| Topic: |
Politics > Politics-USA |
| User: |
"Captain Compassion" |
| Date: |
13 Nov 2007 10:09:53 AM |
| Object: |
No consensus on IPCC's level of ignorance |
No consensus on IPCC's level of ignorance
By John Christy
Professor of Atmospheric Science, University of Alabama
As the Intergovernmental Panel on Climate Change (IPCC) puts the
finishing touches to its final report of the year, two of its senior
scientists look at what the panel is and how well it works. Here, a
view from a leading researcher into temperature change.
The IPCC is a framework around which hundreds of scientists and other
participants are organised to mine the panoply of climate change
literature to produce a synthesis of the most important and relevant
findings.
These findings are published every few years to help policymakers keep
tabs on where the participants chosen for the IPCC believe the Earth's
climate has been, where it is going, and what might be done to adapt
to and/or even adjust the predicted outcome.
While most participants are scientists and bring the aura of
objectivity, there are two things to note:
this is a political process to some extent (anytime governments are
involved it ends up that way) scientists are mere mortals casting
their gaze on a system so complex we cannot precisely predict its
future state even five days ahead The political process begins with
the selection of the Lead Authors because they are nominated by their
own governments.
Thus at the outset, the political apparatus of the member nations has
a role in pre-selecting the main participants.
But, it may go further.
Unsound bites
At an IPCC Lead Authors' meeting in New Zealand, I well remember a
conversation over lunch with three Europeans, unknown to me but who
served as authors on other chapters. I sat at their table because it
was convenient.
After introducing myself, I sat in silence as their discussion
continued, which boiled down to this: "We must write this report so
strongly that it will convince the US to sign the Kyoto Protocol."
Politics, at least for a few of the Lead Authors, was very much part
and parcel of the process.
And, while the 2001 report was being written, Dr Robert Watson, IPCC
Chair at the time, testified to the US Senate in 2000 adamantly
advocating on behalf of the Kyoto Protocol, which even the journal
Nature now reports is a failure.
Follow the herd
As I said above - and this may come as a surprise - scientists are
mere mortals.
The tendency to succumb to group-think and the herd-instinct (now
formally called the "informational cascade") is perhaps as tempting
among scientists as any group because we, by definition, must be the
"ones who know" (from the Latin sciere , to know).
You dare not be thought of as "one who does not know"; hence we may
succumb to the pressure to be perceived as "one who knows".
This leads, in my opinion, to an overstatement of confidence in the
published findings and to a ready acceptance of the views of anointed
authorities.
Scepticism, a hallmark of science, is frowned upon. (I suspect the
IPCC bureaucracy cringes whenever I'm identified as an IPCC Lead
Author.)
The signature statement of the 2007 IPCC report may be paraphrased as
this: "We are 90% confident that most of the warming in the past 50
years is due to humans."
We are not told here that this assertion is based on computer model
output, not direct observation. The simple fact is we don't have
thermometers marked with "this much is human-caused" and "this much is
natural".
So, I would have written this conclusion as "Our climate models are
incapable of reproducing the last 50 years of surface temperatures
without a push from how we think greenhouse gases influence the
climate. Other processes may also account for much of this change."
Slim models
To me, the elevation of climate models to the status of definitive
tools for prediction has led to the temptation to be over-confident.
Here is how this can work.
Computer models are the basic tools which are used to estimate the
future climate. Many scientists (ie the mere mortals) have been
captivated by an IPCC image in which the actual global surface
temperature curve for the 20th Century is overlaid on a band of model
simulations of temperature for the same period.
The observations seem to fit right in the middle of the model band,
implying that models are formulated so capably and completely that
they can reproduce the past very well. Without knowing much about
climate models, any group will be persuaded by this image to believe
models are quite precise.
However, there is a fundamental flaw with this thinking.
You see, every modeller knew what the answer was ahead of time. (Those
groans you just heard were the protestations of my colleagues in the
modelling community - they know what's coming).
In my view, on the other hand, this persuasive image is not a
scientific experiment at all. The agreement displayed is just as
likely to do with clever software engineering as to the first
principles of science.
The proper and objective experiment is to test model output against
quantities not known ahead of time.
Complex world
Our group is one of the few that builds a variety of climate datasets
from scratch for tests just like this.
Since we build the datasets here, we have an urge to be sceptical
about arguments-from-authority in favour of the real, though
imperfect, observations.
In these model vs data comparisons, we find gross inconsistencies -
hence I am sceptical of our ability to claim cause and effect about
both past and future climate states. Mother Nature is incredibly
complex, and to think we mortals are so clever and so perceptive that
we can create computer code that accurately reproduces the millions of
processes that determine climate is hubris (think of predicting the
complexities of clouds).
Of all scientists, climate scientists should be the most humble. Our
cousins in the one-to-five-day weather prediction business learned
this long ago, partly because they were held accountable for their
predictions every day.
Answering the question about how much warming has occurred because of
increases in greenhouse gases and what we may expect in the future
still holds enormous uncertainty, in my view.
Explosive view
How could the situation be improved? At one time I stated that the
IPCC-like process was the worst way to compile scientific knowledge,
except for all the others.
Improvements have been adopted through the years, most notably the
publication of the comments and responses. Bravo.
I would think a simple way to let the world know there are other
opinions about various aspects emerging from the IPCC font would be to
provide some quasi-official forum to allow those views to be
expressed.
We should always begin our scientific pronouncements with this
statement: 'At our present level of ignorance, we think we know...'
These alternative-view authors should be afforded the same protocol as
the IPCC authors, ie they themselves are their own final reviewers and
thus would have final say on what is published. At that point, I
suppose, the blogosphere would erupt and, amidst the fire and smoke,
hopefully, enlightenment may appear.
I continue to participate in the IPCC (unless an IPCC functionary
reads this missive and blackballs me) because I not only am able to
contribute from my own research, but there are numerous opportunities
to learn something new - to feed the curiosity that attends a
scientist's soul.
I can live with the disagreements concerning nuances and subjective
assertions as they simply remind me that all scientists are people,
and do not prevent me from speaking my mind anyway.
Wise teachings
Don't misunderstand me.
Atmospheric carbon dioxide continues to increase due to the undisputed
benefits that carbon-based energy brings to humanity. This increase
will have some climate impact through CO2's radiation properties.
However, fundamental knowledge is meagre here, and our own research
indicates that alarming changes in the key observations are not
occurring.
The best advice regarding scientific knowledge, which certainly
applies to climate, came to me from Mr Mallory, my high school physics
teacher.
He proposed that we should always begin our scientific pronouncements
with this statement: "At our present level of ignorance, we think we
know..."
Good advice for the IPCC, and all of us.
John R Christy is Professor and Director of the Earth System Science
Center at the University of Alabama, Huntsville, US
--
The object of life is not to be on the side of the majority but to
escape finding oneself in the ranks of the insane. -- Marcus Aurelius
"...the whole world, including the United States, including all that
we have known and cared for, will sink into the abyss of a new Dark
Age, made more sinister, and perhaps more protracted, by the lights
of perverted science." -- Sir Winston Churchill
Joseph R. Darancette
daranc@NOSPAMcharter.net
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