Bitcoin’s price surged Sunday evening stateside after Tesla CEO Elon Musk said the electric vehicle maker could accept bitcoin transactions again in future.

As of 1:52 a.m. ET Monday, Bitcoin surged 12.79% to $39,533.81, according to data from Coindesk. Since the start of the year, bitcoin has surged more than 30%, though its current price is way off the all-time high of $64,829.14 hit in April.

Those gains came after Musk said Sunday that Tesla will resume allowing bitcoin transactions “when there’s confirmation of reasonable (~50%) clean energy usage by miners with positive future trend.”

Teslas halted car purchases with bitcoin in mid-May, citing concerns over the climate impact of cryptocurrency mining.

Crypto mining requires massive amounts of energy to fuel powerful computers — bitcoin mining consumes more energy than entire countries such as Finland and Belgium, according to the Cambridge Bitcoin Electricity Consumption Index.

The latest development marks yet another example of large market moves following comments by the Tesla CEO and billionaire.

Hundreds of billions of dollars were wiped off the cryptocurrency market after Musk tweeted in May about Tesla’s suspension of car purchases using bitcoin. Musk’s past tweets have also been linked to moves in the stock market — ranging from so-called meme stocks such as GameStop, to the investor of viral song “Baby Shark.”

Bitcoin under environmental spotlight

The environmental impact of bitcoin mining has come under intense scrutiny.

As part of its crackdown on bitcoin, China’s Inner Mongolia region — a major bitcoin mining hub — in late-May proposed punishments for companies and individuals involved in digital currency mining. It came after Chinese Vice Premier Liu He said it is necessary to “crack down on Bitcoin mining and trading behavior” to prevent the “transmission of individual risks to the social field.”

Elsewhere, Iran’s government in announced in May a ban on the mining of bitcoin and other cryptocurrencies until Sept. 22, after officials said blackouts in the country’s capital of Tehran and several other large cities were in part due to the energy-intensive activity.