The devil in Obama’s new emissions target for the US lies in base year details

President Barack Obama announced a new climate change target for the United States’ electricity generation sector on August 3. Hailed by many as ambitious, the plan dictates that power plants in the world’s largest economy and second largest polluter reduce their emissions below 32% of their 2005 levels by 2030. The US had already committed to a 25% reduction from 2005 levels by 2025 in a deal with China made in October 2014. The new commitment now requires more than a doubling of the pace of emission cuts.

Such declarations allow economies like the US to assume leadership of the international climate negotiations at a time when declarations from other countries have been tardy. At the same time, the US has also given itself some leeway despite the symbolic headstart, the advantages of which lie in the historic details. Consider this chart, compiled by the World Resources Institute:


Among the five greenhouse gases that countries prioritise cutting down on, two contain carbon: methane and carbon dioxide. The chart above shows the methane emissions of the USA and the five BRICS nations from 1990 to 2011. The US’s methane emissions were at their minimum in 2005 – so any future commitment on methane emissions premised on 2005 levels are likely to represent daunting challenges. The dip happened because at that time the US was maximising its extraction and processing of shale gas, activities that emit little methane. But on the question of carbon dioxide emissions, consider the chart below:


The US’s carbon dioxide emissions peaked in 2005, at 5,828.63 million metric tons. This convenient choice of a base year allows the US a leeway that’s 18.64% higher than its 1990 emissions – 1990 being the year that the Kyoto Protocol uses as a base. The absence of any rules on what can or can’t constitute base years is leveraged by many countries. In Europe, for example, the base year is 1990 because that’s when emissions peaked followed by a steady decline in industrial activity as well as a growing adoption of renewable energy options.

However, the absence of options in choosing a base year – as under the Kyoto Protocol – is problematic for developing nations. Their domestic demands for energy translate to increasing emissions, so the choice of 1990 as a base year restricts such economies to feeble, economically infeasible increments in energy production. This is one reason why India and China feature among the protocol’s second-phase’s non-ratifiers, being opposed to agreements that legally bind them to their targets.

As it happens, the US is also a non-ratifier for the same reason. Based on the WRI data, its rate of emission cuts between 2005 and 2011 was 70.8 million metric tons of CO2 per year. Assuming a simplistic linear rate of cuts until 2030, its power plants will have to knock off 83.53 million metric tons of CO2 emissions per year starting 2015 to meet its target of having 32% less carbon emissions than it did in 2005. But had it gone with 1990 as the base year, it would’ve had to knock off 122.46 million metric tons of CO2 year on year – an averaged annual leeway of 46.6%.

The Wire
August 5, 2015

About Me

I’m a science editor and writer in India, interested in high-energy and condensed-matter physics, research misconduct, pseudoscience, science’s relationship with society, epic fantasy, open source/access/knowledge systems, H.R. Giger’s art, Goundamani’s comedy, Factorio, and most things that require a lot of time to get the hang of.