The Climate series: a reference post.
________
This continues the Climate Catastrophe series I've been doing lately. Most recently, these have included:
■ Hugging the monster: Climate scientists and the C-word (Catastrophe)
■ The epic heat wave: "Of course it's about climate change"
■ Hansen on 3°C: Quarter to half of species on earth may die from global warming
I'll have a number of others — including a set of five that deal with Bill McKibben's recent (and must-read) article in Rolling Stone.
But before I continue, I want to look at the term I've been using as a substitute for the overly-polite "climate change" and its older cousin, the more accurate "global warming." My substitute — Climate Catastrophe.
What is "climate catastrophe"?
"Climate catastrophe" is not just a scare phrase, a metaphor. It's a description. Recently I quoted James Hansen in his paper "Perceptions of Climate Change: The New Climate Dice" (pdf):
If global warming approaches 3°C by the end of the century, it is estimated that 21-52% of the species on Earth will be committed to extinction.That's Hansen writing, not me. Note that a rise in 3°C is about 6°F (actually 5.4°F). Not much. And as you'll soon read, we've already achieved .8°C of that 3°C — we're more than a quarter of the way there.
Now look at Hansen's estimated extinction rate — in round numbers, 20–50% of species gone for good. (That's a pretty wide range, by the way. As climate predictions go, we've been "exceeding expectations" lately, so I would anticipate the higher part of that range to be more likely, something like 30% or above.)
Here's what percentages of mass extinction look like over the history of life on earth:
 |
| Marine extinction intensity through time. The blue graph shows the apparent percentage (not the absolute number) of marine animal genera becoming extinct during any given time interval. It does not represent all marine species, just those that are readily fossilized. (source and image info) |
The most recent spike in extinctions — a modest one, with about 14% of species going away — was 30 million years ago. Look at the far right end of the chart for it.
Hansen is talking about an extinction rate of 1.5 to 3 times that, 20% to 50% of species going extinct. Given the tendency of recent climate predictions to be low, I'd start at 30% as the lower boundary. So look at the whole chart for spikes above 30% extinctions. There are only six that I can identify. Six 30%–or–more extinction events in 542 million years. At the 40% level, there are only three.
Six extinctions events with 30% or more species eliminated; three with 40% or more. Hansen's high estimate is 50%.
There is only one extinction event that eliminated 50% of the species on earth, at the Permian–Triassic boundary, some 250 million years ago. Here's what occurred (some emphasis added; my paragraphing; see original for cite-notes):
The Permian–Triassic (P–Tr) extinction event, informally known as the Great Dying, was an extinction event that occurred 252.28 Ma (million years) ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras.The mother of all mass extinctions. So far.
It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct.
Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years. This event has been described as the "mother of all mass extinctions."
This is "climate catastrophe" — Humans poised to knowingly cause the seventh greater-than-30% extinction event in the history of life on earth. If not worse.
According to Hansen, if we increase the global average temperature less than 6°F by the end of this century, those extinctions could occur as we watch — in our, our children's and our grandchildren's lifetimes.
What happens on the way to these mass species extinctions?
Climate catastrophe is not just the extinctions themselves — it's also the world-historical convolutions in human life as we get there.
These are just a few: Mass migration of populations. Mass starvations. Global reshaping of coastlines. The fall of national political structures; the rise of local barons and strongmen. Revenge by the starving dying masses on those who are blamed.
Need more? They are easy to devine. All of this is contained in the phrase "climate catastrophe."
Another data point — what are the odds that one of those extinctions won't end up being us? After all, the larger species (top predators) are hit hard in these events. And I do rank us up there as top predator; we are literally, in fact, our own worst enemies. I fear no species like I fear my own; most people I know would agree.
Bottom line
I think many of us are proud of our predatory status. It would be a shame if we were our own next victims, but that looks like a possibility.
Am I wrong? Consider just the mass starvation caused by huge disruptions in food supply. Remember, the earth is not a cylinder, with equal mass to the north of the U.S. The growing area in Canada, if Canada becomes the breadbasket of North America, will certainly be smaller than the equivalent growing area now within our borders. And that doesn't touch the food wars that will occur in the rest of the world.
If water and food are scarce, there will certainly be mass migrations. Imagine this compressed into two generations.
I won't dwell here; I'm looking for solutions. But "hugging the monster" means recognizing the problem. It breeds urgency and concentrates the effort.
Looming climate catastrophe — that's definitely a problem worth recognizing.
GP
To follow or send links: @Gaius_Publius
