2,500 years of wild climate change in southern Europe: It was warmer in Roman Times than now

By Jo Nova

Nothing at all about the modern era stands out as unusual

Thanks to David Whitehouse at NetZeroWatch who has found a remarkable paper: Pyrenean caves reveal a warmer past

The new study on stalagmites in caves of the Pyrenees shows that modern climate change is nothing compared to normal fluctuations in the last 2,500 years, when it was at times much hotter, colder, and more volatile. Rapid shifts between temperatures were common.

The researchers looked at 8 stalagmites in 4 caves and local lake levels, but they also compared their results with other European temperature proxies and reconstructions and the pattern is consistent across the region. The Roman Warm Period was much hotter than today, and for hundreds of years as well, even though coal plants were rare. Apparently, there was a reason Romans were dressed in togas.

The Dark Ages were very cold, especially around 520 – 550AD — which may be related to what the researchers call a “cataclysmic” volcanic eruption that took place in Iceland in 536AD. It was followed by two other massive volcanic eruptions in 540 and 547AD. This effect is apparently visible in European tree rings which showed “an unprecedented, long-lasting […]

European heatwaves: Soldiers died in the heat in 1160, Rivers ran dry in 1303, animals fell dead in 1393

By Jo Nova

Medieval “climate change” was filled with heatwaves, droughts, and crop failures

One thousand years ago, “rivers ran dry under the protracted heat, the fish were left dry in heaps and putrefied in a few hours.” Men and animals venturing in the sun in the summer of 1022 fell down dying.”

It was so hot in 1132 that the rivers ran dry and “the ground was baked to the hardness of stone”. Around 1200 at the Battle of Bela “there were more victims made by the sun than by weapons”. In 1303 and 1304, the Seine, the Loire, the Rhine, and the Danube could all be crossed with dry feet, and they dried up again in 1538-1541. In 1393 and 1394 the crops were “scorched up” and “great numbers of animals fell dead”. In 1625 in Scotland, it was so hot “meat could be cooked merely by exposing it to the Sun.”

And so it goes — history that was known in the 1800’s appears to be disappearing, leaving us with a generation of snowflakes who think they are the only humans who ever faced hot weather. They with their air-conditioned bedrooms, mobile phones and filtered water.


Denying 2000 years of the Medieval Warm Period, Little Ice Age on every continent

Here we go again. For five or so years believers didn’t really mention the Medieval Warm Period. Too bruised by the embarrassment of Hockey Stick Zombie failures. But it’s an inconvenient era they have to rub out because none of the expert models can explain what caused it, and it’s hard to panic about same temperatures that Edward the Confessor survived with oxen and carts.

And it’s hard to call the modern warmth “man-made” if nature created something just like it 1,000 years ago.

Climate change: We haven’t experienced anything like this in the past 2,000 years

By Michael Collett, ABC, Environmental Copy and Paste Promoter

Climate scientists writing in the journal Nature have found there is no evidence for “globally coherent warm and cold periods” over the past 2,000 years prior to industrialisation.

That’s significant, because climate change deniers have sometimes pointed to epochs like the so-called “Little Ice Age” or “Medieval Warm Period” to argue that the current global warming is one among multiple similar global climate events.

But what the research actually shows is that other “peak warming and cooling events” over the past two millennia appear to have […]

Antarctica was warmer one thousand years ago — and life was OK

Remember when polar amplification was the rage? So much for that theory

Antarctica is twice the size of the US or Australia. Buried 2 km deep under domes of snow, it holds 58 meters of global sea level to ransom. The IPCC have been predicting its demise-by-climate-change for a decade or two.

A new paper looks at 60 sites across Antarctica, considering everything from ice, lake and marine cores to peat and seal skins. They were particularly interested in the Medieval Warm Period, and researched back to 600AD. During medieval times (1000-1200 AD) they estimate Antarctica as a whole was hotter than it is today. Antarctica was even warmer still — during the dark ages circa 700AD.

Credit to the paper authors: Sebastian Lüning, Mariusz Gałka, and Fritz Vahrenholt

Feast your eyes on the decidedly not unprecedented modern tiny spike:


The little jaggy down after 2000 AD is real. While there was rapid warming across Antarctica from 1950-2000, in the last twenty years, that warming has stalled. Just another 14 million square kilometers that the models didn’t predict.

We already knew the Medieval Warm Period was a global phenomenon, thanks to hundreds of proxies, and 6,000 boreholes. But […]

Scottish summers not doing anything they haven’t done for 800 years already

Gotta love a long unbroken proxy.

Scientists looked at 44 pines sites across the Scottish Highlands and used their tree rings to create a continuous temperature series for the last 810 years. Showing admirable restraint, they did not paste on adjusted thermometer records to create a hockey stick effect. Instead we can see that Scottish summers were just as warm in the 1300s, the 1280s and around 1500 as well.

The rate of warming is not unprecedented. The temperature is not unusual. But thermometers don’t tell the same story as the tree rings in the last 50 years. They both can’t be right. Either the tree rings are always unreliable thermometers or the thermometers are placed near ice cream trucks and adjusted up-the-kazoo?

Thanks to CO2Science:

Rydval et al. extended “the previously published Scottish dendroclimatic record (Hughes et al., 1984) by nearly 500 years,” in order to create an 810-year-long proxy over the period AD 1200-2010. The reconstruction was derived from a network of 44 Scots pine (Pinus Sylvestris) sites across the Scottish Highlands from both living and subfossil samples that correlated well with summer (July-August) temperatures.

In placing the most recent warming of the instrumental […]

Chinese scientists find 2,000 years of not-hockey stick

There was no Medieval Warm Period in China. No little ice age either. Not warm in Roman times either.

Obviously CO2 controls this climate.

(Click to enlarge)

Quansheng et al show that weather is lumpy, that modern warming is a lot like past warming. They go so far as to say that there are regular cycles and hint that sun might have something to do with it, and volcanoes.

“…centenial variation is significantly correlated with long-term changes in solar radiation—especially cold periods, which correspond approximately to sunspot minima, as well as the frequency of large volcanic eruptions.”

They go on to say that rate of warming was about half a degree per century lately. It may have been the fastest rate, but then again, it may not. It was hard to tell with the error bars being so wide. It was all done with proxies and has a ten year resolution. Obviously it is in need of having homogenadjustoided thermometer data added after 1960 as is the custom in climate science.

The Medieval Warm Period was global Medieval Warm Period found in 120 proxies. Plus Roman era was similar to early 20th Century. Sun controls half of […]

How to make climate graphs look scary — a reply to XKCD

This week XKCD (a popular Geek comic site) posted an epic cartoon called “A Timeline Of Earth’s Average Temperature”. It was a cutesy long godzilla hockey-stick — “scary” to the unwary.

It’s easy to make a scary historical-looking temperature graph — so easy that the artist probably didn’t even know how. (Thank Shakun, Marcott, Annan, Hadcrut and the IPCC for doing the tricky part.) First, guesstimate temperatures over last 20,000 years with anything at hand: tree-rings, ice bubbles, coral, fossilized tea leaves, whatever. Blend. Then stop the proxies, tack on thermometer data that was recorded in a different way with different errors and a very different response to faster temperature changes. Finally, launch that line into the future with unvalidated, skillless multivariate models that predict a fingerprint which 28 million weather balloons can’t find. Then take the models that didn’t work for the last twenty years, and run with the errors to the next century… Voila!

I took the 14,000 pixel cartoon and squeezed it to one shot that shows the curve that matters. See the error bars? Me neither.

(But who needs an uncertainty range when you have faith?)

Click to enlarge.

The secret to a good hockey-stick […]

Sun controls half of the groundwater recharge rate in China for last 700 years

Could this be why climate models do rainfall with all the competence of tea-leaf-reading? Tiwari et al report that as much as 47% of the recharge rates of ground water in China are controlled by the sun. Apparently climate models miss the minor factor of the major cycles.

Try this radical idea on: imagine a world where climate models worked. Not only could the BoM warn people that there would be a drought coming, they could name the region, and the years.

Tiwari et al:

Here for the purpose of comparison of long term ground water recharge rates with long term solar activity, we used the 10-year average sunspot time series, for the period 1300 to 1905 AD, published by Solanki et al., [2004]. Also the additional average annual sunspot number time series (1700 to 2000 AD) is used from data source Solar Influences Data Analysis Centre. In addition to decadal data annual sunspot number data from 1700 to 2000 AD downloaded from Solar Influences Data Analysis Centre is used in the present study. The cross-correlation coefficient (+0.63) between the groundwater recharge rate time series and decadal sunspot number [Solanki et al., 2004] shows that there is statistically significant solar […]

The North Atlantic jet stream correlates with Solar output over a millennium

A new paper (Moffa-Sánchez et al) reports that they looked at layers of dead plankton in ocean mud (otherwise known as foraminifera in marine sediments) and have reconstructed the temperature and salinity of a couple of spots in the North Atlantic between 818AD – 1780 with data on δ18O and the Mg/Ca ratios. One immediate thought, an aside, is that if this technique works, there is no shortage of ocean mud, surely, and perhaps we could drill and analyze more mud for solar correlations in other places. (I hear foraminifera live in the Southern Hemisphere too). Perhaps no one is looking for the connection with the sun?

Moffa-Sánchez et al find the big climate shifts (the 100-year variations) correlate with total solar irradiance (TSI). See especially that orange line black line track in the d graph below. I stress, correlations don’t mean causation and the mechanism is mere speculation. But I find the graph intruiging. There are a lot of turning points, and in pure “curve fitting” type of analysis, this is a better curve fit than the one with CO2. (Find me a turning point that matches with carbon dioxide!) I suspect we’ll be referring back to this paper, […]

Ocean heat content around Indonesia shows Medieval Warm Period and 2C warmth in holocene

Rosenthal et al have put out quite a humdinger of a paper. They’ve reconstructed the temperature of the water flowing out of the Pacific to the Indian Ocean over the last 10,000 years and as deep as 900m. The Indonesian Throughflow is pretty significant in global ocean currents. There’s narrow routes for Pacific upper waters to squeeze through to the Indian Ocean through the Makassar and Lombok Straits, and via the Lifamatola Passage through the Banda Sea, and water comes in from both the North and South Pacific.

An important point in global ocean currents where the Pacific flows through to the Indian Ocean.

Points to note (assuming the study is right):

Temperatures started rising around 1700AD — long before our carbon emissions. That temperatures were much warmer (0.65C) in 1100AD than they were in 1950. 8,000 years ago water was 1.5 to 2 degrees warmer — isn’t that meant to be a global catastrophe? Apparently coral reefs, fish, and turtles survived.


Figure 4. Holocene changes in Pacific Ocean heat content. (A) Reconstructed anomalies in Pacific OHC in the 0- to 700-m depth interval for the early Holocene, mid-Holocene, MWP, and LIA periods. Reconstructed anomalies are calculated […]

The message from boreholes

There have been suggestions that Jo Nova might be trying to hide or ignore the most recent boreholes graph from Huang et al. So here it is. This is the last 2,000 years according to 6000 boreholes, with the last 100 years also using the “instrumental record” which gives us that hockey-stick uptick at the end. Below I explain the pros and cons of this study and update my thoughts.

Huang and Pollack 2008: Their latest boreholes published study


A borehole sounds like a bit-of-a-stretch as a proxy. How could we tell if the world was warmer in 1066 by drilling a hole in the ground? Yes, fair point. But what makes boreholes useful is that they are global and there is a lot of data: specifically 6,000 holes all over the world.

I’ve been looking at boreholes in more detail, analyzing them in the light of newer proxies. When all the evidence is considered, boreholes turn out be not-much-use at giving us meaningful numbers in degrees C, and in my opinion, not-too-hot at telling us the “when” of an event either. Too much depends on assumptions.

But what are they good for is that, when combined with […]

Medieval Warm Period found in 120 proxies. Plus Roman era was similar to early 20th Century.

Two major proxy studies, larger than ever, were released in April and June 2012. They show that the Medieval Warm Period (MWP) existed, and was similar to current temperatures. These comprehensive studies suggest current temperatures are not unusual, and that itself is not all that surprising — I’ve mentioned before how there are hundreds of proxy studies showing it was as warm or warmer back then. (CO2science has been documenting them.) But these studies are worth a mention because they are so large.

Climate models cannot explain what caused the warming 1000 years ago, nor the cooling 300 years ago, so they can’t rule out the same factors aren’t changing the climate today (though they claim they can). If climate models can’t explain the past, they can’t predict the future.

The last 12 Centuries

Ljungqvist used 120 proxy records — nearly 3 times as many proxies as previous studies and conclude: “during the 9th to 11th centuries there was widespread NH warmth comparable in both geographic extent and level to that of the 20th century”. Their proxies included ice-cores, pollen, marine sediments, lake sediments, tree-rings, speleothems and historical documentary data.

Ljungqvistet al 2012 Fig. 4. Mean time-series of centennial […]

Chinese 2,485 year tree ring study shows natural cycles control climate, temps may cool til 2068

A blockbuster Chinese study of Tibetan tree rings by Liu et al 2011 shows, with detail, that the modern era is a dog-standard normal climate when compared to the last 2,500 years. The temperature, the rate of change — it’s all been seen before. Nothing about the current period is “abnormal”, indeed the current warming period in Tibet can be produced through calculation of cycles. Liu et al do a Fourier analysis on the underlying cycles and do brave predictions as well.

In Tibet, it was about the same temperature on at least four occasions — back in late Roman times (those chariots!), then again in the dark ages (blame the collapse of industry), then in the middle ages (the Vikings?), then in modern times (blame the rise of industry).

Clearly, these climate cycles have nothing to with human civilization. Their team finds natural cycles of many different lengths are at work: 2-3 years, 100 years, 199 years, 800 years, and 1,324 years. The cold periods are associated with sunspot cycles. What we are not used to seeing are brave scientists willing to publish exact predictions of future temperatures for 100 years that include rises and falls. Apparently, it will […]

Climate helped drive Vikings from Greenland

Qassiarsuk: This is the site of the Viking settlement of 972 and unlike much of Greenland, offers relatively sheltered grazing land for sheep. Photo: John McLean. (Click to see more images of Greenland).

For the first time temperatures over the last 5,600 years have been reassembled from the inhabited area of Greenland. (Other estimates were from ice-cores that are far inland.)

William D’Andrea, the paper’s first author says: “.. we can say there is a definite cooling trend in the region right before the Norse disappear.”

8.2 out of 10 based on 5 ratings […]

The Medieval Warm Period hit west Antarctica

What do you know? The Medieval Warm Period, which either “didn’t exist” or “only happened in Europe”, also hit Western Antarctica.

Booth Island and Mount Scott are also on the Antarctic Peninsula. Photo: Stan Shebs.

The climate models don’t know why the world was warmer 1000 years ago. They don’t know why it cooled into the Little Ice Age either. The models don’t do regional projections well, and they don’t do seasonal projections with any skill, and they (in the last ten years) don’t work on short decadal timeframes either, but surely when it comes to big global temperature changes the models have got all the major forces figured out? Surely they’d be able to predict large movements across the entire globe eh? — but the first test we come to, a mere thousand years ago, shows the models have a predictive ability not significantly different from a coin toss.

Just because it was warmer 1000 years ago (due to some other reason), doesn’t mean that CO2 isn’t responsible for this warming cycle, but when all the evidence for CO2’s guilt comes only from models that can’t get the last warming cycle right, and from argument from ignorance (“Our […]

Is the Western Climate Establishment Corrupt? Part 4: Past Temperatures

The public might not understand the science, but they do understand cheating

Dr. David Evans

6 October 2010

[A series of articles reviewing the western climate establishment and the media. The first and second discussed air temperatures, the third discussed ocean temperatures.]

Click to download a pdf file containing the whole series

They Don’t Tell You: The Current Global Warming Trend is Over 300 Years Old

A Scene on the Ice by Hendrick Avercamp, circa 1600

Satellite data only goes back to 1979, and global land-thermometer records only go back to 1850. Before that we have to resort to “proxies”, which are various natural phenomena from which temperature can be deduced. As we go further back in time, the errors and uncertainties increase.

7 out of 10 based on 8 ratings […]

News from the Non Intergovernmental Panel on Climate Change

A sample of recent scientific news from NIPCC * The Glaciers of Greenland were smaller 5000 years ago; * African savanna trees thrive with increases in CO2; * It was hotter in China a thousand years ago, and by a whole degree; * Marine-life-with-shells can’t agree on their favourite CO2 level and * Temperatures make no difference to the 5000 year record of hurricanes. […]

Mann sues: Minnesotans say “Go ahead. Make my day”

A joint post with Baa Humbug

It’s all about audacity.

Michael Mann’s contribution to modern science may one day be remembered as the guy who made it statistically possible to get a thousand year temperature graph using any local telephone directory as a data source. (Who needs tree-rings?)

If you were a guy who’d been caught producing scientific work so inept that people could pour in random data and get the same “curve”, then you might take a satirical video on the chin (or crawl into a hole). But if you’re Michael Mann, and you also used the wrong proxy, you hid your data, used graphs upside down, and invented deceptive “tricks” to hide declines, then you might call your lawyers.

The Minnestoans for Global Warming (M4GW) made the hilariously popular Hide The Decline video, which has now been removed from YouTube. Mann claims they defamed him “by leaving viewers with the incorrect impression that he falsified data to generate desired results in connection with his research activities”. The Minnesotans said “please do”, and responded undaunted by producing a new version (see below).

10 out of 10 based on 4 ratings […]

The big picture: 65 million years of temperature swings

Greenland Interglacial Temperatures – last 10,000 years. Are we headed for an ice age? (See below for more detail.)

David Lappi is a geologist from Alaska who has sent in a set of beautiful graphs–including an especially prosaic one of the last 10,000 years in Greenland–that he put together himself (and which I’ve copied here at the top).

If you wonder where today’s temperature fits in with the grand scheme of time on Earth since the dinosaurs were wiped out, here’s the history. We start with the whole 65 million years, then zoom in, and zoom in again to the last 12,000 from both ends of the world. What’s obvious is that in terms of homo sapiens history, things are warm now (because we’re not in an ice age). But, in terms of homo sapiens civilization, things are cooler than usual, and appear to be cooling.

Then again, since T-rex & Co. vanished, it’s been one long slide down the thermometer, and our current “record heatwave” is far cooler than normal. The dinosaurs would have scoffed at us: “What? You think this is warm?”

With so much volatility in the graphs, anyone could play “pick a trend” and depending […]

Unscientific hockey sticks and hidden data

These maps and graphs make it clear just how brazenly unscientific the Hockey Stick is.

It’s clear that the world was warmer during medieval times. Marked on the map are study after study (all peer-reviewed) from all around the world with results of temperatures from the medieval time compared to today. These use ice cores, stalagmites, sediments, and isotopes. They agree with 6,144 boreholes around the world which found that temperatures were about 0.5°C warmer world wide.

8.2 out of 10 based on 36 ratings […]