[Vision2020] U of I Sustainability Symposium Wed. 3-30-11: "McKibben calls for global uprising against fossil fuels"

[Paul Rumelhart]

On 04/01/2011 11:44 AM, Ted Moffett wrote:
> There was no mention of rising sea levels from climate change, which
> should always be emphasized in discussions of climate change impacts.
> Even if adaptation to negative climate changes on land (heat waves,
> flooding, drought, fires, desertification, agricultural failures,
> species extinction, etc.) are more successful than might be predicted,
> the global impact of only a one meter rise in sea level by 2100 (and
> futher future increases based on positive long term feedbacks) would
> be immense, including displacement of human populations and
> destruction of important coastal infrastructure and agriculture:
> "Global sea level linked to global temperature" Proceedings of the
> National Academy of Sciences:
> http://www.pnas.org/content/106/51/21527.full

I'm afraid the numbers just don't add up.  To obtain the frequently 
cited 1m sea level increase by 2100, the average rate of increase would 
need to be:

1m = 1000 mm, 2100 - 2011.5 = 88.5 yrs, avg rate of increase = 1000 mm / 
88.5 yr = 11.30 mm/yr

This paper 
(http://www.jcronline.org/doi/pdf/10.2112/JCOASTRES-D-10-00157.1) from 
the Journal of Coastal Research gives a value derived from U.S. tide 
gauges of 1.7 mm/yr.  That's off the required amount by a factor of 
6.6.  Satellite altimeters give readings of around 3.15 mm/yr since 
1993, which conflicts with the tide gauge record.  This is still short 
of the needed average increase by a factor of 3.5.

So, to get there, we need an acceleration in the rate of increase, 
right?  Well, unfortunately, the paper cited above 
(http://www.jcronline.org/doi/pdf/10.2112/JCOASTRES-D-10-00157.1) 
concludes that there has been no acceleration in sea level rate of 
increase in U.S. tide gauge records during the 20th century.

So while it's not impossible that we'll get a 1m increase in sea level 
rise by 2100, it doesn't look likely at this point without a rapid 
acceleration in sea level rise starting right now.  And the longer we 
wait before we see a rapid acceleration in sea level rise, the faster it 
will have to happen to reach that number.

Paul