebate to fill his gas-guzzler if
he likes, but most people will eventually reduce their use of fuel in
order to save money, and will spend the rebate on something else. With
slow and continual increases of fuel cost, energy consumption will
decline. The economy will not be harmed. Indeed, it will be improved
since the trade deficit will be reduced; so will the need to protect
US access to energy abroad by means of diplomatic and military action.
US manufacturers would be forced to emphasize energy efficiency in
order to make their products competitive internationally. Our
automakers need not go bankrupt.

Would this approach result in fewer ultraheavy SUVs on the road?
Probably. Would it slow the trend toward bigger houses with higher
ceilings? Possibly. But experts say that because technology has
sufficient potential to become more efficient, our quality of life
need not decline. In order for this to happen, the price of energy
should reflect its true cost to society.

Do we have politicians with the courage to explain to the public what
is needed? Or may it be that such people are not electable, in view of
the obstacles presented by television, campaign financing, and the
opposition of energy companies and other special interests? That
brings me to Al Gore's book and movie of the same name: An
Inconvenient Truth. Both are unconventional, based on a "slide show"
that Gore has given more than one thousand times. They are filled with
pictures -- stunning illustrations, maps, graphs, brief explanations,
and
stories about people who have important parts in the global warming
story or in Al Gore's life. The movie seems to me powerful and the
book complements it, adding useful explanations. It is hard to predict
how this unusual presentation will be received by the public; but Gore
has put together a coherent account of a complex topic that Americans
desperately need to understand. The story is scientifically accurate
and yet should be understandable to the public, a public that is less
and less drawn to science.

The reader might assume that I have long been close to Gore, since I
testified before his Senate committee in 1989 and participated in
scientific "roundtable" discussions in his Senate office. In fact,
Gore was displeased when I declined to provide him with images of
increasing drought generated by a computer model of climate change. (I
didn't trust the model's estimates of precipitation.) After Clinton
and Gore were elected, I declined a suggestion from the White House to
write a rebuttal to a New York Times Op-Ed article that played down
global warming and criticized the Vice President. I did not hear from
Gore for more than a decade, until January of this year, when he asked
me to critically assess his slide show. When we met, he said that he
"wanted to apologize," but, without letting him explain what he was
apologizing for, I said, "Your insight was better than mine."

Indeed, Gore was prescient. For decades he has maintained that the
Earth was teetering in the balance, even when doing so subjected him
to ridicule from other politicians and cost him votes. By telling the
story of climate change with striking clarity in both his book and
movie, Al Gore may have done for global warming what Silent Spring did
for pesticides. He will be attacked, but the public will have the
information needed to distinguish our long-term well-being from short-
term special interests.

An Inconvenient Truth is about Gore himself as well as global warming.
It shows the man that I met in the 1980s at scientific roundtable
discussions, passionate and knowledgeable, true to the message he has
delivered for years. It makes one wonder whether the American public
has not been deceived by the distorted images of him that have been
presented by the press and television. Perhaps the country came close
to having the leadership it needed to deal with a grave threat to the
planet, but did not realize it.

Notes

[1] Henry Holt, 2005. See the review by Bill McKibben, "The Coming
Meltdown," The New York Review, January 12, 2006.

[2] See "The Ominous New Pact," The New York Review, February 23,
2006.