Archive for the ‘Greenhouse gases’ Category


The cost of contributions

The process of national governments submitting Intended Nationally Determined Contributions (INDCs) to the UNFCCC is well underway, with a number of developing and least developed economies also submitting plans. Most recent amongst these is a detailed and ambitious plan from the government of Kenya.

The Kenya INDC proposes a 30% reduction in national greenhouse gas emissions from a business-as-usual (BAU) trajectory, which it is also very clear in defining. The plan notes that Kenya strives to be a newly industrialized middle income country by 2030. Current emissions are very low, with the majority coming from land use change (LULUCF). In 2010 emissions were 73 MtCO2eq, with the IEA reporting energy CO2 emissions of 11.4 Mt for that year. Given the population of 41 million in 2010, that gives an energy linked CO2 per capita of 0.28 tonnes, amongst the lowest in the world. Kenya has projected BAU emissions of 143 MTCO2eq by 2030, so that gives them a goal of just on 100 MTCO2eq for that year on the basis of their INDC.

Kenya has also made it clear that their INDC is subject to international support in the form of finance, investment, technology development and transfer, and capacity building. With some of this support coming from domestic sources, they estimate the total cost of mitigation and adaptation actions across sectors at US$40 billion, through to 2030. My first reaction to this was that it seemed like quite a hefty bill, but better to look at the numbers.

First of all, a few assumptions. These are all open to challenge, but they help frame the issue and allow some assessment of the numbers to at least establish a ballpark estimate of value for money and the implications flowing from that.

  1. I will look at mitigation only, so let’s assume that the $40 billion is split between mitigation and adaptation, but with emphasis on mitigation. That allows ~$10+ billion for major public works and capacity building programmes focussed on areas such as water and agriculture and $20-$30 billion in the energy system.
  2. I will assume that energy system growth and adaptation funding allows for a plateau and then gradual decline in LULUCF emissions, such that by 2050 these are below 10 MT per annum.
  3. A BAU for energy emissions only would see Kenya rising to nearly 2 tonnes per capita by 2030 (current Asia, excluding China) and 6 tonnes per capita by 2050 (approaching current Europe). This would mean extensive use of fossil fuels, but supplemented by their geothermal and hydroelectric resources in particular. This is the pathway that they might be on in the absence of this INDC.
  4. Kenya’s population rises in line with the UN mid-level scenario, i.e. to 66 million by 2030 and 97 million by 2050.

Based on the above, energy emissions could rise to some 120 Mt p.a. by 2030 and 600 Mt p.a. by 2050 under a BAU scenario. But in the INDC scenario, this could be curtailed such that they are at 70 Mt p.a. in 2030 and perhaps as low as 130 Mt p.a. in 2050, or 70-80% below BAU. The 2030 number is the more important one for this calculation as this is what the $20-$30 billion delivers, although the benefits of the investment stretch beyond 2030. However, further additional investment would be required to keep emissions at such a low level through to 2050 as energy demand grows.

The deviation from BAU is nearly 50 Mt p.a. by 2030, with that deviation starting in the early 2020s. If the gains are held through to 2050, then the cumulative emission reduction over the period is around 1 billion tonnes. On a simple 20 year project life with no discounting, that equates to around $25 per tonne of CO2 against the $20-$30 billion investment in the 2020s. On that basis, this looks like a good deal and is well within the bounds of plausibility. It could equate to a mixture of expanded renewable energy deployment, natural gas instead of coal and possibly some biofuel development for transport.

What is perhaps more interesting is how this scales up across Africa and other parts of the world where energy access is currently limited. If 1-2 billion people globally need support for similar energy infrastructure, that implies a financial requirement of about US$1 trillion over the period 2020-2030 just for mitigation (i.e. 30+ times the Kenya population of 50 million, multiplied by $US30 billion). This equates to $100 billion per annum, which is also the number that was agreed in Copenhagen in 2009 as the call on increased financial flows to developing countries, although that was for both mitigation and adaptation purposes. It also implies that if the world does reach the US$100 billion per annum goal, then most of this will be for mitigation in the least developed economies as they build their 21st century energy systems.

The flip side of this is that the emerging economies will probably have to self-fund, which argues for the implementation of a carbon price on a far wider basis than is currently envisaged. China is leading the way here, but so too are countries like Mexico and Chile.

The Kenya INDC offers some interesting insight into climate politics in the years to come.

The last days of March have seen the start of submissions of Intended Nationally Determined Contributions (INDCs) to the UNFCCC. The United States, Switzerland, European Union, Mexico and Russia have all met the requested deadline of the end of Q1 2015. As is expected and entirely in line with the UNFCC request, the INDCs focus on national emissions. After all, this is the way emissions management has always been handled and reported and there is no sign of anything changing in the future.

As was to be expected, the United States submitted an INDC that indicated a 26-28% reduction in national emissions by 2025 relative to a baseline of 2005. This is an ambitious pledge, and highlights the changes underway in the US economy as it shifts towards more gas, backs out domestic use of coal, improves efficiency and installs renewable generation capacity. So far the USA national inventory indicates that the 2020 target is being progressively delivered, although it will be interesting to see whether this trend changes as a result of the sharp reduction in oil prices and a couple of summer driving seasons on the back of that.

US 2020 and 2030 Reduction Target

My own analysis in 2011 (see below) was that the USA would come close to its 2020 goal, but may struggle to meet it. The different overall level of emissions in the charts is the result of including various sources (e.g. agriculture) and gases, or not.

US 2020 Goal with 2010 data

Direct emissions represent just one view of US emissions. Some would argue that the national inventory should also include embedded emissions within imported products, but this introduces considerable complexity into the estimation.

Another representation of US emissions which is perhaps more relevant to the climate issue is the actual extraction of fossil carbon from US territory. As the climate issue follows a stock model, the development of global fossil resources and subsequent use over the ensuing years is a measure that is closer to the reality of the problem. The larger the resource base that is developed globally, the higher the eventual concentration of carbon dioxide that the atmosphere is likely to reach. This is because the long-term accumulation will tend towards the full release of developed fossil fuel reserves simply because the infrastructure exists to extract them and as such they will more than likely get used somewhere or at some time. This isn’t universally true, as the closure of some uneconomic coal mines in the USA is showing; or are they simply being mothballed?

A look at US carbon commitment to the atmosphere from a production standpoint reveals a different emissions picture. Rather than seeing a drop in US emissions since 2005, the upward trend that has persisted for decades (albeit it a slower rate since the late 1960s) is continuing.

US emissions based on extraction

In the case of measured direct emissions, reduced coal use is driving down emissions. But for the extraction case, additional coal is now being exported and the modest drop in coal production is being more than countered by increasing oil and gas production. Total carbon extraction is rising.

While there is no likelihood that national emission inventories will start being assessed on such a basis, it does nevertheless throw a different light onto the picture. In a recent visit to Norway it was interesting to hear about national plans to head rapidly towards net-zero emissions, but for the country to maintain its status as an oil and gas exporter. This would be something of a contradiction if Norway was not such a strong advocate for the development of carbon capture and storage, a strategy which will hopefully encourage others to use this technology in the future.

Getting to net-zero emissions

It is looking increasingly likely, but not a given, that a reference to global net-zero emissions or even a specific goal to achieve net-zero emissions by a certain date (e.g. end of the century) will appear in the climate deal that is expected to emerge from the Paris COP at the end of this year. But like many such goals, it is both open to interpretation and raises questions as to how it might actually be achieved.

The background to this is that the issue itself implies that this outcome is necessary. The IPCC says in its 5th Assessment Report;

Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Limiting risks across RFCs (Reasons for Concern) would imply a limit for cumulative emissions of CO2. Such a limit would require that global net emissions of CO2 eventually decrease to zero and would constrain annual emissions over the next few decades (Figure SPM.10) (high confidence).

However, the term net-zero needs some sort of definition, although this is currently missing from the UNFCCC text. One online source offers the following;

Net phase out of GHG emissions means that anthropogenic emissions of greenhouse gases to the atmosphere decrease to a level equal to or smaller than anthropogenic removals of greenhouse gases from the atmosphere.

The above effectively means stabilization of the atmospheric concentration of CO2, which also aligns with the ultimate aim of the UNFCCC Convention (stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system). This could still leave room for some level of emissions in that climate models show atmospheric concentration of carbon dioxide will decline if anthropogenic emissions abruptly stopped. In a 450 – 500 ppm stabilization scenario emissions could remain in the range 7-10 billion tonnes CO2 per annum without driving the atmospheric concentration higher. This is far below current levels (35 billion tonnes per annum from the energy system alone), but it isn’t zero. It can be classified as net-zero though, in that the atmospheric concentration isn’t rising.

However, such an outcome, while stabilizing the atmospheric concentration may not be sufficient to prevent dangerous interference with the climate system. In that case an even lower level of emissions may be required, such that atmospheric concentrations do begin to fall and stabilize at a lower concentration.

Another definition of net-zero may simply apply to anthropogenic emissions directly, irrespective of what the concentration in the atmosphere might be doing. In this case, any remaining emissions from anthropogenic sources (and there will be some) would have to be offset with sequestration of carbon dioxide, either via CCS or a permanent forestry solution. In the CCS case, the carbon dioxide would need to come from a bio-source, such as the combustion of biomass in a power station. This is what the IPCC have termed BECCS.

A final step which goes beyond net-zero, is to have an anthropogenic net-negative emissions situation, which is drawing down on the level of carbon dioxide in the atmosphere through some anthropogenic process. This would be necessary to rapidly lower the concentration of carbon dioxide in the case of a significantly elevated level that comes about in the intervening years between now and the point at which the concentration stabilizes. Very large scale deployment of BECCS or an atmospheric capture solution with CCS would be required to achieve this.

Finally, there is the consideration that needs to be given to greenhouse gases other than carbon dioxide. Methane for example, while a potent greenhouse gas, is relatively short lived (a decade) in the atmosphere so will require some thought. Even in a zero energy emissions system, methane from agriculture and cattle will doubtless remain a problem.

Both of the Shell New Lens scenarios end in a  net zero emissions outcome by the end of the century, but this is within the energy system itself and does not encompass the full range of other sources of CO2 emissions and other long lived greenhouse gases. Nevertheless, with extensive deployment of CCS the Mountains scenario heads into negative emissions territory by 2100 and the Oceans scenario soon after that (which means there is potential to offset remaining emissions from very difficult to manage sources). Oceans relies on this approach in a major way to even approach zero in the first instance

Many look to renewable energy as a quick solution to the emissions issue, but the reality is far more complex. While we can imagine a power generation system that is at near zero emissions, made up of nuclear, renewables and fossil fuels with CCS, this is far from a complete solution. Electricity currently represents only 20% of the global final energy mix (see below, click for a larger image: Source IEA).

Global final energy 2012

Solutions will need to be found for a broad range of goods and services that give rise to greenhouse gas emissions, including non-energy sources such as limestone calcination for cement and cattle rearing for dairy and direct consumption. While we can also imagine a significant amount of global light transport migrating to electricity, shipping, heavy transport and aviation will not be so simple. Aviation in particular has no immediate solution other than through a biofuel route although there is some experimentation underway using high intensity solar to provide the energy for synthesis gas manufacture (from carbon dioxide and water), which is then converted to jet fuel via the well-established Fischer–Tropsch process. There are also dozens of industrial processes that rely on furnaces and high temperatures, typically powered by fuels such as natural gas. Metal smelting currently uses coal as the reducing agent, so a carbon based fuel is intrinsic to the process. Solutions will be required for all of these.

Whether we aim for a very low level of emissions, true net-zero anthropogenic emissions or negative emissions is somewhat academic today, given the current level of emissions. All the aforementioned outcomes are going to require a radical re-engineering of the energy system in a relatively short amount of time (< 80 years).

The release of the IPCC 5th Assessment Report Synthesis document on Sunday was a useful reminder of the wealth of measurements, observations and science behind the reality of the anthropocene era and the impact it is having on global ecosystems. While some may embrace this material as proof of society’s “wicked ways” and others may contest it on the grounds of conspiracy or hoax, the real job at hand is to find a way of dealing with the challenge that is posed. Within the 100+ pages of text of the longer report, two parts in particular highlight the scope of what needs to be done.

Within 1.2.2:

Despite a growing number of climate change mitigation policies, annual GHG emissions grew on average by 1.0 GtCO2eq (2.2%) per year, from 2000 to 2010, compared to 0.4 GtCO2eq (1.3%) per year, from 1970 to 2000. Total anthropogenic GHG emissions from 2000 to 2010 were the highest in human history and reached 49 (±4.5) GtCO2eq yr-1 in 2010.

Within 3.2 and 3.4:

Global mean surface warming is largely determined by cumulative emissions, which are, in turn, linked to emissions over different timescales. Limiting risks across reasons for concern would imply a limit for cumulative emissions of CO2. Such a limit would require that global net emissions of CO2 eventually decrease to zero.

There are multiple mitigation pathways that are likely to limit warming to below 2 °C relative to pre- industrial levels. Limiting warming to 2.5 °C or 3 °C involves similar challenges, but less quickly. These pathways would require substantial emissions reductions over the next few decades, and near zero emissions of CO2 and other long-lived GHGs over by the end of the century.

The IPCC have now fully embraced the cumulative emissions concept and taken it to its logical conclusion; near zero emissions within this century. This wasn’t explicitly mentioned in the 2007 4th Assessment Report, but was only really there by inference in the mitigation scenario charts that extend beyond 2050. Anyway, the reference is very clear this time around.

This represents a formidable task given the other half of the problem statement also shown above; that emissions are rising faster than ever. There is a second uncomfortable truth buried within this paragraph, which is the implication that current mitigation policies aren’t working.

So there we have it in a nutshell;

Emissions are rising faster than ever, current policies to stop this aren’t working, but we need to be at zero in 85 years.

Eighty five years is the lifetime of an individual. It means that someone born today will need to see a radical change in energy production within the course of their life, to the extent that it is constantly changing for all 85 years, not just locally but everywhere in the world. Arguably someone born in England around 1820 saw this as the industrial revolution unfolded and the Victorian era took hold. But someone born in 1930 hasn’t actually seen a fundamental change in the energy system, rather an enormous scaling up of what was starting to become commonplace at the time of their birth.

This is the issue that I explore in my new book and which is tackled in the Shell New Lens Scenarios released last year. Both the scenarios show that this puzzle is solvable, albeit in very different ways and with different policy approaches but with different levels of success. A critical factor in both scenarios is the timing and deployment rates of carbon capture and storage (CCS). The earlier this starts and the faster it scales up, the higher the chance of limiting warming to around  2°C. This is also highlighted in the IPCC Synthesis Report which says in Section 3.4;

Many models could not limit likely warming to below 2 °C over the 21st century relative to pre-industrial levels, if additional mitigation is considerably delayed, or if availability of key technologies, such as bioenergy, CCS, and their combination (BECCS) are limited (high confidence).

CCS is of course dependent on a price for carbon dioxide or in its absence a standard of some description to implement capture and storage. These policies are largely absent today, despite over two decades of effort since the creation of the UNFCCC. There are certainly some major carbon pricing systems in place, but most are delivering only a very weak carbon price signal and none are leading to large scale rollout of CCS or show any signs of doing so in the near future. Rather, the emphasis has been on promoting the use of renewable energy and increasing the efficiency of energy use. Both of these policies will bring about change in the energy system and efficiency measures will almost certainly add value to most, if not all economies, but it is entirely possible that large scale adoption of these measures doesn’t actually cause global CO2 emissions to fall.

The IPCC have also put a cost on this policy failure in Table 3.2, which shows mitigation costs nearly one and a half times greater in a world which does not deploy CCS. This high cost comes about because the only way to resolve the scenario models is to limit economic activity as means of mitigation; CCS rollout prevents that from happening.

Another way of looking at this is to imagine the actual climate change consequences of delaying CCS rollout, since the likelihood of limiting economic activity is very low. A back calculation from the Shell scenarios implies that every year large scale rollout of CCS is delayed, 1 ppm of atmospheric CO2 is added to eventual stabilisation. This comes about from the cumulative nature of the problem. As such, a 30 year delay means accepting an eventual concentration of CO2 that is some 30 ppm higher than it need be which in turn has consequences for impacts such as sea level rise.

The negotiators now preparing to head to Lima for COP20 and then to Paris a year later may well be poring over the pages of data and dozens of graphs in the 5th Assessment Report, but the message is nevertheless a simple one, although requiring some bold steps.

Some energy system home truths

One point of note on the annual calendar of energy events is the release by BP of their Statistical Review of World Energy. The data, all available to download in Excel format, covers the period up to the end of the previous year (i.e. the current data is to the end of 2013) and as such is about 18 months ahead of the equivalent data from the IEA (which is currently up to 2011 but will be updated later this year). Just about anything you might want to know on energy supply, energy consumption, CO2 emissions, fossil fuel reserves etc, is there for the interested user. In recent years BP have updated the tables to include a more comprehensive look at renewable energy as well.

The most recent release by BP was just a couple of weeks ago, so here are a few key energy/climate home truths within it;

Global CO2 emissions just keep on rising: This is hardly a surprise, but given the recent burst of capacity from the renewable energy sector there might be some sign of some levelling off at least. OECD emissions are at least flat now, but non-OECD emissions continue to rise sharply as coal use increases in particular (chart below in millions tonnes CO2 per annum).

Global emissions


The global CO2 intensity of energy isn’t budging: This is a bit more surprising given the influx of natural gas into the global economy and the build rate of renewables. But coal continues to surge and quite some nuclear has been shut down in Japan. The chart below shows the OECD intensity falling as renewables take off in Europe and natural gas increases in the USA, but non-OECD intensity offsets this to give a flat picture overall (chart below is in tonnes of CO2 per barrel of oil equivalent).

Global CO2 intensity of energy


The annual increase in fossil fuel use far exceeds the increase in renewable energy production: While many will readily quote the annual increase in renewable energy investment or annual increase in renewable energy capacity as evidence of turning the corner, the reality in terms of renewable energy produced is somewhat different. The chart below compares the annual coal increase with global solar and wind increases. For reference, the total fossil fuel increase from 2012-2013 was 183 Mtoe (million tonnes oil equivalent). The whole picture is rather distorted by the global financial crisis, but coal alone is increasing by something like 100-150 Mtoe per annum. At least for the last couple of years solar has been flat at about 7 Mtoe annual increase.

Increase in coal use

Solar and wind are growing rapidly, but the fossil fuel share of global primary energy is high and steady: Both solar and wind are in their early rapid growth phase where double digit annual increases are expected, but as they become material in the energy system at around 1% of global energy production, don’t be surprised to see this start to level off. The chart below has a log scale (otherwise solar and wind are barely discernible) and shows fossil fuel up in the mid 80’s as a percent of the global energy mix.

Energy mix fraction

Even in Germany it is taking a while for solar to make a showing: While solar PV in Germany is having a profound impact on electricity generation on long sunny days in June, the annual story when looking at total energy use is different. Solar has reached about 2% of the mix (i.e. reached materiality) and might even be showing some signs of slowing up and growing at a more linear rate (but a few more years data are needed to see the real trend). Again, this is a log chart.

German solar


Thanks to BP for the time and effort they put into this work every year.

A final contribution from Warsaw

As most will have seen from various media reports, delegates to COP 19 in Warsaw continued negotiating the outcome until late Saturday night. The key sticking points were “loss and damage” and the shape of national actions that would ultimately form the foundation of the 2015 deal (for implementation post 2020).

The agreement from the Doha COP (3/CP.18) to create a mechanism for “loss and damage” related to climate change was delivered on, but probably fell far short of what many developing country negotiators were hoping for. Those at the extreme of this may have been interpreting it as a formula to assess the climate component of national reparations from a given event or weather trend and then bill emitters accordingly, but this is not how the problem was addressed by the negotiators in Warsaw. Rather, the Warsaw International Mechanism for Loss and Damage establishes an advisory and information sharing body with an executive committee that must report annually to SBSTA and SBI and make recommendations. At least for now, this issue has been kicked into the long grass, but it will return in 2016 when it is subject to review at COP 22.

As noted, the second major sticking point was over the nature of national mitigation actions post 2020. The agreed text seeks to have these tabled in the next 18 months, i.e. by Q1 2015. Specifically the text says:

To invite all  Parties to initiate or intensify domestic preparations for their intended  nationally determined contributions,  without prejudice to the  legal nature of the contributions, in the context  of adopting a  protocol, another legal instrument or an agreed outcome with legal force under the Convention applicable to all Parties towards achieving the objective of the Convention as set out in its Article 2 and to communicate them well in advance of the twenty-first session of the Conference of the Parties (by the first quarter of 2015 by those  Parties ready to do so) in a  manner that facilitates  the clarity, transparency and understanding of the intended contributions, without prejudice to the legal nature of the contributions;

Reaffirming the mandate agreed in Durban which aims to see all countries treating mitigation similarly, the negotiators landed on the wording “prepare contributions”, rather than some countries being asked for specific reduction targets or commitments and others for appropriate (to their development status) actions. The latter would have been a retreat back towards the strict developed / developing country division of the Kyoto Protocol, so this wording is a positive development in that sense.

But the compromise word of “contribution” has its own issues and is not the same as “commitments”. The two words have very different meanings;

Commitment: the state or quality of being dedicated to a cause, activity, etc., or, an engagement or obligation that restricts freedom of action. 

Contribution: a gift or payment to a common fund or collection (e.g. the part played by a person or thing in bringing about a result or helping something to advance).

What the world has settled on is essentially a voluntary role for nations as this is the essence of a contribution, rather than the obligation that arises from a commitment. Perhaps we all knew this, but it is now becoming clear that nobody has any particular requirement to do anything with regards mitigation. It is certainly looking unlikely that this choice of wording is preparing nations for what is necessary if they are indeed going to achieve the objective of the Convention as set out in Article 2:

. . . . stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.

While there is certain to be a long argument at some point about the exact level of stabilization that is necessary, the above statement nevertheless requires that anthropogenic emissions are eventually reduced to about zero (or at least net zero), in that without such a reduction stabilization is not really possible. It is also likely to be the case that this needs to happen during this century so as to avoid an excessive global temperature excursion and therefore dangerous anthropogenic interference with the climate system (the official line here is of course 2°C, which implies net zero emissions rather sooner than the end of this century, but still in the second half).

A further aspect of the intended global agreement is that while it currently lacks any structure, it will seemingly require contributions now that eventually deliver on the needs of the Convention (although the 2015 outcome will probably only cover the period 2020-2030).  In theory and if negotiators followed this line of argument, it would give nations only one variable left to play with in determining said contributions, that being the date at which they intend to reach net zero emissions. Statements of this magnitude hardly fall into the category of voluntary efforts, rather they become national obligations that may well restrict freedom of action in the future, at least at a national level. That sounds very much like a commitment.

It could therefore be argued that the frantic last hours of a long COP that started out with very low expectations have delivered a challenging legal paradox. Of course it will be unraveled by a focus on the word “towards”, in that it implies a 2015 agreement that doesn’t require a statement of zero emissions now, but at least a pathway that eventually gets there. But this is meant to be a global agreement for the long term, not another interim step towards real action. Whether or not the 2015 agreement embraces a concept such as “net zero emissions” remains to be seen, but if it does then it is hard to see that “contributions” will be a robust approach to getting there. If it doesn’t embrace the concept then it won’t be the global agreement the world actually needs, which means that “contributions” will probably do for now but stabilization of greenhouse gases in the atmosphere will continue to remain elusive.

As expected and as had been widely leaked, the IPCC 5th Assessment WG1 Report released last week presented a range of evidence that further underpinned the case for anthropogenic induced warming of the climate system. By contrast with the 4th Assessment Report issued in 2007, the chance of a human link shifted from likely to extremely likely. Pages of supporting evidence were presented. 

But there was another important development since the 2007 report, the concept that cumulative total emissions of CO2 and global mean surface temperature response are approximately linearly related. There was only one reference to cumulative emissions in 2007 and that was simply a means of describing the mitigation challenge we face over this century. The 4th Assessment Report noted that;

Based on current understanding of climate-carbon cycle feedback, model studies suggest that to stabilise at 450 ppm carbon dioxide could require that cumulative emissions over the 21st century be reduced from an average of approximately 670 GtC to approximately 490 GtC.

The 5th Assessment Report takes this much further and devotes considerable attention to the subject. On page 20 of the Summary for Policy Makers, the report states;

  • Cumulative total emissions of CO2 and global mean surface temperature response are approximately linearly related (see Figure SPM.10). Any given level of warming is associated with a range of cumulative CO2 emissions, and therefore, e.g., higher emissions in earlier decades imply lower emissions later.
  • Limiting the warming caused by anthropogenic CO2 emissions alone with a probability of >33%, >50%, and >66% to less than 2°C since the period 1861–188022, will require cumulative CO2 emissions from all anthropogenic sources to stay between 0 and about 1560 GtC, 0 and about 1210 GtC, and 0 and about 1000 GtC since that period respectively. These upper amounts are reduced to about 880 GtC, 840 GtC, and 800 GtC respectively, when accounting for non-CO2 forcings as in RCP2.6. An amount of 531 [446 to 616] GtC, was already emitted by 2011.
  • A lower warming target, or a higher likelihood of remaining below a specific warming target, will require lower cumulative CO2 emissions. Accounting for warming effects of increases in non-CO2 greenhouse gases, reductions in aerosols, or the release of greenhouse gases from permafrost will also lower the cumulative CO2 emissions for a specific warming target.

The report also featured the chart below.

 IPCC Cumulative Carbon


This is important in that it clearly introduces into the mainstream the notion that the atmospheric CO2 issue is a stock problem, which brings with it a number of implications for both the energy system and the solution set.

For the energy system, the key issue this raises is that the amount of carbon already in the pipeline for consumption is considerably more than the remaining stock equating to a 2°C temperature anomaly goal. This has been picked up by a variety of organizations, both NGO and financial, and is at the core of the recent discussions on a “carbon bubble”.

But it also points to a critical aspect of finding a solution to the CO2 problem, the use of carbon capture and storage (CCS). I have written a great deal about this in previous postings. Sequestration (or removal of atmospheric carbon) is the only reliable mechanism for managing the stock, which means either increasing the permanent bio stock of carbon through forestry and land use or capturing and storing carbon dioxide geologically (CCS). Unfortunately this doesn’t get much of a mention from the carbon bubble proponents, which is a clear shortfall in their analysis. With the mitigation report coming out from the IPCC in the first half of next year, this WG1 finding may be an important placeholder for a more substantial discussion around sequestration.

One area that is left unaddressed, at least for me, is a better discussion on the role of short lived climate pollutants (SLCP) such as methane, particularly in the context of a stock framework for thinking about the climate issue. Although the IPCC say that the effective stock of CO2 must be reduced to account for the warming impact of SLCP, this isn’t the whole story. The difficulty is that while anthropogenic CO2 stays in the atmosphere for a very long time, gases such as methane do not – they break down to CO2. This means that methane isn’t a stock issue, but a flow issue, i.e. the impact of methane released today is to change the rate of current warming, but not really the peak warming that we will likely see at some point late this century or early next century. Methane emissions at that time will impact peak warming. It also means that the current efforts to reduce methane now could be undermined unless CO2 is also reduced.

So that is my take on this first release of the 5th Assessment Report. Of course there is a wealth of data to work through and understand, but this critical concept of cumulative carbon is one that needs to filter through policy circles. Once the penny drops on this story, we might actually see some real progress in policy making that will make a difference.

Last week PWC released the 2012 version of its “Low carbon economy index”, the fourth edition of a publication that started just prior to the Copenhagen COP. The main message delivered by the publication is a grim one, although hardly surprising, that the much discussed 2°C target is now effectively out of reach.

 We estimate that the world economy now needs to reduce its carbon intensity by 5.1% every year to 2050 to have a fair chance of limiting warming to 2°C above pre-industrial levels. Even to have a reasonable prospect of getting to a 4°C scenario would imply nearly quadrupling the current rate of decarbonisation. The decarbonisation rate required for a 2°C world has not been achieved in a single year since World War 2. The closest the world came to that rate of decarbonisation was during the severe recessions of the late 1970s/early 1980s (4.9% in 1981) and the late 1990s (4.2% in 1999). The expected reduction in emissions resulting from the current economic slowdown has not materialised, partly because of sustained growth in emerging markets.

Even more bad news follows, with an analysis of the various national pledges made following the Copenhagen COP. Not only does the publication make it clear that the cumulative impact of the stated contributions is insufficient for a 2°C pathway, but that many nations appear to be falling short of actually meeting them.

Even more worryingly, with eight years to go, it is questionable whether several of these pledges can be met.

The resurgence of gas in the global energy mix features in the report as an important driver of change, albeit with the concern about long term lock-in. Nevertheless, growth in natural gas production is leading to a real reduction in emissions in some parts of the world, but particularly the United States.

No matter which country or region you look at, progress made is pretty dispiriting. In a table of some 20 key countries, the worst performer in 2011 was Australia, although over the last decade it hasn’t done too badly in terms of its change in carbon intensity. I suspect that is more due to the fact that it didn’t plunge into recession like almost everybody else, so carbon intensity continued to fall as growth remained high. Therein lies a problem with using carbon intensity as the metric – appearances can sometimes be deceiving.

With 2°C pretty much condemned to the history books, the report goes on to look at the increasing risk of a much higher temperature rise over this century. Even the possibility of an excursion to 6°C is mooted. This outlook isn’t too far off the Shell Scramble (2008) scenario which resulted in CO2e levels approaching 1000 ppm by the end of the century and a consequent temperature rise of over 4°C and rising. By contrast, Blueprints saw temperatures beginning to plateau at between 2°C and 3°C.

None of this is good news, particularly given the amount of change that can take place in the global ecosystem as a result of small changes in temperature. Take sea level, for example. Although it could take well over a millennium to reach a new equilibrium level, the end result is incredibly temperature sensitive. We shouldn’t be surprised by this given that sea level was over 100 metres lower than today during the previous ice age, when temperatures were lower by about the amount we are worried they may rise in the future. As indicated below, a shift from 2°C to 2.5°C adds about 10 metres of eventual sea level rise (although not anytime soon).


All this raises the question as to what we should or could do, given that 2°C is not feasible. The “numbers guys” at PWC don’t go there and arguing for a higher target is a political non-starter, but at some point the discussion is going to have to happen.

 Based on the work of Allen, Meinshausen et al, which equates a given stock of atmospheric CO2 with long term temperature rise, it is possible to derive a chart which shows, for a given annual reduction until emissions are zero, the impact in terms of expected (midpoint) temperature rise.

For example, starting today, 2°C requires about a 2.5% year on year reduction in emissions – and this is now deemed infeasible by PWC. But if we delay until 2025, the required reduction is over 4% p.a.

Knowing that the world isn’t going to do much until 2020 when a new global agreement is scheduled to kick in, a 2.5°C goal requires about a 1.6% p.a. reduction, assuming action starts immediately. This would mean no new emissions from 2020, plus some 100 very big CCS projects (1 GW power station) starting up each year through the 2020s on existing facilities – and so on. This isn’t very different to the rate at which new coal fired power plants are appearing today, so it is probably feasible from an implementation perspective. Of course keeping all other emissions in check will be a further challenge, but that task could potentially be achieved by aggressive fuel switching and renewable energy deployment, supported by efficiency improvements.

The PWC report is a timely reminder of the situation that we are now in and the ambition that the proposed new global agreement is going to have to aspire to.

  •  Allen, M. R. et al (2009) Warming caused by cumulative carbon emissions towards the trillionth tonne, Nature, 458:1163-1166, which argues that a one trillion tonne release of carbon gives a most likely warming of 2°C, with a likely (one-sigma) uncertainty range of 1.6-2.6°C.
  • Meinshausen, M. et al (2009) Greenhouse gas emission targets for limiting global warming to 2°C, Nature, 458:1158-1162, which argues that a total release of 0.9 (0.71) trillion tonnes of carbon gives a 50% (25%) risk of temperatures exceeding 2°C.
  • Allen, M. R. et al (2009) The Exit Strategy, Nature Reports Climate Change, 3:56-58, which provides a commentary on the implications of the above papers for non-specialists.


US emissions continue to fall

If you dig down a few layers through the US State Department website, you will come across a Press Release from February 2010 where the USA pledged to reduce its greenhouse gas emissions.

Press Statement

Todd Stern,  Special Envoy for Climate Change Washington, DC

February 4, 2010

Special Envoy Stern: We are pleased to be among 55 countries – including all of the world’s major economies — that have submitted pledges to limit or reduce their greenhouse gas emissions under the Copenhagen Accord. These countries represent nearly 80% of global emissions. In supporting the Accord, we are taking an important step in the global effort to combat climate change.

In addition to the countries that have submitted targets or actions, a number of others have conveyed their support for the Accord. We urge all countries to join this broad coalition by promptly conveying their support for the Accord to the UNFCCC Secretariat.

The Copenhagen Accord includes important advances on funding, technology, forestry, adaptation and transparency. The United States is committed to working with our partners around the world to make the Accord operational and to continue the effort to build a strong, science-based, global regime to combat the profound threat of climate change.

I have commented on the commitment in previous postings, but just to be reminded of what was said, here is a copy of the letter sent by the US to the UNFCCC. 

Last week the US EIA released the latest greenhouse gas emission figures and they show that the country is well on track to meet this pledge, even though there is no formal program in place to ensure delivery. 

Following the sharp recession led drop, two continuing drivers for the change are the drop in coal emissions as older coal fired power plants close and the fall in automotive emissions due to tougher vehicle efficiency standards and the continuing higher oil price. As expected, natural gas emissions have risen as this fuel replaces coal in power generation, but with less than half the carbon footprint of the coal.

This trend could well continue over the coming years as further coal capacity is closed in response to the combination of EPA air quality regulation, expected greenhouse gas regulation and the growing supply of natural gas. In addition, CAFE standards should ensure further improvements in vehicle efficiency.

My original analysis of this trend produced the following chart. Two years on and we still seem to be at least in the same ballpark.