The climate crisis in three easy charts

UPDATE: This has been edited since first publication, and will continue to be revised until this sentence no longer appears. I’ve introduced mark-up in the charts, clarified (and in one or two cases, corrected) the language, and enhanced a number of explanations. This piece is part of a three-part set that together explains the climate crisis from “10,000 feet” — a very high-level view with the most basic elements explained for the interested lay reader.

The three parts of this set of posts are:

The climate crisis in three easy charts — the view from 10,000 feet (this piece)

 ▪ A closer look at global temperature, both before and during the age of man

Climate crisis: Why we’re on track for 7°C warming or greater by 2100

Thanks for reading.

I’m preparing to pivot back to climate crisis, starting with some reformatting of the 2012 Climate Series posts — the transition to WordPress wasn’t kind to them — and the organization of this material into book form. (There’s also a climate-themed novel in the works. Thriller fans, stay tuned.)

As a result, I’m working to refine both the concepts (or rather, the explanation of them) and the dating of coming events (the earliest time when the crisis, in its various stages, unfolds).

The first part of that pivot includes two media appearances this week. I’ll be on Virtually Speaking With Jay Ackroyd this Thursday (May 2) at 9 pm ET to discuss climate crisis for a full hour, followed by a Sunday appearance with Avedon Carol as part of the Virtually Speaking Sundays weekly media panel. (Links lead to archived shows.)

Here I’d like to focus on climate, beginning with a look at three diagrams that, taken together, detail the long view, the “view from 10,000 feet.” The long view has just three pieces:

▪ A view of life on earth, in particular its three main phases to date — early life, Age of Reptiles, Age of Mammals

▪ An view of changes in climate across that period, with special attention to climates before the age of man, then climate during the age of man

▪ A look at where climate is headed and how that compares with previous climate periods

There’s a remarkable and frightening symmetry in this picture. But it’s not a complicated — just striking.

Climate catastrophes usher in new geologic eras

Long-scale earth history is divided into “eons,” then “eras,” then “periods,” them “epochs.” (You can see the whole set of them — eons, eras, periods, epochs — laid out here.) But in fact, prior to the Cambrian Period, when life on earth exploded in number and variety, earth history is the story of either pre-life or small single-celled and multi-celled life. For our purposes — a study of the effect of climate on life — we need look no further back than the Cambrian Period.

In addition, from the Cambrian Period onward, there’s only one geologic “eon,” so considering eons is pointless. What we’ll look at, therefore, is geologic “eras” (main divisions in the kind of life on the planet) and their important sub-divisions (mainly the important geologic “periods”).

So let’s start there, with the Cambrian Period and the flourishing of life on earth. Consider the chart below:


The source is here; I’ve added some mark-up. The divisions across the top are geologic periods, starting with the Cambrian (“Cm”), the period of “visible life.”‘ In the Cambrian, life on earth exploded, starting in the sea. We know this from the proliferation of hard-shelled species preserved as fossils, as well as from other data.

On the chart, the numbers across the bottom (the X axis) are millions of years ago, usually abbreviated “mya”. The spikes in the chart itself show mass extinction events, as measured by the extinction of marine species only, for apples-to-apples comparison, since land plants evolved later, roughly 475 million years ago, and amphibians later still, roughly 375 million years ago.

“Extinction intensity” is a measure of marine extinctions that’s adjustsed to account for the fact that it’s easier to identify some extinctions than others, based on data from so long ago. Despite not being a literal count of extinct species, “extinction intensity” is considered an excellent measure for making relative comparisons across time periods.

Starting with the Cambrian Period we’ve had just three geologic eras (the larger divisions):

Paleozoic Era — literally “old life”
Mesozoic Era — literally “middle life” or the Age of Reptiles (including the dinosaurs)
Cenozoic Era — literally “new life” or the Age of Mammals (including man)

The Paleozoic Era runs from the Cambrian at the start of the graph to the big spike at 250 million years ago. It encompasses six geologic periods and ended in the greatest mass extinction event on the planet — geologists call it the “Great Dying”.

The Mesozoic Era runs from the Great Dying at 250 million years ago to the big spike at 65 million years ago, the event that wiped out the dinosaurs. That extinction event cleared the way for mammals to grow big and thrive.

We’re now in the Cenozoic Era. The Cenozoic is also called the Age of Mammals, and it includes us, who show up very late. As you’ll see later, our earliest ancestor doesn’t appear until the end of the Neogene Period (“N” on the chart), a little over 2 million years ago.

Keep those transitions in mind — when mass extinctions change which groups of species can evolve and dominate, it’s the end of an era and the start of another. Check the chart again — so far there have been just three geologic eras. The next extinction event on the scale of the one at 250 million years ago or the one at 65 million years ago will change once more the shape of life on earth and usher in the next new era.

So your first takeaway — We could be on the cusp of a new geologic era, one that may not include us. That’s what’s at stake if we set off another mass extinction on this scale. Ready for that?

Where does man fit in?

Great question — where does man fit in? Answer: We come in very late.

First, notice the last three geologic periods at the top-right in the chart above, the periods abbreviated K, Pg and N. The period marked “K” is the Cretaceous, the period at the end of the Mesozoic (“middle life”) Era. The next period (“Pg”) is the Paleogene, the one that marks the start of the Cenozoic (“new life”) Era. The period after that (“N”) is the Neogene, which ended just 2 million years ago. The period after that, not shown, is the Quaternary Period (abbreviated “Q”), our current one.

The Neogene-Quaternary boundary is the start of the time of great glaciers, and the best way to show that is with the chart below, showing earth temperatures mapped across the geologic periods (left quarter of the chart through the end of the Mesozoic) and then the geologic epochs (the rest of the chart to the right).


Click the chart to open a larger version in another tab. It’s big and interesting. (Source here.)

I’ve marked up the original with the three geologic eras, and for the Cenozoic Era, I’ve indicated its three periods — the Paleogene (Pg), the Neogene (N), and the Quaternary (Q) — which the original doesn’t show. For the first two eras, the boxes across the top represent the periods, as in the first chart above. For the Cenozoic Era, the boxes represent smaller divisions, the epochs, since we need to see more detail. I’ve added the Cenozoic’s three periods above those boxes. (Again, to see all eras, periods and epochs in relation to each other, click here.)

First, get oriented. The Y axis shows change in global average temperature, measured in °C, using the year 1800 as the norm or zero mark. (The scientific symbol for “change” is Δ. Unless otherwise noted, the global pre–Industrial Revolution temperature is generally the mark from which other climate temperatures are measured. In the climate science world, temperatures are measured in °C. To convert from °C to °F, just double the number and back off slightly; you’ll be very close. One degree Celsius is slightly less than two degrees Fahrenheit.)

The X axis shows time — first in millions of years ago, then in thousands of years ago. It starts with the Cambrian Period, the first period in the Paleozoic Era, and continues through “now,” the Holocene epoch, the age of civilized post–hunter-gatherer man.

Note how late our ancestors show up. Homo habilis appears about 2.33 million years ago, followed by homo erectus, numerous other cousins, and finally us, homo sapiens, as the baby in the family. We don’t appear until about 250 thousand years ago. (Homo erectus, by the way, lasts a long time on this earth. Longer than us by a lot.)

For the most part, the various species of man evolved in the Pleistocene Epoch, the modern age of glaciers, and only became civilized (settled, with villages and farms) during the Holocene. Look at that chart again, at the climate during those two time periods. Do you see the difference between them? Do you see where this discussion is going? I thought so.

Your second takeaway — The age of “civilized” man exactly coincides with a very narrow range of temperature changes. How narrow a range? No more than about ±½°C, a range we’re already outside of.

Where are we headed? Let’s see.

First the bad news

To see where we’re headed, we need to look at the extreme past first, at the left-most part of the second chart. During the first two geologic eras, and especially during the Paleozoic Era, the Y axis shows huge changes in global temperature relative to pre-Industrial norms. The earliest spike, which occurred across a span of roughly 50 million years, looks especially large.

Now take another look at the far-right end of the same chart, at that little spike. Note that it’s already higher than the highest peak through the entire Holocene, as measured by the dark black line.

I’ll have more to say about why the narrow temperature range during the Holocene matters. But for now, just know this — that little climb in temperature you see on the right is already outside the Holocene range, and it’s just the beginning. To see where we’re headed, let’s look at some predictions based on a number of scenarios, starting with Figure 21 from the Copenhagen Diagnosis, a report prepared by … I have to say it … nearly every one of the world’s top climate scientists, for the benefit of world “leaders” who met in 2009 to discuss how to … I have to say it … pass the climate buck one more time.

The figure itself is reproduced from an earlier IPCC document released in 2000. (IPCC is the Intergovernmental Panel on Climate Change, the main science body for this stuff.) Note what it shows about future climate, between 2000 and 2100, under a number of prediction scenarios, indicated by variously colored bands:


Starting from the left, what you see are temperature reconstructions from 500 AD through 1800 (the fuzzy blue line), followed by temperature observations through 2000 (the black line), followed by a number of prediction scenarios through 2100. See the scenario labeled “A1FI”? It’s the band in red. The A1FI scenario is as close to a “do nothing” scenario as the IPCC produces. (There’s an actual “do nothing” scenario created by the scientists at MIT, but A1FI will work for now. We’ll discuss the MIT scenario later.)

The “do nothing” scenario — otherwise known as the “Keep David Koch Wealthy” scenario (keep that name in mind) — is exactly what we’re doing now. So far, we’re doing exactly nothing relative to what’s needed to change our trajectory.

All you need to know? We could be on track for about +7°C — the peak temperature in the big Cambrian spike — by the year 2100.

Your third takeaway is stark:

The Cambrian temperature spike is 6–8°C higher than pre-Industrial levels.

If we don’t stop emitting carbon now, it’s also the temperature we’re headed for — compressed into the next 90 years. 

There’s a fearful symmetry in that, even though there’s nothing “natural” about +7°C as a stopping point.

Are we really headed to another terrible temperature spike, and in that short a time? Again, if we don’t stop ourselves, yes, we really are.

Now the good news

It’s not over yet, despite all this doom and gloom. Truly. By my calculation, we have at least 5–10 years to avoid the catastrophe. Perhaps we have more, but we better not count on it. Five to ten years … and yes, that’s enough, if enough people are awake to what’s going on around them. We’re sitting on a carbon bomb, but we can defuse it ourselves — and that’s good news.

It won’t be easy, however — we’re past the point where any transition will be smooth — but we can make the transition and survive as a civilized (non–hunter-gatherer) species, humans in a recognizable world. Two things are needed, however:

  1. This must be our top priority, which means you and everyone you know must be fully awake and in full battle gear. (For reference, it’s called “hugging the monster.”)
  2. It’s us vs. David Koch and all of his friends and enablers. Tackling any other enemy is tackling a dummy. The David Kochs of the world must not be allowed to monetize their carbon.

Think of it this way; you can educate your friends and put a wrench in the Koch machine at the same time. How’s that not a plus?

Your fourth bottom line — If the Koch Bros keep getting rich, we move backward. If Barack “Hope & Change” Obama approves Keystone, we move backward. If the U.S. develops “domestic carbon” resources, we move backward. For every new car (“carbon-to-air-delivery system”) sold, we move backward. People need to know this and think like this. We can stop the crisis, but only if we stop carbon. It’s that simple; and that stark. But it’s also doable, and we’re the species that’s most equiped for “doable.” It’s what our big brains are for.

I’ll have more in the weeks and months ahead. I haven’t given up and you shouldn’t either. But we can’t pull out of a tail spin if we don’t admit we’re in one. Me, I think we can pull out.


To follow or send links: @Gaius_Publius

Gaius Publius is a professional writer living on the West Coast of the United States.

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