At the end of October UNFCCC Executive Secretary Christiana Figueres was reported by the BBC as saying

The INDCs have the capability of limiting the forecast temperature rise to around 2.7C by 2100, by no means enough but a lot lower than the estimated four, five, or more degrees of warming projected by many prior to the INDCs.

In the context of the objective of limiting prospective global warming to 2C this statement gives encouraging news. Already the policy proposals are most of the way towards that objective, so a final push at COP21 in Paris is all that is required.

Summary

The analysis by the UNFCCC shows that the policy proposals contained within the INDCs will make very little difference to trends in global emissions of greenhouse gases to 2030. In the accompanying literature, the UNFCCC makes no projections of the difference the INDCs will make beyond 2030. The claim that policy will limit forecast temperature rise to the 2.7C by 2100 is claimed by two other organisations, and is only referenced in a table at the very end of a separate technical annex without any discussion or endorsement. One of these, the IEA, achieves the projection by, post 2050, replacing forecasts contingent on the policy impact of the INDCs with an average of modelled RCP emissions pathways. The RCP website explicitly states that they are not forecasts of potential emissions or climate change, whether with or without policy action. It also states that any of the differences between the pathways be directly attributed to policy differences. The IEA thus replaces real emissions forecasts with data that is unrelated to the real world. The other claim, by Climate Action Tracker, has no explicit statement of how the increasing global emissions through to 2030 start tracking downwards post 2030. Contributing factors may include understating the emissions impact of India and China, along with excluding the likely increasing emissions in the coming decades from the poorest nations.

The claim that any agreement reached in Paris based on the INDCs will constrain to global average temperature rise to 2.7C by 2100 through constraining GHG emissions is therefore unsupported by any rigorous forecast of the policy impact in the referenced documents. Such forecasts are based on making a forecast without policy, then modelling the impact policy will make, stating the assumptions. With 40,000 people attending a conference, the UNFCCC could surely have set aside a couple of million dollars to obtain such a forecast from genuine experts.

In Detail

If Christiana Figueres is correct, the INDC submissions, covering the period 2015-2030 have dramatically changed the course of prospective warming getting two-thirds of the distance between the non-policy and the target of limiting warming to two degrees. Bjorn Lomborg’s recent paper “Impact of Current Climate Proposals” published in the Global Policy journal stated

All climate policies by the US, China, the EU and the rest of the world, implemented from the early 2000s to 2030 and sustained through the century will likely reduce global temperature rise about 0.17°C in 2100. These impact estimates are robust to different calibrations of climate sensitivity, carbon cycling and different climate scenarios. Current climate policy promises will do little to stabilize the climate and their impact will be undetectable for many decades.

Having read the policy proposals on a large number of INDCs I concur with Lomborg. There is very little in the INDCs that will alter the future course of warming. So why the difference between my reading and the UNFCCC? The Executive Secretary has the World’s leading experts behind her, so there must be substantial support for the claim. The BBC article provides a link to the UNFCCC Synthesis report on the aggregate effect of INDCs. The link is to a number of documents. The main document makes no attempt to project forward the policy impacts to 2100. In fact if it did, the prognosis would be similar to Lomborg’s. The main graphic in Figure 2, also as a separate file, is shown below.

The orange is the pre-INDC pledges, the yellow the INDCs and the blues various scenarios to stay below two degrees.

To the right is two graphics for 2025 and 2030. The yellow arrow is “Reduction due to INDCs” and the blue arrow “Remaining reduction for least-cost mitigation“. For 2030 the INDCs seem to get a quarter of the way to the desired reduction. There is nothing about trends beyond 2030. The graphic could not be clearer. If the INDCs are to obtain constrain emissions consistent to the 2C of warming, the increasing trend from 2010 to 2030 would have to be rapidly turned into a decreasing trend post 2030, with global emissions reduced by half in two decades. As the non-policy trend is for about 4.5C of warming, then to obtain a 2.7C forecast requires the INDCs to collectively cause emissions to peak and then start a downward trend.

It is clear that there is no mention at all of the 2.7C of warming by 2100. No bridge of the 70 years from the period covered by the INDCs to the end of the century. What is more there is nothing in the aggregate policy contained in INDCs that would cause global emissions to first peak, then be set on a downward trend. So where is the reference?

For that you need to look in the Technical Annex section M. Summary of results from other studies. Even then the text does not mention 2100, but table 6 does.

Instead of the UNFCCC making projections to 2100 on the basis of the INDCs for themselves, they use those of others. Yet the UNFCCC should have the expertise in projecting the impact of policy. I will look at three – that of another UN organisation and the two estimating 2.7C resulting from the INDCs.

UNEP Gap Report

The link within the footnote to table 6 is to the Executive Summary of the UNEP Emissions Gap Report 2015. The proper reference should have been to all the documents related to the Gap Report found here. The Executive Summary states

Full implementation of unconditional INDC results in emission level estimates in 2030 that are most consistent with scenarios that limit global average temperature increase to below 3.5 °C until 2100 with a greater than 66 per cent chance.

There is no actual projection from the INDCs. Rather, it looks at the emissions levels and emission trends in 2030 and compares them with modelled estimates that are similar. It is these modelled estimates that produce the 3.5C of warming in 2100. There is no reconciliation between the country-by-country INDCs and the overall global emissions scenarios. Rather it is just picking estimates that seem to fit at a global level. In terms of assessing the impacts of policy it is useless, as the modelled estimates may be markedly different from a forecast based on the latest information.

International Energy Agency (IEA) World Energy Outlook 2015

The link within the footnote to table 6 is to a press release for the IEA’s World Energy Outlook 2015. The footnote d. to table 6 gives an explanation of how the 2.7C projection was arrived at. In particular is the final point

To assess the impact on global average temperature increase, we used MAGICC with an emissions pathway post-2050 in between the representative concentration pathways (RCP) 4.5 and (RCP) 6 scenarios from the IPCC’s Fifth Assessment Report as this was interpreted as representing the best available trajectory compatible with IEA’s INDC Scenario.

The RCP (“Representative Concentration Pathways”) scenarios are explained on the RCP website

RCP 4.5: … is a stabilization scenario where total radiative forcing is stabilized before 2100 by employment of a range of technologies and strategies for reducing greenhouse gas emissions.

RCP 6.0: … is a stabilization scenario where total radiative forcing is stabilized after 2100 without overshoot by employment of a range of technologies and strategies for reducing greenhouse gas emissions.

Under “Characteristics and guidance” the website states (bold mine):-

The RCPs are named according to their 2100 radiative forcing level as reported by the individual modeling teams. …….

The RCPs are not forecasts or boundaries for potential emissions, land-use, or climate change. They are also not policy prescriptive in that they were chosen for scientific purposes to represent the span of the radiative forcing literature at the time of their selection and thus facilitate the mapping of a broad climate space. They therefore do not represent specific futures with respect to climate policy action (or no action) or technological, economic, or political viability of specific future pathways or climates. …..

The RCPs are four independent pathways developed by four individual modeling groups. The socioeconomics underlying each RCP are not unique; and, the RCPs are not a set or representative of the range of potential assumptions. …. The differences between the RCPs can therefore not directly be interpreted as a result of climate policy or particular socioeconomic developments. Any differences can be attributed in part to differences between models and scenario assumptions (scientific, economic, and technological).

The IEA has therefore used a hybrid of emissions scenarios as emissions forecasts to assess the impact policy when the group producing them has specifically said that these scenarios are not directly comparable and should not be used for policy purposes. In so doing, they implicitly make a set of assumptions about policy that may not relate to the real world and are definitely not related to the policies proposed within the INDCs.

Climate Action Tracker (CAT)

CAT tracks the INDCs from 32 nations that currently have about 80% of global emissions. Their estimate of the INDC impact until 2030 is broadly consistent with the UNFCCC. However, I am not sure where they obtain the historical emissions figures. For countries they appear to be from the World Resources Institute CAIT2.0. CAIT2.0 figures which are slightly different from those in the UNFCCC Country Briefs, but not markedly so in total. CAT’s methodology does have the advantage of providing a breakdown by country until 2030 between the BAU, but beyond 2030 details are distinctly hazy. The 2.7C claim is made on a briefing of 1^st October 2015. The main graph behind the 2.7C estimate is reproduced below.

The impact of the INDCs is to see emissions peak about 2030, then gently fall through to the end of the century. From the detailed explanation it is not possible to determine how the emissions peak at the level as collectively the INDCs appear to show an upward trend. The reasons for this are probably from the following:-

India – The INDC that estimates a tripling of emissions between 2014 and 2030 was not available when the briefing was published, which only assumes a doubling. The country assessment for India then tries to reconcile the difference by some fancy assumptions (lower economic growth rates and a higher emissions intensity reduction than in the INDC), without adjusting the overall assessment. If CAT’s 5GtCO2e estimate of 2030 emissions turns out to be correct (9% of global emissions), it will only be emissions growth delayed not a lower emissions peak. It is unlikely that India’s emissions will peak at less than 10GtCO2e, equivalent to over 20% of 2010 global emissions.

China – will likely reach peak emissions prior to 2030, but that peak will be likely higher than the 13.6GtCO2e forecast The CAT country assessment admits this is the case, but makes no allowance in the emissions forecast.

Missing Countries – Most of Africa, along with Pakistan, Vietnam, Bangladesh, Thailand and Myanmar are missing from the sample. Collectively their current emissions are small, but in the coming decades the share will rise. Africa’s emissions will rise as most of the global population increase in the latter half of the century is forecast to be within the continent. In South Asia there is already economic growth above the world average that will likely continue as the poorer countries follow in the wake of India. By 2100 these countries could collectively have emissions greater than current emissions of the OECD and China combined.

Ambiguities in the INDCs – Many of the INDCs are highly ambiguous. The historical figures are inconsistent; the forecasts are opaque; some key figures are missing; and it is not clear if some pledges in the INDC are in addition to the others, or part of the whole. CAT maximises the impact, rather than trying to frame questions for the submitting countries to clarify. There should be an assessment of these pledge risk factors. These will likely reduce the estimated policy impact.

Without any other hidden assumptions, CAT’s methods are likely to massively overstate the impact of policy. Critically is how increasing global emissions though to 2030 become decreasing global emissions post 2030. As inferred above, I believe it is due to systematic understating emission projections in the sample countries and ignoring the growth in the other countries. It may also be due to making further policy assumptions for the period beyond 2030. We will only be able to assess the impact if CAT provide a full country-by country projections of emissions in 2100 for the sample countries for both BAU and with INDC scenarios, along with projections for the rest of the world. Putting the figures on a table, rather than spending time creating graphs from which figures have to be estimated, would ease the process. If proper forecasts have been generated (that is making a forecast without policy, then modelling the impact policy will make) then the outline figures will be available already.

Concluding Comments

The UNFCCC presents no evidence that policy contained within the INDC submissions will make more than a small difference to global emissions in 2100. Instead they rely on external organisations. One quite clearly substitutes real world forecasts with emissions scenarios that do not relate to real world situations, and assume implementation of policy quite different to that contained with the INDCs. The other is likely to have massively overstated the policy impacts, but a lack of any clear statements as to how the conclusions were arrived at means quantification is not possible. The claims that the policy pledges within the INDCs will massively alter global emissions levels in the latter part of this century (and, subject to the climate models being broadly correct, the rise in global average temperatures) are without any proper foundation. The UNFCCC Executive Secretary Christiana Figueres is has made a misleading statement to drive through policies that are both costly and ineffective.

Such forecasts are based on making a forecast without policy, then modelling the impact policy will make, stating the assumptions. With 40,000 people attending a conference, the UNFCCC could surely have set aside a couple of million dollars to obtain a rigorous forecast from leading experts in that field. The methodology is fairly straightforward. It requires making a forecast for each country without policy, then modelling the impact policy will make, stating the assumptions. The important parts are data gathering, adhering rigorously to a consistent method and leaving an audit trail.

Kevin Marshall