Wednesday, 23 October 2013

Does I = PAT?

The equation I = PAT was invented by Barry Commoner in 1972 and is widely used by the pressure group Population Matters in arguing for population control. It asserts that humanity's environmental impact (I) depends on population (P), affluence (A) and technology (T). The last factor is best understood as a measure of the resource inefficiency of our various industrial, agricultural and other processes.

The terms P and A are easy to understand and relatively easy to measure. GDP per head is a workable measure of A. I and T are much harder since there are many kinds of environmental impact, eg greenhouse gas emissions, deforestation, mineral resource depletion and loss of biodiversity, which are not always strongly correlated. (see, eg, Cole and Neumayer, 2004).  That is, we need a set of IPAT equations, one for each kind of environmental impact. Each will need its own T value which will be defined as I/PA rather than calculated independently.

IPAT, therefore, is not so much a proposed law of nature as a suggestion for relevant factors when considering environmental change. Initially IPAT was useful but it can now be seen to be rather misleading.

The variations between groups
The equation suggests (at least when applied globally) that the affluence of the world's population can be expressed by a single number. Though technically correct it's very misleading. The reality, obviously, is of vast variations in affluence and lifestyle both between countries (contrast Somalia and Switzerland for instance) and within countries (contrast bankers and farm workers).

Single numbers are sensible where everyone is the same or where a characteristic shows a normal distribution (as for human height for instance). Affluence shows a Pareto or, colloquially, 80:20 distribution (20% of the people own 80% of the wealth) and is thus not well represented by a single number.

The interdependence of P and A
The equation suggests that population and affluence are independent variables which in general they are not. During the 19th century the UK's population and prosperity rose together as the agricultural, industrial and scientific revolutions (plus the spread of empire) produced ever more food, manufactured goods and services. In this period the true independent variable was probably 'progress'. This pattern has been repeated many times as other countries have industrialised and in most cases the main growth phase has been followed by a marked reduction in population growth.

Today growth in affluence is greatest where population growth is modest.

The parity of P and A
The equation suggests that population and affluence are of comparable importance in creating environmental impact. In fact that's not true. In recent decades our impact has risen much faster than population and is largely driven by increasing affluence. Some of this is due to the increasing wealth of the mega-rich 1% (or 0.1% globally I suppose) but much is due to the increasing numbers of Koreans, Brazillians, Indians and Chinese who can afford cars, meat and broadband Internet.

The meaningless differential
The equation suggests that its first differential would be
            dI/dP =AT.

That is, that a small (say 1%) increase in population will produce the same proportional increase in environmental impact. That, of course, is unreal. The world's population comprises many subpopulations with very different lifestyles and levels of affluence. One extra Briton will consume much more than one extra Bengali and will have correspondingly more impact.

So this first differential will be accurate only if every subpopulation increases by the same small amount. But that isn't happening. Some countries are still experiencing rapid population growth whilst growth elsewhere is static or even negative.

The first differential also requires an associated growth in the local economy to provide the extra people with goods and services. It is, at least, unclear whether local economies can respond in this way without accelerating impacts on the environment. Two examples may illustrate this:
  • As people migrate to London suburbs they will need roads, houses and schools. If they find work and pay taxes they can afford them. But since there can be no more land we may expect more air pollution, less green space, higher house prices and higher population densities.
  • As population increases in many East African villages the women must walk further for firewood. That gives them less time for farming and childcare whilst reducing the ground cover.
The complexity of things
The IPAT equation suggests a simplicity that simply does not exist. The complexity of things is not in doubt and its time to stop using this simplistic equation.

Cole, M. A. and Neumayer, E. "Examining the impact of demographic factors on air pollution," Population Environment 26.1 (2004): 5-21.

Commoner, Barry. 1972:  “The Environmental Cost of Economic Growth.” in Population, Resources and the Environment. Washington, DC: Government Printing Office Pp. 339-63, 1972.

Thursday, 17 October 2013

Methane hydrates: Threat or promise?

Methane is a valuable fuel and a potent greenhouse gas. At low temperatures and high pressures it combines with water to make methane hydrates. There's a huge amount of the hydrates - perhaps twice as much as all other fossil fuel deposits - on the seabed - especially in the far north.

The obvious threat is that warming waters - those in the north are warming fastest - will destabilise the hydrates releasing vast amounts of methane and thus accelerating climate change. This is a particularly scary possibility for three reasons:
  • It's a positive feedback loop. Once established it will probably overwhelm all the other mechanisms.
  • The sea warms slowly and warming lags the relevant gas releases. 
  • Hydrate deposits are poorly understood so we can't forecast how much methane will be released how soon. 
It's therefore possible that we have already released enough greenhouse gases to create catastrophic climate change. Most climate scientists think this unlikely; but the IPCC consensus has usually been over-optimistic.

Hydrates also have a promise. Methane is a very clean fuel and its extraction from hydrates will probably be an efficient process. IF we switched from coal and oil to methane and IF we could keep leakage well below 1% then we would reduce the greenhouse effect. It's no panacea but it would help a lot.

Those are big IFs. In practice new energy sources usually add to consumption. The US currently benefits from fracked methane but instead of closing coal mines it is exporting coal - much of it to Europe.

In a sane world hydrates might be an opportunity. In fact they remain a dreadful threat.

Wednesday, 16 October 2013

Geo-engineering is coming of age

According to New Scientist (12/10/13, p 10) the IPCC now sees geo-engineering as essential if we are to avoid catastrophic climate change. That was the conclusion of the recent Oxford Conference on Negative Emmission Technologies. 

New Scientist's summary shows seven technologies any one of which could, if energetically implemented, remove at least one gigaton of carbon per year from the atmosphere. That's 10% of annual emissions.

The costs, for what are often theoretical technologies, are highly uncertain and fall in the range $10 to $2,000 per ton of CO2 captured. So the cost of removing one gigaton of carbon per year would be on the order of $400 B dollars per year. That's a lot by any ordinary standard. On the other hand it's just a quarter of the world's annual arms bill.

But money isn't the only issue. Some methods require physical resources such as gas-tight strata or land for tree planting and these are needed for other purposes too.

Has aviation seen the light?

New Scientist (12 Oct 13, p 6) reports that the airlines have agreed to participate in an emissions trading scheme. That's a useful point of principle gained but may have no real effect. It will only be worthwhile if the airlines are given significantly LESS permits than their current emissions. (Why give them any? Beats me but that's how it is.)

Experience with the EU ETS and the shipping rules are discouraging but I suppose we have to hope.

Friday, 20 September 2013

Nonsense and sense about ice

Tom Yulsman has a good article. He attacks David Rose's irresponsible journalism and summarises the Arctic ice evidence. I was interested to see the graph on ice VOLUME.

Saturday, 17 August 2013

Knowing ourselves: The Core of Green Political Philosophy

In ancient times the words inscribed in the forecourt to the temple of Apollo at Delphi were: “Know thyself”. Part of the meaning of this aphorism was that we should know that we are mortal men and women, not gods, and behave accordingly. The ancient Greeks condemned the arrogance which they called hubris.
In later centuries Europe adopted a different faith whose god gave man dominion over all living creatures as if he was not one of them. This faith, like the other Abrahamic religions, stressed the special nature of humanity and saw the right goal of humanity as something apart from the everyday world and often to be achieved only after death.
Yet we are living creatures – specifically mammals – and we share the planet with millions of other species. And we do, more than most species, need food, warmth and shelter. This is at once a commonplace of country living and the message of modern science which sees us as one species, evolved from others and connected to others. New research shows these connections to be more intimate than we thought. For instance, our health depends on that of the bacteria that we all carry in our guts.
This ecological understanding is the basis of all Green philosophy. It has some direct implications:
1.     We are part of nature and not apart from it.
2.     We have no moral right to grab the lion’s share of the land, sea and air.
3.     We owe respect to other species and should value them for their own sakes.
4.     Since we depend on other species in many ways – probably more than we yet understand – we should protect the living world for our sake as well as its own.
The green philosophy has consequences for how we live and work and for our politics for all of them have to be decided in the wider context that it gives us. That context sets some limits and its immediately apparent that we have greatly overstepped the those limits, showing the hubris deplored by the Greeks. This is obvious from our destruction of the rainforests, from the number of species recently made extinct or threatened with extinction, from the still growing greenhouse gas emissions that drive climate change and even from the increased congestion in so many major cities.
Now Greens differ in how they understand these follies. Some point to increasing population as the ultimate cause. Yet our impacts on the rest of nature have, in recent decades, increased much faster than our population. In this period it is increasing prosperity that has multiplied our impacts.
Others blame the greed of individuals for consumer goods. Yet much of the world’s consumption is for ordinary things. It does not seem greedy to want a fridge, a house or a car and the impacts are only unsustainable because there are so many of us to want them and because our industry is so wasteful.
Still other Greens blame the greed of industrialists and bankers. Now there are certainly industrialists and bankers who are greedy, irresponsible and corrupt. But even the most honest are constrained by a financial system that demands ever-increasing sales and profits. Industrialists and bankers who don’t deliver will soon cease to be industrialists or bankers. And this system is itself bolstered by newspapers, universities and governments many of which are subject to similar pressures or are simply the paid agents of the corporate world. Nor must we forget that for most of the last 25 years most politicians and commentators in the developed world have sincerely believed that the ‘capitalist’ system was the best possible economic system.
Arguing about blame can be fun but it can easily be a distraction from the real question: What shall we do about the problems? Some answers are obvious:
·       We need to stop the most environmentally destructive activities.
·       We should discourage population growth and must find ways of supporting an aging population.
·       We need to make industry less wasteful. In particular we must cut back greenhouse gas emissions sharply. We may need to actively remove such gases from the atmosphere.
·       We must free the economic system from the tyranny of growth targets.
We have to be honest about the implications of the last two. They imply a fundamental restructuring of the economy and of the governance of major corporations so as to reduce the rights of shareholders and increase those of workers and the community. Also, some way has to be found to represent the interests of the rest of nature and of future human generations in public and corporate decision-making. This will be a revolution – though not the one that traditional Marxists talk about.
They also imply a real reduction in the amount of economic activity dedicated to providing people in the developed world with goods and services. We can take up part of this reduction by producing fewer but longer-lasting products. Even so, we in the West will get poorer in material terms. This is necessary both to reduce total impacts and to give the world’s poorer people a fairer share of the planet’s bounty.
Now the citizens of the developed countries will not accept this unless they are persuaded of the need and that they will get some benefit. Happily some benefits – more leisure, better health, greater well-being from greater equality and stronger communities – are entirely consistent with consuming fewer goods and services. And those are the benefits that matter most in a Green philosophy.
So here we have one of those happy coincidences that are so rare in politics. The very policies that are needed to moderate our impact on the rest of nature – social justice, shorter working hours, stronger community institutions – are policies that most Greens already believe in for their own sakes.
The ecological understanding of the relationship between humanity and the rest of nature lies at the centre of Green politics. It is both the most important and the most distinctive feature of our politics. But it is not and must not be the whole of our politics. There is room for the traditional values of community and mutual respect. And there is room for the enlightenment values of equality, liberty and reason.
There is not and perhaps will never be a Green creed or a universal Green political programme. Either would be a recipe for tyranny. Healthy Green politics consists precisely in the interplay of our knowledge and values in the light of our ecological perspective. And that is stronger than the ideologies of left and right which must always suppress truth and dissent in the interests of political purity.

Tuesday, 2 July 2013

Climate change threat to one third of species

In a previous post I commented on one aspect of the threat world trade poses to amphibians. Now there's evidence that climate change poses an greater threat to birds, corals and amphibians.

A team of scientists at the International Union for the Conservation of Nature (IUCN) has assessed species as at  risk if their climate is changing, they are vulnerable to the changes and they are unable to adapt or relocate. The proportion of species they find to be at risk are:
  • Birds              24 to 50%.
  • Amphibians   22 to 44%
  • Corals            15 to 32%.
Many of these species, and most of the bird species rated at risk, are considered safe by the Red Book - the usual reference for such judgements - so we now need to treat all Red Book assessments as optimistic.

Commenting on these results Chris Thomas of the University of York said "the conservation programme you might need to put in place [is] mind-boggling". But this, as he surely knows, is fantasy. Nither the money, nor the will nor the land needed are available. We can keep the threatened species only if we put a stop to climate change.

Wednesday, 26 June 2013

Water in the Desert: A Tale from Mali

The River Niger is a geographical oddity. It starts in the hills of Guinea then runs away from the coast into Mali, finally reaching the ocean thousands of miles later.

Each year seasonal flows flood the wetlands near Mopti in Mali, creating a rich ecosystem that feeds fish, migrating birds, cattle and some 1.5 million people who live there. Not, perhaps, for much longer.

Fred Pearce has reported two threats to this ecosystem. Upriver from the wetlands engineers are diverting water from the river to create, by irrigation, new farmlands; farmlands that the government of Mali has given to foreign companies. In 2012 the proportion of river water averaged 8%, but went as high as 70% during the dry season. According to Lansana Keita, the engineer in charge, the barrage is supposed to release at least 40 cubic meters per secoind at all times but sometimes doesn't: "We do our best, but irrigation has priority."So far the wetland area has been reduced by 600 square kilometers and fish yields have fallen. The government of Mali plans a tenfold expansion in new commercial farmlands. Irrigation for this will require the whole flow of the river during the dry season.

And further upstream, in Guinea, the government plans a new hydroelectric dam. This would capture most of the wet season flow. According to dutch hydrologist Leo Zwarts, who has modelled the effects, the combined effect will be to dry out the wetlands about every four years creating poverty, starvation and driving more than a million people off the land.

There's an obvious precedent for this - the Aral Sea. The sea lost 80% of its volume between 1960 and 1998 due to diversion of water for agriculture. The results for pollution, health and losses of livelihoods and biodiversity that have been horrible and widely reported. We might have hoped that the government of Mali and its foreign partners would have noted the lessons. Yet Jane Madgwick, head of Wetlands International, has described the likely results for Malean wetlands as a “human catastrophe as vicious and shameful as the drainage of the Aral Sea". 

Finally (I think) we should note that the mighty river Niger does not end in Mali. What about the downstream users?

When the River Niger leaves Mali it flows into Niger and then into Nigeria. (You can tell its importance from the country names can't you? It's the largest river in both countries!) What will be the consequences for them? And what might they do to avoid those consequences?

This is a depressing tale with a number of lessons:
  • Intensive commercial farming and irrigation schemes may increase food production in a country. Much of the extra food, and profit, will be exported making the local benefits somewhat uncertain and likely to accrue to the local elites.
  • They may create poverty and hardship for existing farmers, fishers and herders. These people are unlikely to be compensated for their losses.
  • We should therefore be highly skeptical of plans to address Africa's problems by encouraging large-scale commercial farming.
  • These problems are not specific to either capitalist or state socialist systems. They reflect drives for status, profit and production that are found in all economic systems plus the fact that national planners are remote from the people and places most affected and are unconstrained by an effective political system.

Thursday, 20 June 2013

Has the US cut its emissions?

You may have seen reports that US greenhouse gas (GHG) emissions fell 3.8% last year; they were all over the media last week. The fall since 2005 is said to be 12%. The main factor driving the fall is a switch from coal to natural gas due, in turn, to the availability of cheap gas from fracking (shale gas) though the recession has also contributed.

That’s good news – but nothing like as good as it looks.

The emissions numbers count gas burnt but ignore gas lost during extraction and transfer to users (Wall Street Journal (18/4/13, Since natural gas is mainly methane and methane is much worse for the climate than CO2 ( it takes only a little methane leakage to offset that saving in CO2 emissions.

To see how much we have to set a timescale and I choose 20 years because that is the critical period for addressing climate change. If we have not solved it well within that period it will be a lost cause.

Because methane is such a potent greenhouse gas there will only be a saving of greenhouse gas emissions relative to coal if leakage is less than 0.7%. In 2011 Robert Howarth and co-workers at Cornell University estimated the leakage in the US at 3.6% to 7.9%, exclusive of accidents. They conclude that switching from coal to shale gas will increase the greenhouse effect of this fuel use by a factor of 1.2 to 2 over 20 years! The effect over 100 years is roughly zero.

Suppose that half of the apparent fall in greenhouse gas emissions was due to a switch from coal to shale gas (which is plausible).  Then the 12% reduction in CO2 would imply that the reduction in total greenhouse gas emissions has been somewhere between 5% and nothing. 

The switch from coal to shale gas is not a solution to the problem of climate change and has no part to play unless the leakage can be very greatly reduced and the other environmental effects eliminated. 

Nor is that the end of the bad news – unlike the policy-driven reductions we seek the US reduction is price-driven and is therefore not locked in. Specifically:
  • Part of the GHG reduction is due to the recession and will likely be reversed as the recession ends.
  • Natural gas prices have been rising so US users have begun to switch back to coal.
Finally, low gas prices in the US have led the US to export the coal it would otherwise have burnt – mostly to Europe!

Fossil fuels are a global market and local prices falls will only increase fuel usage. We can only reduce GHG emissions if we raise the price of fossil fuel.

Nasty but necessary.

Friday, 26 April 2013

Good News 4: Heat pumps and heating schemes

New Scientist (13 April 2013, p 30-33) reports a number of related initiatives based on ground-source heat pumps. The Vancouver Olympic Village meets 70% of space and water heating needs from heat pumped from untreated sewage whilst in Helsinki ground-source heat warms 93% of the city's heated spaces.

The UK, as always, drags behind with only 172,000 homes are warmed this way even though half the country's heat load is in areas where district heating would be viable.

Lots of opportunities then.

Tuesday, 26 March 2013

Another nail in the climate coffin

Japan has started drilling into deposits of methane hydrate off its eastern coast. The deposits are thought to contain enough methane to power Japan for a hundred years. That's probably enough to push the world's climate over the edge.

Source: New Scientist  9/3/13 p 12-13.