UPDATE March 4, 2020: I mis-interpreted the 2030 GHG emissions reduction target. I thought it was supposed to be a 60% reduction but it is only a 40% reduction. As a result the sector reductions needed to meet that target have been modified.
In the summer of 2019 the 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. In one of the first implementation tasks the New York State Department of Environmental Conservation (DEC) has started the process to calculate a statewide Greenhouse Gas emissions (GHG) limit for this law. This is a background post that defines the emissions targets that I will reference in future posts about the reductions necessary.
New York State greenhouse gas emissions are available from the New York State Energy Research & Development Authority (NYSERDA) in their annual inventory of GHG emissions. The most recent report, Greenhouse Gas Inventory 1990-2016 contains a detailed inventory of historical greenhouse gas emission data from 1990-2016 for New York State’s energy and non-energy sectors. Table S-2 New York State GHG Emissions 1990–2016 (MMtCO2e) from that report lists emissions from different sectors in million tons of CO2 equivalent (CO2e). They use this unit of measure in order to include all greenhouse gases in the control strategy as a function of global warming potential (GWP). Despite the fact that this is a perfectly good emissions inventory the law mandates a new inventory with slightly different methods.
The CLCPA inventory requirements are included in § 75-0105: Statewide greenhouse gas emissions report. The regulation states that “No later than two years after the effective date of this article, and each year thereafter, the department shall issue a report on state-wide greenhouse gas emissions, expressed in tons of carbon dioxide equivalents, from all greenhouse gas emission sources in the state, including the relative contribution of each type of greenhouse gas and each type of source to the statewide total”.
There are two methodological differences between the CLCPA inventory requirements and the methodology used for the NYSERDA report. Firstly, the legislation states “§ 75-0105(3): The statewide greenhouse gas emissions report shall also include an estimate of greenhouse gas emissions associated with the generation of imported electricity and with the extraction and transmission of fossil fuels imported into the state which shall be counted as part of the statewide total.” Secondly, in the definitions § 75-0101(2) “Carbon dioxide equivalent” is defined as “the amount of carbon dioxide by mass that would produce the same global warming impact as a given mass of another greenhouse gas over an integrated twenty-year time frame after emission”.
I have not quantified how those differences will affect the emissions relative to the NYSERDA report. The lifecycle approach to the GHG inventory has not been used to date by the agencies to estimate extraction and transmission of fossil fuels emissions. Presumably this will increase the historical numbers. I was not familiar with the nuance of global warming impact time frames so did some internet research. The GHG Management Institute “What is global warming potential and which one do I use?” states:
The second complication is one that occasionally trips people up. Remember above when we defined GWP by saying “cumulative radiative forcing…integrated over a period of time”? Well, that means that we have to define a time period for the integration to occur. You have to know what the integration period is to make sure you are using the correct GWP. The typical periods that the IPCC has published are 20, 100, and 500 years (the latest report quit publishing values for 500 years).
Now, to be clear, everyone pretty much universally uses 100 year GWP values, so you often never see the time period even cited. It is just assumed you know it is 100 years. But occasionally, someone will use something different, not realizing that they are breaking convention. It is also possible to compute an infinite time horizon GWP value, which would basically mean that accounted for every bit of radiative forcing of every molecule of gas as long as it existed in the atmosphere.
It is notable that this author says: ”everyone pretty much universally uses 100 year GWP values” but the CLCPA uses 20 year values. In Intergovernmental Panel on Climate Change fifth assessment report Chapter 8 IPCC Table 8.7 GWP and GTP with and without inclusion of climate–carbon feedbacks lists GWP values for methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and carbon tetrafluoride but not sulfur hexafluoride which is a listed chemical in the CLCPA. The 20 year GWP is greater than the 100 year GWP for methane, hydrofluorocarbons, and perfluorocarbons.
The CLCPA specifies reductions in the future from 1990 emission levels per “§ 75-0105(5): The statewide greenhouse gas emissions report shall also include an estimate of what the statewide greenhouse gas emissions level was in 1990”. As noted above these levels will have to be re-calculated using the CLCPA methodology but we can get an idea what is needed by looking at the NYSERDA inventory.
The CLCPA GHG Emissions Targets 2016 Update table presents the emissions status for the 2030 CLCPA target to reduce GHG emissions 40% from the 1990 level and the 2050 CLCPA target to reduce GHG emissions 85% from the 1990 level. According to the NYSERDA methodology 1990 GHG emissions were 236.2 million metric tons of CO2e. The 2030 target limit is 94.5 million metric tons and in 2016, the last year of the NYSERDA inventory, NYS emissions were 205.6 million metric tons. Therefore, in order to meet the CLCPA target in 2030 another 63.9 million metric tons have to be reduced. By 2050 emissions have to be reduced 170.2 million metric tons from 2016 levels.
This post specifies the CLCPA emission targets for future reference. Originally, I was going to develop these numbers and combine them with the observed cost efficiency for existing NYS GHG emission reduction investments to estimate the potential cost of the program but there are other things to look at too. For example, New York state reduced GHG emissions 30.6 million metric tons in the 26 years between 1990 and 2016 but has to reduce them another 63.9 million metric tons in 14 years to meet the 2030 CLCPA target. That deserves analysis and its own post. Rather than a huge post covering all the aspects of these numbers I will prepare shorter posts on each aspect that reference these numbers. Stay tuned.