🚀 go-pugleaf

On Fri, 29 Oct 2010 14:05:39 -0500, "SaPeIsMa" <SaPeIsMa@HotMail.com>
wrote:

>>
>> That the surface of the Earth has warmed over the last several
>> decades is a fact supported by many independent sources . . .
>>
>
>Unfortunately, there is NO GOOD EVIDENCE that the warming was caused by 
>humans.
>
I expect it will be difficult to prove that beyond doubt.  However,
many years ago increasing levels of CO2 were predicted to cause
warming, and since then warming has occurred and is continuing to
occur.

That suggests to me that the warming is probably caused by humans.

The IPCC has been saying that the warming is "very likely" caused by
humans--so also not claiming proof.

However, others have formed stronger opinions.  Eg
http://www.france24.com/en/20101028-global-warming-unquestionably-due-humans-france
28 October 2010  

<Start extract>

AFP - Global warming exists and is unquestionably due to human
activity, France's Academy of Science said in a report published
Thursday and written by 120 scientists from France and abroad.

"Several independent indicators show an increase in global warming
from 1975 to 2003. This increase is mainly due to the increase in the
concentration of carbon dioxide," the academy said in conclusion to
the report.

"The increase in carbon dioxide, and to a lesser degree other
greenhouse gases, is unquestionably due to human activity," said the
report, adopted unanimously by academy members.

<snip>


The Academy's report said that "solar activity, which has dropped
slightly on average since 1975, cannot be dominant in warming observed
during this period" even if the mechanisms involved "are not yet well
understood."

"Major uncertainties remain on how to model clouds, the evolution of
marine ice and the polar caps, the connection between the oceans and
the atmosphere, the biosphere's evolution and the carbon cycle," the
report said.

Allegre said it was impossible to predict the climate's long-term
evolution, but the Academy said that "climate evolution predictions of
30 to 50 years are little affected by uncertainties on modelling slow
evolution processes."

"These predictions are particularly useful in responding to society's
current concerns, worsened by the predictable population growth."

The IPCC's deputy head, Frenchman Jean Jouzel, welcomed the report.

"Even if in this text lots of space is given to the arguments put
forward by climate change sceptics, I note that the document clearly
reaffirms the IPCC's broad conclusions," he told AFP.

"Clearly sceptics will find some things to make their case. It says
that not all is clear about the sun's role. The debate is never over,"
he said.

The report was the result of written contributions as well as
closed-door discussions held at the Academy on September 20 and
subsequent exchanges, the Academy said.

<End extract>