Climate Change for Dummies #1: How do we know that recent increases in CO2 levels are man-made?

 Climate Change  Comments Off on Climate Change for Dummies #1: How do we know that recent increases in CO2 levels are man-made?
Mar 292016

This is the first blog in a series I intend to write called Climate Change for Dummies.

So, How do we know that recent increases in atmospheric CO2 levels are man-made?

Over the last 150 years or so, the level of Carbon Dioxide (CO2) in the atmosphere has increased from about 280 parts per million by volume (ppmv) to over 400 ppmv – that’s an increase of roughly 43%!  Before explaining why we are absolutely certain that this increase is due to human activities, let’s quickly look at how scientists have measured this increase over time.

The chart below shows the levels of CO2 measured at the Mauna Loa Observatory in Hawaii. You can look this up and even download the measured figures here if you so wish. The red wiggles on the chart are caused by the respiration (breathing) of all the plant life on Earth, and the fact that there are more plants in the northern hemisphere. So, during the northern summer months these plants breathe in more CO2 than average and thus a seasonal cycle (or wiggle) is seen. (Isn’t science wonderful?).


Looking at this chart, it’s pretty obvious that there is a big upward trend here. The chart below shows just the last 5 years, and I urge you to look at the most recent few points in detail. Why? Because not only is the average level climbing, but the rate at which it is climbing is also increasing. In fact, Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years.


The chart below further illustrates that, in recent years, the rate of increase of CO2 has gone up, and is still going up.


You may be thinking “Hang on a minute, how can anyone just state that the levels of anything are increasing faster than they did over the past several 100,000 years?” A very good question and one that any sceptical person should be asking. The answer lies in the fact that there are other ways of measuring CO2 levels other than having a CO2-level-o-meter on top of a mountain in Hawaii! The trick is to drill ice-cores from ancient ice sheets. I can’t improve on the explanation from the British Antarctic Survey here, and the introductory paragraph from their webpage is as follows:

Ice cores are cylinders of ice drilled out of an ice sheet or glacier. Most ice core records come from Antarctica and Greenland, and the longest ice cores extend to 3km in depth. The oldest continuous ice core records to date extend 123,000 years in Greenland and 800,000 years in Antarctica. Ice cores contain information about past temperature, and about many other aspects of the environment. Crucially, the ice encloses small bubbles of air that contain a sample of the atmosphere – from these it is possible to measure directly the past concentration of gases (including carbon dioxide and methane) in the atmosphere.

When this is done (no mean feat I would add) we see that CO2 levels today are not only higher than they have been for a very long time, but they are increasing at a rate faster than at any time in a very long time.

The chart below shows this over the last 400,000 years, but I should add that this has been going on for at least 800,000 years, and probably for more than 1,000,000 years. When you think that modern humans have been around for about 200,000 years, you start to put that timeframe into some kind of perspective. Also note that the ‘Current Level’ marker on the chart below (drawn up to 2010) is slightly out of date – today’s CO2 level is over 402 ppmv.


So, we’ve established that CO2 levels are higher and rising faster than in any time in the whole of the history of anatomically modern humans, and beyond!

Incidentally, if you’re curious about why there are regular cycles in the CO2 levels in the above chart then these indicate the coming and going of recent ice ages. We know that Earth’s climate has changed throughout history, and indeed it is by studying the natural changes in the climate that scientists know that the current rate of (human-caused) change is unprecedented. In the last 650,000 years there have been 7 cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era. Human civilisation has blossomed in this current interglacial period. It is not the right place to explain in detail why these cycles occur, but the brief explanation is that they are due to long-term changes in the orbit and tilt of the Earth.

Get to the point!

Now let’s move on and tackle the main point of this article – how is it that we are sure that this increase in CO2 is caused by humans?

Firstly, before we get to the ‘killer’ arguments, let’s just consider the fact that since the industrial revolution, we have been burning fossil fuels and clearing and burning forested land at an unprecedented rate. We know that these activities convert organic carbon into CO2, and we also know that the approximately 500 billion metric tons we have produced is enough to have raised the levels to about 500 ppmv. Why is it then that the current levels are lower and nearer 400 ppmv? The answer lies with the world’s oceans and biosphere which act as ‘carbon sinks’ and end up absorbing some of the CO2 from the atmosphere. However note that we still produce CO2 faster than these sinks can absorb it, and the net effect is the observed increase as shown in the discussion above.

To be quite honest, that should be enough to convince any reasonable person, but there’s more…

It’s all in the isotopes

Carbon comes in several flavours or ‘isotopes’. Most of the elements in the Periodic Table do. The thing that makes a particular element the way it is is the number of protons in its atomic nucleus. Casting your mind back to your ‘O’ level chemistry (at least if you’re British like me) you will know that the atomic nucleus of an element contains the protons and neutrons, with the wispy electrons whirling around the nucleus like planets revolving around a star. The fact that Quantum Physics says that this mental image is completely wrong is neither here nor there – it’ll do for our purposes here.  Also, remember that the whole subject of Chemistry (well, pretty well all of it) is explained by the number and arrangement of the negatively charged electrons which balance out the positively charged protons in the nucleus.  Therefore, an element can have a varying number of neutrons and still be chemically the same element.

And so it is with Carbon (C) which has three naturally occurring flavours, or isotopic forms namely 12C, 13C and 14C (normally pronounced as “C 12”, “C 13” etc). The numbers come from the total of the number of protons and neutrons, and Carbon has 6 protons and varying numbers of neutrons. 12C is the most common form with 13C making up about 1% and 14C only accounting for about 1 atom in a trillion. 12C and 13C are stable isotopes but 14C is unstable with a half-life of 5,700 years which is why it is extremely useful in dating objects using a technique called Radiocarbon Dating.

The killer argument

It just happens that, during photosynthesis, plants have a preference for the lighter 12C over 13C and so they end up being made up of Carbon with lower ratios of 13C relative to 12C, and since the fossil fuels that we burn are mainly derived from ancient trees and plants, when the CO2 produced from burning fossil fuels is released and mixed into the atmosphere, a lower ratio of 13C/12C is found there also. This means that the isotopic ratio of 13C/12C measured in a sample of today’s atmosphere will be lower than a sample from the past (when less CO2 from fossil fuel burning was mixed into the air).

Another piece of killer evidence comes from studies of the 13C/12C ratio in both tree rings and the bubbles of atmosphere captured in ice cores. Trees lay down the familiar rings that we can count to find out how old a tree is, and the analysis of the material in the rings can tell us what the isotopic ratio in the atmosphere was at the time the ring was formed.  It has been found, from tree rings and ice core gas, that at no time in the past 10,000 years is the C13C/12C ratio as low as it is today. Also, this ratio starts to decline at around 1850 AD – which is when CO2 starts to dramatically increase due to the burning of ‘old plants’.

Recent measurements are also showing that the lower 13C/12C ratio is showing up in the surface waters of the ocean and also in the shells and bodies of sponges and corals. This is analogous to the evidence found in tree rings, but it reflects the changes in the chemistry of the oceans rather than in the atmosphere (but remember, the oceans absorb the CO2 in the atmosphere). These measurements also show that the decline in the carbon isotopic ratio started when the activities of the industrial revolution started to pump more CO2 into the air.

The chart below shows how the percentage of 13C has decreased in the atmosphere over the past 25 years, which reflects the growing influence of fossil-fuel carbon in the atmosphere.


Case closed!

The next article in this series will focus on how we know that CO2 and other ‘greenhouse gases’ do actually cause the Earth to warm.

 Posted by at 2:46 pm

Man-made Climate Change: False Balance in the Press

 Climate Change  Comments Off on Man-made Climate Change: False Balance in the Press
Mar 192016


If you look up the term “False Balance” you will, no doubt, come across the Wikipedia definition. Here is the first sentence from the Wiki article:

“False balance is a real or perceived media bias where journalists present an issue as being more balanced between opposing viewpoints than the evidence actually supports”

To give an extreme example, if an article shows a picture of the Earth from space, we shouldn’t need to hear the views of a spokesman for the flat-earth society about how the picture can be explained, or if we hear about about a new fossil discovery from the Cambrian, we really don’t need to hear from a biblical creationist! Why? Because there is so much evidence for the fact that the Earth is (nearly) spherical, and so much evidence that the Earth is 4.5 billion years old (and not 6,000 years old) that there is no point. If we were to include the views of every spokesperson holding every crackpot belief, we wouldn’t get anywhere, and we would also be guilty of applying “False Bias” to our article.

The situation is the same with climate science. The overwhelming evidence is that man-made emissions of greenhouse gases (mainly CO2) since the beginning of the industrial revolution (and more specifically since the 1950s) have cause the Earth to warm up. However, there are parts of the press that seem to think that we should give equal weight to the views of climate change deniers as we do to the the scientifically-based views of proper climate scientists. By the way, I’ll use the term “deniers” or “contrarians” rather than “sceptics” because real scepticism is valuable in science and should not be hijacked so easily by those involved in peddling psuedoscience or straightforward denial in the face of a mountain of evidence.

Let’s just get things straight. There is so much evidence for man-made (anthropogenic) global warming (AGW) that it is an indisputable fact. Scientists are as certain of this as they are that smoking cigarettes causes lung cancer. We should, therefore, be concentrating on the solutions to this, perhaps the greatest challenge ever to face mankind, rather than give air-time to the politically and financially motivated deniers. Additionally over 97% of climate scientists agree with this, and a lot of the minority of contrarians take up their positions because of some sort of overriding political belief system or through their association with lobbying groups funded by the fossil fuel industry.

Does this sound like scientific dogmatism? After all, scientists have been wrong many times in the past, and isn’t it true that great leaps in science have been made by those great radical thinkers who have thought ‘outside the box’ and fought against the established views of their times? Well, yes, but the subject of climate science is all about the measurement and collection of huge amounts of data, and the statistical interpretation of this mass of data. There is no chance for a Newton, or Einstein to come along with a new and radical way of thinking about the subject; the physics is well understood and, contrary to what you might hear from the deniers, climate models are good, and have been so for many years. Climate Sciience is an ongoing process, one that relies on hundreds of dedicated men and women getting out there and applying themselves to the task. The truth is driven our by that great engine of science called the peer-review process. If you’re not sure what that is, see the Wikipedia definition, and here are the first sentences from that definition:

“Peer review is the evaluation of work by one or more people of similar competence to the producers of the work (peers). It constitutes a form of self-regulation by qualified members of a profession within the relevant field. Peer review methods are employed to maintain standards of quality, improve performance, and provide credibility.”

AGW deniers hate peer-review as their arguments (such as they are) simply fall apart when subjected to the process. Unfortunately they are very successful at spreading their messages no matter how ludicrous they may be. Deniers and contrarians will keep repeating their nonsense well after it has been debunked by real scientists, ethical bloggers and journalists.

Many newspapers and television news outlets will attempt to “balance” the overwhelming scientific viewpoint by also interviewing a climate contrarian to present “the other side.” The problem is that by disproportionately representing the small minority of climate contrarians, a false impression is created among the public that their numbers are greater than they are in reality. Even the BBC fall foul of this, and in fact they are particularly bad at doing so. The fact that they examined their internal practises, found them wanting but then ignored the findings is very disappointing.

Even the process of debugging the myths put about by the deniers can be dangerous unless handled carefully. The very act of making reference to the offending article or programme can draw more attention to it. This is known as the “familiarity backfire effect”.

There are seemingly endless examples where climate contrarians are spectacularly wrong about climate change but somehow the media still treat them as credible experts on the subject – this has got to change. If you want to read about many examples of this try Dana Nuccitelli’s excellent book Climatology Versus Pseudoscience: Exposing the Failed Predictions of Global Warming Skeptics.

 Posted by at 6:08 pm

Ted Cruz and Lord Lawson. Strange bedfellows? (perhaps not)

 Climate Change  Comments Off on Ted Cruz and Lord Lawson. Strange bedfellows? (perhaps not)
Jan 292016

This is the first time I’ve dabbled with an article on Climate Change in my blog. It’ll probably be my last, as I guess I’ll be the target of much vitriol, get upset, and pull the plug like the sensitive chap I am. However, as I have been passionately concerned about the subject ever since my Green Party days of the 1980’s I thought it was about time I stuck a toe in the water, so here is a small article on a subject that has been eating away at me for several weeks.

lawson-cruzPhotograph credits : Lawson: Martin Argles The Guardian, Cruz: Chris Keane, Reuters

With the huge amount of recent publicity following the ridiculous Donald Trump, the rest of the candidates for the US Republican Party can get somewhat overshadowed. We seem to now hear less about Ben Carson and his Christian fundamentalist beliefs than we did, but there is one other candidate for the leadership of the ‘Grand Old Party’ (the GOP) who grabs a huge amount of news (as seen here in Europe, at least), that being the Senator from Texas, Ted Cruz. Trump maybe nasty and a racist – stupid even, but Cruz is more dangerous I would say, and definitely not stupid.

It is this intelligence that I want to highlight with regard to the Senator’s incredible stance with regard to Climate Change, and it is also here that similarities to the ex British Chancellor of the Exchequer Lord Nigel Lawson become apparent, but more about Baron Lawson of Blaby later, let us first deal with Ted Cruz.

It’s hard to know where to start with just how wide of the mark Senator Cruz is with his ‘beliefs’ on Climate Change. Perhaps reading this article would serve as some sort of primer, but Cruz (incredibly) chairs the Senate’s Subcommittee on Space, Science, and Competitiveness, and back in December 2015 appeared prominently in a meeting devoted to Climate Change where, amongst other things he displayed a graph which he stated proved that “there has been no significant global warming for the past 18 years.” You can watch his performance and see the graph here , but my point is that the chart is an example of cherry-picking the data to make a point, and Cruz knows this because, as already mentioned, he is not dumb. (I won’t go into massive detail here, but the cherry-picking includes ensuring that the El Nino enhanced temperature figure for 1998 is shown on the left of the chart, and thus deliberately lessening the real growth in global temperatures seen and measured over the past several decades, which is only explainable by including mankind’s emissions of greenhouse gases). I’m guessing also that Cruz must have staff members who prepare these things for him – perhaps advising and coaching him on what to say.

What, therefore, makes a person (and their staff – how can these poeple live with themselves!) knowingly present information in this false and deliberately misleading way? I am certainly unable to imagine the commercial, corporate and political factors that must contribute to the pressures on such a smart man making himself look and sound so ridiculous. Unfortunately, Ted Cruz has a huge following, and that’s what makes him so dangerous (see here for how dangerous he could be). But how does such an educated person manage to internalise and bury the deceit, and convince himself that he is right? I can only assume that this sort of denial of the work of thousands of scientist is akin to the way that the (very) occasional qualified biologist denies the fact of evolution and subscribes to the belief of creationism and that the world is only 6,000 years old!

So, what of Lord Lawson? How can we draw any parallels between the current Senator of Texas, and a Westminster School and Christ Church Oxford educated British politician (obtaining a first class honours degree in PPE) who served in Margaret Thatcher’s government? Surely we couldn’t have picked two more dissimilar people? Well, both are very smart, yet subscibe to incredibly dumb views related to Climate Change! Lawson founded the Global Warming Policy Foundation (GWPF) and has ridiculed himself several times by spouting nonsense about Climate Change. Unfortunately the GWPF has the means to represent this nonsense as ‘facts’ in such a way as to convince the more credulous members of the public and also many politicians (who should know better). For a detailed discussion of the utter twaddle that Lord Lawson spouts, I can do no better than to refer you to this immaculately-written blog article by Graham Wayne which really is worth a read.

In summary, you can be both very smart and a dickhead, all at the same time!

 Posted by at 4:39 pm
Sep 112015

Here are three different versions of M16, The Eagle Nebula in the constellation of Serpens Cauda. Interestingly, the constellation of Serpens is unique in that it is the only one that is split into two distinct pieces, namely Serpens Caput (the head) and Serpens Cauda (the tail). All of these images have been recently taken using the amazing telescope that I co-share with Australian amateur Jason Jennings. This scope is hosted in the ‘barn’ at the Siding Spring Observatory, Coonabarabran, NSW, Australia. I’ll write another post about the scope soon, but it is an amazing 16″ f/3.5 astrograph.

This first version is a ‘traditional’ LRGB image, meaning it has been made by taking separate images using Clear (Luminance), Red, Green and Blue filters and then combining those to make a final colour image. This should be close to how the eye would perceive the colour because the R,G and B filters pass frequencies of light similar to the sensors in our tri-colour vision system. The clear filter is used as a luminance channel and is where most of the sharpened detail resides.

As with all the images, please click on them to see a full-sized version.

M16 LRGB Version

This next version is taken using three narrowband filters. These are H-Alpha (Ha), OIII and SII. The wavelength of these filters are commonly used by astronomers because there are a lot of emission nebulae that have excited atoms in them that emit light in these wavelengths (especially Ha which is nearly always the strongest). So, to produce an ‘RGB’ image from them requires that they are mapped to the Red, Green and Blue channels of the image. I have chosen to use the ‘Hubble Palette’ which maps the SII to Red, Ha to Green and OIII to Blue. Here is the result:

M16 Narrowband Version

You will notice that the star colours are not good in the narrowband version and this is a consequence of the filter mapping and also because of the relative strengths of the three channels. So, in the third image below, I have combined the stars from the RGB image with the nebulosity from the narrowband image. Here it is:

M16 – NB with RGB stars

I’m not sure which version I prefer!

Finally, a 4th image (I lied!) taken last year with a longer focal length instrument (12″ f/9 RCOS) which shows the ‘Pillars of Creation’ in more resolution. This was also taken using the Hubble Palette which is appropriate because the iconic pillars were made famous by those fabulous images from the Hubble telescope.

The heart of M16

 Posted by at 2:13 pm

Nova Delphini 2013 – It’s official!

 General Astronomy  Comments Off on Nova Delphini 2013 – It’s official!
Aug 162013

The possible nova with the catchy designated name of PNVJ20233073+2046041 has now officially been named as Nova Delphini 2013.

It was clear here last night for an hour or so just as the sky was dark enough for me to make out the stars in Delphinus and Sagitta, so I took this shot of the new star with a 50mm lens on a Canon 60D. I’ve annotated the image so that you can where to find the Nova.

 Posted by at 7:59 am

A New Star in Delphinus

 General Astronomy  Comments Off on A New Star in Delphinus
Aug 152013

A bright Nova has appeared in the little constellation of Delphinus (The Dolphin). It is on the limit of naked-eye visibility, at roughly magnitude 6.3,  but binoculars will show it well. Here is an image I took of it this morning from a telescope in Australia, but it is well placed now for Northern hemisphere observers, and I hope it might be clear enough tonight to photograph it from here in the South of England.


Below is a map showing the constellation of Delphinus relative to Altair in Aquila and Albireo the head star of Cygnus the Swan. The position of the Nova is marked by the red circles. Click on the map to see a full size version.


This Nova, discovered by Japanese amateur Koichi Itagaki, is caused in a double-star system when material from one of the Stars builds up, or accretes on to its companion star (normally a white dwarf) until it undergoes a thermonuclear explosion and brightens very dramatically.

For those interested in finding the exact position, the co-ordinates are RA 20h 23m 30.7s, Dec +20° 46′ 03″


 Posted by at 3:59 pm

Zooming in on The Ring Nebula

 Deep Sky, General Astronomy, Zoom in on ... series  Comments Off on Zooming in on The Ring Nebula
Aug 092013

What was it about The Ring Nebula (M57) that inspired me to put together this little blog article? I guess it must be that it was the first telescopic ‘deep-sky object’ that I ever learned how to find and observe . (I didn’t call them deep-sky objects back then and the brighter wonders such as the Andromeda Galaxy and the Orion Nebula which are visible to the naked eye don’t count! ) I remember using my 60mm Tasco refractor back in 1971, as an 11 year old to look at this lovely object, and was amazed by it. Within a few months I would see it in Patrick Moore’s 12″ Newtonian Reflector – well what can one say – incredible!

It was always likely to be M57 (out of many other objects) because it is really easy to find, located as it is between two stars in the ‘parallelogram’ of Lyra the lyre. Also, Lyra itself is easy to find because of its brightest star Vega, and the fact that Lyra is a compact constellation right next to it.

Before we go zooming in on M57, what exactly is it? It is a planetary nebula, so called because, at first glance,  it presents a planet-like disk to an observer through the telescope. However, instead of being at Solar System distances, it is roughly 2,500 light-years away and was formed when a dying red-giant star blew out its outer layers before becoming a white dwarf. Such a fate will probably befall our own Sun in about 5 billion years! Now, we see the remaining shell of ionised gas as it expands into the interstellar medium.

So, the idea behind this blog is to locate M57, and zoom into it using images that go from wide-angle camera shots to high resolution images from large telescopes. First, I’ll transport you back to my world of the early 1970’s by showing this scan from the wonderful star maps at the back of the classic Norton’s Star Atlas. I still reach for this book when I need to remind myself of various bits of the night sky! Here is the scan, I added the insert showing Lyra at a larger scale, but the map itself in very evocative to me, covered with the rubbed-out tracks of pencil-drawn trails from long-gone Perseid or April Lyrid meteors. You will see M57 indicated between the stars β (Beta) and γ (Gamma) Lyrae at the bottom of the parallelogram shape (which I have outlined).


Now, on to the first image. I took this back in early June this year using a Canon DSLR camera and an 18mm lens, giving a nice wide field view. (as with all these images – click on them to see them at full size, then click again to return). I have indicated a large green triangle which is known as The Summer Triangle consisting of the 3 bright stars Vega, Deneb and Altair. I have also annotated the cross shape of the constellation of Cygnus the Swan which is getting rather swamped by the Milky Way in this picture. You can see Lyra near the top.


The next image is only a bit more of a close up Lyra, taken with a 28mm lens this time. I have added the names of the two stars that straddle either side of the ring nebula. As you can see Beta Lyrae has the proper name of Sheliak, and Gamma is called Sulafat. Also annotated are a few of the other brighter stars in this field – Albireo is the head (or beak) star in the cross of the Swan. Many of the proper names of stars in use today come from an Arabic origin and Sulafat comes from the Arabic for ‘turtle’ or ‘tortoise’ as it seems that most fine harps (or lyres) were decorated in tortoiseshell.


So, let’s zoom in a bit further. Next I changed to a 50mm lens and have also added an insert to this image. The insert is at the full resolution of the image whereas the rest of the picture has been much reduced in size to get it on this page. Now we can actually see the Ring Nebula! It’s pretty small as you can see, in fact it is approximately 3.5′ (arc-minutes) across which is, roughly speaking, only one tenth the apparent diameter of the Moon. Note the use of the word ‘apparent’ there; The true size of M57 is some 3 light-years across!


Now the last camera shot, before moving to a ‘proper’ telescope (telephoto lenses are telescopes really, but you get the idea). This time, I used a 200mm lens and I have cropped out the Sheliak/Sulafet region. Now we can see the ring and can understand why this is known as a planetary nebula.  It certainly confused its discoverer. French astronomer Antoine Darquier de Pellepoix in January 1779, reported that it was “…as large as Jupiter and resembles a planet which is fading.”  This is a good description as Jupiter is typically about 45′ across, but much brighter of course! Another Frenchman, Charles Messier, independently found the same nebula later on in the same month while searching for comets. He entered into his famous catalogue as the 57th object (Note that the main reason for Messier’s famous list was so that he would remember these ‘fuzzy’ objects and not confuse them with Comets which were his main interest).


The following image was taken with my Celestron C11 telescope and an ATIK 383L cooled CCD camera. I used a filter called an H-Alpha filter which passes light in a very narrowband of frequencies. I was after the outer shell of M57 – something I had never really seen in older photographs, but nowadays it is commonly captured by amateur astronomers using sensitive CCDs. It does require long exposures to bring the faint outer shell out, and I stacked together several 20 minute exposures to reveal it here.



The previous, rather noisy, image is certainly not my finest moment! I really don’t have a good telescopic image of M57. So to finish this article with a splendid image, I asked Robert Gendler if I might use one of his (for those of you who don’t know, Robert is one of, if not the best deep-sky imagers and image processors in the world) . He kindly suggested that I use this incredible image of M57. For more information about this particular image, and about M57 in general see Robert’s page here:


That’s it for my take on M57. Maybe I’ll make the Zoom into theme a regular feature here, so watch this space!


 Posted by at 4:23 pm