See update below for some comments on Bob Tisdale's protest (4th WUWT article).
With paleo studies coming thick and fast the deniosphere is finding it hard to keep up. A paper from PAGES-2k came out in Nature Geosciences only a day ago. So far WUWT has written
three four articles, but with barely a protest (except for a suggestion that Europe = the entire world - and now Tisdale's weak and silly protest below). Nothing like the furious pace of protest articles and downright silliness that the Marcott study brought out. I suppose there's time for that. Maybe Anthony is thinking that if he doesn't make too much fuss about scientific evidence it will all just go away and leave him to deny in peace.
Meanwhile the Auditor has bunkered down, obsessing with little details of individual proxies, ignoring the whole picture as usual. Probably trying to figure out which of the dozens of collaborating institutions he'll pick for his next barrage of vexatious FOIs. He can mutter in his beard all he wants, but it won't change the past or reverse global warming.
Continental temperatures of the past 2000 yearsNow for people who are actually interested in regional and continental temperatures over the past 2000 years:
- The paper itself - Continental-scale temperature variability during the past two millennia (subs req'd)
- RealClimate.org article on the paper by Darrell Kaufman (lead? author)
- SkepticalScience article by Dana
- Columbia University
- Joe Romm at Climate Progress
- From the Border Morning Mail (my local rag)
- The ABC (Australia)
- Nick Stokes has a neat interactive tool so you can play around with the data.
Study backgroundSome background from the FAQ: PAGES was formed in 1991 through the International Geosphere Biosphere Programme (IGBP). It allowed teams all around the world to join forces and do research on climatic and environmental dynamics by studying the past. In 2006, the PAGES 2k network was set up to look particularly at the last 2,000 years of data.
There were 78 people from around the world who collaborated in the study, a vast undertaking. The result is a detailed picture of temperature changes at a regional / continental level all around the world.
The most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended late in the nineteenth century.
At multi-decadal to centennial scales, temperature variability shows distinctly different regional patterns, with more similarity within each hemisphere than between them. There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age, but all reconstructions show generally cold conditions between AD 1580 and 1880, punctuated in some regions by warm decades during the eighteenth century. The transition to these colder conditions occurred earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere regions.
Recent warming reversed the long-term cooling; during the period AD 1971–2000, the area-weighted average reconstructed temperature was higher than any other time in nearly 1,400 years.
It's getting hot (and the MWP wasn't global)The issue deniers are zoning in on is the confirmation from more and more scientific sources that periods of warming in medieval times were not synchronous around the world. The world as a whole didn't get hotter. Different regions warmed and cooled at different times. The Medieval Warm Period (MWP) in northern Europe was local not global.
Even though it would be foolish in the extreme to say "the world's got warmer before therefore this time around it's not CO2" - that's precisely what some deniers used to say. With this and other recent studies they no longer have a leg to stand on in that regard. That doesn't stop deniers still regurgitating drivel of various different kinds, as seen by these comments from WUWT.
April 23, 2013 at 12:56 am So if they show it was clearly warmer in the past, and we didn’t “tip” into a disaster, doesn’t that kind of put a hole in that whole “tipping point” idea…It also seems that they can’t quite accept that natural variation which worked in the past can continue to work today, and have to embrace a new cause (CO2) for modern temperatures. Just a tiny bit tacky…
While Tom tries to downplay the problem:
Tom Harley says:
April 23, 2013 at 1:10 am It’s still just ‘weather’.
April 23, 2013 at 1:17 am Of course, it’s an established and accepted scientific fact that the MWP was a worldwide warm period; warmer than the present. We don’t need doubtful proxies, flawed studies or so called climate experts to tell us that. The Vikings grew potatoes on Greenland, for goodness sake!
RCSaumarez says:The last sentence sums up the typical denier. Show them the instrumental record and they'll say "who believes thermometers". Show them proxy evidence and they'll say "who believes proxies". Show them bits of the moon brought back by astronauts and they'll say "it's just cheese". Well, you get the picture.
April 22, 2013 at 3:52 pm Who believes proxy studies?
Luckily for humanity, only about 8% of people are so "dismissive".
Update 1(10:30 pm 23 April 2013)
Bob Tisdale, in the fourth WUWT article about the study puts up a few different figures and, after giving us his usual silly spiel about the oceans causing global warming (they don't, it's mostly our waste CO2), writes:
Now, hasn’t this been one of the arguments by climate skeptics since the hockey stick was introduced—that the hockey-stick appearance is a regional phenomenon? That regional reconstructions show current temperatures have been exceeded in the past in many parts of the globe?Lets break this down. Has it been 'one of the arguments of climate skeptics'? Well, it might have been, who am I to judge. Fake climate skeptics come up with a zillion silly 'arguments' on a daily basis. You can see a whole list of them here on SkepticalScience.com (174 and counting).
Have regional reconstructions shown some regions have been hotter in the past? Umm, probably. The big worry now is that on average, the entire world is heating up. That's why it's called "global warming". (That doesn't mean that every place on earth is getting hotter. It means the earth as a whole is getting hotter.)
What's happening now is not just one or two warmer regions, with other regions getting cooler and balancing out, so there isn't much change in global average temperature. What's happening now is that the global average temperature is rising, reversing a global cooling trend.
This is what the authors say in the abstract:
Recent warming reversed the long-term cooling; during the period AD 1971–2000, the area-weighted average reconstructed temperature was higher than any other time in nearly 1,400 years.Their study can't say more than that because it doesn't provide the data for all regions going back 2,000 years. Other studies do that.
Anyway, look below and judge for yourself how many places are heating up. About the only place that was much warmer for any length of time was Antarctica. The Arctic was much cooler than now. Asia, North America, South America and Australasia show up the recent heating as a new trend. Europe had a few warmish spells of shorter duration - maybe as hot as it is now or even for a short time, warmer. Everywhere looks poised to keep on heating up. And nothing below negates what the paper's authors stated: The period from 1971 to 2000 was higher than at any time going back nearly 1400 years (at least). And bear in mind that the temperature rise has continued into the 2000s! There's no going back now. The best we can do is slow the heating and hopefully help future generations stop it.
Here is a chart from the supplementary information. (Click image to enlarge.)