Three articles linked to the past couple of days in TreeHugger tell of
some client scientists coming to the conclusion that overall warming
of the global climate is reaching such a serious stage of advancement
that it will be necessary to simply put an absolute cap on total
allowable emissions and beyond that, simply keep from exploiting any
of the "dirtiest" hydrocarbon resources (coal, tar sands etc.) once
conventional current oil and gas resources have been exhausted.
1. Editorial in the current online edition of Nature:
Nature 458, 1077-1078 (30 April 2009) | doi:10.1038/4581077a;
Published online 29 April 2009
Time to act
Without a solid commitment from the world's leaders, innovative ways
to combat climate change are likely to come to nothing.
It is not too late yet � but we may be very close. The 500 billion
tonnes of carbon that humans have added to the atmosphere lie heavily
on the world, and the burden swells by at least 9 billion tonnes a
year (see page 1117). If present trends continue, humankind will have
emitted a trillion tonnes of carbon into the atmosphere well before
2050, and that could be enough to push the planet into the danger
zone. And there is no reason to think that the pressure will stop
then. The coal seams and tar sands of the world hold enough carbon for
humankind to emit another trillion tonnes � and the apocalyptic
scenarios extend from there (see page 1104).
Nations urgently need to cut their output of carbon dioxide. The
difficulty of that task is manifest: emissions have continued to rise
despite almost two decades of rhetoric, diplomacy and action on the
matter. But that unhappy fact should not be taken as a licence for
fatalism. Governments have a wide range of pollution-cutting tools at
their command, most notably tradable permit regimes, taxes on fuels,
regulations on power generation and energy efficiency, and subsidies
for renewable energy and improved technologies. These tools can work
if applied seriously � so citizens around the world must demand that
seriousness from their leaders, both within their individual nations
and in the international framework that will be discussed at the
United Nations Climate Change Conference in Copenhagen this December.
As essential as it is, however, simply agreeing to cut emissions will
not be enough. The fossil fuels burned up so far have already
committed the world to a serious amount of climate change, even if
carbon emissions were somehow to cease overnight (see page 1091). And
given the current economic turmoil, the wherewithal to adapt to these
changes is in short supply, especially among the world's poor nations.
Adaptation measures will be needed in rich and poor countries alike �
but those that have grown wealthy through the past emission of carbon
have a moral duty to help those now threatened by that legacy (see
Even a complete halt to carbon pollution would not bring the world's
temperatures down substantially for several centuries.
The latest scientific research suggests that even a complete halt to
carbon pollution would not bring the world's temperatures down
substantially for several centuries. If further research reveals that
a prolonged period of elevated temperatures would endanger the polar
ice sheets, or otherwise destabilize the Earth system, nations may
have to contemplate actively removing CO2 from the atmosphere.
(...continues at the above link)
2. A second freely available article on the Nature site:
Published online 29 April 2009 | Nature 458, 1091-1094 (2009) | doi:
Climate crunch: A burden beyond bearing
The climate situation may be even worse than you think. In the first
of three features, Richard Monastersky looks at evidence that keeping
carbon dioxide beneath dangerous levels is tougher than previously
Download a PDF of this story.
In 2007, environmental writer Bill McKibben approached climate
scientist James Hansen and asked him what atmospheric concentration of
carbon dioxide could be considered safe. Hansen's reaction: "I don't
know, but I'll get back to you."
After he had mulled it over, Hansen started to suspect that he and
many other scientists had underestimated the long-term effects of
greenhouse warming. Atmospheric concentration of CO2 at the time was
rising past 382 parts per million (p.p.m.), a full 100 ticks above its
pre-industrial level. Most researchers, including Hansen, had been
focusing on 450 p.p.m. as a target that would avoid, in the resonant
and legally binding formulation of the United Nations Framework
Convention on Climate Change, "dangerous climate change". McKibben was
aware of this: he was thinking of forming an organization called
450.org to call attention to the number, and his question to Hansen
was by way of due diligence.
As he thought about McKibben's question, Hansen, who runs NASA's
Goddard Institute for Space Studies in New York, began to wonder if
450 p.p.m. was too high. Having spent his career working on climate
models, he was aware that in some respects the real world was
outstripping them. Arctic sea ice was reaching record lows; many of
Greenland's glaciers were retreating; the tropics were expanding.
"What was clear was that climate models are our weakest tool, in that
you can't trust their sensitivity in any of these key areas," he says.
Those warning signs � and his studies of past climate change � led
Hansen to conclude that only by pulling CO2 concentrations down below
today's value could humanity avert serious problems. He came back to
McKibben with not 450 but 350. In 2008, he published a paper spelling
out his rationale for that target1.
The difference between 350 and 450 is not just one of degree. It's one
of direction. A CO2 concentration of 450 p.p.m. awaits the world at
some point in the future that might conceivably, though with
difficulty, be averted. But 350 p.p.m. can be seen only in the rear-
view mirror. Hansen believes that CO2 levels already exceed those that
would provide long-term safety, and the world needs not just to stop
but to reverse course. Although his view is far from universal, a
growing number of scientists agree that the CO2challenge is even
greater than had previously been thought.
Several recent studies, for example, indicate that it may be
exceedingly difficult to cool the climate down from any eventual peak
or plateau, no matter what CO2 concentration is chosen as a target by
the international community. And by looking at the problem in a new
sort of way � by tallying the total amount of carbon injected into the
atmosphere across human history � two papers in this issue of Nature
reveal how close the world has come to the danger point (pages 1158
and 1163). "It's tougher than people have appreciated. We have less
room to manoeuvre," says Malte Meinshausen, an author of one of the
papers and a senior researcher at the Potsdam Institute for Climate
Impact Research in Germany.
(...more at above link...)
Also in this issue, Myles Allen of the University of Oxford,
Meinshausen and their colleagues describe how they ran a series of
simulations using a simple combination of climate and carbon-cycle
models (page 1163). They find that if humankind could limit all CO2
emissions from fossil fuels and changes in land use to 1 trillion tons
of carbon in total, there would be a good chance that the climate
would not warm more than 2 �C above its pre-industrial range. Because
half of that trillion tons has already been spewed into the
atmosphere, and emissions now average about 9 billion tons a year and
rising, the trillion-ton limit would allow the world to follow its
current trend for less than 40 more years before giving up carbon
emission for good, all at once.
One way of looking at that challenge is put forward by Hansen. Go
ahead and burn all the remaining oil and gas in conventional reserves,
he says, and at the same time concentrate all efforts on quickly
phasing out coal � or capturing and storing the emissions associated
with it. If nations can cut off coal use by 2030 and avoid tapping
unconventional fossil fuels, such as tar sands and methane hydrates,
the world could limit future CO2 emissions to 400 gigatonnes of carbon.
Although the results of the studies might seem too daunting, they do
offer a few rays of hope. Andrew Weaver, a modeller at the University
of Victoria in British Columbia, Canada, says that in the new studies,
what matters is how much pollution goes into the sky, not when it gets
emitted. "This allows you some flexibility," he says. From a political
perspective, the idea of a cap on total emissions "is a lot easier to
get your head around" than a concentration target or, say, a 20%
reduction below 1990 emission levels. A cap is like a budget. Once you
use it up, there's nothing left to spend.
Unfortunately, the world is behaving as though it expects to be able
to arrange a large overdraft. And researchers can only come up with so
many ways of presenting the gravity of the carbon problem to the rest
of the world. "At some point, you begin to throw your hands up. It's
very frustrating," says Weaver, who pulls a reference from an ancient
global crisis. "Climate scientists," he says, "have begun to feel like
a bunch of Noahs � thousands of Noahs."
3. Elsewhere, in Australia, scientists have written a letter to coal
powered stations asking them to shut down:
Scientists ask coal plants to shut down : thewest.com.au
Scientists ask coal plants to shut down
1st May 2009, 12:30 WST
A group of scientists have written a letter to the operators of coal-
fired power stations asking them to shut up shop to save the planet.
They say real action on climate change will require that existing coal-
fired power stations �cease to operate in the near future�.
The seven scientists - three of whom have worked on the
Intergovernmental Panel on Climate Change - said coal plants should be
replaced with clean energy.
No new coal plants should be allowed unless they had zero emissions,
and this would not be possible for some time.
�The warming of the atmosphere, driven by human-induced emissions of
greenhouse gases, is already causing unacceptable damage and suffering
around the world,� the scientists said in the letter, sent to every
coal-fired power station in the country.
�We cannot emphasise enough just how serious the situation has become.�
Shutting down coal plants would require a social transition for coal
workers which had to be managed, but the task was unavoidable, they
Professor David Karoly, from the University of Melbourne�s School of
Earth Sciences, headed up the signatories.
Montreal QC Canada
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