Re: [Phys-l] gigo

["A. John Mallinckrodt" <ajm@csupomona.edu>]

The characteristics of a waterfall depend on minute details of rock sizes, shapes, and placements, wind currents, temperature, etc. but one needn't know more than the general contour from precipice to pool and the flow rate to know 99% of everything most people might care about.

In the case of global warming we know that CO2 concentrations are far larger than they have been at any point in the last million years, we know how much radiative forcing the increased concentrations of CO2 and other greenhouse gases cause, we know the temperature rise to be expected from that increased forcing, and we are seeing temperature rises pretty much in keeping with those expectations.  Under the circumstances, it seems to me that those who claim there is no human component to the observed warming have a pretty serious obligation to explain how that could be.  To give their clams any credence without demanding that explanation seems to me to indicate a lack of appropriate skepticism.

John Mallinckrodt
Cal Poly Pomona

James Espinoza wrote:

> If a model does not take into account the sun, or clouds, or cosmic rays, or 
> changing orbits,or is incomplete in some other way, and only carbon dioxide 
> matters, how confident can one be about the predictions?
> ... When it comes to global warming it appears that many scientists have 
> lost their skepticism, which I always tell my students is essential in science,
> and physics in particular.