Wednesday, 20 May 2015

Week 3–Making sense of climate denial continued

I left one of the points raised in Week 3’s dog-and-pony-show out of my last post. It’s sort of a big deal as it concerns the relationship between CO2 and temperature.  That’s really the point of the whole global warming debate.

In Al Gore’s infamous Inconvenient Truth he shows the big graph of temperature above a big graph of CO2 and says that rising CO2 caused rising temperature. When the graphs are (properly) placed on top of each other, they show that usually temperature rose prior to the rise in CO2. Sort of an Inconvenient Fib.

It’s difficult to imagine how a rise in CO2 could cause a rise in temperature in the past. I‘m pretty sure Einstein proved it couldn’t. In nature, cause has to precede effect. (Not necessarily in our imaginations or “climate science” though.)

Anyway, in 2012 Shakun et al. published a paper: Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation.

‘Deglaciation’ of course, is the process of a glacier melting. The normal reason for glaciers to melt is warmer temperatures. Of course, a warming atmosphere isn’t the only thing that can melt ice. A volcano, like the one under West Antarctica can do that too. Click to read about the West Antarctica volcano(s).

The last deglaciation began about 18,000 years ago, paused for a while about 13 thousand years ago continued warming rapidly until about 11,000 years ago at the start of the geological period called the Holocene. Click to see a reference for glacial timelines.

In twenty words or less, Shakun et al. claim that rising CO2 levels preceded the warming at the end of the last ice age. Even if correct, this would not ‘prove’ cause and effect. Correlation is not causation.

I read the paper during the week. Click here to download it. In brief, they used climate proxies to look at CO2 and temperature from 80 locations around the Earth. The proxies were things like ice cores, pollen trapped in sediment and various chemicals and atomic isotopes.

Week 3, Shakun et al figure 1a spatial distribution of proxies

Figure 1 | Proxy temperature records. a, Location map. CBT, cyclization ratio of branched tetraethers; MBT, methylation index of branched tetraethers; TEX86, tetraether index of tetraethers consisting of 86 carbon atoms; Uk037, alkenone unsaturation index. b, Distribution of the records by latitude (grey histogram) and areal fraction of the planet in 5u steps (blue line). (Shakun et al., 2012)

The map shows how the proxies are distributed around the globe. The little graph on the left is interesting. It shows the number of proxies at each latitude. Half are along the equator, between 30 degrees north and 30 degrees south. There are a total of four proxies for the entire part of the globe below 50 degrees south.

The paper states that 13 proxies cover the 29% of Earth’s surface that’s land and 67 cover the 71% that’s covered by water. Even if the proxies were evenly distributed, each land proxy would cover more than 11 million square kilometres (4.4 million square miles) and each ocean proxy would cover 5.4 million square kilometres (2 million square miles). It strikes me that the proxies are a bit few and far between, but then I’m not a climate scientist.

The big deal is the next graph.

Week 3, Shakun et al figure 2a proxy temperature and CO2

Figure 2 | CO2 concentration and temperature. a, The global proxy temperature stack (blue) as deviations from the early Holocene (11.5–6.5 kyr ago) mean, an Antarctic ice-core composite temperature record42 (red), and atmospheric CO2 concentration (refs 12, 13; yellow dots). The Holocene, Younger Dryas (YD), Bølling–Allerød (B–A), Oldest Dryas (OD) and Last Glacial Maximum (LGM) intervals are indicated. Error bars, 1s (Methods); p.p.m.v., parts per million by volume. (Shakun et al., 2012)

The red line is temperature data and the yellow dots are CO2 data from locations in Antarctica. It’s a little unclear exactly which papers and therefore which data were used, but it appears that the CO2 data comes from Monnin, E. et al. Atmospheric CO2 concentrations over the last glacial termination. Science 291, 112–114 (2001). The temperature data is reported to have come from Pedro, J. B. et al. The last deglaciation: timing the bipolar seesaw. Clim. Past Discuss.7, 397–430 (2011).

The the CO2 data (Monin et al, 2001) comes from the Concordia Dome (Dome C) while the temperature data is not actually reported in the reference given (Pedro et al., 2011) and the paper does not refer to the Concordia Dome, although it does refer to other locations in Antarctica.

The blue line is the amalgamation of the 80 proxy temperature records. Notice the horizontal scale is time with most recent time at the far right and 22,000 years ago (22 kyr) at the far left. “Now” is actually 1950 so the scale is years before 1950. I’m sure there’s a good reason for that.

Anyway, to the point:

When you look at the yellow dots and the red line, CO2 and temperature appear to go up and down more or less together. In the area between about 15 and 13 kyr, labelled ‘B-A’ on the graph, CO2 has risen quite sharply, but temperature goes down a bit and then back up a bit. So what? No clear relation of one preceding the other.

When you look at the blue line, however, between 17 and 14 kyr and again between 12 and 10 kyr, CO2 goes up and THEN temperature goes up. That’s called CO2 leading temperature or temperature lagging CO2.

This at least opens the door to the idea that rising CO2 could cause rising temperatures, but, of course, doesn’t really say anything at all about cause and effect.

Nevertheless, it caused quite a stir in 2012, particularly with media like the BBC in the UK proclaiming “CO2 'drove end to last ice age'”. (BBC, 4/4/2012)

After reading the paper and looking for the actual data, I located a couple of posts on Watts Up With That (WUWT), the most widely read blog on climate science. Click here to see WUWT

The posts examine the data from the Shakun paper and point out the following:

The temperature data has huge spread.



The first graph shows just the temperature data as it really is, all spread out. The Shakun paper averages the values all together that implies that the measurements are made with incredible accuracy. They’re not.

The second graph says it all:

Did CO2 rise before temperature or did temperature rise before CO2?

Answer: Who knows? You certainly can’t tell from this data. The first post can be found by clicking here.

The second post goes a step further.  The author gather lots of additional CO2 data from lots of other sources, not just the single Antarctic ice core used in the Shakun paper.


Again,  the CO2 data is buried in the blur of the temperature data, but look at what happens at the right hand side. Since about 8000 years ago, CO2 has been rising, but temperature has levelled off. Click here for the second post

Shakun et al. would have been well aware of that, but cut the right hand side of their graph off at about 7000 years ago.

Lesson?: Never spoil a good hypothesis by showing all of the data.

Thursday, 14 May 2015

Week 3–Making sense of climate denial


Well, the slick lessons march on. This week we were told how bad humans have upset net natural balance of nature, how CO2 enhances the greenhouse effect and explores those wonderful fingerprints we were promised in week 1.

The most exciting thing about this week was the poll:

Poll Question: What human fingerprint do you think is the most clear indication of human-caused global warming?

The answered are displayed in a nifty ‘word cloud’.  My answer of ‘none’ didn’t do too well.

word thingy week 3

The Carbon Cycle

The first part on the carbon cycle was a bit of ho-hum. I’m not sure anybody contests the view that there’s more CO2 in the atmosphere now than there was in 1958 when it started being measured at Manua Loa in Hawaii.

I’ve always had lots of questions about the measurement of CO2. Here’s a few:

  1. Why just measure it at Manua Loa? Is is that hard to measure? Does the fact that there are active volcanos in Hawaii influence the readings?
  2. How was CO2 measured prior to 1958? The partial answer is not all that well. Most measurements are based on three ice cores from Law Dome in Antarctica by Etheridge.
  3. Is the CO2 concentration the same everywhere in the atmosphere? Does it vary with height? Does it vary with latitude and longitude?
  4. What’s the uncertainty in CO2 measurement?

This looks like a topic for a future post.

One of the main claims by the lecturer is that CO2 level were unchanged for hundred of thousands of years until wicked humans started burning fossil fuels.  The rise didn’t actually start till the 1950s when it actually started being measured. Sort of a coincidence, but I’m reasonably happy to accept that CO2 has increased due to burning of fossil fuels.  I just don’t think it matters much.

One interesting point that was highlighted was one I hadn’t really considered before. While humans supposedly put 7.8 GT (Giga tonnes, billions of metric tons) into the atmosphere each year, the wonderful Earth removes 4 GT for us. I was actually told “nature is resisting the increase”. Good old Nature. No physical explanation was offered for this happenstance so I can only assume it’s one of Gaia’s mysteries.

The final part of the carbon cycle lesson dealt with Residence time and Adjustment time. The claim is that man-made CO2 stays in the atmosphere for about 4 years (the residence time) but if we stopped using fossil fuels it would take 50-200 years to get back to ‘normal’ levels. Since I can’t see that happening anytime soon it seems a silly thing to worry about.

I also wondered what happens to the extra 4 GT that Gaia removes each year out of the kindness of her heart? Would she stop?

The Greenhouse Effect

The next lesson dealt with the so called ‘greenhouse’ effect. We’ve all been in a greenhouse or at least a car on a hot day. The Sun beats down, heating up the inside and the heat can’t escape so the temperature goes up. Simple.

Except we’re talking about the atmosphere that doesn’t have a glass cover over it. Greenhouse gasses absorb infrared radiation reflected off the Earth’s surface and re-emit it in all directions so some of it, instead of being sent back out into space, heats up the atmosphere.

If CO2 doubled, the physics says the atmosphere would heat up about one degree Celsius, over a period of hundreds of years if nothing else like cloud cover changed. That’s an interesting scientific idea but nothing to get excite, or spend money, about.

The lesson talks about the CO2, never mentions the projected feedbacks and never mentions the one degree of warming.

It was all pretty vague and really nothing I would bother arguing about too much.

The lesson talked about straw-man myths like CO2 is a trace element so it doesn’t matter.

The fingerprints

This was the big one I have had been waiting for.  Yet another disappointment.  The whole forensic beat-up was based on satellite measurements (CERES) showing an energy imbalance of 0.6 Watts per square meter out of an energy input of 340 Watts per square meter. 0.6 is probably less than the accuracy of the instrument, but I’ll look that up.

The other fingerprints were supposed tiny changes to the differences between day and night temperatures and a slight cooling of the upper atmosphere.

I’ll check these again, but none of them are the least significant to my recollection.

So I waited for week three to particularly learn about the ‘fingerprints’.  It was a bit of a disappointment.

Friday, 8 May 2015

Week 2 – Making sense of climate denial


This week’s “course” dealt with temperature records. I really didn’t learn much because there wasn’t much to learn. I had hoped that the topics would deal with issues like errors in the historical temperature records and uncertainties in more recent records.

No such luck.

The main messages were:

1. The temperature record is incredibly accurate because “scientists” say so. Sure it keeps getting adjusted but that’s good science. Also, nothing effects temperature except CO2.

2. The temperature doesn’t matter.  It’s only the number of records that get broken that matters. Really. Here’s an actual quote:

“Instead we can compare the number of hot and cold records in any decade. If the number of hot and cold records is about equal, then the weather is not changing. If we see more hot records than cold records, then it is getting warmer, and vice-versa.” Kevin Cowtan, 2015.

3. When glaciers heat up, the ice melts. It’s all caused by CO2 and nothing else.

4. Anyone who says the temperature hasn’t risen appreciably since 1998 is ‘cherry-picking’.

5. The ‘hockey-stick’ is alive and well. If you’re not familiar with the ‘hockey-stick’ controversy, I’ll cover it briefly below.

The first video in the Temperature lesson had a nice ‘hockey-stick’ graph, startlingly similar to the discredited one from the IPCC’s 2001 Third Assessment Report.

Week two, Building a robust temperature record 4min43sec

I tried to find out where this data came from by viewing the ‘Attribution 4’ information flashed at the end of the video.

Week two, Building a robust temperature record 5min53sec

As you can see, it’s produced by Kevin Cowtan from Global Historical Climatology Network and is based on “Natural Thermometers”, apparently tree rings and such. I couldn’t find any actual references.

The following graph from the IPCC’s 1999 First Assessment Report shows a similar (but not identical) time period . Notice how Kevin’s graph leaves out the Medieval Warm Period and the Little Ice Age?

Global temperature from 1000 AD

There was a large controversy a few years ago. The ‘hockey-stick’ graph has been discredited up to and including accusations of actual fraud. I won’t mention the researcher’s name as he’s fond of tying critics up in expensive court cases.

The ‘hockey-stick’ graph never been seen again in an IPCC report, and in fact, nowhere else where it’s taken seriously.

Until University of Queensland's Climate Denial 101x.