UNEP EMISSIONS GAP REPORT
UNEP EMISSIONS GAP REPORT

 

Also in this chapter:

4.2 Findings for 2° C

Table 2 summarises the gaps that result from four different interpretations of how the pledges are followed, and for a “likely” (greater than 66 per cent) and a “medium” (50-66 per cent) chance of staying below 2° C.

In Chapter 2 it was shown that emission levels of 44 GtCO2e in 2020 (range of 39-44 GtCO2e)54 are consistent with a “likely” chance of limiting global warming to 2° C.

In Chapter 3, four pledge cases or possible negotiation outcomes were identified. Here we compare the gap in 2020 between expected emissions based on these cases and emission levels identified in Chapter 2. As a reference point, business-as-usual emissions in 2020 would result in a gap of 12 GtCO2e (range of 10-21 GtCO2e).

  • Case 1 – “Unconditional pledges, lenient rules”. Countries implement their lower-ambition pledges and maximise the use of “lenient LULUCF credits”55 and surplus emissions units to meet their goals. In this case, the gap is 9 GtCO2e with a range of 8-18 GtCO2e. The unconditional pledges would thus reduce the gap by about 20 per cent compared to business-as-usual.
  • Case 2 – “Unconditional pledges, strict rules”. Countries implement their lower-ambition pledges but do not use “lenient LULUCF credits” and surplus emission units to meet their goals. In this case, the gap narrows to 8 GtCO2e (range of 6-16 GtCO2e). Compared to business-as-usual, this is equivalent to achieving about 30 per cent of the overall mitigation effort towards 2° C by 2020.
  • Case 3 – “Conditional pledges, lenient rules”. Countries implement their higher-ambition pledges and make maximum use of “lenient LULUCF credits” and surplus emissions units. In this case, the gap is reduced to 7 GtCO2e (range of 5-14 GtCO2e). Compared to business-as-usual, this is equivalent to achieving about 35 per cent of the overall mitigation effort towards 2° C by 2020.
  • Case 4 – “Conditional pledges, strict rules”. Countries not only implement their higher-ambition pledges, but also do not use “lenient LULUCF credits” and surplus emission units to meet their goals. The result is a further narrowing of the gap to 5 GtCO2e (range of 3-12 GtCO2e). This corresponds to the smallest gap assessed in Table 2, and is equivalent to reducing the overall mitigation effort towards 2° C by almost 60 per cent compared to business-as-usual in 2020. As a point of reference, the remaining gap is about the level of emissions in the European Union in 2005 or from the world’s road transport in that same year.

Hence, moving from (lower-ambition) unconditional pledges to (higher-ambition) conditional pledges narrows the gap by about 2 to 3 GtCO2e—the majority of this reduction would come from industrialized countries, whose pledges are sometimes conditional on the ambitious action of other countries or on domestic legislation. A smaller, but still important, part of the reduction would come from developing countries, whose pledges are sometimes conditional on the adequate provision of international climate finance or technology transfer.

In addition, the gap can be reduced by around 1 to 2 GtCO2e by ensuring that “strict” rules apply to the use of LULUCF credits and surplus emission units. If industrialized countries apply “strict” accounting rules to minimise the use of what we refer to as “lenient LULUCF credits”, they would strengthen the effect of their pledges and thus reduce the emissions gap by up to 0.8 GtCO2e. Likewise, if the rules governing the use of surplus emission units under the Kyoto Protocol were designed in a way that would avoid the weakening of mitigation targets, the gap could be reduced by up to 2.3 GtCO2e. These include units carried over from the current commitment period and any potential new surpluses created in the next. See Chapter 3 for more details56.

There are also a number of important factors, mentioned in Chapter 3, that could increase or decrease the gap and that are not included in these cases. The double counting of international offsets towards both industrialized and developing countries’ goals could reduce the overall amount of mitigation and thus increase the gap by up to 1.3 GtCO2e. Conversely, the implementation of ambitious existing national plans, beyond what is included in the Copenhagen Accord, could narrow the gap by up to 1.5 GtCO2e (as compared to the fourth pledge case).

To have a “medium” rather than a “likely”chance of staying below 2° C, the emission levels for the pledge cases can be about 1 GtCO2e higher, and the corresponding gap 1 GtCO2e lower for all pledge cases (Table 2).

Explanation of the range of results of the emissions gap for 2° C

The range of the gap presented for the different cases in Table 2 is based on the “majority of results” (20th to 80th percentile) across both the pledges and the 2° C emission levels. The upper bound estimate of the gap combines low 2° C emission levels (20th percentile) with high emissions from pledges (80th percentile). As explained in Chapter 2, emission levels consistent with the 2° C limit tend to be lower in 2020 when followed by comparatively slower emission reduction rates thereafter, or when negative emissions are not achieved over the long run.

Conversely, at the low end of the gap range we find a combination of higher 2° C emission levels in 2020 and low expected emissions as a result of the pledges. Emission levels that are consistent with 2° C tend to be higher in 2020 when reduction rates are comparatively high after 2020 (3.1 per cent per year) and/or it is assumed that negative emissions take effect over the long run. Under these conditions, emissions can afford to be higher in 2020, since they will be reduced more quickly afterwards.

The size of the gap is therefore strongly dependent on expectations about emission reduction rates after 2020 and the prospects for negative emissions later in the century. Both depend, of course, on the rate of technological development.

In addition, the reader will note that the range around median estimates is not symmetric; the lower bound extends by about 1-2 GtCO2e below the median, whereas the upper bound rises 7-9 GtCO2e above it (for a “likely” chance). This is found for all the pledge cases examined and arises because of the skewed distribution of pledge estimates with a more pronounced tail on the upper bound. One interpretation of this skewed range is that the gap may in reality tend to be on the higher side of the median.

This chapter has so far focused on the “majority of results” (20th to 80th percentile of estimates). Results outside this range indicate that emission levels for a “likely” chance of staying below 2° C could be as high as 48 GtCO2e (Chapter 2), while at the same time expected emissions under case 4 (“conditional pledges, strict rules”) could, according to one estimate, be as low as 45 GtCO2e in 2020. Under these conditions, no gap exists. On the other hand, looking at the other end of the range, we find 2° C emission levels for a “likely” chance of staying below the 2° C limit can range as low as 26 GtCO2e, while the highest estimate of emissions under case 1 of the pledge cases (“unconditional pledges, lenient rules”) is 61 GtCO2e, resulting in a gap as high as 35 GtCO2e.