U.S. Methane Mitigation 2015: A Review of Climate and Public Health Impacts

Jan 14 2015 the U.S. EPA, in response to the Obama Administration’s mandate for methane emission reductions, released its plan to cut emissions from the oil and gas industry by 40% – 45% from the 2012 baseline. Response to the proposal has been mixed with many environmental groups immediately applauding the measure before questioning the administration’s narrow focus on new emission sources only.

Here, we’ve set out to assess the climate and public health outcomes of the proposed mitigation based on currently available data.

Part I: Climate

To understand the impact of the methane mitigation proposal in a climate context, we need to look back on climate actions and accords preceding this new proposal, as well as the current scientific consensus on what needs to be done to avert a 2° C rise above per-industrial in global mean temperature.

The most recent IPCC (AR5) consensus finds that limiting atmospheric concentrations of greenhouse gases at 450 ppm CO2eq by 2100 (based on updated GWPs integrated over a 100 year time frame) will likely keep temperature increases below the critical 2° C over both over the long and short term. The mitigation scenario assumes a 100 year integrated time frame, but accounts for short-term forcing of emissions. This scenario requires 41% to 72% reductions in global greenhouse gas emissions (CO2eq) relative to 2010 baseline by 2050 and reductions increasing to 78% – 118% by 2100. There is some room for emissions overshooting over the next 10-20 years, but the mid-century target is critical.

U.S. Emission Targets

Highly industrialized countries, such as the U.S., are responsible for a larger portion of greenhouse gas pollution and, therefore, bear a greater responsibility in mitigation. To this end, the U.S. has committed to an 83% reduction in economy-wide greenhouse gas emissions by 2050. Note that this accounting assumes the U.S. policy use of the 1996 GWPs (CH4-CO2eq = 21 integrated over a 100 year time frame), while the IPCC percentage of emissions required for mitigation assumes updated GWP values (CH4-CO2eq = 34 integrated over a 100 y time frame).

Meeting the 2050 target requires incremental emission reductions set with carefully planned near-term targets and periodic reviews of the progress made in meeting those targets. The first of such near-term targets is the U.S. pledge to reduce national greenhouse gas emissions by 17% by 2020, relative to the 2005 baseline[1]. Adjusting to EPA accounting to reflect revised GWPs, this equates to total U.S. emissions of roughly 6,270 million metric tonnes (MMT) CO2eq in 2020[2]. If the 2020 target can be met, staying on track to meet the 2050 target of 83% will require maintenance of the roughly 1.6% per annum reduction through to 2050 despite economic and population externalities.  Table 1 presents the target years and reductions relative to 2010 emission levels

Table 1.1 Committed Emission Targets, United States 2020 – 2050
	2005	2020	2025	2050
% Total Emissions	BASE	17%	26%	83%
MMT CO2eq*	7548.9	6265.6	5586.2	1283.3
* EPA (2014) reported emissions for 2005, adjusted to reflect revised IPCC GWP (34); estimates exclude LULUCF

The Emissions Gap

Early emission projections made it clear that the U.S., under the existing regulatory environment (2012), would not meet emissions target (U.S. State Department, 2013; see figure 1).

Figure 1.1 Projected total greenhouse gas emissions (CO2 eq; revised IPCC GWP of 34) to 2030 under 2012 existing policies. Source: http://www.state.gov/documents/organization/218993.pdf

While CO2 emissions were projected to fall more than 6% relative to 2005 levels, increasing methane emissions (+5.4% as CO2eq) would cancel out these savings (see fig 2). In response, the Obama Administration released the President’s Climate Action Plan (PCAP)[3]. The PCAP aims to close the emissions gap mainly through further reductions from the power sector and energy efficiency measures (Clean Power Plan[4]), and by directly addressing increasing methane emissions from various economic sectors head-on (Strategy to Reduce Methane Emissions[5]).

Figure 1.2  Projected methane emissions (CO2 eq; revised IPCC GWP of 34) to 2030 with 2012 existing policy measures. Source: http://www.state.gov/documents/organization/218993.pdf

Assuming full implementation and high estimated emission reduction, the PCAP could meet the 2020 emission targets, though there is wide variability in the total emission reductions possible under the plan. Under the lower range of possible emission reductions, the 2012 plan would still fall short of near-term targets even with full implementation.

Figure 1.3 Projected emissions (CO2 eq; revised IPCC GWP of 34) to 2020 for the 2012 policy scenario and economy-wide emissions reductions (high and low estimates) proposed in PCAP and the 2015 proposed methane mitigation plan. Sources: U.S. State Department. 2013. First Biennial Report, U.S. State Department. 2014. Sixth U.S. National Communication, U.S. White House Press Office. 2015. Fact Sheet: Administration Takes Steps Forward on Climate Action Plan by Announcing Actions to Cut Methane Emissions.

Further methane reductions of 117.8 MMT CO2eq by 2025 ( eqivalent to a reduction of 45.5 MMT CO2eq relative to the mean projected emissions by 2020 by linear interpolation), as described in the Administration’s 2015 methane reduction proposal will more than likely close the uncertainty in previously proposed emission reductions and ensure that at least the 2020 target is met (Fig 3), assuming that the current political landscape and 2016 election results allow for full implementation of the complete suite of mitigation strategies proposed by the Obama Administration.

Meeting the Mid-Century Target

Whether or not the plan is adequate to ensure that future targets are met is still being assessed.  A 2014 analysis by Climate Action Tracker (CAT) concluded that the 2025 and 2050 targets could not be met through the PCAP and it seems unlikely that the currently proposed methane plan will be enough to close a continuously widening gap(fig 4).  Assuming a 12-year atmospheric life of CH4 and a 20-year operating life of a well, mandatory emission reductions from existing oil and gas sources appear unlikely to a provide a significant mitigation effect for the 2050 targets.

Figure 1.4 CAT analysis of U.S. climate actions plan as of November 2014. Projected emissions include the PCAP, but not the 2015 proposed methane reductions for the oil and gas sector. Source: http://climateactiontracker.org/countries/usa/2014.html

Conclusions for Climate

1. Currently available data suggests that the 2015 proposed methane mitigation strategy, in combination with previously proposed climate mitigation strategies (PCAP),  is likely adequate to meet near-term emission reduction targets, despite the regulatory exclusion of existing sources in the oil and gas sectors.
2. The ability to meet near-term emission goals hinges on full implementation of the proposals and post-election (2016) support of the mitigation strategies proposed by the Obama Administration. While –  from a climate impact point of view  –  maximum emission reductions are perferrable (i.e. inclusion of existing sources in the oil and gas sector), we recognize that mitigation strategies must balance effectiveness and long-term political support.  The proposed 2015 methane reductions on new emission sources from the oil and gas sector – though not ideal and still contentious – are less likely to be repealed relative to more stringent measures thereby providing a strong probabilitiy of meeting at least the near-term emission targets.
3. Though the 2015 methane proposal is likely a win for near-term targets, current data suggests that the combined effect of the PCAP and 2015 methane mitigation strategy is unlikely to meet the 2050 emissions target and that additional action will be needed to close the gap.

From a climate impact point of view, the Administration’s 2015 methane mitigation proposal appears adequate in the short-term, despite the exclusion of existing emission sources in the oil and gas sector. Next, we look at the impact of the proposal on air pollutant emissions and human health.

Part II: Public Health

To Be Continued . . .

[1] 2009 Conference of the Parties of the United Nations Framework Convention on Climate Change, Copenhagen DK