Without further implementation net zero targets will not deliver their intended climate mitigation. Many countries have promised to cut their greenhouse gas emissions to almost zero around mid-century, while compensating the remaining emissions: net zero. However many net zero targets are not legally binding, nor are they accompanied by a either a long term plan or effective short term policies, a new study finds. For the Paris climate goals to come within reach this would need to happen.
The conversation around climate policy used to be about target setting, but is increasingly moving towards monitoring implementation. Recent net zero targets still leave great uncertainty as to how much the world will actually warm. For the first time a new study published today in Science an international team of researchers with PBL Netherlands Environmental Agency projects the credibility of promises into climate outcomes.
“A critical question is whether we can believe countries will deliver on the commitments they have made. Are long term net-zero targets legally binding, is there a credible long term plan and are countries actually delivering on the short term? Our analysis finds many net zero targets to be lacking credibility, leaving the world still on a risky climate track,” says Michel den Elzen (PBL Netherlands Environmental Assessment Agency & VU).
Analyses, that only look at concrete current policies show a projected temperature rise of 2.5 to 3.0 degrees at the end of the century. On the other hand, optimistic projections that factor in all current pledges and voluntary net-zero targets result in 1.5 to 2 degrees increase and put the Paris goals within reach. The new study covers the as-of-yet unprobed grey area between these extremes that have already been explored in the literature.
Credibility ratings for all net zero targets of big economies
To reduce the uncertainty surrounding the likelihood of optimistic and pessimistic scenarios, the researchers assigned a ‘confidence’ to each net-zero policy. They assessed 35 net zero targets, covering every country with more than 0.1% of current global greenhouse gas emissions.
The confidence assessment wa based on three policy characteristics: whether the policy was legally binding, whether there was a credible policy plan guiding implementation, and whether short-term plans would already put emissions on a downward path over the next decade.
Most net-zero targets, including China and US, are not ‘highly’ credible
Based on this, policies were given ‘higher’, ‘lower’ or ‘much lower’ confidence of being fully implemented. Some regions scored highly, including the European Union, the United Kingdom and New Zealand, but around 90% scored ‘lower’ or ‘much lower’ confidence, including China and the US, which together account for more than 35% of current emissions.
From this assessment, the team modelled five scenarios of future greenhouse gas emissions and resulting temperatures. These were: considering only current policies; only adding in policies that have a high confidence of being implemented; adding policies with high and low confidence; adding all policies regardless of confidence as if they are implemented; and a scenario where all policies are fully implemented and all NDCs are met (the most forgiving scenario).
Paris goals within reach if all net zero goals completely implemented
The most conservative scenario with only current policies had the largest uncertainty, with a range of 1.7-3°C and a median estimate of 2.6°C. The most optimistic scenario has a range of 1.6-2.1, with a median estimate of 1.7°C. This shows that, if all net-zero policies are fully implemented, the Paris Agreement goals are withing reach. However, with so many policies ranked in the low-confidence end of the scale, this would be wishful thinking in absence of further efforts. The analysis also shows that if only the highest confidence net-zero targets are achieved, global temperature is expected to exceed the Paris Agreement goals.
Climate goals set out in the Paris Agreement include keeping temperature rises well below 2°C above the average temperature before the industrial revolution and ideally below 1.5°C. The main way to achieve this is the reach ‘net-zero’ greenhouse gas emissions as soon as possible, where any remaining emissions are effectively offset.
12 out of 35 net zero policies legally binding
Only twelve out of 35 net zero policies are currently legally binding. Besides the EU, the UK and New Zealand, this includes Canada, Colombia, Chile, Nigeria, Australia and South Korea. Michel den Elzen (PBL & VU): “Increasing this number would ensure the policies survive long-term and are more likely to be complied with. Also, many countries lack clear pathways for different sectors, outlining exactly what changes are needed and where the responsibility lies.”