Not Good Enough: Meta-Analysis Of Climate INDC Studies

Last week, analysts Kelly Levin and Taryn Fransen of the World Resources Institute munched and crunched about a dozen very recent reports that examine how far the world’s climate action commitments (intended nationally determined contributions) will combat global warming. Not far enough, it turns out, by 0.7–1.7°C.

The consensus has it that the already submitted INDCs will lower our current emissions, but they’re not capable of meeting the carbon budget — limiting warming to below 2°C over preindustrial levels by the end of the century, and thus steering us away from some significant climate impacts. (Even at 2°C, we can expect to see water availability decrease in critical river basins, forest fires in the Amazon more than double by 2050, and coral reefs struggle to recover from bleaching.)

Two weeks ago, the United Nations Environment Programme, voice for the UN’s 190+ world nations on the environment, released its definitive UNEP Emissions Gap Report. Despite adjusting the assessment level up to 52 billion tons by 2020, the report made it crystal clear that we still have a problem. UNEP scientists reported that the world could cut up to 11 GtCO2e from projected emissions in 2030. However, that number is only around half of the total cuts needed to reach a global emission level that has a likely chance (>66%, or two out of three) of staying below the 2°C target in 2100.

“The challenge is to bend the emissions trajectory down as soon as possible to ensure that the net zero emissions goal in 2060-2075 is within reach,” says the UNEP team. Nonetheless, says UNEP Executive Director Achim Steiner, “The current INDCs, combined with policies over the last few years, present a real increase in ambition levels and demonstrate an unprecedented commitment and engagement by member states in tackling this major global challenge.”

The WRI study attempts to compare UNEP’s numbers with all the other analyses and to clarify what’s behind the deficit. Previous trends might have led to 4–5°C of warming, but the 2.7–3.7°C found in the meta-analysis still fails to meet the chosen goal.

Levin and Fransen analyzed the 12 recent studies. All compare global emissions pathways resulting from the INDCs to one or more alternative scenarios without the INDCs. Some also cover the impact of expected emissions on temperature.

• 

  World temperature rise scenarios (climateactiontracker.org)

  Australian-German Climate and Energy College (CEC),

• Climate Action Tracker (CAT),
• Climate Interactive,
• Danish Energy Agency (DEA),
• European Commission Joint Research Centre (EC-JRC),
• International Energy Agency (IEA),
• London School of Economics (LSE, Grantham Institute),
• Massachusetts Institute of Technology (MIT),
• MILES Project Consortium (MILES),
• PBL Netherlands Environmental Assessment Agency,
• UNEP Emissions Gap Report, and the
• UNFCCC Synthesis Report itself.

Because the more than 150 national climate promises are so diverse in reporting methods and content (despite a common basic framework), each organization approached them differently and then aggregated them with future emissions projected from countries, sectors, and gases not covered by INDCs. The differences among studies boil down to three factors:

• Which INDCs the analysis covers,
• Assumptions about the INDCs, and
• Assumptions about what happens after the INDCs.

Here’s how the studies stacked up on the issue of temperature rise. (More details at this link.)

The 2025 and 2030 emissions numbers are critical to the world’s progress in 2100. WRI explains this phenomenon:

“The higher emissions are in the near term, the greater the required emissions reductions in later decades for limiting warming. Steep rates of emissions reductions are far costlier than more gradual rates of decline. They also risk failing to achieve the 2°C target, and rely more on carbon dioxide removal technologies (e.g., bioenergy and carbon capture and storage), which have yet to be proven at scale.”

The chart below shows median values for anticipated emissions levels in 2025 and 2030, given the 2015 INDCs. For a least-cost emissions pathway consistent with 2°C, emissions need to be 51.1–57.2 Gt CO2e in 2025 and 52–61.1 Gt CO2e in 2030. 

The UNEP has summed up world progress:

“The INDCs will likely have benefits beyond the estimated reductions to GHG emission levels as new climate policies and actions are being galvanized by the process, the report says. The preparation of the INDCs has incentivized the exploration of links between development and climate, and the development of new national climate polices, and may be considered as the first step in a transition towards low-carbon economies. The Paris Agreement could build on and support these processes and provide the framework for mobilization of the enhanced mitigation efforts required.”

UNEP will release its final update to the report in early 2016 and will incorporate the results of COP21.