People watch photovoltaic (solar) panels during the 'Intersolar' Europe trade fair in Munich June 5, 2014. Around 1100 exhibitors will present their new technologies at the trade fair running until June 6, 2014. Reuters

The amount issued of so-called “green” bonds, debt instruments that raise money for specifically low-carbon projects, is soaring exponentially, according to a report released Thursday by the London-based Climate Bonds Initiative.

The organization’s annual report on the state of the bond market found bonds it labels green have jumped from less than $4 billion in 2012 to $11 billion last year. By June 10 of this year, the market had issued $18.35 billion in green bonds -- on track to reach $50 billion by the end of 2014 and $100 billion in 2015.

“The green bonds era has begun,” the report states. “Since our first edition in 2012, the green and climate bonds landscape is unrecognizable.”

The Climate Bonds Initiative’s labeled bonds make up 10 percent of the overall bond market and span seven themes: transport, energy, climate finance, buildings and industry, agriculture and forestry, waste and pollution control and water.

Notable corporations that have issued bonds include solar panel installer SolarCity, carmaker Toyota, Dutch food processor Unilever, French utility GDF Suez, Italian utility Hera and Washington, D.C.’s water utility, which recently decided to issue $300 million of debt in 100-year bonds.