Abstract
In 2019, New York State passed aggressive new climate legislation to reduce greenhouse gas (GHG) emissions and laid out major changes for how emissions are reported. One change is the inclusion of emissions from outside of the boundaries of the State if they are associated with energy use within NY; the traditional inventory considered emissions only within the State. The new legislation also mandated that methane emissions be compared with carbon dioxide over a 20-year time frame rather than the 100-year time frame previously used by NY and still used by virtually all other governments globally. This reflected the desire of NY’s policymakers for a tool that evaluates emissions from the standpoint of energy consumption and that more heavily weighs the role of methane as an agent of warming over the next few decades. This paper compares emissions based on the new approach for GHG reporting with the traditional inventory.
Generated Summary
This journal article examines the recent changes in greenhouse-gas (GHG) reporting requirements for the State of New York, focusing on methane emissions from fossil fuels. The study analyzes the implications of the Climate Leadership and Community Protection Act (CLCPA) of 2019, which mandates significant changes in how GHG emissions are reported, particularly concerning the inclusion of emissions from outside the state associated with energy use within New York and the adoption of a 20-year time frame for evaluating methane emissions. The research employs a consumption-based GHG footprint approach, contrasting the new CLCPA guidelines with traditional inventory methods. The methodology involves analyzing statewide annual energy consumption data, emission factors for various fossil fuels, and sector-specific emission apportionments. The study aims to provide a comprehensive understanding of the impact of the CLCPA on assessing and managing GHG emissions, with a specific focus on the role of methane and carbon dioxide.
Key Findings & Statistics
- In 2019, New York State enacted the Climate Leadership and Community Protection Act (CLCPA 2019), setting ambitious goals for statewide greenhouse gas (GHG) emission reductions of 40% by 2030 and 85% by 2050 compared to 1990 emissions.
- Methane emissions increased by almost 30% between 1990 and 2015, largely due to the increased consumption of natural gas.
- According to the new GHG reporting rules, methane contributed 28% of all fossil-fuel emissions in 1990 and 37% in 2015.
- Total GHG emissions remained virtually unchanged from 1990 to 2015.
- In 2015, carbon dioxide emissions had declined by 15% since 1990 due to an 88% decrease in coal consumption and a 27% decrease in consumption of petroleum products, although consumption of natural gas had increased by 57%.
- The traditional inventory is driven almost entirely by carbon dioxide emissions.
- As of 2015, these carbon dioxide emissions had declined by 15% since 1990 due to an 88% decrease in coal consumption and a 27% decrease in consumption of petroleum products.
- In 2015 using the CLCPA approach, carbon dioxide makes up 63% of total emissions from fossil fuels and methane 37%.
- Total methane emissions from all energy use in 2015 was reported as 2.6 Tg CO2-eq yr by NYSERDA (2018) and is estimated as 107 Tg CO2-eq yr from the CLCPA approach.
- Total GHG emissions for New York State, following the guidance of the CLCPA, equalled 365 Tg CO2-eq yr in 1990 and 362 Tg CO2-eq yr in 2015.
- In 2015, direct carbon dioxide emissions are 15% less than in 1990 while methane emissions are 29% greater.
- Methane emissions from natural gas production over the past decade was emitted to the atmosphere (Howarth 2019), is likely that at least 3.5% of new methane emissions from natural gas production.
- In 2015, the estimate for distribution emissions of 4.4 Tg CH4 yr.
Other Important Findings
- The CLCPA mandates the inclusion of emissions from outside of the boundaries of the State if they are associated with energy use within NY.
- The new legislation also mandated that methane emissions be compared with carbon dioxide over a 20-year time frame rather than the 100-year time frame.
- The choice of time frame for comparing methane and carbon dioxide is therefore quite important. The 100-year time frame places less emphasis on methane than does a shorter time frame.
- The largest change is to include GHG emissions that occur outside of the boundaries of New York State if they are associated with the use of energy within the State.
- Another major change required under the CLCPA is to report methane emissions expressed in carbon-dioxide equivalents (CO2-eq) evaluated over a 20-year integrated time horizon.
- Methane has a half-life in the atmosphere of approximately 12 years, and so the greatest direct influence of methane emissions on climate is during the few decades after emission.
- Reducing methane emissions can aid significantly in reaching the COP21 climate target, since the predicted uptake of carbon dioxide by oceans and the terrestrial biosphere is increased.
- The take-home message from the CLCPA-based approach is different: emissions from natural gas dominate, particularly in the residential and commercial sectors, with methane contributing somewhat more than carbon dioxide to these emissions.
- The guidelines specify that estimates for both gases be presented clearly, with the methane emissions compared to carbon dioxide over a 20-year time frame and based on a full-lifecycle, consumption-oriented analysis.
Limitations Noted in the Document
- The study acknowledges that the 3.6% emission factor used for methane emissions from natural gas consumption may be conservative, potentially underestimating emissions in 2015 due to increased petroleum production from shale oil.
- The emission factor for methane emissions for coal in 2015 may not be well represented.
- The analysis focuses primarily on direct emissions and does not include indirect carbon dioxide emissions associated with the development and transportation of fuels, which are part of the CLCPA mandate.
- The study notes that the estimate of methane emissions from shale gas in the United States, which is used for analysis in New York State, may or may not apply to the entire United States.
- The study’s reliance on a 20-year GWP, while consistent with the CLCPA, may differ from other studies that use a 100-year GWP.
Conclusion
The analysis of methane emissions from fossil fuels in New York State under the CLCPA reveals significant shifts in how greenhouse gas emissions are assessed, emphasizing the importance of considering emissions from energy consumption within the state’s boundaries, even if those emissions originate outside the state. The use of a 20-year time frame for evaluating methane emissions highlights its more immediate impact on global warming, aligning with the state’s ambitious goals to reduce GHG emissions. The study underscores that a consumption-based approach provides a different perspective on emission sources, with natural gas dominating emissions, especially in residential and commercial sectors. This perspective is crucial for policy makers to understand the complete climate footprint and design effective mitigation strategies. The research emphasizes the importance of reducing natural gas consumption and promoting electrification in heating and transportation to meet the CLCPA’s emission reduction targets. Although there are limitations, the study’s findings indicate that total emissions have changed remarkably little over the past 25 years, and the take-home message from the CLCPA-based approach is different: emissions from natural gas dominate, particularly in the residential and commercial sectors, with methane contributing somewhat more than carbon dioxide to these emissions. Future improvements in the CLCPA approach should include indirect carbon dioxide emissions and emphasize the need to balance short-term and long-term consequences. The CLCPA mandates that total GHG emissions in New York State should be reduced by at least 40% by 2030 relative to emissions in 1990 and by at least 85% by 2050, using the GHG-footprint approach of the CLCPA. To reduce overall GHG emissions for New York State, electrification of heating and transportation systems must proceed as quickly as possible, even if this precedes reduction of fossil fuels to produce electricity.