California continues to lead in green tech innovation, but traffic created by the booming economy and housing crisis means it may struggle to hit future greenhouse gas reduction goals, according to a new report.

Despite efforts by President Donald Trump’s administration to roll back environmental regulations, researchers said California is proof that an economy can grow with strong carbon regulations.

“California just dominates total investment for clean technology across the board,” said Adam Fowler, an economist for Beacon Economics and one of the authors of the Green Innovation Index. “We’re a powerhouse.”

Although greenhouse emissions in the state continued to decline, the rate slowed due to a spike in pollution from cars and trucks, according to the report commissioned by Next 10. The nonpartisan, non-profit focuses on the California economy and environment, and released its ninth annual report Monday night.

The report argues the state’s tough emissions standards — setting goals for renewable energy sources and promoting low-emission vehicles — may help boost the state’s economy and innovation.

As a region, Silicon Valley continued to lead in green tech patents and clean vehicle rebates. The metro area defined as San Jose, Santa Clara and Sunnyvale had the second highest number of clean energy patents in the state, trailing only San Francisco.

Fowler said the patents are a strong leading indicator of innovation and job growth. The state has also pulled ahead in transportation-related patents, he said, leaving Texas and Michigan far behind.

Investments in clean tech across the U.S. have dipped, although they grew in California. About two-thirds of the $2.5 billion invested in clean tech went to California-based companies.

But the report found warning signs for curbing pollution. Poor municipal and regional planning and higher housing prices have led to longer commutes. Low gas prices have also encouraged travel and added to carbon emissions.

The state is on track to meet its 2020 goals for reducing greenhouse gases, but could struggle in following years.

“You have the challenges here,” said Next 10 president and founder Noel Perry.