There is an opinion piece in the Sydney Morning Herald in which Paul Sheehan is impressed by Ian Plimer’s new book which suggests that we don’t have to worry about global warming. I’ve looked at some of Plimer’s arguments before and wasn’t terribly impressed. I was going to look at the SMH piece in more detail but found another blog which had already said much of what I had in mind – so I recommend going to check out The Michael Duffy Files. There is more at Pure Poison, Floating Life and the Courier Mail (from Graham Readfearn). Also Barry Brook has dealt with similar arguments from Plimer before at Brave New Climate – here and here.

I’ll just focus on a couple of issues, which do overlap somewhat with my earlier posts. I’ll tend to use points raised in the article as a jumping off point for general musings, rather than a detailed rebuttal since I haven’t read the book that Sheehan is discussing. Even so, we can still assess whether the issues discussed in the article lead to the conclusion that there is no need to worry about climate change.

I was going to look at the whole thing now but the post has been getting very long so for now  I’ll just focus on the ideas that the current warming is insignificant on geological timescales, and that warming is good anyway.

The article tells us that geologists look at climate change differently because of their perspective on time.  The IPCC are certainly aware of history of climate going back at least 400 million years and know about eras of high CO2 as is shown in the figure below, which is figure 6.1 from the AR4 report on the physical basis of climate change.

Figure 6.1 of the IPCC AR4 WG1

The top part shows the last 400 million years. The lines show the Co2 levels given by various proxies and the blue bars at the top show the extent of glaciation.

So it’s no secret that on geological time scales the climate has been vastly different. What is also worth bearing in mind is that over such timescales the sort of life which has inhabited the planet has been vastly different.  The first appearance of mammals in the fossil record is during the Jurassic (150-200 million years ago), the first primates around 55 million years ago, and homo sapiens just 200,000 years ago. Civilisation as we know it began with the first farmers perhaps 9000 years ago. The fact that life adapted to change millions of years ago is not particularly relevant to human civilisation now. Going hand-in-hand with this climate change in the geological past have been lots of extinctions as well, including at least five major extinction events which each saw the range of life on the planet change drastically. Of course not all life became extinct, another feature exhibited over such timescales is evolution. It should be kept in mind that evolution is driven by natural selection, that is, it is driven by certain members of the population dying before reaching reproductive age. Is this something comforting?

Even in the recent era of humans there have been significant changes in climate, and corresponding adaptations to that change. For example, it is generally considered that the spread of humans across the planet was motivated by changing climate. Large scale migration isn’t much an option now though, given that we cover all of the inhabitable parts of the planet. And even if we do have somewhere to migrate to I still don’t consider that a reason to not worry. How would it feel if, for example, the majority of the population of Adelaide had to move away because of climate change. Climate induced mass migration would involve huge social upheaval – sure, it wouldn’t count for much on geological timescales, but I’d rather not be in the midst of it. For all those worried about mitigation adversely affecting the economy, would forced adaptation be any better?

It’s not all about humans either. We rely on entire ecosystems which need to adapt. This includes plants which are a bit slow at migrating than we are. There are however other forms of life which can migrate quite quickly, such at mosquitos or pine-beetles. Not all good then.

Another sort of adaptation is to use technology. There is a theory that the first farmers may have been motivated by adverse climate change. So it’s OK then – it may bring on new technology and a whole new era of prosperity. But don’t you think that was because of the sort of people who said “there is a problem and we have to do things in new ways” rather than the ones who said “don’t worry, everything’s fine we can just carry on as before”. It’s strange to say that our ability to adapt will keep us out of trouble whilst making an argument in favour of inaction.

One further point is that it is clear that adaptations to change were not always successful. Many civilisations have collapsed, often these can be attributed to failures to adapt to changes. The human race continued on, but do you want to be part of a failing civilisation? In the long-term view the collapse of Roman civilisation is OK, things in Europe picked up again and far exceeded the achievements of the Romans by any measure … but if you could go back and explain it to someone in the midst of the descent into the “dark ages” would they find it particularly comforting? “Sure the Roman garrison’s gone and your town is now ruled by a barbarian warlord. Literacy, and with it, much of the knowledge accumulated for hundreds of years is disappearing. No more clean water from the aqueducts. No more trade with much of the rest of the world. But in about 1000 years the Renaissance will be really marvelous. Shame you won’t see it really.” (I freely admit that my early medieval history may not be 100% accurate – also this example was inspired by an article on this topic I read recently but can no longer remember where – if anyone can suggest it then I’ll put in a link)

Climate is defined as the average of weather over 30 years. It is often explained that this length of time is to smooth out short term, chaotic variations. We could go further and look at average conditions over thousands or millions of years – but this wouldn’t really be very useful would it? We want to know about climate because of it’s affect on things like agriculture – which has existed for only about 9000 years. On the geological timescale your life and the life of everyone you know is nothing. The place where you live is nothing. Your country, in fact all of human civilisation is nothing. The entire period of human existence is the briefest moment in geological time. Yet this perspective is supposed to inform policy decisions on how to respond to changing climate? Suppose an astronomer discovered an asteroid heading for an impact with the Earth – how would the argument “On geological timescales Earth has been struck by lots of objects, including some much larger than this one” be taken? It would be perfectly true, but not particularly useful. One way that perspective might be useful would be if you had some sort of “asteroid denier” claim that it’s impossible. The geological evidence would prove them wrong. In the same way the geological evidence shows that the Earth’s past is full of changes. The climate system is not as stable as we would be lead to believe if our knowledge was restricted to historical time. Is this not something to give more cause for concern? We know what happened to much of that extra carbon that used to be in the atmosphere. It ended up as fossil fuels, which are now being dug up and burnt, releasing it back there again. If the evidence suggested that Earth was much the same in those days then we wouldn’t have much cause for concern, but rather it shows that it was a very different place. Which leads to the next point.

The SMH article also contains the suggestion that warm weather is fine, it is good for us

The history of time shows us that depopulation, social disruption, extinctions, disease and catastrophic droughts take place in cold times … and life blossoms and economies boom in warm times.

Human civilisation has thrived in warmer times – but warmer relative to various  colder periods during the last few thousand years but not warm relative to today (and certainly not compared with the much warmer climates of millions of years ago). Consider the following figure, again from Chapter 6 of the AR4 showing a temperature reconstruction for the northern hemisphere from multiple proxies for the last 1200 years.

Fig6.10 from the IPCC AR4 WG1 report

The zero line is the mean for 1961-90, and for most of the last 1200 years northern hemisphere temperatures are below this.

Really if you want to know weather the affects of global warming are likely to be harmful the best thing to do would be to get a group of experts in diverse fields to survey the peer reviewed literature on the possible effects and compile it into a report … oh look, someone’s done that. That is exactly what the report by the IPCC’s working group 2 is about – “Impacts, Adaptation and Vulnerability”. They were quite thorough, there’s 20 chapters worth covering a wide range of topics. Remember these people didn’t just make this stuff up, it is a survey of the scientific literature, with references to hundreds of studies. The short version is the summary for policymakers (link to pdf). The story it tells is not that warming is all good.  Wet places become wetter, dry places dryer. Food production increases at some latitudes, decreases at others, and beyond about 3 degrees it’s bad news everywhere. Ecosystems are in big trouble with more extinctions, and positive feedbacks leading to further warming. Bad for fisheries too. Coastal areas will be affected by sea level rise, with poorer countries with little adaptive capacity suffering the worst of it. Health effects are mixed, less cold-related deaths, more heat related deaths, some changes in ranges of certain diseases benefiting some areas, harming others. The overall balance is judged to be negative. There are many more details for each region of the world. It’s worth reading the whole summary (I’ve just provided only a very brief summary of a summary of a report which reviews hundreds of individual studies – anything you want to know more about – just follow it up the chain).

Consider some of the chaos caused this summer in Adelaide and Melbourne by record temperatures. Well, in the long term, Adelaide’s still here, no problem. In the short term, there were blackouts and public transport failures (e.g. due to buckled train tracks), but even worse our morgue was full. I don’t think that’s OK. I don’t think a change that requires my city to need a bigger morgue is something that can just be shrugged off. Note that I’m not attributing a particular event to global warming, just pointing out that it is obvious that the predicted warming will have very real detrimental effects on our lives, this is just the beginning.

There are numerous other claims in the SMH piece which I take issue with, I’ll hopefully return to them in an upcoming post if I have time.