[Coral-List] coral reefs in 5th (U.S.) National Climate Assessment

[Douglas Fenner]

Mass coral bleaching due to heatwaves which are increasingly caused by
global warming is widely considered to be the greatest future threat to
coral reefs, and has probably already killed more coral colonies than
anything else that humans do.

The report can be accessed at:

https://nca2023.globalchange.gov/

To quote from the report:

"Even short-term extreme events such as heatwaves78
<https://nca2023.globalchange.gov/chapter/8/#fn:78>,79
<https://nca2023.globalchange.gov/chapter/8/#fn:79>,80
<https://nca2023.globalchange.gov/chapter/8/#fn:80> can generate
significant species impacts. For example, coral reefs are threatened by
cumulative impacts of ocean warming and acidification, marine heatwaves
resulting in bleaching and higher susceptibility to diseases, increasingly
powerful tropical cyclones causing loss of structural complexity, hypoxia
(low oxygen) events, overfishing, and pollution (Figure 8.10a
<https://nca2023.globalchange.gov/chapter/8/#fig-8-10>, b
<https://nca2023.globalchange.gov/chapter/8/#fig-8-10>; Box 10.1
<https://nca2023.globalchange.gov/chapter/10#box-10_1>; KMs 9.2
<https://nca2023.globalchange.gov/chapter/9#key-message-2>, 10.1
<https://nca2023.globalchange.gov/chapter/10#key-message-1>).81
<https://nca2023.globalchange.gov/chapter/8/#fn:81>,82
<https://nca2023.globalchange.gov/chapter/8/#fn:82>,83
<https://nca2023.globalchange.gov/chapter/8/#fn:83>,84
<https://nca2023.globalchange.gov/chapter/8/#fn:84>,85
<https://nca2023.globalchange.gov/chapter/8/#fn:85>,86
<https://nca2023.globalchange.gov/chapter/8/#fn:86>"  (quote from chapter
8   https://nca2023.globalchange.gov/chapter/8/ )
Reference 81: Carlson, R.R., S.A. Foo, and G.P. Asner.  2019. Land use
impacts on coral reef health: a ridge-to-reef perspective. Frontiers in
Marine Science 6: 562.

Reference 82: Evensen, N.R., Y.-M. Bozec, P.J. Edmunds, and P.J. Mumby.
2021. Scaling the effects of ocean acidification on coral growth and
coral-coral competition on coral community recovery. PeerJ 9: e11608/

Reference 83: Johnson, M.D. et al. 2021. Rapid ecosystem-scale consequences
of acute deoxygenation on a Caribbean coral reef. Nature Communications 12
(1) 4522.

Reference 84: Magel et al, 2019. Effects of bleaching-associated mass coral
mortality on reef structural complexity across a gradient of local
disturbance. Scientific Reports 9(1) 2512

Reference 85: Sampaio, E.C., et al 2021. Impacts of hypoxic events surpass
those of future ocean warming and acidification. Nature Ecology & Evolution
5(3) 311-321.

Reference 86: Smale, D. A. et al. 2019. Marine heatwaves threaten global
biodiversity and the provision of ecosystem services. Nature Climate Change
9(4) 306-312.


The report has loads of information on the climate change that threatens
coral reefs, including things like:

Present-day levels of greenhouse gases in the atmosphere are higher than at
any time in at least the last 800,000 years

The rate of sea level rise in the 20th Century was faster than in any other
century in at least 3000 years.

Global temperature has increased faster in the last 50 years than at any
time in at least the past 2000 years.

The current drought in the western US is now the most severe drought in at
least 1200 years and has persisted for decades.

Wind and solar energy costs dropped 70% and 90% respectively over the last
decade, while 80% of new electricity generating capacity in 2020 came from
renewable sources.

Between 2018 and 2022 the US experienced 89 weather events that each
cost a billion dollars or more.  Extreme weather events cost the US over
$150 billion dollars a year.   Florida alone had $90 billion in costs
between 2018 and 2022.

Land areas are warming faster than oceans, and polar areas (particularly
the Arctic) are warming faster than tropical areas.

In other news, the last 12 months were the hottest 12 months in recorded
history, and 2023 is likely to be the hottest calendar year in
recorded history.

https://www.nature.com/articles/d41586-023-03523-3?WT.ec_id=NATURE-202311&sap-outbound-id=B2FD55754B1E18A2FF3F0FDFC89C7D069C43BF7F

Cheers, Doug

-- 
Douglas Fenner
Lynker Technologies, LLC, Contractor
NOAA Fisheries Service
Pacific Islands Regional Office
Honolulu
and:
Coral Reef Consulting
PO Box 997390
Pago Pago, American Samoa 96799-6298  USA

Huge expansion of fossil fuels planned, will be very destructive
https://www.theguardian.com/environment/2023/nov/08/insanity-petrostates-planning-huge-expansion-of-fossil-fuels-says-un-report

"without policy changes, the world will heat up enough by the end of the
century that more than 2 billion people will live in life-threatening hot
climates"         Will you be in that area???
https://www.yahoo.com/news/scientists-sounding-alarm-dangerous-problem-123000792.html

World subsidies for fossil fuels reached an all-time high of over $1
TRILLION in 2022, the last year for which data is available.  The subsidies
MUST end.

https://blogs.scientificamerican.com/observations/fossil-fuel-subsidies-must-end/