There's not really anything online that I can think of which offers a substantial focus in environmental management.

The closest you'll probably get is an online program that also offers a certificate option - but these are usually pretty minor programs, compared to Warwick. I'm thinking of East Carolina University, which offers a certificate in environmental planning, but which also has a much more regionally-oriented alumni base.

UMass Dartmouth also offers an MBA program that can be take online - and has a concentration in environmental policy.

But really, unless you did an in-class program at a ranked school like George Washington (which offers a great concentration in environmental management,) you'll most likely be better served by the more general Warwick online program.

I also remember that University of Cambridge has a part time Master of Studies in Sustainable Leadership with an important component of environmental management.

Thank you mba hipster and cvm for your kind advise.