Three years ago, everyone started talking about green jobs. President Obama had pledged $500 million for environmental job training, and another $150 billion to create 5 million new sustainability-related jobs. The U.S Conference of Mayors was trumpeting a report that predicted there would be 4.2 million new green jobs introduced over the next 30 years.

Fast-forward to the present, and suddenly everyone is talking about green MBAs. Today, there are already 3.1 million workers employed in the green economy nationwide. The Bureau of Labor Statistics found that the bulk of those jobs are in the private sector, particularly in manufacturing, construction, transportation and waste services. The public sector had 860,000 green jobs in 2010, with local government providing more than half of them. As a result, sustainability knowledge is in demand, and a rapidly rising number of universities are offering degrees in sustainability and sustainability management.

Nearly 60 percent of all new academic programs or training opportunities in 2011 focused on green careers, according to the nonprofit Association for the Advancement of Sustainability in Higher Education. The annual review found that colleges and universities developed a total of 137 academic programs on sustainability in 2011, compared to 146 in 2010. More than $540 million was earmarked for green ed. Green job-training efforts increased 142 percent compared to 2009.

“Education is at the forefront of this change,” said Deborah Cerminaro Eldridge, a professor at St. Petersburg College in Clearwater, Fla. Speaking about her college’s own degree program in sustainability management at a Governing event in June, she predicted that the public sector’s share of green jobs will continue to grow. From sustainability directors and environmental engineers to carbon analysts and energy efficiency consultants, “government is obviously a key player [in the field],” she said.

To that end, Eldridge called on more cities to partner with colleges for what is “essentially free labor.” More than just funding green job-training programs, states and localities can give students meaningful, hands-on experiences in green projects and maybe, in return, find their future workforce.