I’ll grant the possibility that CO2 is heating things but I have no idea how much, and I also accept the possibility that it cools the atmosphere at all levels–not just the ionosphere–in combination with the rain cycle. What I don’t accept is anything but the most remote possibility that we are doomed by burning fossil fuels. CO2 is way down on my list of environmental concerns. All the problems of a growing population, logging, farming, habitat destruction in general, exotic species introduction, every step humans make causes disaster for some species or another. Humans are the most adaptable of all species. Polar bears are probablly the safest of all the big carnivores–it’s the tigers that are in trouble; and pandas and tasmanian devils, and thousands of ocean species that are now competing with the bilge water of the seven seas.

Ultimately I believe people are the most important, but if I had to worry about beach zoning, I would worry in this order: 1) tsunamis; 2) hurricanes and ground subsidence; 3) low pressure systems and rogue waves; 4) sewage and ship leaks; 5) sea level rise. The Japanese tsunami measured 10 meters; century sea level rise is between 15 and 20cm, with 7cm projected from AGW. Current annual rise is 3mm. That’s one ten thousandth of the big wave.

So the more important question is not whether, but how significant? –AGF

There’s a small problem with your claim – you’re talking about a different paper than I am. You’re talking about this paper on lake sediments, whereas I’m talking about this paper on moss and lichen Let’s be sure not to confuse the two.

BTW, if you look at the latest Clyde data, it shows a bit more recent warming than the data that Watts put up, although it might not have when Watts posted the older station data.

Let me ask you a couple of questions, AGF – if humanity isn’t the cause of the warming, what is? Where is the CO2 coming from?

It seems I conceded your point prematurely: no T rise, no GW, no amplification, even with presumably unprecented melting. Unprecedented within the last 2000 years that is–it was about 5 degrees warmer during the LIG, which warming clearly did not cause the Greenland ice sheet to reach a tipping point.

James Hansen would have the Dutch worry much about sea level rise, but they don’t. They know better. It’s clear North Africa dried up, which desiccation decimated the population, but it’s not certain this was due to T rise. In this age of reported T rise rain has increased in the Sahara, and vegetation is returning to much of it, according to National Geographic anyway (July 31, 2009). And true, models predict greater T rise (if not greater max T) at the poles than at the tropics, and supposedly this is happening, even if not at Baffin Island, where (again) unprecedented melting is supposedly occuring without T rise or amplification. But such is the science. The more I study the more skeptical I become.

Camels evolved in the desert or on its fringes–deserts have been around since K/T. But they come and go, and whole ecosystems with them–sometimes within a few centuries or millennia. Vandals and Moors didn’t wipe out the coastal Berbers–the sand did. If GW can green up the desert, more power to it.

But to the point: are Baffin midges more telling than Viking fleas? Not much, it seems. –AGF

Second, you’re correct that I made an error with respect to the IPCC. I misunderstood the NH data for the global data.

Third, the second IPCC quote does support my contention that the MWP was regional in the NH:

The evidence currently available indicates that NH mean temperatures during medieval times (950–1100) were indeed warm in a 2-kyr context and even warmer in relation to the less sparse but still limited evidence of widespread average cool conditions in the 17th century (Osborn and Briffa, 2006). However, the evidence is not sufficient to support a conclusion that hemispheric mean temperatures were as warm, or the extent of warm regions as expansive, as those in the 20th century as a whole, during any period in medieval times (Jones et al., 2001; Bradley et al., 2003a,b; Osborn and Briffa, 2006). [emphasis added]

Fourth, I don’t believe we know all the reasons why populations grow, move, and shrink specifically because we lack temperature proxies for, for example, the desert. Changes in precipitation could be the cause as much as changes in temperature. As an hypothetical example, a change in weather patterns due to ocean circulation could result in a multi-decade long drought that overwhelms the culture’s ability to adapt, cause starvation and war, and so on. This is one of the projected outcomes of human-caused climate disruption, in fact, because similar events have been widely recorded in historical and archaeological records.

Fifth, we expect more warming in MANY places than we expect out in the Libyan desert. Look at IPCC Figure 10.8 for example, where the greatest changes are expected in the NH polar regions. Anthropogenic CO2 emissions are running above the A1B scenario (middle row), BTW. Also look at the regional projections (which do have greater uncertainty) and you’ll see that seasonally and annually, the Libyan desert and the Sahara region of Africa are going to get hotter, but the increase in temperature there will be dwarfed by the temperature increases around the Arctic Ocean. Going from 130 to 132 °F won’t have anywhere near the impact of going from, say, 28 to 30 °F (just as an example).

Sixth, look closely at Figure 6.10c, the third breakdown of the image. It shows the overlap of all the different proxy reconstruction uncertainty bands (5-95%) as different shades of tan and brown, with darker meaning that more reconstructions have that zone within their uncertainty band. In other words, the darker brown the image, the more likely it is that the real temperatures were within that range. 6.10c shows that only one reconstruction has an MWP temp that exceeds modern temperatures, a second comes close, but that the region of greatest likelihood (darkest brown) is around a negative temp anomaly of about -.25 °C. And Figure 6.10b shows the mean values for all those different proxy reconstructions, the warmest of which has a MWP temp anomaly of about +0.1 &degC. Compared to the modern temperature anomaly of 0.6 °C. So much for “one instance of temp higher than MWP.”

There’s no question that more data is needed, especially in lower latitudes and in the southern hemisphere. But thus far, the evidence strongly suggests that you and the many others like you are simply wrong on the MWP.

“There are far from sufficient data to make any meaningful estimates of global medieval warmth (Figure 6.11). There are very few long records with high temporal resolution data from the oceans, the tropics or the SH.
“The evidence currently available indicates that NH mean temperatures during medieval times (950–1100) were indeed warm in a 2-kyr context and even warmer in relation to the less sparse but still limited evidence of widespread average cool conditions in the 17th century (Osborn and Briffa, 2006). However, the evidence is not sufficient to support a conclusion that hemispheric mean temperatures were as warm, or the extent of warm regions as expansive, as those in the 20th century as a whole, during any period in medieval times (Jones et al., 2001; Bradley et al., 2003a,b; Osborn and Briffa, 2006).” (IPCC 2007:

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-6.html )

You admit desiccation and population loss in the Sahara and Mesopotamia–do you believe this involved any temperature rise? The reason I ask is that there is no proxy data available from the Sahara or Arabian desert–the map you provide is modeled entirely as far as those regions are concerned. See the maps at the IPCC reference above. I accept the argument from Baffin Island: if the conclusions are correct it would indicate at least regional T higher than that of the MWP, but you have already argued for the limitations of such regional variation, and I add to that the caviat of the IPCC itself, quoted above. And since you refuse to address MWP English viticulture, could you at least find a regional British proxy that shows regional heating?

As for the lack of proxies in the Sahara, Arabian Desert, Australia, Atacama, and so on, be advised that the hottest T recorded in the world was in the Libyan Desert half a century ago, and as far as I know it hasn’t been broken. And where more do we expect GW than the Libyan Desert? So the way I see it, you have only shown one instance of current T higher than MWP, one regional proxy, against plenty of anecdote and solid historical evidence. I’ll admit the possibility of a hockey stick that beats MWP; but the probability? Not yet. And we’re addressing a small part of the “science” –haven’t touched sea level rise yet, and that entails the larger farce.

The “science is incontrovertible”? Not even the IPCC agrees with you. –AGF

The entire Mediterranean drainage basin is 8.5 million square km. That seems like a lot until you realize that the entire surface of the Earth is 510 million square km, so the drainage basin for the Mediterranean is about 1.7% of the surface of the planet. Europe seems like a large area until you run the numbers and find that it’s only 2.0% of the Earth’s surface. The North Atlantic is believe to have been warmer during the MWP, but global climate reconstructions show that the rest of the world was likely cooler during the same period, meaning that the MWP was a regional climate change rather than a global one. The following image is from one of those reconstructions

Note how much of the Southern Hemisphere was cooler, how much of central Asia was cooler, but how the area around the North Atlantic was warmer.

What you’re suggesting is that we ignore globally-derived data and analyses in favor of regional anecdotal evidence that, at best, indicates that the climate has changed in the past, but not how or why the climate changed. Only science can tell us how and why, and you’re flat out saying that neither matters in this discussion. You have rejected the scientific method in favor of belief that what happened in a tiny percentage of the world (Europe)represents what was happening in the entire rest of the world at the time.

Again, I recommend you read the many links to climate papers I’ve pointed you to, such as the IPCC, the Baffin Island paper, and the paper on the regional nature of the MWP. Don’t take my word for it – but don’t take McIntyre’s, or Watts’, or ID’s, or Montford’s, or Loehle’s either. Read the actual published papers yourself and form an informed opinion based on them. That’s what I’ve done, and the science is incontrovertible.

For an introduction to the end of the LIA as reported historically see http://noconsensus.wordpress.com/2009/06/16/historic-variation-in-arctic-ice-tony-b/

But we could go back much further. Pliny noted during the Common Era that Egypt had an average of three thunderstorms per summer. About two centuries before that travel across North Africa by horseback came to a halt, and camels were used from then on. Leptis Magna, in Tripolitania, now Libya, provided most of the wheat for the Roman dole. The same city produced a Roman Emperor, Septimius Severus. The city was covered by sand dunes on and off for centuries, till modern excavations. Two notable post-Hellenistic ancients believed the earth was flat. Both were African. And in fact, if you were to tally a census of notable Greek thinkers you would find that more came from Africa and the Middle East than from Europe or Anatolia, and there’s a simple reason for this: the population of North Africa at the time was greater than the population of Europe. In fact we can quite easily blame ongoing desiccation for the downfall of Islamic civilization and the rise of Christianity–the population of North Africa dwindled to nearly nothing, cutting off the Maghrib from Baghdad, leaving great cities like Timbuctu as minor outposts, and leaving cities like Sabratha empty.

Of course all this only continued the earlier climate change which turned the Saharan savanna into desert. Rock art across the Sahara abounds with vanished game. The artists vanished with it. And the Pleistocene river systems were buried in sand. But we’re more interested in the more recent events. Capt. Cook was a brilliant observer with a mission to find a northern passage back to England. He went through the Bering Strait in 1778 and sailed along the coasts of Siberia and Alask as far as he could, but found pack ice “ten to twelve feet high” wherever he went. This translated of course into ice 90-100 feet thick.

You can deny the veracity or relevance of this all you want, but you are taking the word of a very few folk at East Anglia and elsewhere over that of a lot of frustrated climatologists who can’t get there papers published, and a lot of frustrated monks who drowned their sorrows in home made wine, in England, centuries ago. It doesn’t do to call this bit of historical viticulture “anecdote.” Even now British viticulture is less than a shadow of its medieval self, and I ask you to ask yourself, is such a certain piece of history compatible with Mann’s reconstruction or Loehle’s? How many degrees of warming did it take for English wineries to flourish, or do you deny that they did? We really need to get past those two questions for this discussion to proceed any further.

Regards, –AGF

What’s even more important, however, is that there are so many different climate proxies that we can remove all of the tree rings and still not impact the overall conclusions. Several papers have done this very thing, but the most recent (and it’s been out since 2008) is Mann et al 2008. I know that some people (JeffID, for one) claim that this paper’s methodology has been demolished, but I’m still waiting for proof of that in the peer reviewed literature. After reviewing Jeff’s own methodology and code, I asked him to reassess his conclusions given that he made a significant error. To the best of my knowledge, he’s never done so. See here.

The problem with anecdotes, AGF, is that they’re local and poorly documented. Having one ship say “Hey, we made it around the northern edge of Ellesmere Island on X date” (to use a fictional example) isn’t enough – to take that claim seriously, a scientist has to have proof. The claim alone, even documented in a logbook, proves only that the captain thinks he did what he wrote. It says nothing about the ocean currents or local weather conditions that might have opened up the passage for a total of a week, and the captain just got lucky. It says nothing about whether the captain was right about where he was, either.

What we do know is that there are rocks being exposed by ice caps that didn’t see the light of day even during the MWP (see this paper). The jist of the paper’s results is this: scientists know how the carbon isotope C14 is created by cosmic rays, absorbed by lichens and mosses, and decays over time. Lichens and mosses are dormant when covered by ice caps and so absorb no C14. So by measuring the C14, C13, and C12 ratios, scientists can determine when the rocks were last uncovered by ice. When the scientists did this, the found that rocks they tested on the edge of a shrinking Baffin Island ice cap had last been uncovered ~1600 year before. This means that, while the MWP did melt a lot of the Baffin Island ice, it didn’t melt the ice as much as has occurred recently. While this is local data, when combined with everything else, it is consistent with human-caused climate disruption driven by human CO2 emissions.

Ultimately, though, that’s the point – there is so much physics, so much data that supports the theory that it would require dozens of independent datasets to all be wrong for human-caused climate disruption to be wrong. If the climate was your car and it had a brake problem, the mechanic would have to explain away all the symptoms of a brake problem before he could rationally convince you that the problem is your clutch.

Science uses data to determine how the world works. Arguing using anecdotes instead of data is OK in some arguments, so long as you don’t try to say that you’re being scientific in the process. But the human-caused nature of climate disruption is fundamentally a scientific question, so anecdotes don’t belong in the discussion.

http://wattsupwiththat.com/2011/04/15/the-un-disappears-50-million-climate-refugees-then-botches-the-disappearing-attempt/

Regards, –AGF

How does one go about combining proxies to recunstruct global or regional climate? How do we avoid regional bias? Surely you don’t just average out all the available data. The point being, the process is hardly objective; it is highly subjective.

Next, how reliable are the proxies? In the first place they must be calibrated by a very short historical record. Again, the least of our problems. How do we assign values to the many factors that go into tree ring growth? Still a minor problem. The biggest problem? How do we correlate temperature and ring width? Do you have any idea what the function is between T and ring growth? It is parabolic, with maximum growth at some species specific temperature. When it’s too cold it cold it quits growing and when it’s too warm it quits growing.

What that means is that there is no absolute correlation, but we have to guess from assumed patterns whether T is rising or falling according to altered ring width. And from such guesses a graph is produced, and by somewhat arbitrarily combining such proxies a regional or hemispherical climate history is reconstructed.

Then we have to consider problems like Yamal, where T is flat not only during the MWP and LIA, but in the 20th century. There is a slightly cooling trend evident in the last two millennia.

So when you say I should submit to your hard science and ignore hard history, I’m not very impressed. Rather I’m inclined to refer you to some thorough studies in climate history, that teach us how Australian navigators sailed over southern latitudes a century ago that had been charted as land two centuries ago when they were still frozen over. And how the British marveled at new North Atlantic passages opening up in the early nineteenth century.

Ice extent doesn’t tell us much about absolute T, but it sure tells us a lot about about warming. And the northern extent of a forest (like Yamal, which dropped southward in the last few centuries) tells us a whole lot more than the tree rings preserved in the forest.

And BTW, there ain’t no hockey stick at Yamal. –AGF

Top graph, labeled “Temperature Change,” is captioned “reconstruction of annual-average Northern Hemisphere surface air temperatures derived from historical records, tree rings, and corals (blue), and air temperatures directly measured (purple). CO2 Concentrations” Oh, and look – there’s a blue section that’s derived from historical records, tree rings, and corals, and a purple section that directly measured air temperatures. Yep, you’re right, that does sum it up.

Middle graph, labeled “CO2 Concentrations,” is captioned “record of global CO2 concentration for the last 1000 years, derived from measurements of CO2 concentration in air bubbles in the layered ice cores drilled in Antarctica (blue line) and from atmospheric measurements since 1957.” And look, there’s a blue line section from the ice cores and a purple line section from atmospheric measurement (click on the image to see the blown up version where the color differences are clearer). Yep, you’re right, that does sum it up.

Bottom graph, labeled “Carbon Emissions,” is captioned “reconstruction of past emissions of CO2 as a result of land clearing and fossil fuel combustion since about 1750 (in billions of metric tons of carbon per year).” And look, the blue section is labeled “Fossil Fuels” in the image and the purple section is labeled “land use change” in the image. Yep, you’re right, that does sum it up.

Last chance, AGF. Point me to scholarly work that supports the many unsubstantiated claims you’ve made and prove you’re not a troll. Put up or shut up.

we will not tolerate trolling or abusive behavior. We moderate our comments and commenters exhibiting bad faith behavior will have their offending comments deleted and they may be banned, possibly without warning. When evaluating the merit of a questionable comment, we will also consider whether said comment seeks to make any meaningful engagement the substance of the original post and/or subsequent comments in the thread. We will not, however, delete comments just because we disagree with you.

So, if you’re not trolling for attention and don’t wish to be referred to as a “troll” as a result, then provide data and references for the Cook ice thickness you describe. Point me to mathematical examinations of the LOD problems that you think debunk sea level rise and the human causes of climate disruption. Show me you’ve read the links I referred you to and, more importantly, that you’ve understood the mathematics and science underlying the explanations.

Regional warming is just that – regional. The proxies you denigrate show a unified world where the LIA and MWP were largely limited to the area surrounding the North Atlantic. See this Science article, for example, as well as many of the links I pointed you to earlier.

Don’t want to be treated like a troll? Prove to me you aren’t one by doing the work necessary to understand actual climate science. Continue behaving like a troll and you’ll be in violation of S&R’s comment policy and you’ll be banned. I’ll be here, waiting for you to decide.