I am interested in learning about scientists who have have completed
studies about global warming.  Of those that submit to peer review,
what percentage of them show that global warming is both (a) man-made
and (b) expected to have a severe negative impact to mankind?

The reason that I ask is that a relative told me she believed it was
about 99% of scientists believed that global warming was real and
caused by humans...and that the remaining 1% were the fringe idiots. 
And, although i know nothing about the subject, her number seemed too
high.

Rich,

 This is an important issue. Thanks for asking this.

Global warming is the subject of ongoing projects in a number of top-notch 
research laboratories in several countries. Not only are 
those researchers subject to peer review, they also receive
government grants, which are subject to  strict criteria.

There are also amateurs, which includes cranks and enthusiasts
and some professional 'think-tanks' which manipulate public opinion
for political purposes and some spin-doctor journalists who  serve
commercial interests.

It is hard to assign percentages unless we specify some quantitative measure:
money spent, number of people involved, number of websites , articles
in popular media and scientific journals and also define where the
term "scientist" ends and "spin-doctor" begins.
I will therefore give a few examples of the above, but first I will
provide a simple answer:

Scientists agree that global temperature is increasing due to two causes
1) astronomical causes (cycles outside of our atmosphere, e.g. sun output)
2) terrestrial changes  due to both human activity and natural changes, such as 
changes in the atmosphere e.g. greenhouse gases, clouds, 
changes in albedo = surface reflectivity, such as snow cover, deforestation ...

Temperature has been increasing since the middle-ages, mostly due to cause #1.
http://en.wikipedia.org/wiki/Little_Ice_Age

Human activity contributes a very small proportion to cause #2.

So

1) "Do scientist believe it?"

I estimate 95% of all scientists would agree with the following
statement but would not call it 'a belief':

 Global warming  is real and a very small fraction of it is caused by humans.

2)  " [do they] expect it to have a severe negative impact to mankind? "

  People in the natural sciences do not speculate about that.
  That is a topic in political science, futurology or anthropology
  because it depends partly  on what people will do in the future.


REFERENCES: 

SCIENCE: International consensus  (UN sponsored site) is reported here:

 ..  during the 20th century Temperature increased by .6 degree Celsius


 Climate Change 2001: The Scientific Basis
http://www.ipcc.ch/


(CENTER ) Here is the view of reasonable 'environmentalists'

 (note they quote IPCC - the above given site as authority- reports
may have different dates).

" The best-guess predicted rate of global warming is an increase in
global average temperature of 0.3 oC per decade, with an uncertainty
range from 0.2 to 0.5 oC per decade..."

(RIGHT politics) Here is a view of the "anti-environmentalists." 

"There is, therefore, no scientific consensus on global warming. ..
But perhaps even more important than whether or not scientists have
reached a consensus, however, is whether or not the scientific data
backs up the theory. Data collected from NASA's TIROs series of
weather satellites show a slight cooling trend of .04 degrees Celsius
over the past 18 years .."

Note that he quotes no actual scientific reports and picks an
arbitrary interval of time, one which may
support his thesis. This looks like a typical 'right-wing think tank site'
The National Center for Public Policy Research in Washington, D.C.)
http://www.tysknews.com/Depts/Environment/myth_of_global_warming.htm

(LEFT politics)- note they do not quote IPCC (the scientific consensus) either.
"Global warming is one of the most serious challenges facing us today.
To protect the health and economic well-being of current and future
generations, we must reduce our emissions of heat-trapping gases by
using the technology, know-how, and practical solutions already at our
disposal..."
© Union of Concerned Scientists
http://www.ucsusa.org/global_warming/



US federal agency view: 
http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsUSClimateActionReport.html

Note that they are quoting IPCC;
 I cannot paste quotes, since they used pdf format, 
but you may look through the reports using adobe acrobat reader. It
says that the U.S. government is recognizing its responsibility for
Earth's environment. That's nice. It also says it is a complex issue
which has an impact on the national economy. That's true.

CONCLUSION
I would conclude that, right now, there is no immediate (10-20 years)
danger of catastrophic changes.
Research on climate change should continue to be funded and, even more
importantly, research on future energy sources should be funded (that
is another, and also complex question).

RFCs are invited and rating is appreciated.

Hedgie

---

Request for Answer Clarification by rich2005-ga on 29 Dec 2005 09:55 PST

Lots of good info in there.  Thanks.  But, unfortunately, it does not
answer my specific question about where scientists who undergo peer
review fall on the subject.  In other words, since my relative told me
that it was a 'fact' that 99% of scientists believed it, I just want a
reliable number to see if someone can verify her fact.

I accept your issue that scientific research varies based on 'money
spent, number of people involved, number of websites, articles in
popular media and scientific journals and also define where the term
"scientist" ends and "spin-doctor" begins.'  Because of that, I would
accept any definition of a 'scientific study' with the only
qualification being that it must undergo peer review.  In other words,
if you want to define scientists as people with PhDs, that is fine. 
If you want to define them as climatologists who are not affiliated
with ExxonMobil or GreenPeace and have spent more than $2 MM studying
it, then that is fine as well.

Also, for the sake of this question, you can assume that my only
interest in learning about global warming is to help interprete what
the X% of scientists believe.  In other words, I do not care whether
the world is getting 1 degree hotter each decade...unless I am first
told that (say) 80% of scientists believe it.

---

Clarification of Answer by hedgie-ga on 29 Dec 2005 14:45 PST

" That hypothesis was tested by analyzing 928 abstracts, published in
refereed scientific journals between 1993 and 2003, and listed in the
ISI database with the keywords "climate change" (9).

The 928 papers were divided into six categories: explicit endorsement
of the consensus position, evaluation of impacts, mitigation
proposals, methods, paleoclimate analysis, and rejection of the
consensus position. Of all the papers, 75% fell into the first three
categories, either explicitly or implicitly accepting the consensus
view; 25% dealt with methods or paleoclimate, taking no position on
current anthropogenic climate change. Remarkably, none of the papers
disagreed with the consensus position.

Admittedly, authors evaluating impacts, developing methods, or
studying paleoclimatic change might believe that current climate
change is natural. However, none of these papers argued that point...


http://www.sciencemag.org/cgi/content/full/306/5702/1686

Fair critique. Sometimes it takes a bit of clicking around to get full answer
to a complex question.  The above quote is about two clicks removed from 
wikipedia reference - and there are other facts nearby which may be of interest.

Hedfie

Thanks for the follow up.  And, happy new year.

Some interesting reading:
http://www.junkscience.com/news/robinson.htm

There are also many other articles that can be found at
junkscience.com and many other sites that don't buy into the hype of
global warming.

http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change

This is a complex issue, and I find it useful to split "global
warming" into 3 parts:

1) Has the climate warmed in the recent past?
2) Will the climate continue to warm?
3) Are human activities responsible for a significant fraction of the warming?

The answer to #1 is clearly "yes".  The answer to #2 is necessarily
speculative, and also depends somewhat on the answer to #3, but nearly
all recent predictions that I have seen call for continuing increases
in global temperature.  Question #3 is the really tricky one.  Some of
the warming in the past couple hundred years is clearly due to natural
causes, but the recent studies I have seen indicate that if there was
no effect from human activities, the global climate should have
stabilized, or even cooled a bit recently.  So the continuing
temperature increase seems to indicate that human activity is the
cause.  We'll know for sure in a couple hundred years.

With reference to the above comment and Hedgie's last clarification,
the problem for scientists who seriously question the "consensus" is
that they cannot support a refutation of it, so they have to deal with
its projections, although these are are not as well founded as their
proponents would like us to believe.  Those in opposition can point
out that 200 years is just a blink in the history of the earth and
that there seems to be increasing information that the climate has
changed over short periods in the past, but as scientists, if they
cannot prove that the consensus is wrong, they can just point out the
weaknesses in the arguments  - and no one can prove projections into
the future unless we are talking about repeatable experiments, which
is the measure of scientific work.

Just as an aside:  When one considers how difficult it is to get
governments to spend money on projects like education that would bring
immediate and demonstrable results, it is remarkable how much they
spend  - and want companies to spend (your and my money) -  to PERHAPS
reduce global warming with its possible effects in the dim and distant
future.

When the NASA satellites measure the surface of the planet on a
regular basis, and report there is no significant change in the
average temperature, only a redistribution, how on earth do you "peer
review" those measurments, except to analyze the accuracy of the
measurements or debate the points selected?

Is NASA junk science?