Putting the life back in science fiction


What mass extinctions look like

Another post, in part to remind myself that I’ll need to update the chapter on reefs in Hot Earth Dreams.  The bad news of March, at least in my opinion (aside from all the rain that didn’t fall on California) was that the bleaching of the northern section of the Great Barrier reef (as mentioned by, among many others, National Geographic, DW, Slate, CNN, and The University of Queensland.  Personally I like the last one the best, but tastes differ).

What’s going on, to be brief and oversimplify, is that coral have a temperature range, and the Coral Sea, or at least parts of it, are exceeding that range with this year’s El Niño.  By itself it’s a tragedy, and it’s one that’s going to leave a mark that’s bigger than you might think.

Here’s why.

I don’t consider myself an expert on the study of mass extinction, just a student of others’ work.  What I’ve noticed, reading the papers, is some fairly fundamental things they teach in introductory paleontology (and yes, I’ve seen this in an introductory textbook).  The bad news is that life forms don’t all fossilize equally, nor do all ecosystems.  You probably know this already, but it’s worth repeating what may be obvious to you.  Fossils tend to accumulate in places where sediments accumulate: lakes, bogs, marshes, swamps, occasionally rivers, sometimes deserts, and most of all, oceans.  Places like mountain tops and islands don’t produce as many fossils as one might hope, nor do places like rain forests, dry forests, and so on.  Most of the ecosystems I’ve worked in (chaparral and oak savannas) won’t leave much of a fossil trace beyond the oak pollen, unless things get weird.

Getting back to the mass extinction boffins, what I’ve noticed, reading some of their papers, is that they tend to focus on evidence from places that accumulate fossil really, really well.  This makes perfect sense, because it minimizes the amount of randomness that messes with their already tenuous fossil records.  Some of the best papers on mass extinctions focus on things like clams and, yes, coral reef fossils.

Coral reefs tend to leave behind really, really good fossils.  Not everything that lives in them fossilizes, but they’re so huge, and the corals are, well, rock, so they get represented disproportionately in the fossil record and in mass extinction studies.  I’ll probably get slapped around if any serious paleontologist reads this, but my sarcastic impression is that at least some studies of mass extinctions are basically studies of how reefs disappear and reappear in the fossil record, with a side of clam shells and a few dinosaur bones thrown in to diversify the sample.

This is the gravely quiet subtext to the Great Barrier Reef tragedy.  If we don’t get this stopped by dealing with climate change like 50 years ago, we will see more and more killer El Niños hit the reefs.  At worst, the Coral Sea could heat permanently to El Niño temperatures, the water too hot to support corals at all (this from Veron’s excellent A Reef In Time).  If this happens (I’m whistling past the graveyard by not saying when), whatever’s left of the dead Barrier Reef will begin its transformation into the next fossil record of a so-called “reef gap,” a time when the oceans were too acidic/anoxic/hot to support coral reefs.  These are the classic sign of extinction events, although they’ve happened more often than the five big mass extinctions.

So here’s the thing about the 2016 bleaching event: we may be seeing the beginning of what future paleontologists will label as the Sixth Mass Extinction.  It’s not set in stone yet (literally), but absent heroic measures starting this Friday when world leaders sign on (or don’t) to the COP21 Agreement, we’re heading into studies of how reef gaps form, as the fossil record formation portion of the Sixth Mass Extinction heats up to working temperature.

Just remember that reefs are home to something like 25 percent of the world’s species.  While the loss of reefs isn’t the loss of all those species–some, like humans, live outside reefs–but it’s the loss of most.  Reefs are up there in diversity terms with tropical rainforests, which leave behind rather poorer fossil records.  They’re also rather richer in high level diversity (32 of 24 animal phyla are found on reefs, compared with 9 animal phyla known from rainforests).    If  our coral reefs disappear, that’s an extinction event in itself, whatever else happens in the rest of the world.  Given what’s happened in past reef gaps, if coral reefs disappear, they won’t return for something like five million years.  That absence is a sad legacy to leave, don’t you think?

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9 Comments so far
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A mass extinction implies that all the current reef species (genera? other?) are new and did not exist as part of the reef ecosystems before the last reef extinction. Is that indeed the case?

In terms of mitigation:

1. How far would artificial reefs allow us to maintain at least a fraction of the species that would be lost with the death of reef corals?

2. Can we protect limited areas of reefs with methods to cool the water and reduce acidity? ( Cooling with upwelled deep ocean water? )

Rather than despair, we need plans B, C, D…etc if plan A, effectively reducing fossil fuel CO2 emissions, fails.

Comment by Alex Tolley

That’s a good point. A lot of modern coral groups do date from the Triassic, because the P-T mass extinction well and truly destroyed all reefs. Corals in general face two problems: hot water and more acid water. The heat can be ameliorated by transplanting them to cooler waters as they warm to become hospitable. Some corals seem to be more resistant to ocean acidification than others, and they may be spread more in the future (which is still a mass extinction, but not a total extinction). Still, IIRC, corals do diversify after each reef gap. Their phyla may be ancient, but the modern species are not.

The other problem is that reefs are composite entities, not just coral. This is an issue I went into at some length in Hot Earth Dreams, and other than pointing out that coralline red algae are essential to holding a reef together, fish are essential to keeping the reef from getting overgrown by algae, and both can suffer as a reef gets chewed up or overheats. Coralline red algae are (IIRC) even more sensitive to acid than are corals. The upshot is that some corals may well survive, but the reefs are less likely to, and without the reefs, there is a mass extinction of things that depend not just on corals but on reefs as habitat.

As for deacidifying the ocean, the simplest thing to do is to get the carbon out of the air before it gets into the water. The ocean’s the biggest sink for atmospheric greenhouse gases, and there’s little we can do to keep the CO2 (or methane) from going into the ocean. We have a lot more control over limiting our production of these gases, and we have some control over getting them into plants and soils, and that’s what we should be doing, rather than trying to re-engineer a system that covers 70% of the Earth’s surface.

Comment by Heteromeles

There has been some work on electrically grown “biorocks” as coral-friendly substrates: http://www.bbc.com/future/story/20150506-why-we-should-electrify-the-ocean

They’re using electricity to provide a higher pH at the chosen cathode, so that a calcium-rich surface for coral to grow on forms there and maintains a micro-environment more conducive to their survival. Note that the solar-powered variation would work fine if people would stop stealing the panels — probably less of an issue as panels become cheaper, also probably less of an issue if you set up the biorocks off the coast of a wealthy country like Australia instead of a poor one like Indonesia.

Heteromeles is correct that a) cutting emissions is the least risky and most comprehensively effective method to head off warming and other problems associated with emissions and b) efforts to cut emissions aren’t happening fast enough to prevent grave problems with rising temperatures across the globe and falling pH in oceanic surface waters.

I expect that later in the 21st century people will start trying more exotic interventions as it becomes clear that efforts to reduce emissions didn’t happen fast enough. These could include locking up carbon via biochar, accelerated silicate weathering, iron ocean fertilization, and boosting Earth’s albedo via deliberate production of high-altitude sulfate aerosols. The first two options can only make a significant dent in the problem if emissions first decrease substantially from their present level — so positing them presumes significant progress in curbing emissions, just more slowly than we’d need to stabilize the climate. The latter two are potentially fast-acting, potentially scalable, but are (IMO) significantly riskier. Also, the sulfate aerosol solution does nothing to counteract the pH effects of CO2 on oceans.

I don’t even like to talk about adaptations and active counter-GHG interventions in popular online forums because the marginal risks, and the costs of the safer forms, are higher than the marginal costs/risks of cutting emissions. Also because presenting backup plans can make people complacent about the need to cut emissions. Also because it can lead to me being mistaken as personally complacent about cutting emissions. Nonetheless, barring a swift global collapse due to e.g. super-pandemic or nuclear war, I believe that the future is going to see developed nations make large scale efforts at adaptation and geoengineering. It’s a prognosis, not something I look forward to — like “based on the subject’s insufficiently rapid reduction of candy bar intake, I foresee medical interventions based on pharmaceuticals and possibly surgery in his future.”

Comment by Matt

Thanks Matt, I’d forgotten about the attempts to make it easier for coral to grow. I hope they work.

As for locking up carbon, biochar has failed to scale above a boutique business to date, so far as I can tell, and the big play is in composting greenwaste and trying to spread it everywhere. That’s Cal Recycle’s strategy, to get all greenwaste out of landfills, and composted and spread elsewhere (including, ironically, as landfill topping), because greenwaste in landfills emits methane, but the gas coming off landfills is too contaminated to make capturing the methane and selling it economical). If you know anything about compost, you can predict as well as I can that there are going to be a lot of problems with this approach, but it’s where they’re going.

As for civilization adapting to climate change, we’re probably using the word differently. My expectation is that global civilization is going to change radically, whatever happens. We’re going to go on to renewable energy, kicking and screaming the whole way undoubtedly, California’s going to run out of groundwater and stop being an agricultural powerhouse, the south is going to continue to turn into a tropical rainforest (that may be what all that rain in Texas is about, incidentally), and so forth. As someone pointed out, one problem we do have in the US is that milder winters can make us complacent about the problems with global warming, because we aren’t yet seeing the killer summers the way they are in, say, India or the Persian Gulf. We’ll get there too, but the US is in the driver’s seat as the #1 polluter, so if we don’t act, the rest of the globe gets hurt disproportionately.

Comment by Heteromeles

composting greenwaste and trying to spread it everywhere. That’s Cal Recycle’s strategy,

The problem is that this will just spread Bermuda Grass seeds, which most gardeners abhor. Bermuda Grass is very hard to get get rid of, and resists most forms of turf removal, springing back up through mulch, gravel paths and between pavers. Once this is known by the community, it will be next to impossible to sell the compost without treating it with noxious chemicals.

US is in the driver’s seat as the #1 polluter
That is no longer the case with CO2 emissions, unless you mean as a result of consumption of goods manufactured in China. The good news is that China appears to be more aggressively moving to replace fossil fuel energy production than the US, although the bad news is that they are building more. .The good news in the US is that despite low oil and gas prices, apparently utility powerplant decisions have moved in favor of renewables due to the long term uncertainty of fossil fuel prices and delivery. Similarly, whilst electric car sales are still tiny, their growth is very high and should continue to do so as prices continue to fall as battery prices decline and energy density increases. We’ve also seen an unprecedented number of bankruptcies in the coal mining industry, including leader Peabody (only Ch. 11 so far). This may be a harbinger of things to come. Expect a number of oil fracking companies to fold permanently in the next few years. So while I tend to agree that we might be dragged kicking and screaming into teh renewables age, it does seem to be happening faster that we could have hoped until recently.

The bad news is that polar ice melt is happening faster than expected (Hansen was prescient again). Maybe the Zika virus will start turning more attention the impact of northward shifting climate zones. Nothing like a higher proportion of microencephaly and related problems in conservative states to make the citizenry question the policies of religious zealots in state legislators. (never let a good crisis go to waste?)

Comment by Alex Tolley

With respect to compost, bermuda grass is just the beginning. There’s a whole plethora of weeds that can be spread through even hot compost. If they do it wrong, they also spread over a dozen Phytophthora species, polyphagous shothole borer, and a bunch of other pests and pathogens. The group I belong to has already gotten blowback from Cal Recycle on pointing this out, along with an “everything’s fine, stop fearmongering,” message. California currently does have a compost quarantine system in place through Cal Ag, but it would be utterly overwhelmed by the volume Cal Recycle wants to process.

Incidentally, this compost thing is already in law, and everyone who currently produces more than 8 cu yard/day of greenwaste has to have a way to compost it and dispose of it that doesn’t send it to a landfill. In a few years it’s going down to 4 cubic yards/day.

Comment by Heteromeles

Did Cal Waste explain satisfactorily how they were preventing pest dispersal in their composts? Is it by processing in some way? Or is this another poorly considered idea that sounds good in theory, but creates headaches in practice? Is there any evidence produced by Cal Waste that the compost is pest free?

Our local landfill sells green waste compost at $15/yard, but I wouldn’t touch it. OTOH, I did buy their wood mulch at $5/yd. It is made from demolition wood materials rather than green waste, and isn’t bad for the price.

Comment by Alex Tolley

According to Cal Recycle, everything’s taken care of. I’m waiting for the headaches to start.

Comment by Heteromeles

Heh, as a guy who focused quite a bit on geology and paleontology in college, I can’t deny that we base it extensively on corals. Hell, the entire P-T ME might’ve not been as bad for terrestrial life than we thought, even if the coral ecosystems were annihilated. I actually went to the region that has some of the best late Permian-early Triassic preservation, and some of the so-called accepted ideas on how the PTME affected terrestrial life is pretty up in the air.

In any case, I would say that there’s one positive with this potential mass extinction of coral; it means that my stupid ultra far future project can get weirder and more different after the mass extinction. A small positive, I know.

Comment by Whachamacallit




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