As the recent Global Climate Action Summit underscored, we’re seeing a steady rise in the number of commitments by cities, states and provinces to address climate change, with over 17,500 actions registered on the NAZCA Climate Action Portal. Not only are these efforts curbing greenhouse gas emissions within their jurisdictions, they can also have far-reaching impacts at the national level.

We know that national commitments are not enough to stabilize the climate, and the efforts of cities and local governments, while crucial, can only go so far toward achieving the Paris Agreement goals. To pick up the pace, we need to strengthen the mutually reinforcing relationship between national and subnational climate actions to support and unlock greater ambition. Subnational innovations can inspire national policy change, which in turn can spread these ideas and actions throughout countries that adopt them.

When this relationship goes awry, it can have significant consequences, especially for cities, which are the economic powerhouses of their economies, representing over 70 percent of GDP. Even in progressive places like California, the challenges can be great. In San Francisco, which just hosted the Global Climate Action Summit, building owners are not able to electrify their buildings, even though that would be a good way to meet the city’s decarbonization goals, because the state Public Utilities Commission does not allow utilities to grant permits for fuel switching which can save money and carbon emissions.

Here are some examples of unlocking action.

Transport Sector, Denmark:nationwide air quality benefits and opportunity for more ambitious local policies.

In 2011, the Danish government’s energy efficiency standards for heavy-duty vehicles improved urban air quality and gave cities permission to introduce low-emission zones. This boost of authority empowered local governments to pursue complementary and potentially more aggressive policies.

Water Sector, China: reduced GHG emissions through nationwide wastewater treatment standards.

Inspired by sludge-to-energy pilot projects in the city of Xiangyang, China drove the adoption of national and state-level wastewater treatment minimum standards and demonstrated the potential environmental and economic benefitsfor other cities in China.

Forest Sector, Brazil: a national restoration commitment that builds upon state-level pledges.

In 2015, Espírito Santo, São Paulo and Mato Grosso made state-level restoration pledges to restore a collective 3.28 million hectares (more than 8 million acres) of degraded forest. Expanding on state-level pledges, the federal government followed suit just one year later, pledging to bring 12 million hectares of land (nearly 30 million acres) into restoration by 2030 under the Bonn Challenge and 20×20 Initiative.

Financial Sector, Canada: Nationwide carbon pricing based on a successful provincial policy.

British Columbia made history in 2008 when it implemented North America’s first broad-based carbon tax. Eight years later, in 2016, Prime Minister Justin Trudeau announced a pan-Canadian price on carbon, basing its design and scope on British Columbia’s effective province-level carbon tax.

Real Estate Sector, Colombia : Cities nationwide have building energy standards that are easier to implement.

Reducing building energy use is central to meeting Colombia’s international climate commitments but the capital city Bogotá struggled to implement building codes passed in 2015. With support from domestic and international partners, Bogotá was able to develop a protocol that made the legislation more realistic and easier to implement.

These examples show that national governments have a unique role in sending clear policy signals, creating incentives, supporting subnational climate success and reducing barriers to subnational ambition. Subnational governments are essential to putting climate policies in action and driving constituents’ support for national climate policies, and they need to be actively engaged in supporting the transition for communities deeply rooted in fossil fuel industry. They are also crucial for building resilience and ensuring adaptation to climate impacts (such as coastal infrastructure, zoning and development). Different levels of government are interdependent and their fates are linked. However, national and subnational actors are frequently out of step, stifling one another’s ambition and abilities.

That dysfunction needs to end. The path needs to be cleared so subnational actors and national governments can play the self-reinforcing roles that can keep global warming below 2 degrees C (3.6 degrees F) or 1.5 degrees C (2.7 degrees) to ward off the worst impacts of a changing climate.

Over the next six months, look for a series of blogs highlighting in more detail specific cases of this virtuous interdependency.

This blog originally appeared on WRI’s Insights.

Cynthia Elliott is an Associate for the Global Climate Program at World Resources Institute.

Emma Stewart is the Urban Efficiency & Climate Director at WRI Ross Center for Sustainable Cities.

Eliza Northrop is an Associate in the International Climate Action Initiative at World Resources Institute.

Andrew Wu is the Research Analyst for the New Restoration Economy at World Resources Institute.

Caroline Gagné is a Research Analyst for the Global Restoration Initiative at World Resources Institute.