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April 30, 2021
Net-Zero Emissions Pledges: Background and Recent
Developments
On January 27, 2021, President Biden signed Executive
Net-Zero Emissions and U.N.
Order 14008, which expressed the intent to “put the United
Framework Convention on Climate
States on a path to achieve net-zero emissions, economy-
Change
wide, by no later than 2050.” A number of other countries,
The United States is a party to the Senate-ratified U.N.
as well as cities, regions, and companies, have also made
Framework Convention on Climate Change (UNFCCC),
“net-zero” emissions pledges. This In Focus explains the
the stated objective of which is “stabilization of greenhouse
concept of net-zero emissions, identifies recent net-zero
gas concentrations in the atmosphere at a level that would
pledges, and presents a series of questions to consider when
prevent dangerous anthropogenic interference with the
examining net-zero pledges. This In Focus does not address
climate system.”
or evaluate the challenges involved in achieving net-zero
targets or the technological advances and/or policy options
Subsidiary to the UNFCCC, the Paris Agreement, which the
that would likely be needed to reach them.
Biden Administration has rejoined, includes a goal to keep
the global average temperature to well below 2°C above
Background
preindustrial levels, while pursuing efforts to limit the
Net-zero emissions refers to a situation where any continued
temperature increase to 1.5°C. One question addressed by
human-caused greenhouse gas (GHG) from an entity (e.g.,
both scientists and policymakers is when global emissions
country, subnational government, company) is balanced by
would need to reach net-zero in order to limit the likely
human, or anthropogenic, carbon removal from the
global mean temperature increase by 2100 to, for example,
atmosphere that stores the carbon dioxide (CO2) in
1.5°C or 2°C. Figure 1 shows a subset of modeling
geological, terrestrial, or ocean reservoirs, or in products.
scenarios that limit likely warming in 2100 to 1.5°C.
Carbon removal can include enhanced carbon storage in
Overall, the Intergovernmental Panel on Climate Change
forests, wetlands, grasslands, and agricultural lands, or the
(IPCC) estimates that if net emissions were zero by
use of removal technologies such as direct air capture,
approximately 2050, then the likely global mean
bioenergy with carbon capture and storage, and enhanced
temperature increase might be limited to 1.5°C by 2100.
weathering of minerals. It excludes natural CO2 not directly
Similarly, the IPCC estimates that the likely global mean
removed from the atmosphere by human activities.
temperature increase might be limited to 2°C by 2100 if
net-zero emissions were achieved by approximately 2070.
A net-zero emissions target may include all GHGs, or
sometimes only CO2. The use of terms can vary. Climate
To meet this temperature goal, the Paris Agreement
neutrality can be a synonym for net-zero emissions, while
includes a net-zero emissions aim, specifically calling for a
net-zero emissions that includes only CO2 may be known as
“balance between anthropogenic emissions by sources and
net-zero decarbonization or carbon neutrality.
removals by sinks of greenhouse gases in the second half of
this century.”
While related, carbon capture and storage is not equivalent
to carbon removal. Carbon capture and storage (CCS) is a
process in which a relatively pure stream of CO2 from
industrial and/or energy-related sources is separated,
conditioned, compressed, and transported to an
underground storage location for long-term isolation from
the atmosphere. In the case of a power plant burning fossil
fuels or a CO2-emitting industrial facility (e.g., steel or
cement plant), CCS would reduce the amount of emissions
that would have been released into the atmosphere, but it
does not directly remove carbon from the atmosphere.
However, when CCS is used in combination with biofuels
as an energy source, some carbon is removed from the
atmosphere because the carbon in the source plants for the
biofuel was recently assimilated from atmospheric CO2.
https://crsreports.congress.gov
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Net-Zero Emissions Pledges: Background and Recent Developments
Figure 1. Global CO2 Emissions over Time Across
Issues to Consider on Net-Zero Pledges
Selected 1.5°C Modeling Scenarios
Net-zero pledges can vary widely in their details. A recent
article in Nature (Joeri Rogelj et al., “Net-zero targets are
too opaque,” March 18, 2021) discussed a number a
questions that could be considered when evaluating net-
zero emissions pledges:
What is the time frame for the net-zero target? Are there
intermediate milestones?
Is the target based on a global temperature goal (e.g.,
1.5°C or 2°C)? Would the global climate goal be
achieved if every country enacted the same target?
What is the scope of GHG emissions? Are all GHGs
included, or just CO2? How are the GHGs aggregated to
determine net-zero?
What are the relative contributions from reductions in
GHGs, direct carbon removals, and offsets? Reductions
and removals are under control of the entity
(government, business), while offsets are purchased
Source: CRS analysis of data from International Institute for Applied
reductions undertaken by someone else.
Systems Analysis, “SSP Database (Shared Socioeconomic Pathways) -
Version 2.0,” at https://tntcat.i asa.ac.at/SspDb/dsd?Action=htmlpage&
What policies, laws, regulations, and funding programs
page=10.
will be established to meet the net-zero target?
Notes: The legend indicates the model name. For each model, there
are multiple runs based on different socioeconomic scenarios. In al
Has the target been set with regard to the financial and
cases net CO2 emissions reach zero by 2060. These are a subset of
technical capacity of the country or considerations of
emissions scenarios consistent with limiting likely warming to 1.5°C
equity and fairness?
in 2100 that use the same socioeconomic assumptions and have
publicly available data.
Could the net-zero target lead to carbon leakage, the
situation where emissions reductions in the country with
Recent Net-Zero Pledges
the net-zero target result in an increase in emissions in
As of March 2021, 59 countries have communicated a net-
another country?
zero target, representing 54% of global GHG emissions,
although they vary as to whether the target is a political
For companies, does the target include only emissions
pledge (e.g., by a head of state such as President Biden),
resulting from their direct activities, or emissions across
incorporated into a policy document, or enshrined into law
their value chains as well?
(Figure 2). For example, France, Germany, and the United
Kingdom have legally binding 2050 net-zero GHG
How will progress on meeting the target be monitored,
emissions goals, while the Republic of Korea and China
reported, and verified?
have carbon neutral pledges for 2050 and 2060,
respectively. By one estimate, as of September 2020 more
How will social and environmental risks be managed?
than 800 cities, 100 regions, and 1,500 companies have
made net-zero pledges. Subnational governments vary in
Additional Resources
how much authority they have in meeting these targets.
CRS Report R46204, The United Nations Framework
Figure 2. Countries That Have Adopted Net-Zero
Convention on Climate Change, the Kyoto Protocol, and
Targets
the Paris Agreement: A Summary, by Jane A. Leggett
CRS In Focus IF11791, Mitigating Greenhouse Gas
Emissions: Selected Policy Options, by Jonathan L.
Ramseur et al.
CRS In Focus IF11501, Carbon Capture Versus Direct Air
Capture, by Ashley J. Lawson
Michael I. Westphal, Analyst in Environmental Policy
IF11821
Source: CRS, based on data from Net-Zero Tracker, World
Resources Institute, at https://www.climatewatchdata.org/net-zero-
tracker.
https://crsreports.congress.gov
Net-Zero Emissions Pledges: Background and Recent Developments
Disclaimer
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