1. "We know that CO2 acts as a 'greenhouse' gas, we know raising atmospheric levels of it will lead to a greater atmospheric heat retention, we know human activity has raised atmospheric levels over the last century, and we know mean temperatures have risen abnormally over the last century. So in my view it's reasonable to take a rebuttable position that agw is likely (and to try to do something about it). "
2. "We know that CO2 acts as a 'greenhouse' gas," Agree
3. "we know raising atmospheric levels of it will lead to a greater atmospheric heat retention," yes, but only if other factors are equal.
4. "we know human activity has raised atmospheric levels over the last century," Disagree --------- we know human activity has raised atmospheric levels over the last century OF MAN PRODUCED CO2 - not necessarily all CO2 -------- most 'probably' yes ---------- but NOT from the generation of CO2 from fossil fuel burning DIRECTLY.
5. "and we know mean temperatures have risen abnormally over the last century." Agree.
6. " So in my view it's reasonable to take a rebuttable position that agw is likely (and to try to do something about it)."
This is where I have a huge problem with AGW and man produced CO2 ---------
The problem lies between the links of 4 and 6.
I am almost certain that the CO2 produced in burning fossil fuels has bugger all to do with the problem.
However, I do believe the catalyst for the problem is burning fossil fuels.
Now I know you will read those last two sentences in detail - I would ask other readers to read them again to make sure my words are clear please.
I strongly suspect it is the other factors (similar to what you mentioned later eg. "There may be other factors that come into play: global dimming, algal blooms,")
that are the real problems in the equation.
I believe most of the problem comes at the absorption side of the equation and also other atmospheric pollutants - like jet trails, vapour and the like - which may well cause the absorption side problems.
Now, I cannot prove this - nor can anyone - why?
Because everyone and his dog has been funding man made CO2 --- there are so many trees to bark up and we have mainly been barking up one ------------ and imo, the wrong one.
Now, if we have a problem ---------- and, again, I am not sure if we have - I will explain that last comment at the bottom ---------- IF we have a problem -- and, we think the problem comes from burning fossil fuels - then we should just get on engineering our lives to get rid of them ---
no matter what the cause - CO2, vapour, god knows what.
Now, to a degree we have done that - but in the most stupid and ridiculous ways -------------------- for god's sake - a carbon tax???????????
1. It's a negative reinforcement - never works well.
2. It is so inefficient in fixing the problem it is ridiculous.
3. There are no inducements whatsoever - a couple of half arsed subsidy schemes for solar and wind - which when the cost of solar dropped through the floor were withdrawn and minimised rapidly for a variety of reasons. AND almost all of those systems ------ ie. solar and wind were the most ridiculous environmental systems you could think to invent.
4. You completely hobble your economy to put a system in place that is going to do stuff all for your perceived problem.
And we did and do all of this ------------ with very limited knowledge of what makes climate work.
Worse still --- we know environmentally and economically all this wind/solar stuff was a load of crap - years ago. It NEVER stacked up.
Now I want clean power, cheap power and environmentally minimal damage power ---------- I believe we deserve it, I believe we owe it to the planet to engineer it ------- but what we have done so far is the exact opposite - all while barking up what I am pretty sure is the wrong tree.
imo, we would have done far better to put what must be trillions now into searching for a real answer -----
write a few cheques and lock a heap of pizza eating coke drinking pimple heads and scientists in a room for a few years and don't let em out until they come up with something that actually works ----------- generation and/or storage.
Instead, we have spent gargantuan sums on building windfarms like forests - that use enormous amounts of energy and resources in their construction - pollute the landscape and fall flat on their bum in efficiency - they never stacked up. Solar systems that if you measure overall what they cost - in dollars and energy to make - just aren't worth it in the end.
I have a mate in NZ who is an energy consultant - and imo a pretty good one (and I don't think that because he is a mate - most of my professional mates I wouldn't employ :) ) -
Anyway, he has consulted on a wide range of things - wind, solar, algae, grasses, wood pellet schemes in Germany - etc..
He did some major solar plants in Europe and China - and he says - basically "it's all bullshit" ------- well, hello, I knew that.
It is my opinion that we should have tipped a lot of money into researching better engineering BEFORE we jumped in and started building these very inefficient systems. I am sure they have a place in the future (possibly if not probably) - but to dive in head long like we have is an atrocious waste of time, money, energy and other resources.
anyway - that's pretty much my thoughts and I have probably bored you to death.
One last point that I said I would come back to
"Now, if we have a problem ---------- and, again, I am not sure if we have"
the 'problem' I was referring to is - AGW -------- we have been seeing it as a problem.
What if it isn't a problem?
What if it is real and it has actually been saving us from going guts up into the next glacial period?
Look at the graphs of interglacial periods ------- now aside from what derty has been saying - if I assumed he was right - then AGW could well be a problem or at least problematic --
however, if he is wrong and our predictions for not entering an new glacial period are WRONG - and nature was heading for another glacial period right on time -------
then AGW could well be saving our butts ---------- BIG TIME.
If that is the case then AGW might very well be the reason why we are sitting here tapping on a computer as opposed to grinding a stone axe on a big rock.
So, for me - I am not even sure if we have a problem.
anyway - I need a coffee ---------- thanks again for you input and have a great day all
