Baselines, metrics and business as usual

The submission of Intended Nationally Determined Contributions (INDCs) to the UNFCCC started in earnest to meet the March 31st agreed date, although many more are still to come. Mexico was the only non-Annex I country (under the Convention) to submit by this date, although the Gabon submission appeared the following day.

A feature of the Mexico submission is the reference to Business as Usual (BAU) as a metric against which to measure progress. Although Mexico is clear on its commendable absolute long term objective, i.e. “. . . . consistent with Mexico´s pathway to reduce 50% of emissions by the year 2050, with respect to the year 2000”, its shorter term progress will be guided by reference to a “Business As Usual scenario of emission projections based on economic growth in the absence of climate change policies, starting from 2013”. The reference to Business As Usual is a factor that we will likely see in many of the upcoming INDC submissions. BAU was also a feature of many Copenhagen pledges, but in several instances the BAU pathway was hard to discern, which made the pledge difficult to understand and rather opaque in terms of actual numbers and therefore effort. This time around numbers will have to be very clear and part of the scrutiny and review process that negotiators are working towards will need to address the credibility and transparency of the BAU reference. In the case of Mexico, the BAU is well documented.

But even when the numbers are published, a BAU reference can make pledges and actions taken appear far more ambitious than may be the case. This is particularly so when energy efficiency is claimed as a major contributor to supposed reductions in emissions. Based on an existing relationship between energy and GDP and assuming a given near-term growth in economic output, it is easy to project what BAU emissions might be in 2020 or 2030 and then argue that a focus on energy efficiency can reduce this, effectively claiming an emissions reduction. This reasoning would appear to show that the country in question is making a large contribution to the global effort and that energy efficiency is an important contributing factor to change, yet in reality the original projection represents a situation that may never have occurred. Business-as-usual also requires improvements in energy efficiency to drive growth, which means that the assumed growth may not have occurred, had the efficiency improvements not helped deliver it. If energy efficiency really is a route to lower emissions, then it needs to pass one clear test, i.e. which known fossil fuel resource will be left in the ground (or a proposed extraction project shelved) because of this? Only then are cumulative emissions potentially impacted.

The Mexico INDC also highlighted a propensity to mix together actions on long lived greenhouse gases such as CO2 and short lived pollutants such as black carbon (very short lived) and methane (short to medium life). Mexico is reasonably transparent here as well, although its highest level number aggregates the two, i.e. “Mexico is committed to reduce unconditionally 25% of its Greenhouse Gases and Short Lived Climate Pollutants emissions (below BAU) for the year 2030”. The problem is that although carbon dioxide and black carbon (which is the major focus in Mexico) both contribute to warming of the climate system, they behave very differently in the atmosphere and mitigation leads to different outcomes which are not interchangeable.

Black carbon remains in the atmosphere for only days or weeks, which means it strongly impacts the rate of warming today but has little impact on the global goal to limit overall warming of the climate system to 2°C, unless of course there is still an unacceptable level of black carbon in the atmosphere at a time in the future when warming is approaching its peak. By contrast, carbon dioxide remains for hundreds to thousands of years and largely sets the thermostat of the future climate. Solving the black carbon problem today would deliver tangible near term benefits on a number of fronts, but unless carbon dioxide mitigation also takes place the long term outcome will hardly shift.

Mexico has set the bar quite high with its clear and well-structured contribution, but the metrics and baseline used highlight issues that the UNFCCC may need to deal with over the coming months as it begins to assess the merit of all the national contributions.