Another benchmark provider is joining the march into environmentally focused indexes with FTSE's launch of the FTSE ET50 Index.

The index covers the world's top environmental technology companies and was developed jointly by FTSE and Impax Asset Management, an investment management firm specializing in the environmental sector. It has an annualized five-year total return of 31.7% versus a return of 19.7% for the FTSE Global All Cap Index.

The 50 components are selected from a universe of 500 stocks determined by Impax. All of the selected components are pure-play environmental technology companies representing categories such as alternative energy and energy efficiency (68% of the index), water technology and pollution controls (15%) and waste technologies and resource management (17%).

"The FTSE ET50 index will appeal to institutional and retail investors who want to gain exposure to and track the performance of these fast growing and dynamic sectors," said Will Oulton, FTSE's head of Responsible Investment. The index is designed to be used as the basis for investable products such as exchange-traded funds (ETFs) and structured products.

The FTSE ET50 Index is part of a trend. Indexes focused on ecology themes, many with ETFs based on them, have been cropping up fairly steadily in the last couple of years. These include companies such as WilderShares, KLD, HSBC and even Standard & Poor's have all recently launched ecologically oriented indexes.

In fact, S&P launched the S&P Eco Index, which covers eco-friendly businesses, just last week.

Call it the "Al Gore Effect" if you like (after his movie "An Inconvenient Truth"), but this particular trend in indexing is less about saving the Earth and more about capitalizing on companies that stand to benefit as global awareness of environmental problems increases.

As policies and practices change to become more environmentally positive, new technologies and innovations will be needed—indexes like the FTSE ET50 seek to capture the performance of the companies that will be offering those products and services.

According to a press release, the FTSE ET50 Index is just the first in what will be a series of indexes that FTSE will develop with Impax.

The benchmark's largest component is Denmark's Vestas Wind Systems, which has a weighting of 11.34%, followed by U.S. company SunTech Power Holdings Co. at 7.25%, First Solar Inc. of the U.S. at 6.03%, Spain's Gamesa at 4.99% and Iberdrola Renovables, also of Spain, at 4.08%.

The top 10 companies in the index have a combined weight of a bit more than 50%. The United States represents about 41% of the index, while Denmark is the second-largest country at nearly 15% of the index. Spain has a weighting of  10.57%, while Germany comes in at 9.10%. The fifth-largest country, Norway, has a weighting of just 2.94%.