[Coral-List] Bleaching

Douglas Fenner douglasfennertassi at gmail.com
Sun Apr 10 20:12:44 UTC 2022

You wrote that "if all sources of Co2 were stopped today it would take
about  half a century for Co2 levels to drop to pre-industrial
levels;"  That appears to be a bit of an understatement.  From
Wikipedia: "Carbon
dioxide has unique long-term effects on climate change that are nearly
"irreversible" for a thousand years after emissions stop (zero further

"If temperature rise will stop at 2 degrees or at 5 degrees, the sea level
will continue to rise for about 10,000 years. In the first case it will
reach 8–13 metres above pre-industrial level and in the second 28–37 metres.
(That would happen, of course, because CO2 will remain in the atmosphere,
keeping temperatures elevated well above the past and the ice melting, for
much of that time, decreasing gradually.  The point is not the exact length
of time, but the fact that CO2 stays in the atmosphere for a very long time
unless something like forests removes the CO2.  Of course, a good portion
of it gets dissolved in the ocean.  And humans can influence a lot of this,
so the future of coral reefs do still depend on what people do in the

"The 20-year global warming potential
<https://en.wikipedia.org/wiki/Global_warming_potential> of methane is 84.
[5] <https://en.wikipedia.org/wiki/Atmospheric_methane#cite_note-5>[6]
<https://en.wikipedia.org/wiki/Atmospheric_methane#cite_note-Gunnar2013-6> That
is, over a 20-year period, it traps 84 times more heat per mass unit
than carbon
dioxide <https://en.wikipedia.org/wiki/Carbon_dioxide> (CO2) and 105 times
the effect when accounting for aerosol
<https://en.wikipedia.org/wiki/Aerosol> interactions.[7]
"Methane has a large effect but for a relatively brief period, having an
estimated mean half-life of 9.1 years in the atmosphere,[21]
[*page needed <https://en.wikipedia.org/wiki/Wikipedia:Citing_sources>*]
carbon dioxide is currently given an estimated mean lifetime of over 100
(Interestingly, a note above this Wikipedia, on that same web page, says
that parts of the info on that page need updating, in particular, the
anthropogenic methane emissions are underestimated in the article, and the
natural emissions are overestimated, as reflected in more recent findings,
so the page needs updating.  That's what it says.  We all live and learn as
new information comes in.)

If you dispute these quotes from Wikipedia, please provide us with quotes
from another Encyclopedia or authoritative source that show they are wrong.

Source for the following information: Table 2.14 in the IPCC AR4 WG-I Report

Greenhouse Gases: How Long Will They Last in the atmosphere?
Greenhouse GasLifetime (Years)100-Year GWP
Carbon Dioxide (CO2) *hundreds* *1*
Methane (CH4) 12 25
Nitrous Oxide (N2O) 114 298
Hydrofluorocarbon-23 (CHF3) 264 14,800
(The lower 100-year number for methane compared to the 84 for 20 years is
because the methane decreases over that 100 year period.  The larger
100-year numbers are because of the combination of a longer lifespan in the
atmosphere and the much greater absorption of infrared radiation per unit
of gas.  You can see why some have advocated for banning CHF3 in cooling
systems like refrigerators and air conditioners, that 14,800 number.  It is
an incredibly powerful greenhouse gas, and relatively easy to reduce
emissions to near zero quickly)

Why does it matter?  Because global warming and climate change, producing
mass coral bleaching and acidification, are projected to be the greatest
threat to the future of coral reefs, and to destroy coral reef ecosystems
in the next few decades and turn them into algae beds and/or rubble beds
with few fish.  Let alone what it will do by the end of the century, and do
to people.  And CO2 emissions, deforestation, methane emissions, etc etc
are the primary causes.  All well documented.

Those who have been reading coral list for some time may remember that I've
posted before that I've heard from several people who know Gene, who say
that he is a nice guy, and I don't doubt it for a minute.  And if I didn't
make it clear before, I am happy to do so now, that I fully respect his
contributions to both geology and the study of coral reefs.  I think his
posts on topics other than climate change have been very helpful to
coral-list, and if I haven't said that, I'm glad to say that now.

But, if Gene posts things publicly on coral-list that are factually
incorrect, or misleading, I think it is necessary for those things to be
corrected on coral-list.  And it is not personal with him, anybody who
posts something factually incorrect (including me!!!) needs to have the
public record corrected.  As scientists, I think we're in the business of
facts and evidence, and trying to discover the truth, and open discussion
is important.  Those who are in the best contact with reality have a
distinct advantage, much as a person who has a clear windshield on their
car has a clear advantage over someone trying to drive with their
windshield blacked out, since crashes will result.  And just because
someone like me thinks Gene's gotten something wrong doesn't make it so,
and that's an open topic for open discussion of course.  I'd be more than
pleased if someone else would like to post corrections when he states
things that are factually incorrect or misleading, but I think someone
needs to do it, since these are matters important to the future survival of
coral reefs.

Cheers, Doug

On Wed, Apr 6, 2022 at 1:22 AM Eugene Shinn via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Thanks Austin, I have become so used to broken promises by governmens
> and businesses that it just bounces off. I recall many climate change
> authors claiming that if all sources of Co2 were stopped today it would
> take about  half a century for Co2 levels to drop to pre-industrial
> levels. Reducing present levels in 8-years is not realistic. Gene
> _______________________________________________
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> Coral-List at coral.aoml.noaa.gov
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