US President Donald Trump announced his intention to withdraw from the Paris climate agreement a little more than a year ago.

Since then, more than 230 cities representing more than 70 million Americans have vowed to uphold the global coalition and fill the gap left by the federal government.

Now these efforts will receive a major boost. Bloomberg Philanthropies is offering 20 cities the opportunity to accelerate their climate change programs through a $70 million policy competition called the “American Cities Climate Challenge.”

Take Action: Ensure All Communities Can Withstand Climate Disaster

“Mayors don’t look at climate change as an ideological issue,” former New York City mayor Michael Bloomberg said in a press release. “They look at it as an economic and public health issue. Regardless of the decisions of the Trump administration, mayors are determined to continue making progress.”

Bloomberg has a long history of promoting climate action, and he’s been one of the most outspoken defenders of the Paris climate agreement following Trump’s withdrawal.

Since Washington’s decision to pull the U.S. out of the Paris Agreement last June, Americans have stepped up to fill the gap. One year later – led by @MikeBloomberg & @JerryBrownGov – our @AmericasPledge initiative makes it clear: We are still in. https://t.co/bWCzagDz53pic.twitter.com/U3Q3URuSRA

— Bloomberg Philanthropies (@BloombergDotOrg) June 1, 2018

The purpose of the new contest is to help the US reach the target it set under the Paris agreement — reducing carbon emissions in 2025 by 26% compared to 2005 levels.

The 20 selected cities have the potential to get 20% of the way there, averting 200 million metric tons of carbon, according to Bloomberg Philanthropies.

Read More: Who Needs Trump? These US Leaders Are Going Right to the UN t Work on Climate Goals

Participating cities will be expected to focus on making transportation and buildings more efficient, which together account for roughly 90% of all city emissions and are areas that can be swiftly addressed, Bloomberg notes.

For example, implementing smart heating and cooling systems, installing solar panels, improving window insulation, and using LED light bulbs are all easy ways to significantly cut down on energy consumption.

As far as transportation goes, enacting car free zones, imposing higher efficiency standards on vehicles, and investing in public transportation are all proven methods for reducing emissions.

Since taking office, Trump has ended the federal requirement that new construction consider climate change and is in the process of unraveling ambitious car emissions standards.

Read More: 8 Ways Cities Are Fighting Climate Change and Environmental Decay

The country’s 100 largest cities will eligible to enter the competition. By June 19, cities have to sign a pledge committing to the Paris climate agreement and submit an application by July 18. In the fall, 20 cities will be selected.

The winners will receive a support package worth $2.5 million that includes advisers, data resources, design help, innovation training, implementation oversight, and “rapid response grants” for specific programs.

Winners will also receive peer-to-peer learning, similar to the networks enabled by another Bloomberg-led organization called C40, which aims to inspire climate action on the city level.

Read More: Why Cities May Be the Key to Stopping Climate Change

The contest will be supported by the nonprofits Natural Resource Defense Council (NRDC) and Delivery Associates.

“Cities across America are on the front lines of climate change—their residents are feeling the heat and watching the floodwaters rise around them,” says Rhea Suh, president of NRDC. “This challenge will empower America’s cities to pursue innovative policies and programs to cut their carbon pollution.”

Global Citizen campaigns on the United Nations’ Global Goals, which call on cities, states, and countries to achieve the Paris climate agreement. You can take action on this issue here.