I don’t think the ‘Roman Optimum’ means what you think it means

Independent, a UK newspaper, has a story online starting with the line “Summers in Europe since 1986 have probably been the hottest in two millennia, according to a scientific survey.” They’re referencing a paper published in IOP Science that analyzed European summer temperatures since the time of the Romans. The abstract is here.

Funnily enough, the Independent thinks that’s evidence of human-caused climate change, writing, “The study claims that the mean summer temperatures across Europe “appear to reflect the influence of external forcing during periods”, or, to put it another way, are the result of man-made climate change.”

Umm, warmer temperatures in the past doesn’t sound like convincing evidence of human-caused climate change, actually. What am I missing?

Recent warming probably does have an element of human contributions as a partial cause, and one of those human contributions is human emissions of CO2. But if they’re telling us that current temperatures were matched (in Europe–this isn’t a global study) 2000 years ago, then human contributions may not be that unusual. Our contributions may just be replacing another cause of warming way back when. Perhaps more importantly, those who fret about Paris and Moscow heatwaves, floods in the UK, etc., may need to reflect–if climate now is like climate then, perhaps weather is too.

The Roman warm period started quite suddenly around 250 BC and ended about 400 AD. The ancient Greeks and Romans lived in a fairly pleasant climate, which you can also see from the airy robes, in which the antique statues are often dressed.

Some studies in a bog in Penido Vello in Spain have shown that in Roman times it was around 2-2.5 degrees warmer than in the present.

The Roman warm period is amply documented by numerous analyzes of sediments, tree rings, ice cores and pollen – especially from the northern hemisphere. Studies from China, North America, Venezuela, South Africa, Iceland, Greenland and the Sargasso Sea have all demonstrated the Roman Warm Period. Additionally, it has been documented by ancient authors and historical events.

…Locating vineyards and olive trees is also a good indicator of climate. During the culmination of the Roman warm period olive trees grew in the Rhine Valley in Germany. Citrus trees and grapes were cultivated in England as far north as near Hadrian’s Wall near Newcastle. Scientists have found olive presses in Sagalassos in the Anatolian highlands of present-day Turkey, which is an area, where it today is too cold to cultivate olives.

The continued spread of vineyards to the north can be deduced from a decree of the Emperor Domitian, which prohibits the cultivation of wine in the Empire’s western and northern provinces beyond the Alps. The decree was 280 AD revoked by Probus, who allowed the Romans to introduce vineyard in Germany and England.”

The Roman Optimum was called ‘Optimum’ because the effects of the climate were better than preceding and following climate regimes. Better for agriculture. Better for transportation. Better for health and prosperity. Better for us and the species we share the planet with.

We haven’t reached that point yet, apparently. However, instead of trying to scare us with mythical and mystical stories about how Xtreme Weather is threatening us all today, perhaps scientists should be telling us where we can add our next olive groves and vineyards.

The climate is benign at present.

I know we need to worry about overshooting the climate optimum. Indeed, I fear we will. Developing countries consume a lot of energy and the developed world isn’t going to renounce their lifestyle.

But while I agree with those who advocate taking precautions to protect our future, I also think we should take some time out and enjoy the Optimum we are experiencing today.


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