On the Persistenceof Climate Change

[danieldwilliam]

In converation with Andrew Ducker I wondered aloud how long the effects of climate change would continue for after we stopped emitting carbon dioxide.

 

The best guess seems to be 1,000 years. Some modelling done by the Canadian Center for Climate Modeling and Analysis suggests that even if we stopped emitting CO2 into the atmosphere we would still be experiencing the impact a millenium from now.

 

This appears to be due to the persistence of CO2 and other greenhouse gases in the atmosphere in the atmosphere. We can expect elevated levels of greenhouse gases for hundreds of years after we stop emitting them. Along side the continued warming effect of greenhouse gases it takes a long time for the additional heat trapped on the surface of the planet to make its way into the various climate systems. The key system for the long tail of climate change seems to be the deeper levels of the southern oceans. Additional heat moves slowly into these systems until it ends up next to the Antartic ice-sheets. These in turn eventually melt leading to an increase in sea-levels of 4 meters.

 

If we stopped emitting CO2 in 2100 the model predicts some 55% of excess carbon emitted during the industrial period would still be in the atmosphere in the year 3000. The changes in climate as a result of the two effects of accumulated climate change persisting into the future and the unwinding of climate change as the distribution of CO2 changes seem to drive significant regional variation with the southern hemisphere seeing increases in tempreture after 2100 and the nothern hemisphere seeing tempretures fall back after 2100.

 

Two big worries flagged up by the model are continuing warming of Antartic seas and the consequent loss of ice from Antartica and a drying effect on northern Africa.

 

The modelling goes out for thousand years and doesn’t appear to show the effects peaking and then reversing over the model’s period.  They are still accumulating a thousand years from now.

 

As a caveat, this is one study. The climate is probably the very definition of a non-linear chaotic system and I think climate change modelling is highly dependent on all sorts of best estimates about things we don’t really understand at all well.  But it’s the best we have.

 

I have to say I’m surprised and dismayed. I’d thought that we would start to see a reversal of climate change within a hundred years or so of us reducing carbon emissions below their aborbsion rates.

 

My source for this is here

 

http://sos.noaa.gov/Docs/ngeo1047-aop.pdf

Comments

[danieldwilliam.livejournal.com]

Aye – I share the general optimism, not that things will be fine without us having to take action but that we’ll be able to make a good and noble life if we chose. Every year technology makes it just that little bit easier and every year the economic growth of the Not First World makes it a bit easier for them.

I also share your view that being depressed or angry about this isn’t going to help.

On using fossil fuels until they are all used up: I’m not so sure. The current marginal price of a barrel of oil or a therm of gas or tonne of coal, puts a floor under the cost of renewables. If you can get below the floor then you win. If you can build a renewable energy system that is cheaper than the current marginal cost of fossil fuels then the hydrocarbon stays in the ground. Which is what I think we’re about to see with solar PV. It’s already cheaper than hooking up to a diesel generator in rural India.

This rather puts the onus on hydrocarbon producers to cut the cost of developing marginal deposits. Which I’m sure they will have a go at. But I think they are on a sticky wicket with that as they are trying to do something which is increasingly hard, increasingly cheaply, compared to the RE sector which is trying to do something increasingly easy, increasingly cheaply.

Or putting it another way. Hydrocarbon extraction will reach the point where each project is substantially unique whilst RE will be doing the same thing again and again.

[f4f3.livejournal.com]

That's an excellent point - I did say that the renewable options would become economically viable, but didn't think we were that close.

And on living a good and noble life - Hillhead Underground Station is being renovated just now. At the top of the escalators is a 30 foot stretch of wall which used to be blank, but now there's an Alisdair Grey quote painted across it: "Work As If You Live In The Early Days Of A Better Nation." I can't think of a better message to greet us as we set off on the working day.

[danieldwilliam.livejournal.com]

I love that quote and have done since the day I first heard it.

[danieldwilliam.livejournal.com]

Yeah, some of them are pretty close to cost parity. It’ll be solar PV first, creeping away from the equator as the cost falls and the efficiency improves. I think as soon as they start to hit parity that increases the rate at which the cost falls as the factories really gear up for mass production.


On-shore windfarms look like they will hit parity with gas power stations next decade. The rest will be a while yet. Some of the changes in infrastructure we’ll need to make to accommodate solar PV will help pave the way for them to be cheaper.

It frustrates me somewhat when climate change denier types unfavourably compare the cost of RE technologies today with the cost of hydrocarbon today. We’ve been burning coal to turn water into steam for more than 200 years. We might have learned how to do it pretty well after making the millionth steam turbine.