Climate scientists are calling for an overhaul of the way climate change pledges are assessed, in order to avoid ‘indefinite procrastination’ on designing efficient mitigation policies.
Writing in Nature Climate Change, they say that the ‘pledge and review’ approach that will form the basis of commitments made at the UN climate change negotiations in December, presents an opportunity to link mitigation goals explicitly to the evolving climate response.
“Scientific uncertainty about the long-term impacts of climate change is often used as an excuse for inaction, or as a basis for recommending highly precautionary worst-case-scenario strategies, which may be unpalatable to policy makers juggling economic and political interests,” said Dr Friederike Otto of Oxford's Environmental Change Institute, lead author of the paper.
“Human-induced warming has brought us 10% closer to 2°C since 2009. So any country whose government acknowledged in 2009 that CO2 emissions must reach net zero by the time temperatures reach the target stabilisation level of 2°C should be 10% of the way there now. However there still is no overall strategy to achieve this.”
The authors, who include the Oxford Martin School's Professor Myles Allen, argue that strategies should be ‘anti-fragile’, meaning they are not just robust under uncertainty but more successful under a wide range of uncertainties, including scientific, economic and political risks. Learning from trial and error is an integral part of such an ‘anti-fragile’ strategy, allowing for evolving knowledge to be incorporated at low costs.
They looked at what climate policy makers could learn from adaptive management techniques, to create an approach to mitigation that more fully accounts for the set of risks that governments care about, is less dependent on a globally binding mandate, and which could, therefore, be a better way to preserve flexibility in climate mitigation.
They recommend an adaptive strategy grounded on an index of the warming attributable to human influence, which is itself based on observed temperatures. Calculated in 2014 the rise in global mean temperature attributable to anthropogenic influences was 0.91?C.
In contrast to global mean temperature the ‘attributable anthropogenic warming’ index is not subject to high year to year and decadal variability. It also requires no complex modelling and could be updated on an annual basis, allowing governments to review their pledges to reduce greenhouse gas emissions.
The paper outlines three policy options using the index and concludes that indexing to attributable anthropogenic warming allows a transparent link between the policy instrument and the policy goal. It is a simple way to monitor the overall consistency between the evolving climate change signal, individual countries’ pledges and the overall goal of achieving net zero CO2 emissions by the time we reach 2°C of human-related warming.
Dr Otto concludes: “At a crucial time for climate negotiations, the proposed index offers a transparent and accountable method of evaluating climate policies that deals with the remaining uncertainty of the climate response, which has so far had a paralysing effect on climate change policies.”
- View the full text of ‘Embracing uncertainty in climate change policy'
- More information on the index can be found at www.safecarbon.org, an up-to-the-second index of human-induced warming relative to the mid-19th century (1861-80) and cumulative carbon dioxide emissions from fossil fuel use, cement manufacturing and land-use-change.
- Human-induced warming is currently increasing at 1.8 hundredths of a degree per year, or 0.6 billionths of a degree per second.