2011-03-04 12:45:21Essential points of climate change
John Cook


A local scientist sent me this document where he tries to break down climate change to its most essential points. I thought I'd reproduce it here in case people find it useful:

Climate change: Essential points (draft 4/2/2011)

Graeme S. Halford
Professor Emeritus,
University of Queensland

The following is an attempt to develop a “minimal complexity” account of the climate change issue:

  1. Greenhouse gas levels in the atmosphere have increased since industrialisation.
  2. Greenhouse gases increase the temperature of the atmosphere.
  3. Global average temperatures have increased over the past century.
  4. Global warming is predicted to destabilise climate, increasing the frequency and severity of extreme weather events, including floods, fires, droughts and storms.


Points 1 and 3 are shown by measurement and point 2 can be demonstrated in laboratories. Therefore all of points 1-3 are established beyond reasonable doubt.

Point 4 is more theoretically based, but is still well substantiated by climate models.

Importantly, I think point 4 is more plausible if points 1-3 are accepted.

Points 1 - 4 can be expanded using material in excellent existing sources, such as those listed below.  However it is essential that focus on essential points not be lost.

While recognising that it goes against the grain for leading scientists and academics to make simplistic statements, the complexity of climate change makes it easy for vested interests to sow doubt and confusion. Therefore it is essential that we find a simple, accurate, memorable (SAM) basis on which people can build their understanding of climate change.



The Science of Climate Change: Questions and Answers. Australian Academy of Science, Canberra, August 2010. ISBN 085847 286 4.

The Big Picture: Session 1: What is climate change? www.csiro.au.

Garnaut, R.  What if Mainstream Science is Right? The Rout of Knowledge and Analysis in Australian Climate Change Policy (and a Chance of Recovery?). Proceedings of the Academy of the Social Sciences in Australia, Canberra, 2010.

Sackett, P.  Nature raw in tooth and claw. Sydney Morning Herald, 15-16/1/2011

2011-03-04 20:13:39


I'm not sure I agree with: "point 2 can be demonstrated in laboratories."

That CO2 absorbs IR can be demonstrated; but the GHE also depends on the efficacy of the adiabatic lapse rate and application of radiative transfer theory. Maybe better demonstration is based on the satellite observations of the intensity of the CO2 absorption lines?

2011-03-05 04:03:44
Ari Jokimäki


I think more accurate would be: point 2 has been demonstrated in laboratory tests and in atmospheric measurements. To me the best demonstration is measurements on the ground of the atmospheric back radiation (but sure, the satellite measurements are important too).

2011-03-05 04:46:51



It seems to me that if you want to demonstrate that radiation is NOT escaping through the top of the atmosphere, you have to measure at the top of the atmosphere. If you're going to rely on back-radiation measurements, why not just rely on the theoretical justification based on radiative transfer theory?

2011-03-05 07:30:22
Ari Jokimäki


Well, I'm build that way that I don't usually believe it unless I see it. If I see back radiation increasing in CO2 frequencies, then I believe that CO2 is warming us here at the surface. I don't want to put down theoretical work, but to convince me you need observations.

2011-03-05 07:59:46


But the connection between the back-radiation and the lack of cooling at the top is also theoretical; and it's the decreased cooling at the top that speaks to the GHE.

2011-03-05 18:02:09
Ari Jokimäki


Yes sure, but also the increased warming at the surface speaks to the GHE. Decreased TOA cooling just means that the radiation went somewhere, but increased radiation at the surface means that it indeed arrives back to the surface and creates a warming effect. That's why I consider back radiation changes at GHG frequencies to be the most convincing observation of GHG warming. It is unfortunate that so few spectral observations exist of back radiation.