Matt Ridley and the Holocene Optimum

If the title of Matt Ridley's new book, The Rational Optimist, sounds a little familiar, that's because it borrows heavily from the world view of one Bjorn "The Skeptical Environmentalist" Lomborg. Both contrarians dismiss global warming as nothing to worry about, although Ridley seems even less convinced that the planet is actually experiencing anthropogenic global warming. I don't have time to read it -- but I did manage to take a look at the kind of thinking that Ridley uses at his blog.

This week, Ridley wrote about what his research in the "Holocene Optimum," uncovered. What he found, he says, is that it was much warmer about back then than it is today, and:

if the heat of 7,000 years ago, so widespread around the globe and so pronounced in the far north, did not cause planetary catastrophe, why should the lesser warmth of this century?

The problem is Ridley's version of the mid-Holocene warming is restricted to the Northern Hemisphere. The rest of the planet wasn't particularly warm at all. In fact, according to a primer on the subject from the U.S. National Climatic Data Center, that warming was a product of changes in the Earth's orbit which ...

... can be easily calculated and predict that the northern hemisphere should have been warmer than today during the mid-Holocene in the summer AND colder in the winter. The paleoclimatic data for the mid-Holocene shows these expected changes, however, there is no evidence to show that the average annual mid-Holocene temperature was warmer than today's temperatures.


In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven "astronomical" climate forcing mechanism cannot be responsible for the warming over the last 100 years.

This is not controversial or new. In a 2002 Paleoceanography paper, a pair of Japanese researchers note that there models show that during the mid Holocone "there is about a 0.35°C cooling of the global mean SST [sea surface temperature]" and that "anomaly is in broad agreement with the observed proxy data."

Here's how a Wikipedia author sums it up:

In terms of the global average, temperatures were probably colder than present day (depending on estimates of latitude dependence and seasonality in response patterns). While temperatures in the Northern Hemisphere were warmer than average during the summers, the tropics and areas of the Southern Hemisphere were colder than average which comprised an average global temperature still overall lower than present day temperatures.

Also, George Monbiot quickly deals with some of the errors in Ridley's book.


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And even if it was warmer, we didn't have a population of 6.7 billion trying to maintain large-scale agriculture in a context of severely degraded ecosystems. 2 degrees of warming in a century might not be such a big deal for "the planet" as a whole under "normal" conditions, but it almost certainly is a big deal for current human society under present conditions.

Excellent point -- jh

After reading the first few hundred pages what you have is a pissed off ex royalty who lost his ass in the free market and is now blaming on everything other than what caused it, his greed.

He is a good writer, and has some interesting ideas if how trade contributed to the evolution on society, but like most rich white anglos liked it a lot better before the common man had a voice.

By Joe stafura (not verified) on 02 Jun 2010 #permalink

Ridley is not actually a "climate denier," but the big point about climate change is that it's NOT, by far, the biggest challenge facing humanity. Rather, it's the boring old problems of poverty, disease, poor sanitation, malnourishment, etc., which threaten much more human harm that does climate change. To the extent efforts to curb global warming -- which, actually, we cannot do -- will make the world poorer, that will make it harder to tackle these real and more threatening problems.

Those interested in Ridley's actually very good book might also wish to know about my own book, THE CASE FOR RATIONAL OPTIMISM (Transaction Books, Rutgers University, 2009), which makes quite similar points and arguments, but develops the case for optimism over a rather broader range of subject areas. See

Rather, it's the boring old problems of poverty, disease, poor sanitation, malnourishment, etc.,

Which boils down to the one big problem nobody wants to talk about any more. That there are two or three orders of magnitude too many people on the planet.

Which boils down to the one big problem nobody wants to talk about any more. That there are two or three orders of magnitude too many people on the planet.

Hard to pin that all on overpopulation when you realize those same problems existed even when we had 1/3 to 1/2 of the population today (i.e. from 1930 to 1960).

Allocation and consumption of resources is the underlying thread between all three of these issues. We're not going to help any developing nation by burning all the cheap fossil fuels before they can afford them; if we're going to share the wealth, we might as well share the next-generation green technologies while we're at it. Overpopulation issues could be managed by stricter protections on the natural environment limiting growth in developed nations, while encouraging improvements in living standards in developing nations and improving reproductive rights for women; factors which lead to declining birth rates in developed nations.

By Left_Wing_Fox (not verified) on 02 Jun 2010 #permalink

Rather, it's the boring old problems of poverty, disease, poor sanitation, malnourishment, etc., which threaten much more human harm that does climate change.

Climate change (in combination with resource constraints and ecosystem degradation) is virtually certain to make those problems significantly worse.


You have to go a lot farther back than the 1930s to get to 2 orders of magnitude fewer people. Say 6 or 7 thousand years back.

While Ridley is, at best, a hypocrit (at least in my view), he reminds of something that a great many of us are guilty of when it comes to our oft-vitrolic debates regarding climate change: gross -- even grotesque, at the extremes -- oversimplification of a dauntingly complex issue.

This is well illustrated by the argument of the skeptics that climate has always changed, sometimes dramatically. And they're absolutely right; even the least-educated people are likely to have a dim idea of the last Great Ice Age (though equally likely they don't know there have been several). But those presenting that argument either fail to take into account time differences. For instance, as the last Great Ice Age ended, it did so quite slowly, in human terms, taking several thousand years. Since the dawn of the Industrial revolution, we've seen a comparable rise in average global temperatures -- in well under 200 years, a small fraction of how long it took for the glaciers to retreat, the snows to melt, and temperatures to inch their way up. If the end of the last Great Ice Age is the tortoise, then the rise since the dawn of the Industrial Revolution is the hare, which makes a good analogy, actually.

That is, given enough time, the tortoise wins. But if the hare can speed up even just a little, *it* will win. So, for us, are our activities providing that extra burst that will tip the balance in favor of the hare -- pushing the climate over the edge?

Though I'm not a scientist of any sort, I follow this debate daily, and no credible climate scientists (nor in related disciplines) argues that nature plays little or no role in climate change. The great majority, however, do see overwhelming evidence that with nearly seven billion of us merrily rocking along, we just *might* outpace Mother Nature, leading to negative results -- at best. A 2-degree Celsius temperature rise within a century, say.

So, human activity and nature both affect climate. And there are other factors. Influences from solar cycles. Planetary orbital variations every 40,000/90,000/120,000 years or so (I've rounded off the estimates), variations that are both are quite predictable and that fit well with estimates of past climate changes.

Further, of late methane as come more to the fore than previously, which is good. I'm constantly amazed by just how many people with whom I speak think there's only one gas to worry about, CO2. When I tell them there are several, they sometimes react with astonishment. (Skeptics and deniers tend to dismiss that out of hand).

Finally, WAY too many people focus on *weather* extremes in localities to support their particular view, though a look at news reports and the like show the the great majority are on the skeptic-denier side. Remember the winter of 2009-2010 when much of the US Atlantic seaboard was buried in snow and shivering in lower than normal temperatures, and some low-temperature records were shattered? Remember the skeptics and deniers leaping on that as proof-positive that the Earth is cooling? That's as silly as saying a drought in Kenya means the crops in Kansas will fail. When I challenged some about that winter in forums such as this, pointing out that parts of Australia -- then in the midst of southern summer -- was experiencing record-shattering high temperatures (Sydney hit 45 degrees C or so), I was almost completely, and simply, ignored.

I read an interesting take on all this just yesterday, written by a climate scientist. He points out that climate change alone, even severe climate change, won't spell the end of Earth as a planet. The question isn't that at all. It's whether the *biosphere* can survive a major climate change -- a rise, say, of 6-8 degrees C -- or to what extent the biosphere will be affected by a serious, though not completely life-destroying, temperature rise -- 3 degrees C, say.

Of course, if the 2012 crowd have it right, then we don't have to worry about climate change EITHER direction, do we??? ;-)

By Mekhong Kurt (not verified) on 08 Jun 2010 #permalink

Excuse the grammar etc. errors in my earlier post -- wish the phone would stop ringing! And I can't edit it, sigh. In any case, apologies --

By Mekhong Kurt (not verified) on 08 Jun 2010 #permalink