Global spending on clean energy projects dipped 15 percent in the first quarter, bringing green investment to its lowest level in two years. Large wind and solar projects slowed in China, Europe and Brazil as the rising U.S. dollar dampened spending, Bloomberg New Energy Finance reported Friday.

About $50.5 billion was invested in the first three months of this year, compared to $59.3 billion a year earlier, the London research firm said. The last period to show weaker investment was the first quarter of 2013, when clean energy spending totaled $43.1 billion.

Even so, last quarter’s results should resolve investors’ questions over whether low oil prices, down 50 percent from last year, would harm global interest in wind, solar, biomass and other renewable energy projects. “These figures indicate the answer is not so much,” Michael Liebreich, chairman of BNEF’s advisory board, said in a statement.

Spending in China dropped 24 percent to $11 billion in the first quarter from a year earlier and plunged 62 percent to $1.1 billion in Brazil. In Europe, first-quarter investment fell 30 percent to $9.7 billion.

One reason for the decline may be that countries spent big in previous quarters and couldn’t sustain the growth. First-quarter spending tends to be the weakest because it follows a flurry of year-end activity by project developers and banks.

“There’s sort of a natural effect that if you have a strong year, it’s difficult the next year to go much above that,” Angus McCrone, a senior analyst at BNEF, told Bloomberg News. “It’s too early to say it’s a meaningful fall in investment that’s going to be continued through the year.”

Other countries did manage to boost clean energy spending in the January-March period. U.S. investment rose 2 percent to about $9.6 billion. India, which aims to grow its solar power capacity 30-fold by 2020, increased spending by 59 percent to $1.6 billion. Spending in South Africa jumped $3.1 billion from “almost nothing” a year earlier, BNEF reported.

"There's a lot of ground still to cover this year. No one knows whether the oil price is going to bounce back or collapse further. There is good momentum toward some sort of climate deal in Paris in December," Liebreich told Reuters.