Digress

On energy: Climate change

On Energy is a series discussing and dissecting the energy sector in the UK.

In part I of this series, we touched upon the key motivations behind the need for a better energy policy. Anthropogenic climate change was one of them, and in this post I’d examine whether there is a point in us doing anything when supposedly “China’s out of control!”.

The climate change argument

The climate change argument is presented thusly:

  1. Carbon dioxide is a greenhouse gas.
  2. Fossil fuels burning by humans causes carbon dioxide concentrations in the atmosphere to rise.
  3. Increasing greenhouse gas concentrations in the atmospheres accelerates the greenhouse effect which increases average global temperatures, which in turn has many other effects.
Figure 1. A layer of greenhouse gases – primarily water vapor, and including much smaller amounts of carbon dioxide, methane and nitrous oxide – acts as a thermal blanket for the Earth, absorbing heat and warming the surface to a life-supporting average of 15 degrees Celsius.

The greenhouse effect is a naturally occurring phenomenon that has allowed Earth to support life. In and of itself, it is not calamitous. But what is indeed calamitous is the human-led augmentation of this process that has been taking place since the mid 1700s. Figure 2 shows CO2 concentrations in the atmosphere since the year 1000 AD. “Sceptics” maintain that the exponential increase in atmospheric CO2 is a natural phenomenon that belies any signs of human influence. Whereas those who can read choose to categorically disagree.

Figure 2. Atmospheric CO2 over the last 1000 years. James Watt patented his steam engine in 1769. 
Figure 3. Coal consumption from 1600-1910 in billions of tons of CO2 released when the coal was burned.

While the first practical steam engine was invented in 1698, the introduction of James Watt’s more efficient design in 1769 kickstarted the Industrial Revolution that will change life on Earth indelibly. One of the very first application of the steam engine was the pumping of water out of coal mines. Figure 3 shows UK and world coal consumption from 1600 to 1910. Back then, coal was used to make iron, to make ships, to heat buildings, to power factories and other machinery, and of course to power the pumps that enabled still more coal to be mined.

Burning coal, and other fossil fuels such as oil, releases carbon dioxide in the air. So the elevated atmospheric CO2 levels in the aftermath of the Industrial Revolution and the exponential coal consumption globally aren’t mere spurious correlations, as some “sceptics” will have us believe. The facts are clear: burning of fossil fuels is the principal reason why CO2 concentrations have gone up.

Human activities send about 29 gigatons of CO2 per year into the atmosphere. The biosphere sends about 440 gigatons a year and the oceans 330 gigatons. This has led some people to conclude that man’s contribution to climate change has been overstated by climate scientists desperate to hold onto their jobs.

What the “sceptics” conveniently ignore is that nature is cyclical. The biosphere and oceans don’t just absorb back all the carbon they send out into the atmosphere, they absorb approximately 54% of anthropogenic emissions too. Figure 4 depicts the disturbance our seemingly insignificant carbon emissions have caused in the natural carbon cycle.

Figure 4. The modern carbon cycle. Carbon reservoir sizes in gigaton of carbon. Changes in gigaton of carbon per year. Pre-industrial ‘natural’ movements in black, and ‘anthropogenic’ movements in red.
Fossil fuels contain 3700 gigaton of carbon, of which we consume 244 gigatons annually, which results in 6.4 gigatons of carbon being released into the atmosphere. From reference 3.

The culprits

Greenhouse gases include carbon dioxide, methane and nitrous oxide; each gas has different physical properties but it’s conventional to express all emissions in equivalent amount of carbon dioxide, where equivalent means having the same warming effect over a period of 100 years. One ton of carbon-dioxide-equivalent may be abbreviated as 1 t CO2e, and one billion tons as 1 Gt CO2e (one gigaton).

In the year 2014, the world’s greenhouse gas emissions were about 36 Gt CO2e per year. Let’s contextualise this mind boggling stat. There were approximately 7.25 billion people on the planet in 2014, so that leaves (36 / 7.25) = 5 tons CO2e per year per person.

Now, all men are created equal, but we don’t all emit 5 tons of CO2e per year. These days it is quite fashionable to blame China for all our problems. Media cries out every other week that China is the “second biggest polluter” in the world. But is it really? The map below from Our World in Data shows the distribution of carbon emissions across the world from 1785-2016. The interactive version is much nicer.

In 2014, China had a per capita emissions of 7.36 tonnes. The United States has been consistently emitting above 7.4 tonnes per capita since 1898. Europe has not been any better, emitting well above twice the world average per capita. In fact, there has never been a time in history where per capita emissions in China were higher than those in the US or in Europe.

So if we something must be done to prevent irreversible climate change, who has a special responsibility to do something? Shouldn’t it be those countries whose emissions are two, three or four times the world average? Like Britain, or Germany, or USA?

But the comparison isn’t fair. The above graphic shows who’s doing the polluting today, or at any given time in the past. But it isn’t the rate of emissions that matter, it’s the cumulative total emissions; much of the emitted carbon dioxide (about a third of it) will stay in the atmosphere for the at least 80 to 100 years. So what is of interest here is a country’s historical footprint. Take a look at Figure 5 taken from a report by Finland’s Ministry of Environment.

Evidently, the USA is the greatest polluter on Earth. Europe hasn’t been slacking off either. It has polluted thrice as much as China overall, and twice as much from 1990–2010. If we are to solve this global challenge, those most responsible must be brave and honest enough to accept their guilt and lead the charge. Alas, that is too much to ask off the self-anointed leader of the so-called Western Civilisation.

Figure 5. Countries’ shares of historical emissions on cumulative-per-capita basis, using different scopes for which emissions and from which time periods are taken into account. LULUCF stands for emissions from land use, land use change and forestry.

Moving on

Figure 6. Share of total global greenhouse emissions by sector. IPCC 2014.

Methane from burping cows may cause more warming than air travel, but even so agriculture makes up only 12% of our total emissions. 76% of world greenhouse gas emissions are energy use related. These include power stations, factories, transportation, oil refining, air conditioning and heating buildings. There is no denying that the climate change problem is principally an energy problem.

While it was important to establish the ethical responsibility for the mess we find ourselves in, the rest of the series will take no such detours. Ethical assertions such as “the biggest polluters have a duty to lead action on climate change” make a good placard, but “the West” has a storied history of not owning up to mistakes and apportioning blame doesn’t inspire a spirit of cooperation.

References

  1. Atmospheric CO2 over the last 1000 years: A high-resolution record from the West Antarctic Ice Sheet (WAIS) Divide ice core; doi:10.1029/2011GB004247.
  2. Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty; doi:10.5194/bg-12-2565-2015, 2015
  3. Climate Change 2007: The Physical Science Basis. Fourth Assessment Report of the Intergovernmental Panel on Climate Change; IPCC
  4. Assessing countries’ historical contributions to GHG emissions, a report by Finnish Ministry of Environment.