Population and Climate Change–one Lukewarmer’s View

Would you care if the population of this planet was 20 billion (as predicted by John Holdren and Paul Ehrlich back in the 70s) if they were powered by wind, solar and nuclear?

This post is cobbled together from some comments I wrote at Bart Verheggen’s excellent weblog My View On Climate Change. I’ve edited them slightly. The post is here. There are a variety of commenters there who disagree vigorously with most of what I wrote. Indeed, some disagree with my right to exist on this planet. (Please remember that this is only my point of view–other Lukewarmers may disagree just as vigorously as my critics.)

Treating population strictly in terms of the Kaya identity leads to over simplistic assertions. Population dynamics change dramatically, often in one generation, to environmental and economic pressures, and without incorporating a feedback loop to include the response of population to policy you end up making policy that’s always a generation behind the times.  I think you have to look at Kaya, Kuznets, Jevons and the energy ladder all at the same time to say useful things.

First, although it seems common-sensical to link population to climate change, it’s not really automatic. The population increased in 2009, but emissions of CO2 went down. The over-consuming United States increased its population in 2009, but emissions declined 7%.

A growing population can change climate in other ways–deforestation, depletion of other resources, pollution, etc. But those are more common in developing nations than developed nations.

People in the developed world use more energy per capita than those in developing countries. However, the variation between developed countries is dramatic. In the U.S., per capita consumption of energy was 323 mbtu’s per annum, while in Denmark it is 161. Variation in developing countries is equally dramatic, depending on where on the scale of development they lie.

The growth rate of the human population is slowing down to almost zero. It has already happened in many countries (mostly developed), and is happening as we write this in emerging countries at a dramatic rate.

So looking at the gross totals of populations does not answer our question, nor does a superficial segmentation into developed or developing countries.

For the purpose of discussing climate change, the first question is, if a larger population did not consume more energy, emit more CO2, or worsen impacts on other climate forcings, would we care about how big the population is?

If the answer is no, then we should look at the variation between populations. If the answer is yes, then we are discussing larger issues than climate change, and will probably get nowhere quickly.

It is not only emissions that fell last year, despite a growing population. Consumption of energy also declined per capita. The U.S. DOE had to make a dramatic adjustment of their forecasts for 2010, from 508 quads to 500.

Energy efficiency is one reason. Continued growth of combined heat and power plants, decommissioning of some old coal plants, continued adoption of ground source heat pumps and better technology in buildings help us get a better bang for the buck even though there are more of us.

Renewable energy is not growing as a percentage of total energy, which is a pity. It provided about 52 of the quads we used in 2009, around 11%, and nobody thinks it’s going to jump to, say, 15% or 20% by 2030. However, if the total energy provided by renewables can keep pace with population growth, we gain in some fashion.

The reason is that it may allow developing countries to skip a few of the dirtiest rungs on the energy ladder.

Countries that are developed today climbed an energy ladder that started with using wood for fuel, and went to charcoal, coal, oil, gas, nuclear and renewables in pretty much that order.

Each step is a dramatic improvement on the previous one, in terms of pollution, energy gained per unit of CO2 emitted, and efficiency in terms of what can be powered with the fuel source.

Developing countries today are trying to move up the energy ladder. 70% of rural inhabitants in India burn kerosene for heat and cooking. Billions use wood as a primary fuel source. 1.5 billion do not have electricity.

If we could provide electrical infrastructure and power generated from the top of the energy ladder, they could leapfrog a generation of energy technology and move towards energy efficiency early. Hey, they skipped landline telephones and went straight to mobile, so why not?

So back to an earlier question–would you care if the population of this planet was 20 billion (as predicted by John Holdren and Paul Ehrlich back in the 70s) if they were powered by wind, solar and nuclear?

The energy used by people in developing countries increases dramatically as they get a) wealthier and b) more urbanized. They accumulate power using devices at an astonishing rate–just look at how quickly cars, TVs, washers and dryers spread through the United States and extrapolate from that.

There are just short of 2 billion people who have already gone through that acquisition process. Eventually, energy use seems to plateau, and then decline slightly. But there is no avoiding the fact that the population is going to increase to about 9.1 billion by 2075 (the mothers have already been born), and so about 7 billion people are going to jump from very low levels of consumption to very high.

That is the dilemma. It is not the number of people, it is their developmental status and desire to live a modern life.

How we address that will be the central question of this 21st Century. If we address this question ethically and intelligently, we will be able to go to our graves proudly. If we try to deprive the newcomers, or limit their growth, we will be condemned.

Population will reach about 8.1 billion in 2030 and 9.2 billion in 2075, when it will peak.

Energy production is expected to reach 687 quads according to the DOE, and the UN expects it to be about 703. However, straight line extension of consumption trends gets you to about 2,100 quads in 2035, and about 3,000 in 2075.

The DOE and UN predict capacity of around 700 quads in 2035. Population will be about 8.1 billion. Millenium Goals for developement and normal economic advancement indicate that taking a straight line for consumption is not absurd. This leads to a ‘latent’ demand for energy of about 1,400 quads, or almost 3 times what the world is using today.

That latent demand will be filled, as these people will be part of developing economies and have cash and urgent needs for energy. How will this latent demand be met?

Renewable energy grew by 2% per year over a decade of strong support and investment–a decade that is probably over. Assume it will continue at 2% and you get about 67 quads by 2035. Not much help there.

Nuclear power may almost double by that time–from about 27 quads to about 47 quads. No help there.

Energy efficiency may ‘produce’ negawatts of about 140 quads. Which leaves well over 1,000 quads of energy to be produced by fossil fuels.

What mitigation or adaptation strategy is adequate to meet this version of reality? Alternatively, what version of reality can be proposed?

Well, at the current rate of flight to urban environments, our other impacts on the environment are actually lessening even as our population grows. More than half of humanity lives in urban environments that take up 3% of the land area. Certainly they need to be fed and that increases the load on agricultural and pastoral land, but we already have the technology in hand to address that, through modern farming methods and the adoption of GMOs. What is driving new land under the plough today is the attempt to meet demand for biofuels.

I should lay out my assumptions regarding my fantastickal claim that we might need 2088 quads of primary energy supply around 2035.

The population will be about 8.1 billion (UN, many others)

World economic development will continue at about 3% per year (UN, IPCC, many others–just a benchmark, but it’s been useful so far. Goldman Sachs projects that Vietnam will have per capita income of $40,000 in 2050. It will be behind countries like China, Brazil and Turkey. These and other countries will be walking up the energy ladder, using more energy per person, and they will have the money to get their energy needs met.

If 7 billion of the 8 billion (there will still be the Bottom Billion to worry about) are consuming energy at an American level (323 million btus per person per year), that’s more than 2100 quads in 2035.

If we can tame expectations and steer development towards the Danish level of 161 mbtu per capita (which surely is enough–the Danish live well), the total drops to 1100 quads. But so far, development is taking the same path Americans took–maybe even a bit more extravagant.

Somebody tell me where I’m wrong and should happily accept the U.S. DOE’s projection of 683 quads for 2035 and the UN’s slightly higher projection of 703. What do they know that I do not?

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One response to “Population and Climate Change–one Lukewarmer’s View

  1. There were 4 nuclear starts in 2004. 10 in 2010. I can count 15 that will start next year. 7 in China, 4 in India, 1 in UAE, 2 in the US and at least 1 in Russia.

    If we use a doubling in starts every 5 years….5 in 2005, 10 in 2010, 20 in 2015, 40 in 2020, 80 in 2025, 160 in 2030 how many do we end up with?

    At what point will the technology be ready for super-critical efficiency’s(45% vs 30%)? 2020? 2025?

    Is the growth rate linear, has it peaked or is it geometric?

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