Climate Change due to Global Warming – a hoax?

[Bored Wombat]

Originally Posted by cbacba

the last million years is chosen because it's the only time in the last 550 million years+ where co2 levels have been anywhere close to as low a level as they are at present.

It's not easy to establish CO2 beyond the ice core record. Most reconstructions seem to have CO2 levels below about 500ppm for the last 40 or 50 million years. Certainly for the Neogene period, about 23 million years ago.

So nearly none of the flora and fauna that you see around has had to endure a climate that we are returning the world to. Your own ancestor of the time preceded Proconsul africanus who looked perhaps a bit like this:

If you don't look much like that any more, then can I recommend a climate that you did co-evolve with?

[Slade]

I think aerosols have a lot more to contribute regardless of what most people think seeing as CFC's remain in the atmosphere for centuries.

[Bored Wombat]

Originally Posted by Slade

I think aerosols have a lot more to contribute regardless of what most people think seeing as CFC's remain in the atmosphere for centuries.

Don't confuse aerosols with aerosol sprays.

Aerosols are fine particles suspended in the air, (which is what an aerosol spray kind of accomplishes). They're opaque, and so cause a cooling effect by simply blocking sunlight. About 10% of aerosols are human generated, and they are concentrated near industrial sites.

CFC's have the opposite effect, being a greenhouse gas. But also CFC emission is moderated by the Montreal protocol, established to preserve the ozone layer, so we don't emit them much any more.

They are, as you say, long lived in the atmosphere.

[cbacba]

Originally Posted by Slade

I think aerosols have a lot more to contribute regardless of what most people think seeing as CFC's remain in the atmosphere for centuries.

I'm wondering if they've ever actually discovered any of these long lived molecules actually in the upper atmosphere. At one time it was assumed they were dispersing upwards because they expected to see more hanging around the ground, but I think that was before they realized the stuff gets absorbed by plants or trees as well.

aerosols are particulates and like clouds reflect incoming light, increasing the albedo.

as for precisely knowing all that is necessary to predict global warming, it seems there is uncertainty in the albedo of the earth to the tune of estimates varying from 29% to 36% with most thinking it's 30% or 31%. When they get it down to about 1 / 100th of a %, they'll be a small step closer to being able to estimate climate models out to a few weeks, maybe even without serious fudge factors.

[Bored Wombat]

Originally Posted by cbacba

When they get it down to about 1 / 100th of a %, they'll be a small step closer to being able to estimate climate models out to a few weeks, maybe even without serious fudge factors.

Did you know that HadCM2 was run for a couple of millennia without drifting? (And no correction factors)

Did you know that that is about one and a half generations of climate model ago?

Did you know that six months ago a predictive climate model was built and run by the Hadley Centre, that had no fudge factors, just the current state of the atmosphere and ocean, plus various emission scenarios? It is designed to do 10 year predictions.

That's strange, I would have thought that I'd have mentioned these things to you by now.

Oh well, we'll just go through this again next time you forget, shall we?

[cbacba]

then maybe they should tell the weather forecasters how to do it so they can forecast whether it's going to be cloudy or clear tomorrow night, whether it's going to rain tomorrow, and what the temperature is going to be high and low to within 2 degrees.

when they do that, then they will have made some headway. otherwise they have a random number generator.

[Bored Wombat]

Originally Posted by cbacba

then maybe they should tell the weather forecasters how to do it so they can forecast whether it's going to be cloudy or clear tomorrow night, whether it's going to rain tomorrow, and what the temperature is going to be high and low to within 2 degrees.

when they do that, then they will have made some headway. otherwise they have a random number generator.

I don't think HadCM3 would be that good at doing weather predictions. The smallest resolution is a couple of hundred km.

Do you know the difference between weather and climate?

[cbacba]

basically, climate is weather averaged over about 30 years. To make a sophisticated model requires knowing the weather for a rather long time.

[Bored Wombat]

basically, climate is weather averaged over about 30 years. To make a sophisticated model requires knowing the weather for a rather long time.

Because it's an average, you can use a less detailed model.

Weather modelling is done on a much finer scale than climate modelling.

[cbacba]

unfortunately for gcm total modelling, the phenomenon needs to be at a finer resolution to avoid missing out on that which determines the future averages.