Re: [Phys-l] Is Global Warming really a one-sided point of, view ora scientif...

[David Appell <appell@nasw.org>]

LaMontagne, Bob wrote:
> OK, using that interpretation, I took the Jan-December average for the
> last block of data (2001-2008) and transferred the data to Excel for a
> linear regression - it came out to -0.2 degrees Celsius per year.

Bob, that can't possibly be right. That would imply a change of roughly 
-1.8 C in the last 9 years, which would be huge and is over twice the 
magnitude of the warming of the 20th century (0.8 C).

When I use the NASA GISS data, I get the following for yearly averages:

1998	57 	
1998	33
2000	33
2001	48							
2002	56
2003	55
2004	49
2005	62
2006	54 							
2007	57 							
2008	44

On this data I get a linear regression slope of +1.0/yr, although the 
correlation is small (R^2=0.13).

In other words, the slope is positive, and about 0.01 C/yr, or roughly 
0.1 C/decade. Not shabby, and even if you interpret this as a plateau, 
it is nothing earlier, which I showed earlier[2]. Such plateau's have 
happened about three times in the last 35 years, and after all of them 
warming resumed.

(Regressing yearly averages hides some information, and so I prefer to 
use the 5-yr[2] or 10-yr moving monthly average.)

The data simply does not dispute the fact that CO2 is a very strong 
greenhouse gas and warms the planet, though other factors (La Nina, 
sunspots, volcanoes) can temporarily shield such temperature advances.

David

[2] http://davidappell.blogspot.com/2008/11/has-global-warming-stopped.html


--
David Appell, freelance science journalist
e: appell@nasw.org
w: http://www.nasw.org/users/appell
m: St. Helens, OR