Tropical coral reef habitat in a geoengineered, high-CO2 world

[Andrew Lockley]

Poster's note:  Hopefully the author (see cc ) will be kind enough to submit her paper to this list, as I lack a URL or copy

Citation

Couce, EM, Irvine, PJ, Gregorie, L, Ridgwell, AJ & Hendy, E 2013, ‘Tropical coral reef habitat in a geoengineered, high-CO2world’. Geophysical Research Letters, vol 40.

Abstract

Continued anthropogenic CO2 emissions are expected to impact tropical coral reefs by further raising sea surface temperatures (SST) and intensifying ocean acidification (OA). Although geoengineering by means of Solar Radiation Management (SRM) may mitigate temperature increases, OA will persist, raising important questions regarding the impact of different stressor combinations. We apply statistical Bioclimatic Envelope Models to project changes in shallow-water tropical coral reef habitat as a single niche (without resolving biodiversity or community composition) under various Representative Concentration Pathway and SRM scenarios, until 2070. We predict substantial reductions in habitat suitability centered on the Indo-Pacific Warm Pool under net anthropogenic radiative forcing of ≥3.0 W/m2. The near-term dominant risk to coral reefs is increasing SSTs; below 3 W/m2 reasonably favorable conditions are maintained, even when achieved by SRM with persisting OA. ‘Optimal’ mitigation occurs at 1.5 W/m2 because tropical SSTs over-cool in a fully-geoengineered (i.e. pre-industrial global mean temperature) world.

Key Points:

• Large reductions in reef habitat suitability under net radiative forcing >3 W/m2
• Rising SSTs are greater threat for tropical coral reefs than ocean acidification
• Solar Radiation Management may help maintain coral reef habitat over near-term

[Andrew Lockley]

Please see below and attached.

A


---------- Forwarded message ----------
From: E Couce <E.C...@bristol.ac.uk>
Date: 15 May 2013 12:47
Subject: Re: Tropical coral reef habitat in a geoengineered, high-CO2 world
To: Andrew Lockley <andrew....@gmail.com>
Cc: geoengineering <geoengi...@googlegroups.com>


Dear Andrew and all,

thanks for the interest on the paper. It can be accessed on
http://onlinelibrary.wiley.com/doi/10.1002/grl.50340/abstract

Attached is an unformatted draft (also available for download free of
charge on my website)

Best regards,
Elena

--

-------------------------------
Dr. Elena Couce
School of Geographical Sciences
Department of Earth Sciences
University of Bristol
E-mail: E.C...@bristol.ac.uk
Web: http://www.bristol.ac.uk/earthsciences/people/elena-m-couce

[Oliver Tickell]

This problem of ocean acidification is surely best solved by application
of ground up olivine bearing rock to land / coast, so removing carbonic
acid and replacing it with alkaline Mg++ and HCO3- (bicarbonate). The
runoff from land will of course end up in the oceans.

Oliver.

[Andrew Lockley]

That would surely depend on the ocean circulation around reefs. It
would be impractical to exert short-term control over reef pH if the
surrounding water was from the ocean. Only where ripurine and coastal
flows were a significant part of the local budget would adjusting the
pH of either be effective. There's only so much adjustment to a
river's pH you could make before destroying its ecosystem, so
well-mixed reef water wouldn't be controllable using river pH tweaks.

A

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[Oliver Tickell]

Where there is a specific need to reduce acidity around a particular
coral reef, or other location, of course you would want to target the
ground rock application to that particular place. This might indeed be
to land in a catchment from which streams run into a coral lagoon, for
example, or it may be to beaches where dissolution would be helped by
wave action. It would also be possible to grind the rock to
nanometer-scale dimensions so as to rapidly dissolve the rock in the
water. However the much larger energy input required to grind very fine
powders would make this less effective in reducing global CO2.

Oliver.

ps - agreed that you would want to be careful of raising river pH too
much - but remember we are already reducing river pH by CO2 / SO2 / NOx
acidification.