In the summer of 2019 Governor Cuomo and the New York State Legislature passed the Climate Leadership and Community Protection Act (CLCPA) which was described as the most ambitious and comprehensive climate and clean energy legislation in the country when Cuomo signed the legislation. On August 14 New York State Department of Environmental Conservation (DEC) Commissioner Basil Seggos released proposed regulations to reduce greenhouse gas emission statewide and implement the CLCPA. A key part of this regulation is defining the baseline 1990 emission inventory and this is a quick initial post about the inventory.
Up until this time the “official” New York greenhouse gas emission inventory was prepared by the New York State Energy Research and Development Authority (NYSERDA) According to the latest edition of the NYSERDA GHG emission inventory Table S-2 New York State GHG Emissions 1990–2016 the New York State 1990 GHG emissions were 236.19 MMtCO2e.
The CLCPA mandates specific requirements for the 1990 emission inventory that I am positive no legislator who voted for the law understood. The most impactful requirement was to specify that the global warming potential (GWP) be calculated over a 20-year time horizon. The following section of the Intergovernmental Panel on Climate Change (IPCC) describes time horizons and the GWP.
Reference: Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
“The GWP has become the default metric for transferring emissions of different gases to a common scale; often called ‘CO2 equivalent emissions’ (e.g., Shine, 2009). It has usually been integrated over 20, 100 or 500 years consistent with Houghton et al. (1990). Note, however that Houghton et al. presented these time horizons as ‘candidates for discussion [that] should not be considered as having any special significance’. The GWP for a time horizon of 100 years was later adopted as a metric to implement the multi-gas approach embedded in the United Nations Framework Convention on Climate Change (UNFCCC) and made operational in the 1997 Kyoto Protocol. The choice of time horizon has a strong effect on the GWP values — and thus also on the calculated contributions of CO2 equivalent emissions by component, sector or nation. There is no scientific argument for selecting 100 years compared with other choices (Fuglestvedt et al., 2003; Shine, 2009). The choice of time horizon is a value judgement because it depends on the relative weight assigned to effects at different times. Other important choices include the background atmosphere on which the GWP calculations are superimposed, and the way indirect effects and feedbacks are included (see Section 220.127.116.11).”
According to the draft regulation released on August 14, § 496.4 Statewide Emission Limits (a) For the purposes of this Part, the estimated level of statewide greenhouse gas emissions in 1990 is 401.38 million metric tons of carbon dioxide equivalent, using a GWP20 as provided in the IPCC assessment report.
More to come on this topic.