Green energy has hit a new milestone: The world added record levels of renewable energy capacity in 2016 despite an investment level that was 23 percent lower than the previous year, according to a new United Nations report.

Globally, those low expenditures -- the lowest seen since 2013 -- were largely due to declining prices in renewable energy, a sign of vitality in the sector. For instance, the average dollar cost per megawatt for solar photovoltaics and wind energy dropped by more than 10 percent, according to the report.

In total, the world spent $241.6 billion on renewable energy last year. (That excludes spending on “large hydro,” which largely refers to projects that use a dam and a reservoir to retain water from a river.)

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The report reflects an important moment, said David Konisky, associate professor at Indiana University’s School of Public and Environmental Affairs.

“It reflects a slow but sustained trajectory towards cleaner sources of energy. It reflects the fact that the cost of renewable technologies are coming down pretty drastically,” Konisky said.

Last year’s spending created 139 gigawatts of renewable energy infrastructure, 8 percent more than the amount of renewable capacity built in 2015.

“The report is a reminder that, if you set aside policy for a moment, there are factors in the marketplace which are continuing to push countries towards cleaner sources of energy,” Konisky said.

Of course, market forces alone cannot create the conditions required for renewable energy transformation. Policy also matters.

Since the election of President Trump, the U.S. has made a dramatic pivot from its global environmental agenda under President Obama.

Earlier this week, the U.S. dealt a blow to international climate cooperation: Top officials from the “Group of Seven” industrial nations reached a standstill in their attempts to draft a joint declaration due to a Trump administration review of climate policies. The final declaration was left incomplete.

A longtime critic of the landmark Paris Agreement, Mr. Trump has vowed to withdraw from the global pact governing lower carbon emissions.

Domestically, Environmental Protection Agency chair Scott Pruitt has ushered in a new chapter in the history of the EPA since his February confirmation, from reversing a key rule underpinning the Clean Water Act to clearing the way for the Keystone XL and Dakota Access pipelines. Before assuming leadership of the EPA, the former attorney general of Oklahoma made a name for himself among EPA opponents for suing the agency more than a dozen times. Recent emails unearthed by the Associated Press reveal Scott Pruitt’s strong ties to business leaders in the fossil fuel industry, an industry whose carbon emissions Pruitt is now charged with regulating.

Reflecting global averages, the UN report painted a rosy picture of renewable energy infrastructure worldwide. However, the report also documented a significant slowdown in China, Japan and some emerging markets.

In looking at the evolution of clean energy, Konisky emphasized the importance of examining multiple forces at play at the same time -- including political and market forces that may be counteracting each other.

“For the U.S., when you have policy moving in the opposite direction as the markets, it may slow down some of the de-carbonization and movement towards clean energy,” he said.