Dying coral reefs and collapsing reef ecosystems: evidence of more progress towards the point of no return on the way to Hothouse extinction

Part 5 of David Spratt’s guidebook to events along the road to Hothouse Hell: Increasingly frequent and stronger marine heatwaves are bleaching and killing corals, architects of reef ecosystems. Rotting organic matter emits GHGs

Coral polyps are the primary architects of the remarkably diverse coral reef ecosystems that border lands and islands in tropical oceans around the world. As such coral reefs provide shelter and sustenance for a significant fraction of our ocean’s biomass for at least part of their lives. Coral polyps are colonial animals related to jellyfish and sea anemones. However, thanks to symbiotic algae that live in their bodies, they are sinks for capturing and sequestering CO₂ in forming the limestone reefs. Over the last 10,000 years or so, they have thrived in waters close to the maximum temperatures their photosynthetic algae can tolerate. However, as the world begins to warm beyond temperatures observed for many 10s of thousands of years corals have had to expel their algae and become bleached. As Spratt describes, bleaching is becoming common event for the Great Barrier Reef, and is leading to dying coral reefs and collapsing reef ecosystems around the world.

As masses of polyps die and rot they become net greenhouse gas emitters (CO₂, methane, hydrogen sulfide – H₂S – where the H₂S is also highly toxic) and end up covered by slimes of bacteria and algae. The dead reef becomes quite toxic, and loses many of the species that originally thrived there through starvation, poisoning, or loss of habitat. Thus, the rising greenhouse gas emissions from dying and decomposing reef ecosystems adds yet another source of positive feedback to drive global temperatures (including ocean temperatures) higher yet.

Great Barrier Reef bleaching 2016

28 January 2022

Have tipping points already been passed for critical climate systems? (5) Coral Reefs: A death spiral

by David Spratt in Climate Code Red
Fifth in a series.
Read 1  |  2  |  3  |  4  |  5  |  6  |  7

Ecosystems, including coral reefs, mangroves and kelp forests in Australia, are degrading fast as the world’s sixth mass extinction gathers pace. 

… 

Corals survive within a narrow water temperature band, and suffer heat stress and expel zooxanthellae if the ocean temperature gets too high. Bleaching events vary in intensity; in the extreme case, all zooxanthellae are expelled and the living colony will appear totally white (hence “bleaching”).  As elevated sea temperatures persist, coral mortality rates increase: corals may recover, if there are any zooxanthellae left in their tissues, but if not, death appears to be inevitable. 

The bottom line: If severe bleaching events occur regularly at shorter than 10–15 year intervals, then reefs face a death spiral of coral mortality followed by inadequate recovery periods. And that is what is happening now. Along Australia’s Great Barrier Reef, the frequency of mass bleaching is increasing, with events occurring in 1998, 2002, 2016, 2017 and 2020.  The 2016-17 events severely bleached half the reef, whose extent has been reduced by three-quarters over the last 40 years. Coral reproduction on the Great Barrier Reef has fallen 89% after repeated recent bleachings.  [My emphasis]

Read the complete article….

Analyses published yesterday shows that it is probably already too late to save dying coral reefs and reef ecosystems (including the Great Barrier Reef) from terminal collapse in the next decade or two

One of these articles is referenced in today’s The Age newspapers.

James Cook University marine biologist Jodie Rummer at work on the Great Barrier Reef. She has witnessed previous bleaching and described it as “scary and disturbing”.Credit:Grumpy Turtle

No climate change refuge for coral reefs: study

by Miki Perkins, 02/02/2022 in The Age

Global warming of 1.5 degrees above pre-industrial levels will be catastrophic for almost all coral reefs, including those that scientists once hoped would act as refuges during climate change.

Only 0.2 per cent of coral reefs globally are likely to avoid frequent heat stress if temperatures warm, according to new research from an international team of universities, including James Cook University in Townsville.

Even thermal refuges, which experts assumed would be more able to endure warming oceans owing to factors such as the consistent upwelling of cool deep waters, would provide almost no protection to reef animals, the study found. It is published today in PLOS Climate.

Read the complete article….

Actually, there were two articles on rapidly rising sea surface temperatures (SST) published yesterday in the science journal, PLOS Climate. Together they seem to seal the fate of most of our planet’s coral reef ecosystems:

Future loss of local-scale thermal refugia in coral reef ecosystems

by Adele M Dixon, et al., 01/02/2022 in
PLOS Climate – https://doi.org/10.1371/journal.pclm.0000004

Global distribution of exposure category in the 1986–2019 climate and at 1.5 and 2.0°C of future global warming. [DHW is the sum of SST anomalies 1°C higher than the long-term maximum monthly mean (MMM) over a 12-week period] Exposure categories are thermal refugia (probability of DHW events > 4°C-weeks less than 0.1 yr‒1), intermediate (probability of DHW events > 4°C-weeks from 0.1–0.2 yr‒1) and exposed (probability of DHW events > 4°C-weeks greater than 0.2 yr‒1). Percentages indicate the regional (on map) and global (right of map) proportion of thermal refugia (blue) and exposed reefs (red). The 12 coral reef regions are outlined in light blue. The base map is made with Natural Earth.

ABSTRACT: Thermal refugia underpin climate-smart management of coral reefs, but whether current thermal refugia will remain so under future warming is uncertain…. We confirm that warming of 1.5°C relative to pre-industrial levels will be catastrophic for coral reefs….

Read the complete article…..

The recent normalization of historical marine heat extremes

by K. Tanaka & Kyle S. Van Houtan 01/02/2202 in
PLOS Climate – https://doi.org/10.1371/journal.pclm.0000007

Decadal evolution of frequency of extreme marine heat from 1980–2019. Extreme heat defined as exceeding the localized (1° × 1°), monthly, 98th percentile of sea surface temperatures (SST) observed during 1870–1919, averaged from HadISSTv1.1 and COBESSTv2 products. Extreme heat, resolved for boreal winter (Jan-Mar) and summer (Jul-Sep), accumulates steadily over time beginning in the Southern, South Atlantic, and Indian basins. Regions of the mid North Atlantic and eastern South Pacific indicate a low occurrence. The base map layer was drawn using the “rworldmap” R package (https://cran.r-project.org/web/packages/rworldmap/index.html:

ABSTRACT: Climate change exposes marine ecosystems to extreme conditions with increasing frequency…. For the year 2019, our index reports that 57% of the global ocean surface recorded extreme heat, which was comparatively rare (approximately 2%) during the period of the second industrial revolution. Significant increases in the extent of extreme marine events over the past century resulted in many local climates to have shifted out of their historical SST bounds across many economically and ecologically important marine regions. For the global ocean, 2014 was the first year to exceed the 50% threshold of extreme heat thereby becoming “normal”….

Read the complete article….

The bottom line: It is almost certainly too late to save the Great Barrier Reef we know from ecological collapse, but we might be able to save keystone species able to rebuild it if we can stop and reverse global warming

Given that we have probably already crossed several tipping points such as permafrost thawing on the road to runaway global warming where natural positive feedbacks will continue working to drive global temperatures ever higher, the Great Barrier Reef as we know it seems to be unavoidably doomed. However, as long as a majority of the keystone architect coral species survive somewhere, they may be able to recolonize their previous ranges and begin building new reefs over subsequent centuries.

Unfortunately, when we should be working all-out to stop anthropogenic greenhouse gas emissions, our present Australian Government lead by Capt. Humbug (AKA Scotty from Marketing) and his deputy Blarny Barney (the Man with the Hat) is working hard to grow and maintain the healthy capacity of the fossil fuel industry to produce and burn carbon for energy. Also, not only are they doing nothing practical to stop and reverse global warming, but they just promised to spend a billion dollars on the Reef (over 9 years) to cloak the fact that they are doing nothing that counts to save the Reef (or for that matter our own human species).

The rapidly approaching Federal Election gives us the opportunity to remove Capt. Humbug and his wooden headed puppets from office and replace them with trustworthy, thinking people who have committed themselves to put work to solve the climate crisis as their first order of business if elected to Parliament. Vote Climate One’s Traffic Light Voting System is designed to help you do this.

Views expressed in this post are those of its author(s), not necessarily all Vote Climate One members.

More than engineering solutions are needed if we are to succeed in solving the global climate emergency — this should start with our government!

by Creutzig et al., – 31/01/2022 in PsyArXiv
Social Science is key to effective climate change mitigation: A reply to Nature editorial
see also Nature Editorial (05/01/2022) – How researchers can help fight climate change in 2022 and beyond

Views expressed in this post are those of its author(s), not necessarily all Vote Climate One members.

No good news here: all major greenhouse gases continue rising — at accelerating rates

compiled by Makiko Sato & James Hansen, 12/2022 – Climate Science, Awareness and Solutions (CSAS)
Columbia University Earth Institute
Atmospheric Greenhouse Gas Abundances
see also Updating the Climate Science — What Path is the Real World Following?
and Global Warming Acceleration (2020/12/14)

Views expressed in this post are those of its author(s), not necessarily all Vote Climate One members.

For the electricity grid to deliver power with zero emissions our steam punk grid will need to be re-thought and re-engineered

A big step in solving the climate crisis will require the rapid stopping of human GHG emissions. Electrical power generation and distribution via the electricity grid is a big chunk where we already know how to stop emissions.

Achieving zero greenhouse gas emissions (GHG) will probably not be enough on its own to stop and reverse the process of global warming. We have allowed the warming to continue long enough to have triggered positive feedbacks from various natural sources. The rising GHG emissions from these will drive global temperatures ever higher. However, if we can reach zero emissions fast enough, we should be able to slow the rate of global warming for long enough to give some more time to geoenineer enough carbon capture and sequestration and/or solar heat reflection technology to stop and reverse the warming. We already know how to achieve zero emissions for electrical power generation and the electricity grid, so it only needs for us vigorously start the task NOW!

A couple of recent articles explain what is required. I’ll quote the slightly more comprehensive article here from The Conversation. A derivative article in Undark (associated with MIT University) gives a tighter focus on the technology per se.

Integrating solar panels with farming can provide partial shade for plants. Werner Slocum/NREL

by Charles F. Kutscher & Geoffrey Logan, 13/01/2022 in The Conversation

A 21st-century reinvention of the electric grid is crucial for solving the climate change crisis

In the summer of 1988, scientist James Hansen testified to Congress that carbon dioxide from burning fossil fuels was dangerously warming the planet. Scientific meetings were held, voluminous reports were written, and national pledges were made, but because fossil fuels were comparatively cheap, little concrete action was taken to reduce carbon emissions.

Then, beginning around 2009, first wind turbines and then solar photovoltaic panels decreased enough in cost to become competitive in electricity markets. More installations resulted in more “learning curve” cost reductions – the decrease in cost with every doubling of deployment. Since 2009, the prices of wind and solar power have decreased by an astonishing 72% and 90%, respectively, and they are now the cheapest electricity sources – although some challenges still exist.

Read the complete article….

Australia has the know-how to do all of this. What the country lacks is the political will and regulatory environment to make it happen. At least since the Abbott led LNP COALition government assumed power in 2013 has worked assiduously to subsidize (Australia Institute: In 2020-21, Australian Federal and state governments provided a total of $10.3 billion worth of spending and tax breaks to assist fossil fuel industries.) and protect its already super-wealthy special interest patrons any kind of government or popular infringements on GHG emitting operations and businesses. This support has been backed up by a continual barrage of humbug, denial, fake news, disinformation, legislative blocking, and misdirection. For their brain fogging techniques see: How decades of disinformation about fossil fuels halted U.S. climate policy; Climate Change Disinformation and How to Combat It; The Climate Denial Machine: How the Fossil Fuel Industry Blocks Climate Action; How Big Oil Lost Control of Its Climate Misinformation Machine; Wikipedia: Climate change denial; see also my 2017 presentation “Positive Feedback and the Evolution of Human Culture“. Capt. Humbug (a.k.a. Scotty from marketing), his deputy Blarney Barney (the man with the hat), and their large troop of wooden-headed puppets are still using these techniques very effectively to stifle any progress towards serious action to resolve the climate emergency.

We Australians don’t have to put up with this longer than a few more months. Short of staging a Trumpist style coup to retain government, it is entirely within our power as voters to replace all the puppets with trustworthy people who will put organizing climate action as their top priority if elected to government. Vote Climate One is producing Traffic Light Voting Guides to help you achieve this – but without telling you how to vote. Basically we are setting out to provide information on every candidate in every electorate that you can use to guide your preferences to maximally support maximize preferences for those you think should have the job while being doubly sure than you don’t preference anyone likely to pass their preferences to an electable puppet of the special interests.

With an environmentally friendly Parliament, we can be working on the very serious work of surviving the climate emergency.

Views expressed in this post are those of its author(s), not necessarily all Vote Climate One members.