Are you keen on starting an environmental blog to post about your opinions regarding the state of the environment or problems plus solutions. One easy way for you to do so is via blogging. If your requirement is not too demanding, you can start putting content on the World Wide Web within minutes using www.blogger.com or www.wordpress.com both of which are free and also host your blog for you for free.
However, if you want more freedom on what you are allowed to do, you will have to go with the self-hosted www.wordpress.org which requires you to purchase/register a domain plus purchasing a package from among one of thest webhosting for your blog.
If you choose this route to a self-hosted blog, one thing you should familiarize yourself with is webhosting security which can be free or paid. It would be useful for you to know about 5 free Open Source Security Options
As a webmaster, it would be useful to read the CMS FAQ (Content Management System Frequently Asked Questions for there are numerous CMS available and choosing one can be a headache.
I would consider the big 4 CMS to be Blogger, Wordpress, Drupal and Joomla although some may argue with me in calling Blogger or even Wordpress (wordpress.org) a CMS but as far as I am concerned, Blogger can work as a kind of rudimentary CMS.