[SustainableTompkins] [tcrp] Avoiding the GHG tipping point

[Jen Maffett]

In a conversation with a guy at NRDC last year, I was told that if we all
stopped driving tomorrow, it would take 100 years to start to feel a
reversal. They would be a good source for stats.

Jen


On 10/5/06, bosak at ibiblio.org <bosak at ibiblio.org> wrote:
>
> A scientific opinion widely quoted recently is that we will reach
> a "tipping point" where climate change becomes irreversible when
> the atmospheric concentration of CO2 reaches 440 ppm.  (We're
> currently at about 382 ppm and at present rates of increase will
> hit the 440 mark in about twenty years.)
>
> It should be obvious that there are a lot of problems with setting
> a specific figure like this, but it's useful in trying to
> understand the situation.
>
> What I want to know is, by what percentage would current world
> consumption of fossil fuels have to decrease in order to avoid
> hitting the tipping point?  There would appear to be a lot of
> hysteresis (i.e., time lag) involved, so the amount of reduction
> would have to be more than the amount needed to maintain a steady
> state once we got there, but how much is that?  Fifty percent?
> Sixty?  Eighty?
>
> Has anyone crunched the numbers on this?  For purposes of
> discussion, I need just one credible, conservative estimate of the
> amount we'd have to reduce global fossil fuel consumption,
> starting today, in order to avoid hitting 440 ppm.  (It would be
> best to have several estimates, since they're bound to differ
> depending on methodology used, but I'd be happy to have just one.)
>
> Jon
>
>
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