Global Warming, the latest IPCC report - and Matt Ridley

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EPA graph illustrating history increase in sea level, a jagged line inclining up to the right

The revised IPCC report suggesting less warming has generated some discussion, particularly with Matt Ridley writing about how we can be less concerned with the possible impacts of AGW - that is "Anthropogenic Global Warming" - or, put another way - global average temperature increase result from our industrial activity increasing carbon dioxide in the atmosphere - see here. So, it's opportune to comment on this development and Ridley's viewpoint, together with my overall view of the AGW debate. There's a lot to cover, but I've segmented it provided links to it below :






1. Revised Global Warming


While the IPCC notes we're warming more slowly, there's two reasons - first,  if we apply heat to the earth, it can either increase the earth's temperature or melt planetary ice - particularly glaciers towards the North Pole. Either way, the earth is absorbing additional heat. Once we're out of ice, we can't absorb heat that way - and the globe will unavoidably heat up - and second, averaging can cover things up.

If you have a mixture of ice and water, warming slowly - as you'd have to keep beer cold at a party - as long ice and water is mixed together, it is going to be at 0 degrees Celsius. Heat doesn't increase the temperature - the ice melts. Only once you've run out of ice will the temperature rise above 0 °C. Similarly, you won't be able to drop the temperature below 0 °C until it's a solid lump of ice.

If you have ice next to something you're trying to keep cold, it might rise above 0 °C - but the ice will slow down its rise in temperature. A kilo of melting ice absorbs as much heat as 80 kilos of water increasing in temperature by 1 °C - so it does not take much ice melting to absorb a lot of heat. This is what's happening to planet earth. Permanent ice is connected to the rest of the world by circulating air and water - this slows the earth's temperature increase depending on how effective the connection is. That's what's happening now. This means the earth is absorbing additional heat - its just not increasing the global temperature. It's certainly embarrassing that scientists did not foresee this possibility. But embarrassment does not mean there's no global warming. This is an issue for the credibility of scientists working in the field vs. science itself.

Matt Ridley spends too much time, IMO, working on the exact words used and the different probabilities as assigned by the IPCC, weighing up the difference between "likely", "very likely" and "extremely likely". It feels like he's doing keyhole surgery - he's not really engaging with the principles behind what's going on, just dissecting words and conclusions without worrying about what's behind them.

Ok, so we can allocate probabilities of different things happening, and there may be a chance that things will work out OK, or the benefits will exceed the costs. But Ridley's approach is superficial and sweeping. Sure, the earth's temperature might just increase with minor consequences. However, there's a chance of cascading effects making things a lot worse. Rainforests could die off, releasing much more CO2. Warming Siberian peat bogs and methane clathrate at the bottom of the ocean could release methane. That could make the temperature changes a whole lot worse. It's been noted that the IPCC ignores these possibilities - see here.

Changing temperature around the globe could cut off currents and winds, dramatically changing the earth's climate - very different to "a small incremental temperature change". Such changes could mean that rainforests die, or that the Gulf Stream / North Atlantic Circulation turns off. At present, these currents act like a fan in a convection oven, spreading heat from the equator around the earth. If it shuts down, paradoxically a hotter earth ( on average ) could mean a colder Europe. The equator would become a lot hotter - but Europe would cool down, no longer being fed with heat from the equator.

Ridley cites all these reports out there which might make things less of a concern; while ignoring the flip side of the coin that there's concerns things could end up worse than indicated in the IPCC. We're both second-guessing the IPCC in our own way - but at least I'm acknowledging both sides of the coin.

The earth's temperature and climate are variable. While it might be possible talk about an average temperature increase, in different places temperatures might increase or decrease. Further, hot does not necessarily mean dry. A hot ocean would mean more evaporation, and as a result, more rain on land - so long as you have winds to bring that moist air over land. Yes, that can mean greater fertility, though there's no reason for it to be evenly spread. The flip side of greater rain and fertility is more fuel for bushfires - and heat itself kills people too. In any case, more "heat" and "more CO2" will have at best a mixed effect on global agriculture - you can't make a sweeping statement.

Ridley makes some sweeping claims about the benefits of warming exceeding the costs. He does acknowledge deaths from high temperatures, but claims that deaths from cold in winter are larger, so the net effect is positive. This does seem to me a string of contestable assurances - as I'll consider later, you can't just say that "more CO2 will increase fertility", and you also have the effects of bushfires, separately to deaths just from heat itself. The case I make out - supported by other's analysis - is that you can't so easily claim the benefits will outweigh the costs - and even if they do, the idea that you'll be able to effectively compensate the island nations which have disappeared is very dodgy.

2. A Defence in Depth - "Ambit" Claims.

Matt Ridley occupies one end of the AGW denial spectrum. You have different viewpoints :

  1. There's no AGW - all the known observations are the result of "natural changes".
  2. Even if there is an AGW effect, it will be dominated by stabilising systems, such as water vapour
  3. There may be an AGW, but it will not be big enough to be a problem, and/or the benefits will outweigh the costs
  4. Even if there is AGW, we'll be able geoengineer and/or find other ways around it


Ridley seems to be at the third point on the spectrum. He's willing to acknowledge, for example, that there's been 0.8 C temperature increase so far. In contrast, though, many AGW denialists seem run a "Defence-in-depth" - they say something like "I don't think there is AGW, but if there is, it won't be a problem".

I think this sort of approach, of using an "ambit claim" is pretty dodgy. It may be a negotiating position, but it is not scientific or ethical. I mostly dig one trench, and defend it to the death. I do have a defence in depth position about advantages - I don't think there will be net benefits, but even if there are, it will be difficult to compensate people in the submerged island nations. That's pretty mild compared to the defence-in-depth that some AGW denialists have set up. A lot of what I write will be addressing Ridley's points, but I'll also be addressing these other viewpoints too.

Of the positions put forward, I think I'm fact closest to the fourth position. But the possibility of geoengineering is no reason to drag your feet on climate change initiatives. In many cases position 4 is used as an excuse for inaction, which is not what I'm talking about.

3. Bushfires

Of course, to start a bushfire you need a flame. In this sense, increased temperatures which aren't hot enough to cause ignition don't start fires, regardless of the source. But, they can make them worse after they start. You can try to minimise the impact of bushfires - but that becomes harder to do. And local random conditions - wind direction and speed - have their own impacts. Sure, increased temperatures do not "cause" bushfires. It is more complex than that. But they sure don't help!

Authorities in Australia say the recent bushfire season has been worse because there was a warm winter with high rainfall, building up more fuel, which was exacerbated by the higher summer temperature ( see bushfires-crf and meteorology-report.pdf ).This unseasonably hot winter and summer weather is consistent with global warming. It is also possible that it just the luck of the draw.

Of course, we can never be certain of the cause. But, statistics with some judgment can make us confident that global warming is more likely to be the cause of the hotter temperatures and bushfires.While these things are not certain, to the extent that we can be confident, that confidence can be undermined in the same way as the link between smoking and cancer was undermined. Engaging with this "statistical reality" can be challenging. Certainly, with all the argument flying back and forth, it can be hard to actually put a considered statistical case on the table.

For sure, there's a vested interest in not engaging with the statistical reality that it might be caused by something you don't like. Upton Sinclair said "It is difficult to get a man to understand something, when his salary depends upon his not understanding it!". I think we're getting something like this with the current Liberal Government, in terms of how Abbott and Hunt are reacting to bushfires and climate change. You can see the political polarisation here.

Yes, bushfires are a tragedy, and that needs to be acknowledged. At the same time, we can try to look at the overall situation with scientific objectivity. And look - temperature - or even AGW - is not the only factor at work. But, it is an important one, and should not be sidelined.

4. Adverse Weather Events

Sure, we have not had a statistically significant increase in the number of tornadoes and similar. However, there is a significant increase in the energy of storms. Other effects are known to be on the rise. Sure such increases could be a coincidence. But I think any impartial observer would have to agree the odds are narrowing. Certainly, hotter oceans mean more evaporation, and more evaporation ought to mean hurricanes with more oomph. Maybe more tornadoes. The exact details are not clear - but it does look like AGW is behind the increase.

5. Averaging Temperatures and Ocean Levels

Measuring the world's average temperature is hard, because winds and other features are forever changing. Local temperatures can fluctuate widely, going against the trend line. Changes in the earth's average temperature could be a statistical artefact, the result of changing weather patterns. In contrast to trying to measure the world's temperature, ocean levels are self-averaging. And the uniform rise in sea level is quite apparent - see the image at the start of this article. It also appears on Wikipedia. This image is in the public domain, being an US EPA image, and appearing on the US EPA climate change website.

Incidentally, I expect most of this increase would be the result of the ocean heating up rather than melting ice. Ice floating on the ocean does not increase the sea level when it melts. However, ice which sits on a continental shelf will increase the sea level when it melts. The North Pole is dominated by ice floating on the water; the South Pole is dominated by ice sitting on land. This is an important distinction. While the arctic sea ice might disappear , this won't change ocean levels. It is the melting of ice on continents, like that in glaciers, that increases the ocean level.

Changing local weather conditions can cause aberrant results. For example, changed winds might mean less snow falls on a peak, so that the glacier retreats - because of changed local snowfall, not global warming. Sure. However, the overall retreat of glaciers cancels out such local effects.

And er ... look, let's acknowledge a clanger. Global warming would not significantly increase earthquakes or tsunamis ( caused by earthquakes ), as has been claimed. Ewwww. Wrong! Bzzzt. But, ahem ... just because people make one mistake does not ruin the whole picture. It would be wrong to think that a single flaw would render the whole picture null and void. ( A more sizeable ocean might change the stresses on the plates, which might make a minor impact on earthquakes - fundamentally, earthquakes are a matter of geology rather than being a physics-chemistry story).

There was a Medieval warming, but it was localised to Europe - but globally the Mediaeval Warm Period was cooler than recent global temperatures. This tells us something about the problems with confusing local and global effects.

6. The Impact of Changing Ocean Levels

Increased temperature is the only reasonable driving force behind recent ocean level increases. These increasing ocean levels are inundating Island nations. It is a side effect of AGW. Ridley claims the benefits of global warming could exceed the costs. Technically, that's possible, but there's a lot of unknowns. Ridley seems to focus on the possible benefits while ignoring the possible costs - for example, bushfire and adverse weather events. In any case, there's another important issue - the inability of global institutions to adequately compensate people for impacts.

You just need to look at Diego Garcia or the natives who were displaced by to make way for atomic bomb tests. Then you have the impacts of US bases in the Philippines. And look, trying not to be biased, I'm sure the former USSR left a trail of wreckage in its wake. The story does not seem good. But look ... tell me those stories about global institutions being effective.

So, there's a lot of ifs - but even if the benefits of AGW would exceed the costs globally, we have good reason to be sceptical of the ability of global institutions to properly share those benefits around.

7. Possible Benefits - Agriculture ?

Ridley claims AGW will benefit agriculture. Well, higher rainfall might well help, but this benefit would be spread unevenly, and would be dependent on the (then) prevailing winds. But another notional benefit is plants growing better in increased carbon dioxide. However, higher carbon dioxide has not improved many plants tested, particularly out in the open as compared to a greenhouse.

How do plants can benefit from CO2?

At a simple level, more CO2 might mean the plants can absorb more CO2, with a linear improvement, so long as there's water and nutrients to support that growth. However, to make a real advance, plants need to change their pore size.

If plants absorb CO2 through pores in their leaves, they are obliged to "leak" water through these pores, and must expend energy replacing this water. So, the higher the CO2 concentration, the less water must be transpired for the CO2 absorbed - if the plant makes its pores smaller. Plants can't just turn down their pore size like you adjust the volume on your TV. Existing plants are optimised for current CO2 concentrations, plants need to adapt (evolve) to take advantage of increased CO2.

There are other factors. If plants are growing more rapidly, they'll need more water. They'll also need nutrients - and it may be that changing weather conditions move the optimum conditions for plant growth to areas where the soil is lacking nutrients. Significant growth only takes place where there's a "sweet spot" - where everything's right. Also, if there's an increase temperature as well as more CO2 ( we assumed above that the only thing we changed was CO2 concentration), the plants will need more water to compensate for the increased temperature ( quite apart from the benefits of reduced pore size ). And then, there's the fact that plant chemistry changes with increased CO2, making them more susceptible to insects and possibly other problems.

Plants need to adapt to take advantage of increased CO2 - it's not like applying extra fertiliser. That takes evolutionary time. For domesticated plants, they have been even more strongly optimised for the current environment - and will probably be harder to change. Sure, with an intimate understanding of the effects ( which we don't have), and a selective breeding program you might be able to speed things up - but there's obstacles to be overcome, and in no way is CO2 a "magic wand" for plant growth.

Yes, with slow rates of CO2 increase over evolutionary time, plants would have been able to take advantage of it in times past. But because of the speed of AGW CO2 increase, you wouldn't expect there to be a CO2 related global increase in fertility in the short term.

8. Water Vapour

Some criticise global warming models in how they ignore water vapour. But think about it. Yes, water vapour has a significant effect. But we've not been changing water vapour. We've been changing CO2. We know that CO2 interacts with the radiation to increase heating, and it's reasonable to expect more heating as the result of CO2. It may be a small increase, but there was the straw that broke the camel's back - you'd have much larger consequences.

AGW deniers claim the world's dynamic system will automatically generate negative feedback to stabilise things. However, it is just as likely there will be positive feedback making things worse. As noted earlier, you could release methane from bogs and the bottom of the ocean, and you could kill rainforests, as well as shutting down the gulf stream.

Yes, clouds at different levels will either heat or cool the earth, especially depending on whether it is day or night. But why would their formation exactly balance an increase in temperature caused by AGW ? It seems a bit rich to me. I see no reason to just assume the climate system is robust against change, which is what's being argued for.

9. Volcanoes

Some say that Volcanoes put out more CO2 and other gases than AGW. In fact, AGW is much larger - see this comment from the University of Hawaii.

10. Geological Temperature Increases, and Australia's Contribution

Sure, the earth's temperature has undergone dramatic increases in geological time. That doesn't mean we should be cavalier about AGW. That's like saying we don't need to worry about man made bushfires - because there are natural ones.

Sure, Australia is a small player in the world economy. However, we can still be a part of the politics of the globe; once upon a time we were contributing significantly to nuclear disarmament.

And yes, let's be real. Australia's direct part in increasing global temperatures will be small. Then you have the part that our coal adds. Terry McBride has said - "Coal is to Australia what Heroin is Afghanistan". In any case, putting this all to one side - thinking we don't need to worry about AGW because of the rest of the world seems vaguely like the argument that there's no problem selling weapons of mass destruction to this horrible despotic third world dictator - because if we don't, someone else will.

11. Toxicity of CO2

Some claim that the AGW campaign is in some way offensive to the positives about CO2, of its positive contribution to the world's ecosystems. This seems more an emotive superficial view which deliberately ignores the detail AGW position. I am concerned about the impact of CO2 on global warming at the same time as I am happy to endorse the value of CO2 in the world's ecosystems. If you look at a tree, it stands there before you in its majestic grandeur because it has fixed CO2 from the atmosphere to into cellulose. All the sugar we use comes from plants that have fixed CO2 in the atmosphere to make it. I recognise this at the same time as I am concerned about CO2 and AGW.

At the same time, CO2 is toxic in large concentrations. They used it to euthanise chickens in order to control the outbreak of Newcastle disease in Mangrove Mountain in 1999, and it is also used to euthanise Indian Mynahs as part of controlled eradication in NSW. Another such chemical with a dual nature is Warfarin. I know people who take it as an anti-coagulant ( "blood-thinner" ). However, in sufficient doses it is used a rat poison. It can both help and hinder life. It realises the saying that "it's the dose, not the substance, that makes the poison".

In the same way, CO2 can be good and bad - in different concentrations, and in different places. It's can be good for plants. It's bad for global temperature.

12. Science and Credibility

I see the worth of the science around AGW. I see it as credible, worthwhile science representing a solid consensus. While nothing is certain, I see people willing to rely on the "judgement" of a medical professional - who may not be certain - but are happy to dismiss the science behind AGW. In fact, they try to distinguish between "good" science - of medicine, of things that progress society - from the "bad" science of AGW.

This is at the same time as they have no scientific credentials themselves - while they make characterisations of science. Yes, credentialism is a worry. And you could say that science is too important a thing to be left to scientists, as military and political matters are too important to be left to the generals and politicians. However, here the argument relates to the place of these affairs in society, which we all have a stake in. Yes, I might debate how much of GDP to put into defence - but I'd never try to correct a general on how to run a battle. It is a similar situation here. We don't want to silence anyone - but we also need to look at the validity of the reasons put forth as to why someone outside a field can comment on the internal details of that field.

I see the science of AGW as being of the same calibre of the "science" that is recognised as "good". It is all part of the same larger picture.

There's been a torrent of invalid arguments against AGW. They fall by the wayside, and AGW deniers pretend they never happened. At the same time, the position on AGW is scrutinised in detail, and past mistakes never forgotten. There's something wrong with this picture. It ain't balanced.

Yes, when you apply the models to try to make accurate forecasts, it can be a struggle. And each little issue is picked over and scrutinised. Each turn which was not foreseen is criticised. Regardless of the details, however, the changes in ocean level and glaciers tell us that something is going on to be concerned about.

13. Consequences and Policies

The possible consequences - lost island nations, changed agriculture, higher temperatures - are sufficiently worrying to justify insurance against that. Things could get really bad, but I don't see us hitting a wall and collapsing back into the stone age. Humanity has a talent for persisting. Of course, the world we end up living in might not be a pleasant one, and the cost of dealing with it might be such that those alive curse past generations.

These possibilities are worth worrying about. Things aren't certain, but you can certainly generate controversy. I don't think it changes the underlying reality.

While economic interventions are not the only thing to do, I do see the worth of Carbon Tax or Carbon Trading. People worry about the effect on their lives, but the major increases in utility prices have been the result of the betrayed promise of privatisation. Companies also talk about the Carbon Tax being the incentives for them to sort out their affairs which has actually resulted in greater productivity. These economic impacts don't have to be as harsh as some make out they will be, but obviously they won't be at zero either.

Interestingly, in Quadrant you will find people talking about investing in Australia's armed forces as "insurance" against something that is unlikely, but worth protecting against. Maybe that's a valid argument. Point is, this is exactly the same argument that can be applied to AGW - there are uncertainties, but there are also risks - risks that are serious enough that it is worth doing something about them.

Intriguingly - when Australia entered the Vietnam war - "Insurance" was an important notion - they were "insuring" against the "Domino principle" Ewwww ....

14. Debate, Science and Government

Many superficial, emotive claims are made against AGW. While promoters of AGW can likewise get emotional about it, I see it as the terrain we must accept. Public debate is going to be distorted and emotional. That is the political and social reality. I accept it, and fight it as best I can.

Government in its current form is susceptible to distortion. Government is not about good decisions - it is about accountable ones. Sometimes we'll even get good decisions. Sure, the time for accountability might be too far down the track. But look - that's how things are. This is how our Government works ( short of revolution - and I'm not advocating for that ). I'm not sure I like it, but I accept it.

15. The Market, Low Carbon Energy, Nuclear Power and ... Geoengineering

As a separate issue, I am concerned about the sustainability of economic growth. However, when it comes to AGW, I see it as a threat, and I'm happy to endorse whatever works. Yes, that does include demand restraint. It also includes moving to a low-carbon economy. But, that also includes geoengineering, market-based mechanisms and also nuclear power - along with renewables. As far as AGW goes - whatever works - I'm not fussy.

I'm in fact relatively pro-nuclear, see here from back in the Howard days. I don't see nuclear as the problem in itself - if there is a problem it is with our human failings in managing nuclear technology - the problem is not with nuclear technology in and of itself.