Tunza is a magazine produced by UNEP (United Nations Environmental Program) and written by and for young people across the globe. Each magazine, available on their web site in PDF format, focuses on a particular environmental theme addressed from a variety perspectives.
The pdf version of the magazine is FREE (I believe the $5 price listed refers to the price of the hard copy since all volumes can be downloaded by clicking on the magazine cover). The magazine is available in English, French and Spanish.
Some themes of particular interest include:
La Economía Verde (vol 9.4, 2012)
La Salud y el Medio Ambiente (vol 8.4, 2011)
Más con Menos-los recursos y el Medio Ambiente (vol 8.3, 2010) This volume includes a wide range of articles about sustainable cities, markets, mundane products made sustainably, the use of plastics (lo bueno y lo malo), sports, food etc. Can be used with level 1 & 2 activities about clothing, furniture, shopping, daily routines, sports; level 3 & 4 activities about cities, the environment, food, politics, etc.
Unidos contra el Cambio Climático (vol 6.4, 2009)
Los Alimentos y el Medio Ambiente (vol 6.2, 2008)
Conexiones con la Naturaleza (vol 5.2, 2007)
Equidad de Género y el Medio Ambiente (vol 4.4, 2007)
Ciudades Verdes (vol 3.1, 2005)
Indigenous Knowledge and the Environment (vol 2.2, 2004)