Tag Archives: Global Carbon Project

Chart of the Day, 29 Jan 2015: China Slowdown a CO2 Emissions Silver Lining

If you follow the climate change debate over time, it is difficult not to get depressed: it’s the feeling of helplessness as the slow-motion cash crash takes place before your eyes.

So when a little bit of light shines through, it comes as a relief. And sometimes, hope comes from the most unlikely of sources–in this case China. It is almost a truism that as go China’s CO2 emissions, so go the world’s. See the chart below (Source: Trends in Global C02 Emissions Report; click for larger image):

Global CO2 Emissions jpeg

Very roughly, global CO2 emissions have gone from around 24 billion tonnes per annum in the early 1990s to around 36 billion tonnes today: an increase of 12 billion, or 50%.

Taking the top six emitters, we see can China’s prime role in this growth more clearly (click for larger image):

Top 6 Emitters jpeg

So we have seen China move from emitting around three billion tonnes of CO2 in the 1990s to around 10 billion tonnes today. Thus of the extra 12 billion tonnes of CO2 emitted per annum globally after 20 years, 7 billion has come from China.

The Global Carbon Project sees emissions continuing to grow to 43 billion tonnes in 2019 (note giga is equivalent to billion).

CO2 Emissions to 2019 jpeg

And again it is China leading the trend:

Regional Emissions to 2019 jpeg

And keep in mind that we have a CO2 budget of around 1,200 billion tonnes of CO2 before we commit the earth to 2 degrees Celsius of warming with a 66% probability. On current trends, that budget will be used up by about 2041, or in around 27 years.

Carbon Budget 2014 jpeg

Over that period, China is likely to emit approximately 15 billion tonnes of CO2 per year on average on present trends. That would mean that by 2041, China would have emitted about 400 billion tonnes of CO2, or a third of the total budget available. Next question: is there any way China can free up more of the budget?

A paper by Luukkanen et al provides us with a detailed decomposition of China’s future emissions using a Kaya identify with a sectoral overlay. To refresh your memory, the Kaya identity allows us to estimate future emissions based on population growth, GDP growth per person, energy intensity per unit of GDP, and carbon intensity per unit of energy (see my post “The Unbearable Logic of the Kaya Identity” for a little more detail).

The paper sets out three fuel-related emission scenarios: reference (business as usual), policy (following the government’s developmental plans) and industry (a  focus on heavy industry and investment-led growth).

China CO2 Scenarios jpeg

Note that the above charts are only looking at fuel combustion emissions. Accordingly, these numbers don’t tally with the Global Carbon Budget numbers that also add in agriculture and industry-related emissions. Nonetheless, where fuel emissions go, so will total emissions.

Here is where the silver lining comes: the most-muted emissions scenario above, termed ‘policy’, still looks far too high growth-oriented to me. Here are the assumptions that underpin this scenario `click for larger image):

China Sectoral Annual Growth Rates jpeg

In the policy scenario, a GDP growth rate of 7.4% is still forecast between 2016 and 2020, and then 5.2% growth  between 2021 and 2030. If you believe in a much quicker slow-down scenario, which I do, then these numbers look hopelessly optimistic (from a growth rather than climate perspective). See my post referring to Michael Pettis’ work.

If you then combine a much swifter descent to growth rates of 3-5%, plus a continued pivot from investment-led growth to consumption-led growth, and then add on an aggressive renewables roll out (which we are seeing), then China could free up an additional 100 billion tonnes of the carbon budget.

Frankly, that still doesn’t get us anywhere near capping climate change to 2 degrees of warming, but it gives us a little bit of extra time. And given where we are, every little bit helps.

The Unbearable Logic of the Kaya Identity

The ‘trillionth tonne’ of carbon is a  powerful risk indicator (I previously blogged about it here). As the Oxford University hosted web site trillionthtonne.org shows, we have used up around 567 billion tonne of our one trillion tonne carbon budget:

trilliontonne.org jpg

So that leaves 433 billion tonnes. If we go over the budget, we likely commit the planet to 2 degrees Celsius of warming above pre-industrial revolution levels. That level of warming is viewed as commensurate with dangerous climate change since it will produce a range of impacts extremely negative for mankind. How quickly we will grind through that 433 billion tonnes is the topic of this post.

The U.S. government agency the Carbon Dioxide Information Analysis Center (CDIAC) publishes a time series of emissions from fossil-fuel burning, cement manufacture and gas flaring going back to 1751 here and for land-use change emissions here. This is the benchmark record of human-induced emissions for most academic studies.

The recent estimate for fossil-fuel and cement related emissions for the year 2011 is 9.5 billion tonnes and can be found on the CDIAC site here. Land-use change emissions are updated less frequently but have been running at around 1.0 billion tonnes per annum (also available on the CDIAC site).

For 2012, the Global Carbon Project, a collaboration between various universities and scientific institutions  from around the world, estimates that fossil fuel emissions (including those associated with cement production) rose by 2.7% in 2012 to reach 9.7 billion tonnes. Put those two numbers together, and we are placing around 10.7 billions tonnes of carbon into the atmosphere. So if we then divide our remaining 433 billion budget by 10.7 billion tonnes of yearly output, we have 40 years before we likely commit ourselves to a world of dangerous climate change.

That is the good news (sort of) since 40 years is quite a long time. The bad news is that carbon emissions are not static, but are expanding every year. Further, that increase is a product of some  very powerful forces that are captured in an identity created by Japanese energy economist Yoichi Kaya. The identity breaks down the rise in global carbon emissions into four major components as can be seen below:

Kaya Identity jpg

Continue reading

A Fraction for Your Thoughts

If you want an up-to-date monthly measurement of atmospheric CO2 concentration—my candidate for the most important leading indicator of welfare in the world—then I suggest you bookmark the home page of CO2now.org. The site gives you easy access to the longest running monthly time series of atmospheric CO2 concentration, which goes all the way back to March 1958.

The American scientist Charles David Keeling pioneered the accurate measurement of CO2 after setting up a laboratory 3,000 metres above sea level at Mauna Loa in Hawaii.  The location was specifically selected to eliminate sample contamination by large-scale factory emissions: no such industry exists for thousands of miles around Mauna Loa.

As the years passed, Keeling’s observations showed a natural annual cyclical movement in CO2 concentrations: an upswing in the northern hemisphere autumn as vegetation died back and CO2 was released; and a downswing in the northern hemisphere spring as renewed plant growth removed CO2 from the air. The explanation for why the northern hemisphere growing season dominates the cycle is simple: 65% of the earth’s land mass resides in the north.

The second observation was even more critical: atmospheric CO2 concentration was on an upward trajectory, a trajectory that has been dubbed the ‘Keeling curve’. And as the years went by it became obvious that the source of this rising CO2 concentration was mankind. A few contrarians (most famously the Australian geologist Ian Pilmer) have suggested that undiscovered volcanoes are responsible for rising CO2 levels, but no mainstream volcanologists support his views; the consensus is that volcano sourced CO2 emissions are around 150 times smaller than those from anthropogenic (human) sources.

An even more simple rebuttal to the ‘it isn’t us’ claim is that any serious alternative must account for where the CO2 from burnt fossil fuels has gone. We know to a high degree of certainty how much oil, coal and gas we are burning, and you can even go onto BP’s web site and look it up here. So if there exists some ‘natural’ source of the CO2 build-up, there must therefore exist a ‘natural’ withdrawal of all the fossil fuel CO2 emissions. Thus for it not to be ‘us’, an unidentified natural process must be removing all the human-produced carbon, while at the same time naturally produced carbon from a separate unidentified source is magically replacing it. I hope the absurdity of this logic is obvious.

More interesting is the fact that annual fossil fuel plus land use change CO2 emissions don’t equate with the rise in atmospheric CO2 concentrations. There are certain numbers I encourage you to get comfortable with. One such number is the annual fossil fuel carbon emission as reported by the US Carbon Dioxide Information Analysis Center (CDIAC). The time series is reported here and the most recent advance estimates for the last two years are here. According to this source, 9.1 giga tonnes of fossil fuel carbon was emitted in 2010 (which is about 33 giga tonnes of CO2).

The next number to etch into your memory is that 1 part per million (ppm) of CO2 in the atmosphere is equivalent to 2.1 giga tonnes of carbon. Keeping this figure in mind, look at the next two tables. They are taken from the Carbon Budget 2010 report published on December 5th by the Global Carbon Project (a body set up to coordinate academic research on the carbon cycle).

You will note that for the 2000-2010 period, CO2 concentration has been rising by an annual average of 1.9 parts per million (ppm), which is equivalent to around 4 giga tonnes of carbon. In 2010, CO2 rose by 2.36 ppm, which is roughly the same as 5 giga tonnes of carbon. You will also recall that fossil fuel emissions were estimated at 9.1 giga tonnes and land use change emissions at 0.9 giga tonnes in that year. So some simple maths tells us that only 50% of what is being discharged into the atmosphere is actually staying there. Ultimately, all the sources of CO2 must balances with all the sinks of CO2, and another chart from the Carbon Budget 2010 shows us what is going where (note that a peta gram, Pg, is the same thing as a giga tonne, Gt):

And similar analysis for 2010:

Over the longer term, the percentage of emissions that remain in the atmosphere, the so called airborne fraction, has stayed around 43%. Thankfully, no change in trend for this fraction has yet been found (see here). Yet year to year there is a significant flux. For example, in 2010 we saw the airborne fraction at 50%, significantly above the 43% ish long-term trend. For the first 11 months of 2011, however, CO2 is up around 1.8 ppm year on year, which is equivalent to 3.7 giga tonnes of carbon. If we assume total emissions (fossil fuel and land use change) come in a little over 10 giga tonnes, the airborne fraction will  have fallen from 50% in 2010 to somewhere around 35% in 2011. The main driver of this year to year shift is the El Nino Southern Oscillation (ENSO) cycle. Simplistically, cold water absorbs more CO2 than warm water, and during a La Nina phase you get more cold water and in an El Nino less.

Unfortunately, just because the CO2 airborne fraction has been well-behaved to date, does not mean it will always be so. The fear is that at some stage carbon land and ocean sinks will become saturated, causing the airborne fraction to rise. Thus, more of the CO2 we pump into the atmosphere will actually stay there. Should that happen over the next few decades, then temperature rise could also accelerate. The UK Met Office has modelled one scenario which sees the Amazon rain forest dying off, so causing a massive down shift in the CO2 land sink uptake. The result is a surge in CO2 concentrations.

Thankfully, the Met Office model’s horrible looking carbon cycle feedback is still an outlier among climate models globally. That said, I make a habit of comparing CO2 emissions with atmospheric CO2 concentrations. We already have one instance of climate models failing to forecast a major structural shift: the far earlier-than-expected collapse in Arctic sea ice extent. Let’s hope the airborne fraction does not follow a similar path; but keep an eye on it just in case.