Thank you folks for your contributions. It has been educational.
I feel the purpose of this thread has been fulfilled and now is a good time to close it. As you may have guessed, it was not about the arguments of climate change deniers.
Closing it also allows me to go completely off topic again and express my own views as a layman on the climate change discussion. Here goes.
There are two types of religious fundamentalists: those who believe nothing in the bible is true and those who believe everything in it is true. Both do err.
We've seen the same thing in the climate change debate. That's not surprising that it borders on a religious debate. People naturally look for final and definitive answers where the reality may be quite different. I tend to avoid discussions with both groups of true believers.
There is no doubt that there is a link between human activity since the industrial revolution and a rise in greenhouse gasses. There is no doubt of a link between a rise in greenhouse gasses and global warming. There is no doubt of a link between global warming and climate change. This is very basic research.
The question is whether the links are causal and whether climate change will be catastrophic.
In the case of the link between human activity and greenhouse gas the answer is yes, it's causal. CO2 levels over centuries are relatively easy to measure both directly and indirectly, and to attribute a source. Other gasses such as CH4 are a little more difficult I believe. How do you measure the amount of cow farts from industrial-scale farms?
To keep this short, I'm lumping global warming and catastrophic change together when looking at their link to the rise in greenhouse gasses.
There may be several ways to establish a causal link. One is to look for answers in the physics and chemistry of the atmosphere. Another may be to establish a model with a proven predictive ability.
The problem with the latter is that it may be too conservative. You will know as photographers that side effects from editing an image in Photoshop are both cumulative and multiplicative. The same for the climate. Example: we don't know the effect of the release of CH4 from melting permafrost. We believe there is a huge amount locked up but we don't know. We aren't sure about the effect on the planet's albedo from human activity such as aircraft exhausts. In the USA scientists were able to measure that when air traffic was shut down after the Twin Towers attacks. From memory I think it was in the order of one to two degrees C cooling.
Another option is observation. We are doing that now and I find that approach convincing. I'm not looking for ironclad proof. That's a waste of time IMO.
So I'm in the camp of a likely catastrophic change. But nasty as that experience may be, I hold some hope for the outcome. Hope however is more religious than scientific, so if you are uncomfortable with that stop reading now (I'm influenced by the work of Thomas Berry).
Violence is part of the natural order from the beginning of the universe, but not its main purpose. As far as I can tell the main aim of the universe is beauty, perhaps along with an evolving awareness of justice, mercy etc. Example: the emergence of carbon and its spread throughout the universe over billions of years would not have been possible without the cataclysmic implosion of countless stars.
Chaos and cataclysm seem built into the DNA of the universe in order for new forms to emerge, and its creative energy to continue.
Apart from the climate, we are seeing the breaking down of our cultural institutions: the economy, religions, education etc.
Many of our institutions are incompatible with life on Earth. Example: free market capitalism and the beliefs of our religions about our place in the universe. What is our place in the universe? I'll take a stab at that. Every species has something unique. Humans seem to have the unique ability of reflective consciousness. The ability of creation to look at itself. That humans are now capable of destroying all life on Earth is evidence of their importance here.
So my hope is that this destructive period is a process of emergence that will end in something better for our world. However it's just that, a hope.
It would be usual to end with some fancy quote on the nature of hope. Google is your friend here.
David