Uncharted Territory

January 22, 2010

Interestingly, Volcanoes can Trigger El Ninos

Filed under: Agriculture, ENSO, Geoengineering, Global warming, Science, Volcanoes — Tim Joslin @ 6:24 pm

Once again, I’m starting this post as I’m halfway through another one that may or may not see the light of day. I was trying to put together a rant following the Royal Society’s (RS’s) panel discussion on geo-engineering (available on royalsociety.tv), which I attended on Tuesday evening. The meeting followed a report issued by the RS last September.

Rather than rule out most of the possibilities, the RS boffins recommend further research. A cynic might suggest this was self-serving; I couldn’t possibly comment.

There are numerous problems with many of the geo-engineering approaches. But I wanted to be original and see if I could find evidence to support my hypothesis (noted in a previous post) that trying to cool the planet by injecting sulphur dioxide (SO2) into the stratosphere where it would produce reflective particles would block a disproportionate amount of sunlight striking the atmosphere at a shallow angle (i.e. more tangentially). More sunlight would therefore be blocked at the ends of the day, high latitudes and in winter.

In fact, the boffins noted on Tuesday that a disproportionate effect in the Arctic could be “beneficial”. This doesn’t stop them apparently relying on a computer modelling study that simply plugs in “a reduction in global mean insolation of 1.84%”.

The RS study repeatedly discusses recent volcanic events in order to assess possible effects of the geo-engineering plan.

Having looked into the matter, I can say this is bordering on a waste of time.

Drs Strangelove want to fire enough SO2 into the sky to block out around 2% (on average) of the sunlight, their sums suggesting this would counterbalance a doubling of CO2 levels.

But this interesting graph (courtesy of WIkipedia) shows what volcanoes do:

Mauno Loa observations of atmospheric transmission of sunlight

Wow! They don’t block 2% of solar radiation, rather 10 to 20% on a regular basis, and presumably even more when a real biggie goes off.

And this is enough to cause real disruption.

First off, the boffins worry about affecting the monsoon and other aspects of the hydrological cycle, citing the effects of the Pinatubo eruption in 1991. But Pinatubo caused massive short-term cooling. Monsoons rely on the land becoming warmer than the oceans, leading to rising air, drawing moist air towards the landmass. Obviously, if you reduce sunlight by 10% or so, the land will warm much slower and could remain too cold, relative to the ocean (which is kept warm by stored heat), for a healthy monsoon.

Second, I noted in a comment on a previous post that El Chichon was followed by a strong El Nino. As can be seen from the graph I gave at the time, there was a weaker one after Pinatubo. “Could they possibly fit together?”, I found myself wondering. Yesterday, via Realclimate, I came across a paper suggesting that yes, indeed they could (pdf).

The point, of course, is that El Ninos occur when warm surface water flows (unusually) east across the Pacific (see also Wikipedia). The warm water builds up in the first place because the initial flow (ultimately due to the rotation of the Earth) creates, in turn, an atmospheric warm zone to the west (around Indonesia), and a cooler region near South America. Lower pressure maintains a significant difference in the surface level between the west and the east of the ocean (maybe 60cm!). But the feedback relies on maintenance of the temperature (and hence atmospheric pressure) differential and eventually breaks down, typically in December (when the sun is not overhead at the Equator) and the whole thing collapses like a lop-sided souffle in an unevenly heated oven. Warm waters temporarily flow east with significant effects on the global climate for a year or two.

Fairly obviously, a general cooling event, such as a volcanic eruption, is likely to trigger an El Nino.

As an aside, it might be worth noting that a warming period is likely to lead to a strong El Nino, as observed in 1997-8, for example. The warming will reinforce the feedback creating the original imbalance. 1982-3 was also a strong El Nino event:

El Chichon anomaly (1983-4 temperatures compared to 1980s)

Maybe the cooling caused by the 1982 eruption of El Chichon enhanced an El Nino that was anyway ready to take place. Or maybe it was always going to be a big one.

At the risk of trying to read too much into limited evidence, it might be possible to surmise that the 1997-8 El Nino was so strong because the global warming trend leading up to it was reinforced by recovery from the Pinatubo cooling event. Similarly, to stretch the point even further, 1972-3 is listed as a strong El Nino, and followed the recovery after the Agung eruption, though that was 10 years before and not so large as El Chichon and Pinatubo (though a graph over at SkepticalScience gives a different impression). Fascinating stuff – no wonder climate scientists can’t wait for another major eruption!

Incidentally, because we mainly measure the temperature at the surface of the planet, El Ninos show as spikes in the data, because warm surface water covers cooler layers over a large area of ocean (and in turn affects temperatures on land). When a volcano triggers an El Nino, the cooling caused by the volcano is therefore partially obscured by the El Nino. An eruption when we were already in an El Nino state would consequently likely appear to have a greater effect on global temperatures than one that triggered an El Nino.

The geo-engineering plan is entirely different to the case of intermittent volcanic forcings. The plan involves a semi-permanent sunscreen to block 2% of sunlight. The problems will be entirely different. Relying on the historical record of the effects of volcanic eruptions won’t allow us to predict all the effects of the geo-engineering proposal.

Logic tells me that an SO2 sunscreen will disproportionately affect high latitudes, where sunlight is a highly valued commodity. Politically, it would of course be next to impossible to achieve broad agreement to go ahead with the geo-engineering plan. Furthermore, in a warmer world, with increased tropical desertification, we may be relying on food production in more northerly areas. Blocking sunlight might not be a bright idea.

Nevertheless, I carried on surfing for a bit for evidence that volcanic forcings could affect high latitudes more. The best I could come up with was the Russian famine of 1601-3, likely triggered by an eruption in Peru.

January 20, 2010

Parking Paralysis (and Housing Horror)

As we head towards what promises to be a fascinating General Election, the absurd first past the post system has ensured the parties are united in their zeal to pander to Middle England. And Middle England, it seems, is consumed with localist fervour.

What is localism, anyway?

The politicians would have you believe that the first stop on the road to true democracy is to “empower communities”. That is, they assert the moral right of the current residents of a given area to make a broad range of decisions without reference to the general interest.

The idea that the primary unit of a complex modern society is a “community” of people living near one another is, of course, absurd. In fact, our personal networks – including families – are, in general, becoming more and more geographically dispersed. We have little in common with most of our neighbours, other than the area where we live.

Harking back to an outmoded idea of the community masks what is really going on. What’s really happening is that the political process is becoming more and more skewed towards vested interests and against the general interest.

Take housing, for example. This morning I heard the Housing Minister, John Healey, on the Today programme, promising to clamp down on “garden-grabbing”.

Let’s put to one side the fact that John Prescott was right: we need to increase housing density. Labour has caved in on this principle as the Tories have gradually captured local government. But below a certain threshold of population density local shops are not economically viable; nor is public transport. Pretty soon everyone’s driving to Tesco’s. And the same nauseating nimbys who prevented “overdevelopment” are complaining about the loss of local shops and whinging about “Tesco towns”.

I consider it absolutely ridiculous that I’m in London Transport Zone 3, but 10 minutes walk from a pint of milk and a newspaper. If there were a few more flats nearby and perhaps fewer large private gardens, maybe there’d be enough people in walking distance to sustain a local corner-shop. If it could get planning permission.

Let’s ignore the “community” narrative and instead consider what’s really happening with the “clamp-down” on “garden-grabbing”. What John Healey is really doing is strengthening the rights of neighbours over the owners or prospective owners of property – despite the fact that the size of gardens has marginal impact on neighbouring properties, or, for that matter, their value. If they reduce the size of a garden, those bogey-men, the developers, are not simply being bloody-minded. The market is telling them that the land has less value as a garden than as building. If the opposite was the case they’d increase the size of gardens.

Obviously, the reason why “building” is more highly valued than “garden” could have something to do with the lack of available housing in many parts of the UK. But clearly our leaders don’t see this isn’t a good enough basis for a decision. The visceral feelings of neighbours are obviously far more important.

A few weeks ago Secretary of State John Denham rejected plans for a development near Ealing Broadway station. He acknowledged that the proposed “scheme would comply with some specific development plan policies relating to the regeneration of Ealing Town Centre and would bring many benefits to the area”, including 567 homes, but judged that all this value was outweighed by his subjective judgement (in response to local concerns) that “the bulk, massing and certain aspects of the design of the scheme would be inappropriate in its surroundings. It would fail to preserve or enhance the character and appearance of the Town Centre conservation area and the setting of the Haven Green conservation area, as well as harming the setting of the Grade II* listed Church of Christ the Saviour.” One person’s fears about their “visual amenity” (an irritating phrase repeated ad nauseam in planning documents) trumps another’s need for somewhere to live.

Look, Haven Green is a mess. It’s simply not that pleasant a place. It could conceivably be improved by removing the buses which stop and indeed park (for driver breaks, I gather) on the diagonal road across the Green. A recent Ealing Council document (pdf) noted that: “A major consideration, as part of both the Crossrail and Arcadia redevelopment proposals, is the provision of better interchange with local bus services.” But Arcadia is not going ahead, and, if I understand the document correctly, Crossrail has no budget to pay for a proper bus station.

The planning process is bad enough, but nowhere is localism more evident than in the battle for control of scarce road space.

Ealing Council, to my horror, is also consulting on a dreaded CPZ (controlled parking zone), which would affect me.

OK, the proliferation of CPZs can be largely explained in terms of local government bureaucrat empire-building, but there is clearly at least enough tacit public approval to allow them to get away with it. Let’s therefore consider the CPZ in my novel terms of the “local” (or “vested”) interest and the “general” interest.

Before a CPZ is implemented in a given street, everyone has an equal right to park there. After its implementation, car-owning residents generally have absolute priority. In fact, often the schemes are implemented with the shocking inefficiency that non-residents can’t even use the space when it is unoccupied! (Schemes variously allocate a few metered bays or, better, allow metered parking albeit for limited periods and at limited times in residents’ bays).

So, in approving a CPZ, residents in effect extend their property a couple of metres into the road in one fell swoop!

Do they pay a fair price for this asset, though?

Of course they don’t.

Permits for residents’ parking on public roads are often less than £100 per year, and rarely more than a few £100s. The market value of such parking – determined by the rates in the few metered bays typically provided or in nearby car-parks – is usually at least several pounds a day – £1000s, not £100s a year.

It’s not just outsiders who, in effect, subsidise permit-holders. Residents who don’t run cars are massively inconvenienced, as is everyone when they have visitors, or use local services. Estate agents, for example, have problems parking when they quite legitimately want to show properties to prospective purchasers or tenants.

What CPZ schemes fail to take account of is that residents’ cars are part of the problem, and not the only injured party. Personally, it seems to me that there would be more social utility in reserving parking places for estate agents than for residents who just want to leave half a tonne of steel and moulded plastic outside their house for 6 1/2 days a week.

If we’re going to have CPZ schemes, then, let’s charge a market rate for the parking space – upwards of £1000 a year (and allow the option of paying a daily rate for those residents who park their car elsewhere most of the time). Then we’d reduce car ownership, spaces could be allocated to car clubs and for visitors and our parking problems would be much reduced.

What Ealing really wants, though, is not an ever-growing CPZ area. What’s happened is they’ve tried to solve the problem of commuters parking near Ealing Broadway and West Ealing stations. Entirely predictably, the small CPZs implemented have just moved the problem. Now they’re consulting on more CPZs. Nice work, if you’re in the CPZ implementation business.

Is there another policy that might make more sense than the inefficiency of selling the public parking space asset at a discounted rate to residents who think they own “their” road? It is entirely legitimate to discourage car rather than bus or shoe-leather use by commuters. Why not, therefore, consider a congestion-charge scheme for non-residents coming into the centre of Ealing? One might hope that some of the London congestion-charge infrastructure could be fairly cheaply deployed just in the centre of Ealing. I’d suggest vehicles entering and leaving are monitored and the software programmed to charge only for those non-residents who stay in the area more than, say, an hour, since the objective in this case is not to penalise through-traffic but relieve pressure on on-street parking.

Perhaps it will take PR to slow the tide of localism. Certainly though, until the political process weighs the general interest more carefully against vested interests, our society will continue to be held back by dysfunctional and misguided decisions.

January 18, 2010

Musings of the Hemispheres

Filed under: Global climate trends, Global warming, Science — Tim Joslin @ 12:58 pm

I should really try to finish one blog post before I start another on a similar topic. My last (published) post noted that the North Atlantic Oscillation (NAO), an atmospheric phenomenon, is not a climate driver, rather it’s a measure of the state of the climate – incidentally, I’m pleased to discover this morning that Philip Eden at Weatheronline.co.uk holds similar views. In a post that may or may not ever appear, I was going to note similar thoughts about the so-called Atlantic Multidecadal Oscillation or AMO.

It’s not my understanding of the oceanic circulation that great surges of current drive the climate. Rather the oceanic circulation is itself driven by changes in heat distribution at the surface. OK, there may be timelags and of course there’s the El Nino, but that’s about it. If the El Nino is driven by ocean currents (which I believe it is), these are, crucially, east-west, not north-south. The planet loses heat partly because heat moves (in water and air) from the tropics towards the poles where it is more easily radiated away (or used to melt ice). I suggest, therefore, that changes in oceanic circulation are primarily caused by changes in the absorption of heat at the surface. For example, if the planet is warming, you’d expect a general strengthening of oceanic circulation.

What’s piqued my renewed interest in this topic is James Hansen’s release of temperature data for 2009, available over at Realclimate. In particular, Hansen includes separate temperature graphs for the southern and northern hemispheres. I reproduce these here for convenience (the diagrams in my previous post were from Wikipedia, btw):

Fig 1: Annual temperatures

Fig 2: Running mean temperatures

Looking at the right hand graphs, comparing temperature changes in the hemispheres, we see that sometimes the northern hemisphere warms quicker than the southern hemisphere, whereas at other times the reverse is true. What would we expect, though? Well, there’s a lot more water in the southern hemisphere and a lot less land. We’d therefore expect the south to warm (and cool) slower than than the north (and, in the long-term, catch up when temperatures stabilise at a different level). And, indeed, this is what appears to happen most of the time: since the mid 1970s, the northern hemisphere has warmed much faster than the south; on the other hand, the cooling (clearest in Fig 1) caused by the Mt Pinatubo eruption in 1991 was most evident in the northern hemisphere.

But – there’s always a “but” – for significant periods of time (I consider the weather can affect annual data, but not decadal trends) – for example, from around 1950 to the mid 1970s – the southern hemisphere has actually warmed when the northern hemisphere has cooled. This requires explanation.

There are only two possibilities: either the one I’ve already dismissed, that large amounts of heat are, by some unexplained causal mechanism, transferred between the hemispheres, or, that there are factors causing the hemispheres to gain different amounts of heat at different times. Specifically, for several decades from around 1950, the southern hemisphere must have either gained heat, whilst the northern hemisphere lost it, or, more probably, two countervailing factors were involved: one causing a general warming and the other cooling, but disproportionately of the northern hemisphere.

We know that increased levels of greenhouse gases are tending to warm the planet. The inescapable conclusion is that another factor tends to cool the northern hemisphere more than the southern hemisphere. The argument that from the 1940s through to the 1970s this was “global dimming“, caused by sulphur dioxide and other pollution is highly persuasive. Most of this pollution is emitted in the northern hemisphere and doesn’t stay in the atmosphere long enough to spread evenly.

What’s happening now, though?

Well, what strikes me in Hansen’s graphs is the levelling off of warming over the last few years. There’s not yet really enough data to reach any sort of conclusion, but Hansen notes 2009 was the second warmest year on record. In fact, though, his data (Fig 1), suggest it was the warmest year in the southern hemisphere and around the 7th warmest in the north.

Given the rapid industrial development of China and India, it seems justifiable to hold a working hypothesis that we face renewed global dimming.

You would expect a layer (or layers) of reflective particles in the atmosphere to reflect a greater proportion of light from the sun in the winter than in the summer, so another way to test the hypothesis would be to examine seasonal rates of warming over the past century or so. The trouble is, seasonal temperatures are very much affected by poleward heat transport and weather patterns themselves dependent on whether the planet (or hemisphere) is warming or cooling, but nevertheless I’d expect average temperatures in continental interiors (with stable seasonal weather patterns and especially anticyclonic conditions in both winter and summer) at high latitudes to fall more in winter than in summer during periods when global dimming increases, i.e. when the rate of warming of the planet as a whole slows down.

Of course, we could also put a bit more effort into simply measuring the strength of sunlight at the top of the atmosphere (to account for variations in solar output) and at ground level in cloudless conditions (or controlling for cloud cover).

If the analysis that the climate is being affected by renewed global dimming is correct, it’s really bad news. What it implies is that, when the presently industrialising nations reduce their sulphur emissions (and assuming other countries don’t repeat the exercise), we could be in for another period of rapid warming (several tenths of a degree C per decade on average in the northern hemisphere), similar to that over the last quarter of the 20th century.

14/6/10: Minor correction, AMO stands for Atlantic Multidecadal Oscillation, not “Meridional”.

January 11, 2010

Snow Madness and the North-West European Anti-Monsoon

Filed under: Global warming, Science — Tim Joslin @ 1:09 pm

In India, apparently, legions of weather-forecasters, from eccentrics to supercomputer-operating state-funded agencies, are devoted to attempting to forecast the characteristics of the annual monsoon.

A collective snow madness grips the UK during cold winters. Legions of weather-forecasters, from eccentrics to supercomputer-operating state-funded agencies attempt to explain events, nowadays with particular reference to global warming.

Now that the snow here is melting and low grey cloud has parked on top of London, the weather is simply downright miserable here.

So it seems a good day to stay indoors and join in the speculative fun.

Monsoon conditions occur when the land heats faster than the ocean during the summer, causing air masses to rise. The rising air – or low pressure – relative to the ocean, draws moist air inland, creating rainfall.

Given the cultural significance of cold winters in the UK – I have a deep desire to roast an ox on the Thames, and fond memories of 1684 are starting to fade – I suggest we should characterise the weather-pattern that brings cold weather to north-west Europe as an anti-monsoon (or perhaps “antisoon”).

The point is that in late December or early January there is often a plunge of cold air towards Western Europe. In many years this fails to reach the UK, but occasionally it does. The breakdown in the normal westerly airflow is caused by the reverse of monsoon conditions. Rapidly cooling air over land (high pressure) tends to flow out over the warmer ocean (low pressure).

I’ve noticed the meteorological profession making bold – in my view even reckless – predictions about future British winters. Rob (or “Reg” as he was introduced by a BBC anchorman!) Varley insists that our cold winters will be less cold in the future. We’re even told that future generations won’t know what snow is!

Actually this is what I thought until recently. Whenever it snows I rush out with my camera, thinking I might never see the white stuff again.

But now I’ve thought about the matter a little more deeply. In fact, I’m ready to spout some speculative scientific ideas.

I now doubt we’ll never see snow again, for the simple reason that the temperature difference between average and cold UK winter weather (the “anomaly”, perhaps) is of the order of 5-10C. Global average temperatures have risen by an order of magnitude less.

Winter weather in Britain depends not on the global average temperature or even the temperature of the North Atlantic. Rather, it simply depends on which direction the wind is blowing in. And it so happens that high pressure over Scandinavia and/or Greenland causes easterly winds over the UK.

When in the future can we expect such high pressure systems to develop? Will they become less frequent? Or perhaps the real question is why they have been rare over the past 30 years or so, leading to a succession of mild winters in the UK?

The meteorologists have an alarming tendency to attribute causal significance to what are in fact the phenomena in need of explanation. The jet stream is a case in point.

During cold UK winters the jet stream moves further south – over Gibraltar, perhaps, rather than the Channel. Depressions therefore track south of rather than across the British Isles.

But the jet stream must be caused by something. In fact, it can only result from pressure differentials in the atmosphere – rising air (to its north) and falling air (to its south) if you like.

This brings us to another meteorological concept: the North Atlantic Oscillation (or NAO). This isn’t really an oscillation at all, rather a measure of the pressure difference between the Azores (usually “high”) and Iceland (“low”). The NAO measure fluctuates rather than oscillates (unlike the El Nino Southern Oscillation, ENSO, which is driven by movements of water). But the NAO concept does bring us a little closer to an explanation of the root causes of UK winter weather. Here’s a graph of the NAO over the last century or so:

Winter NAO Index

I’d say there appears to be some correlation between the NAO and cold and mild winters. 1947, 1963 and 1979 were all years of low (negative) NAO, whereas the recent run of mild winters occurred while the NAO was high.

But what determines the NAO?

Here’s my hypothesis. We need to look at not how warm the planet is, but at whether or not it is warming.

The point is that there is a lag between atmospheric warming and warming of the ocean (we’re concerned here with the ocean surface, not the deep ocean, where the warming lag is centuries rather than just years). When the planet is warming, therefore, the land (affected directly by the atmospheric temperature) will be warmer relative to the ocean than is usual. The reverse will be the case when the planet is cooling.

When the planet is cooling, therefore, the North-West European Anti-Monsoon will tend to be stronger, bringing the possibility of cold winters to the UK.

Here’s another graph:

Average Global Temperatures

Compare this graph of temperatures with the NAO graph above. Someone can so some maths (differentiate the temperature graph!), but I’d say the NAO correlates with the rate of change of temperature. When the planet is warming rapidly, the NAO tends to be positive; when the underlying warming trend slows or reverses, the NAO tends to be negative.

And when the NAO is negative we get those proper UK winters that somehow satisfy the soul.

This set me thinking a little more.

A sudden cooling trend can result from volcanic eruptions. The cold decade of the 1810s is explained this way. Remember, the average global temperature declined by “only” 0.5C below normal back then, but the UK experienced White Christmases more often than not!

The current levelling off in warming cannot be explained by volcanic activity. Neither can 1963, for instance, although the eruption of Mt Agung occurred during the cold snap!

But the evident cooling in the 1960s can be explained by “global dimming“, resulting from particulates emitted by fossil-fuel burning.

Could the same thing be happening now? We keep hearing how many coal-fired power-stations are being opened in China. They must be having some effect, surely?

It might be worth pointing out that reflection of sunlight by particulates in the atmosphere would be expected to be more significant in winter than in summer, because the angle of incidence of sunlight would mean it having to pass through more air to reach the surface (and random scattering would be more likely to deflect the light out of the atmosphere altogether).

Or maybe the sceptic-fuelling hesitation in the rise in average temperatures over the noughties is just unexplainable “natural variation”, as climatologists suggest.

The warmest year on record, 1998, was the start of an el Nino, when warm water spreads across the surface of the Pacific. In 2010 we are seeing the start of another el Nino. I can believe the start of an el Nino would disrupt normal weather patterns and help cause a cold UK winter (cooling and a negative NAO is a necessary, but not a significant causal factor). Here’s my wager, though: next year (2010-11) will not be a cold winter. The el Nino warmth will by then have had time to spread through the entire atmosphere. We’ll have a positive NAO and a weak antisoon. I should say, in case anyone really does want to put money on the prediction, that a perusal of the historic record does suggest that while cold winters can, and often do, occur in an el Nino year, they don’t tend to occur the year afterwards.

We might be able to blame China for this cold winter, but a longer-term problem with warming the planet may be that at some point we have to stop. And maybe even let it cool down, bringing on some strong antisoons. With a bit of luck, though, it won’t be so warm by then that we won’t be able to put that ox on a spit in front of Parliament!

PS I do realise that embanking the Thames during the 19th century and the demolition of the old London Bridge (which obstructed the flow of the river) make it less likely it will freeze over. I still dream of the day, though!

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