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
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.
Human activity contributes a very small proportion to cause #2.
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.
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
(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.)
(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
© Union of Concerned Scientists
US federal agency view:
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.
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.
Request for Answer Clarification by
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
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...
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.