State Resources for Action on Climate: Frequently Asked Questions

March 7, 2022

State Resources for Action on Climate

Frequently Asked Questions & Answers

1. Why is EPA developing this data now?

EPA is in a unique position to provide existing data on state-level GHG estimates that are
consistent with the Inventory of U.S. Greenhouse Gas Emissions and Sinks because of the
work that EPA already undertakes in preparing the national Inventory that requires
consistency with international reporting guidelines. EPA also already prepares the Global
Mitigation of Non-CC>2 Greenhouse Gases: 2015-2050 and has prepared a comparable
analysis and data for U.S. States.

This data will provide state governments, independent researchers, and other stakeholders
with a rich datasetfor policy making and policy assessment (e.g., filling gaps in sectors that
are particularly challenging to estimate such as agriculture, land use change and forestry).

Finally, this effort will also provide updated information for EPA's existing State Inventory
and Projection Tool, which allows states to compile and analyze their own estimates that
reflect state policies and priorities.

More information is available at https://www.epa.gov/ghgemissions/state-and-tribal-
greenhouse-gas-data-and-resources.

2. How do official inventories published by states inform EPA's estimates?

EPA's state-level GHG data should not replace official state GHG Inventories. We understand
that some states develop independent inventories of their own GHG emissions, in some
cases making use of different estimation methodologies, data inputs and/or
inclusions/omissions of GHG source and sink categories, geographic boundaries and choice
of scopes. Often state-level inventories are central to planning, implementing, and assessing
state-specific laws and regulations. States may wish to make use of this EPA state-level data
as complementary and supplementary information appropriate within their own state
inventory frameworks.

To achieve the goal of providing estimates that are consistent with the Inventory of U.S.
Greenhouse Gas Emissions and Sinks (see Q5 below), EPA's state-level estimates need to be
linked directly with the national methodologies and datasets, rather than compiled from
independent reports. Again, we recognize that there will likely be differences between the
EPA state-level estimates and some state GHG inventories developed independently by
states. This is due to different state regulations and scope of state-level emission estimates.

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March 7, 2022

EPA has prepared a methodology report describing methodological and accounting
approaches used in the Inventory by state to facilitate understanding of differences with
how states may compile their inventories available at
https://www.epa.aov/ahaemissions/state-aha-emissions-and-removals.

We are also providing information on how the public, including researchers, can access up-
to-date official data from state governments where it exists. EPA has a new web page
providing these links. EPA has included caveats in presenting data to ensure it is not viewed
as official data of any state government.

We anticipate that as individual states continue to improve their own inventories, there will
be targeted case by case opportunities to incorporate new state-level information into
national-level calculations. These opportunities could come where national level methods
can accommodate state and regional inputs, and where improving data at this scale will
lead to a more accurate national total. Improvements to national estimates will then also be
reflected in better state-level disaggregation.

3. How does EPA's data compare with existing states Inventories?

We recognize that there will likely be some differences between the EPA state-level
estimates and some state GHG inventories developed independently by states. We
understand that states develop independent inventories of their own GHG emissions, in
some cases organizing and allocating estimates by economic sector rather than IPCC sector,
making use of alternate methodologies, data inputs and/or inclusions/omissions of GHG
source and sink categories, geographic boundaries and choice of scopes. Often state-level
inventories are central to planning, implementing, and assessing state-specific laws and
regulations. States may wish to make use of this EPA state-level data as complementary and
supplementary information appropriate within their own state inventory frameworks.

4. How do the mitigation estimates overlap with potential CH4 regulations?

The mitigation estimates represent a snapshot of currently available mitigation
opportunities. Potential future CH4 regulations may take advantage of the mitigation
opportunities estimated by the analysis, but the analysis does not explicitly model potential
future CH4 regulations.

5. What does "consistent with the Inventory of U.S. Greenhouse Gas Emissions and Sinks"
mean?

Disaggregation consistent with the Inventory of U.S. Greenhouse Gas Emissions and Sinks
means that the state-level estimates:

• Adhere to international standards, including the Intergovernmental Panel on Climate
Changes (IPCC) Guidelines and United Nations Framework Convention on Climate

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Change (UNFCCC) transparency reporting system (i.e., the emissions and removals
presented in this report and the report are organized by source and sink categories
within the five IPCC sectors [energy, industrial processes and product use (IPPU),
agriculture, Land Use, Land-Use Change, and Forestry (LULUCF) and waste] and their
respective source and sink categories).

• Are based on the same methodologies as the national Inventory and reflect the
latest methodological improvements in the national Inventory, including the use of
Greenhouse Gas Reporting Program (GHGRP) data.

• Cover the complete time series consistent with the national Inventory, starting with
1990 through the latest national Inventory year (i.e., 2019)

• Cover all anthropogenic sources and sinks, and all seven gases (carbon dioxide [CO2],
methane [CH4], nitrous oxide [N2O], hydrofluorocarbons [HFCs], perfluorocarbons
[PFCs], sulfur hexafluoride [SFe], and nitrogen trifluoride [NF3]). The completeness
and geographic disaggregation of the report are consistent with the national
Inventory, meaning in addition to estimates for states, the methods also address
emissions and removals occurring in the District of Columbia, U.S. territories, and
tribal lands.

• Estimates were compiled to avoid double counting or gaps in emissions coverage
between states. This ensures that state totals, when summed, will equal totals in the
national Inventory. This is important for those looking for consistent, comparable,
and complete state data for analyses and other purposes where double counting or
omissions would be problematic.

6. Can states that have developed their own estimates contribute directly to EPA's analysis?

To achieve the goal of providing estimates that are consistent with the Inventory of U.S.
Greenhouse Gas Emissions and Sinks (see Q5), EPA's state-level estimates need to be linked
directly with the national methodologies and datasets, rather than compiled from
independent reports.

We understand that U.S. states develop independent inventories of their own GHG
emissions, in some cases making use of alternate methodologies, data inputs and/or
inclusions/omissions of GHG source and sink categories, geographic boundaries and choice
of scopes. Often these state-level inventories are central to planning, implementing, and
assessing state-specific laws and regulations. States may wish to make use of this EPA
state-level data as supplementary information appropriate within their own state inventory
frameworks.

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lead to a more accurate national total. Improvements to national estimates will then also be
reflected in better state-level disaggregation.

7. What is the relationship between the State Inventory and Projection Tool (SIT) and the
GHG Inventory by U.S. State data?

The SIT tool was developed in 2003 to assist states in compiling their own GHG inventories.
The tool provides users with a choice between default emissions factors and activity data
and entering state-specific data and emissions factors. The default information in the SIT is
largely based on methodologies, emissions factors, and other data from the national
Inventory. In some cases, state-level data has not been available (e.g., due to confidential
business data or the use of national level modeling) or lags behind national-level data.
Therefore, the default approaches in SIT may not fully reflect the latest updates for some
categories (e.g., use of GHGRP data) and may not reflect all categories reflected in national
Inventory for which 2006IPCC Guidelines provide methods. In addition, the SIT provides two
alternate approaches to estimating emissions (calculating C02from transportation based on
vehicle miles traveled (VMT) and calculating emissions from electricity consumption), which
are not based on national Inventory methods. EPA is providing a crosswalk of the
methodologies and data used by the GHG Inventory by U.S. State and SIT to clarify the
differences between the two resources. Download the crosswalk at

https://www.epa.aov/svstem/files/documents/2022-03/factsheet-crosswalk-between-ahg-
by-state-and-sit.pdf.

The version of SIT published in February 2022 includes several updates that bring it in closer
alignment with the GHG Inventory by U.S. State including the addition of 2019 data,
updating default activity data and emissions factors across all sectors, and moving to
regional apportionment ofODS substitutes. EPA is currently evaluating how to use the
additional state-level data and/or methodological approaches available through the
national Inventory disaggregation to supplement or improve the embedded calculations and
defaults in SIT. SIT users will retain the ability to customize the tool with their own data in
lieu of using defaults. EPA will continue to coordinate with state agencies on how to
prioritize and implement updates to SIT.

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