James Hansen is widely considered the pre-eminent scientist when it comes to understanding the potential for global climate change and human contributions to the problem.
He recently presented testimony to Congress on the 20th anniversary of his initial insights into the reality that climate change was likely underway in 1988.
I give you Dr. James Hansen of NASA:
Guest Opinion: Global Warming Twenty Years Later
Tipping Points Near
Today,
I will testify to Congress about global warming, 20 years after my June
23, 1988 testimony, which alerted the public that global warming was
under way. There are striking similarities between then and now, but
one big difference.
Again
a wide gap has developed between what is understood about global
warming by the relevant scientific community and what is known by
policymakers and the public. Now, as then, frank assessment of
scientific data yields conclusions that are shocking to the body
politic. Now, as then, I can assert that these conclusions have a
certainty exceeding 99 percent.
The
difference is that now we have used up all slack in the schedule for
actions needed to defuse the global warming time bomb. The next
President and Congress must define a course next year in which the United States exerts leadership commensurate with our responsibility for the present dangerous situation.
Otherwise,
it will become impractical to constrain atmospheric carbon dioxide, the
greenhouse gas produced in burning fossil fuels, to a level that
prevents the climate system from passing tipping points that lead to
disastrous climate changes that spiral dynamically out of humanity's
control.
Changes
needed to preserve creation, the planet on which civilization
developed, are clear. But the changes have been blocked by special
interests, focused on short-term profits, who hold sway in Washington and other capitals.
I
argue that a path yielding energy independence and a healthier
environment is, barely, still possible. It requires a transformative
change of direction in Washington in the next year.
Then: Time to "Stop Waffling"
On June 23, 1988, I testified to a hearing chaired by Senator Tim Wirth of Colorado that
the Earth had entered a long-term warming trend, and that human-made
greenhouse gases almost surely were responsible. I noted that global
warming enhanced both extremes of the water cycle, meaning stronger
droughts and forest fires, on the one hand, but also heavier rains and
floods.
My
testimony two decades ago was greeted with skepticism. But while
skepticism is the lifeblood of science, it can confuse the public. As
scientists examine a topic from all perspectives, it may appear that
nothing is known with confidence. But from such broad open-minded study
of all data, valid conclusions can be drawn.
My
conclusions in 1988 were built on a wide range of inputs from basic
physics, planetary studies, observations of ongoing changes, and
climate models. The evidence was strong enough that I could say it was
time to "stop waffling." I was sure that time would bring the
scientific community to a similar consensus, as it has.
While international recognition of global warming was swift, actions have faltered. The United States refused to place limits on its emissions, and developing countries such as China and India rapidly increased their emissions.
The Coming Storm
What
is at stake? Warming so far, about two degrees Fahrenheit over land
areas, seems almost innocuous, being less than day-to-day weather
fluctuations. But more warming is already "in-the-pipeline," delayed
only by the great inertia of the world ocean. And climate is nearing
dangerous tipping points. Elements of a "perfect storm," a global
cataclysm, are assembled.
Climate
can reach points such that amplifying feedbacks spur large rapid
changes. Arctic sea ice is a current example. Global warming initiated
sea ice melt, exposing darker ocean that absorbs more sunlight, melting
more ice. As a result, without any additional greenhouse gases, the Arctic soon will be ice-free in the summer.
More ominous tipping points loom. West Antarctic and Greenland ice
sheets are vulnerable to even small additional warming. These
two-mile-thick behemoths respond slowly at first, but if disintegration
gets well under way it will become unstoppable. Debate among scientists
is only about how much sea level would rise by a given date. In my
opinion, if emissions follow a business-as-usual scenario, sea level
rise of at least two meters is likely this century. Hundreds of
millions of people would become refugees. No stable shoreline would be
reestablished in any time frame that humanity can conceive.
Animal
and plant species are already stressed by climate change. Polar and
alpine species will be pushed off the planet, if warming continues.
Other species attempt to migrate, but as some are extinguished, their
interdependencies can cause ecosystem collapse. Mass extinctions, of
more than half the species on the planet, have occurred several times
when the Earth warmed as much as expected if greenhouse gases continue
to increase. Biodiversity recovered, but it required hundreds of
thousands of years.
Getting to 350 ppm
The disturbing conclusion, documented in a paper[1] I
have written with several of the world's leading climate experts, is
that the safe level of atmospheric carbon dioxide is no more than 350
ppm (parts per million), and it may be less. Carbon dioxide amount is
already 385 ppm and rising by about 2 ppm per year. Stunning corollary:
the oft-stated goal to keep global warming less than two degrees
Celsius (3.6 degrees Fahrenheit) is a recipe for global disaster, not
salvation.
These
conclusions are based on paleoclimate data showing how the Earth
responded to past levels of greenhouse gases and on observations
showing how the world is responding to today's carbon dioxide amount.
The consequences of continued increase of greenhouse gases extend far
beyond extermination of species and future sea level rise.
Arid
subtropical climate zones are expanding poleward. Already an average
expansion of about 250 miles has occurred, affecting the southern United States, the Mediterranean region, Australia, and southern Africa. Forest fires and drying-up of lakes will increase further unless carbon dioxide growth is halted and reversed.
Mountain
glaciers are the source of fresh water for hundreds of millions of
people. These glaciers are receding worldwide, in the Himalayas, Andes,
and Rocky Mountains. They
will disappear, leaving their rivers as trickles in late summer and
fall, unless the growth of carbon dioxide is reversed.
Coral
reefs, the rainforests of the ocean, are home for one-third of the
species in the sea. Coral reefs are under stress for several reasons,
including warming of the ocean, but especially because of ocean
acidification, a direct effect of added carbon dioxide. Ocean life
dependent on carbonate shells and skeletons is threatened by
dissolution as the ocean becomes more acid.
Such
phenomena, including the instability of Arctic sea ice and the great
ice sheets at today's carbon dioxide amount, show that we have already
gone too far. We must draw down atmospheric carbon dioxide to preserve
the planet we know. A level of no more than 350 ppm is still feasible,
with the help of reforestation and improved agricultural practices, but
just barely - time is running out.
Moving Away from Fossil Fuels
Requirements
to halt carbon dioxide growth follow from the size of fossil carbon
reservoirs. Coal towers over oil and gas. Phasing out the use of coal
except where the carbon is captured and stored below ground is the
primary requirement for solving global warming.
Oil
is used in vehicles, where it is impractical to capture the carbon. But
oil is running out. To preserve our planet we must ensure that the next
mobile energy source is not obtained by squeezing oil from coal, tar
shale, or other fossil fuels.
Fossil
fuel reservoirs are finite, which is the main reason that prices are
rising. We must move beyond fossil fuels eventually. Solution of the
climate problem requires that we move to carbon-free energy promptly.
Special
interests have blocked the transition to our renewable energy future.
Instead of moving heavily into renewable energies, fossil fuel
companies choose to spread doubt about global warming, just as tobacco
companies discredited the link between smoking and cancer. Methods are
sophisticated, including funding to help shape school textbook
discussions of global warming.
CEOs
of fossil energy companies know what they are doing and are aware of
the long-term consequences of continued business as usual. In my
opinion, these CEOs should be tried for high crimes against humanity
and nature.
But
the conviction of ExxonMobil and Peabody Coal CEOs will be no
consolation if we pass on a runaway climate to our children. Humanity
would be impoverished by ravages of continually shifting shorelines and
intensification of regional climate extremes. Loss of countless species
would leave a more desolate planet.
If
politicians remain at loggerheads, citizens must lead. We must demand a
moratorium on new coal-fired power plants. We must block fossil fuel
interests who aim to squeeze every last drop of oil from public lands,
off-shore, and wilderness areas. Those last drops are no solution. They
yield continued exorbitant profits for a short-sighted, self-serving
industry, but no alleviation of our addiction or long-term energy
source.
Pricing Carbon Emissions
Moving
from fossil fuels to clean energy is challenging, yet it is also
transformative in ways that will be welcomed. Cheap, subsidized fossil
fuels engendered bad habits. We import food from halfway around the
world, for example, even with healthier products available from nearby
fields. Local produce would be competitive were it not for fossil fuel
subsidies and the fact that climate change damages and costs, due to
fossil fuels, are also borne by the public.
A price on emissions that cause harm is essential. Yes, a carbon tax. A carbon tax with a 100 percent dividend[2] is
needed to wean us off of our fossil fuel addiction. A tax and dividend
allows the marketplace, not politicians, to make investment decisions.
A
carbon tax on coal, oil, and gas is simple, applied at the first point
of sale or port of entry. The entire tax must be returned to the
public-an equal amount to each adult, a half-share for children. This
dividend can be deposited monthly in an individual's bank account.
A
carbon tax with a 100 percent dividend is non-regressive. On the
contrary, you can bet that low- and middle-income people will find ways
to limit their carbon tax and come out ahead. Profligate energy users
will have to pay for their excesses.
Demand for low-carbon, high-efficiency products will spur innovation, making U.S. products
more competitive on international markets. Carbon emissions will
plummet as energy efficiency and renewable energies grow rapidly. Black
soot, mercury, and other fossil fuel emissions will decline. A
brighter, cleaner future, with energy independence, is possible.
America's Role
Washington likes
to spend our tax money line-by-line. Swarms of high-priced lobbyists in
alligator shoes help Congress decide where to spend, and in turn the
lobbyists' clients provide "campaign" money.
The public must send a message to Washington.
Preserve our planet, and creation, for our children and grandchildren,
but do not use that as an excuse for more tax-and-spend. Let this be
our motto: "One hundred percent dividend or fight!"
The
next President must make a national low-loss electric grid an
imperative. It will allow dispersed renewable energies to supplant
fossil fuels for power generation. Technology exists for direct-current
high-voltage buried transmission lines. Trunk lines can be completed in
less than a decade and expanded, in a way analogous to interstate
highways.
Government
must also change utility regulations so that profits do not depend on
selling ever more energy, but instead increase with efficiency.
Building-code and vehicle-efficiency requirements must be improved and
put on a path toward carbon neutrality.
The fossil fuel industry maintains its stranglehold on Washington via demagoguery, using China and other developing nations as scapegoats to rationalize inaction. In fact, the United States produced
most of the excess carbon in the air today, and it is to our advantage
as a nation to move smartly in finding ways to reduce emissions. As
with the ozone problem, developing countries can be allowed limited
extra time to reduce emissions. They will cooperate: they have much to
lose from climate change and much to gain from clean air and reduced
dependence on fossil fuels.
The United States must
establish fair agreements with other countries. However, our own tax
and dividend should start immediately. We have much to gain from it as
a nation, and other countries will copy our success. If necessary,
import duties on products from uncooperative countries can level the
playing field, with the import tax added to the dividend pool.
Democracy
works, but sometimes it churns slowly. Time is short. The 2008 election
is critical for the planet. If Americans turn out to pasture the most
brontosaurian congressmen, and if Washington adapts to address climate change, our children and grandchildren can still hold great expectations.
Dr.
James E. Hansen, a physicist by training, directs the NASA Goddard
Institute for Space Studies, a laboratory of the Goddard Space Flight
Center and a unit of the Columbia University Earth Institute, but he
testifies here as a private citizen.
