Subnational and non-governmental actors are expected to provide important contributions to broader climate actions. A consistent and accurate quantification of their GHG emissions is an important prerequisite for the success of such efforts. However, emissions embodied in domestic and international supply chains, that can undermine the effectiveness of climate agreements, add challenges to the quantification of emissions originating from the consumption of goods and services produced elsewhere. This study examines emission transfers between the states that have joined the U.S. Climate Alliance (USCA) and others. The results show that states pledging to curb emissions consistent with the Paris Agreement were responsible for approximately 40% of total U.S. territorial GHG emissions. However, when accounting for transferred emissions through international and interstate supply chains of the products they consume, the share of Alliance states increased to 52.4% of the national total GHG emissions. The consumption-based emissions for some Alliance states, such as Massachusetts and New York, could be more than 1.5 times higher than their production-based emissions. 

Ambition of Cities, Regions and Companies 

• As of March 2023, 3,008 cities and 175 subnational states and regions made quantifiable emission pledges covering 26.5% of the total global population. Three-quarters of these subnational governments come from the EU. In Australia, the United Kingdom and Japan, more than 99 percent of the national population is covered by city and regional climate targets. In some countries, cities and regions took the lead in setting net-zero targets before their respective national governments, demonstrating their ability to catalyze more ambitious climate actions.

• Encouragingly, the number of cities and regions with quantifiable emission reduction targets has increased in 2023 compared to 2022, although some of this growth is due to enhanced data collection methods. North American countries, including Canada, the United States, and Mexico, have all seen notable increases in cities and regions recording targets.

• A growing number of cities and regions have pledged net-zero and carbon neutrality. 572 cities and regions are aiming for 100 percent emission reductions, carbon neutrality or net-zero, with one-third aimed at before 2050 and the majority for 2050 or later.

Tracking the progress of climate mitigation for global cities 

• Following a brief slump post the COVID-19 pandemic, subnational climate action is beginning to rebound. As of March 2023, more than 3,000 cities and 175 subnational states and regions, accounting for 26.5% of the global total population, have pledged to reduce their greenhouse gas emissions . This number represents an increase in the number of cities and regions pledging quantifiable emission reduction targets, compared to 2022. 

• While more cities and regions are reporting needed data to evaluate progress towards their own declared mitigation targets, the overall picture of implementation remains weak, with less than 40% of total subnational governments on track. 

• To correct course toward achieving their emission reduction targets with an average remaining time of 17 years, cities and regions need an average annual reduction of nearly 3%. The median reduction is, however, only 1.6% per year. They will need to double efforts to stay on track. 

• To align their targets with 1.5°C-climate scenarios, cities and regions would need to increase the overall ambition of current efforts by 2.5 times. On-track targets are achieving a median annual emission reduction of 3.6% per year, falling short of the required 4% per year needed for 1.5°C goals. Less than one-fifth of cities and regions meet this threshold.  

Greenhouse gas (GHG) emissions in the U.S. peaked and declined in the first decade of the 21st century, largely attributed to the increased use of natural gas and renewable energy replacing coal. However, if and to what extent household consumption also played a role in this trend is still debated. Finding demand-side options is necessary to hedge against the risks of technology solutions failing to materialize. To fill this gap, this study analyzes the change in GHG emissions driven by U.S. household consumption, explores the drivers of this change and the contribution of different income groups. To this end, this study combined the U.S. consumer expenditure survey with an environmentally-extended multi-regional input-output framework to analyze changes in GHG emissions induced by household consumption between 2001 and 2015. This study further analyzed how much population, consumption volume and consumption patterns drove emission changes by quintile income groups. The results show that changes in household consumption contributed approximately one-third of the national emission decline. The decline in GHG emissions from U.S. households was mainly associated with a decrease in the consumption of carbon-intensive products, including gasoline, electricity, and animal-based food products. The top quintile income households were the main contributors to the emission increase before the peak, while the third and fourth income quintiles became emission mitigation leaders after 2010. Carbon inequality increased during the 2001–2006 period, mainly driven by increased wealth and consumption of high-income households, and was relatively stable after the peak. Emissions from certain consumption categories of the top quintile group are significantly higher than the bottom four quintiles with increasing trends, especially leisure-related services and goods, which require more attention in future policymaking for emission reduction.