We tend to associate polar regions with vast stretches of white ice. Yet we rarely think of the permafrost - a layer of soil or bedrock that has been continuously frozen for years. By thawing permafrost in the Arctic, climate change is not only freeing vast amounts of carbon dioxide and other gases into the atmosphere. It could also stand to release another harmful substance into our air and waters.

“Over 100 countries around the world have so far guaranteed their citizens the right to a healthy and clean environment; however, the enforcement part of such initiatives has been a challenge,” – Arnold Kreilhuber, Deputy Director of the Law Division, UN Environment.

According to the latest data from Global Witness, at least 4 environmental defenders are killed every week

Of the more than 100 videos we produced in 2017, here are seven that bring out some of the highlights of the year.  1. World Pangolin Day On 18 February, we marked World Pangolin Day, which celebrates one of the planet's most bizarre - and endangered - species.    2. Launch of the Clean Seas campaign

Charito Elcano turned 60 this year, a milestone in a life fraught with ups and downs, challenges and opportunities and – in her case – tragedy. A tragedy that took the life of her brother and son and made her a fierce advocate for non-mercury small-scale gold mining.

Every year up to 15 million artisanal and small-scale gold miners are exposed to toxic mercury fumes. Around one third of these miners are women and children.

Geneva, 02 October 2017 – In a landmark display of international cooperation, more than 160 countries committed to tackling one of the world's greatest chemical health threats at the first meeting of the Conference of the Parties to the Minamata Convention on Mercury. The world's first environmental and health treaty in a decade saw many countries pledge political and financial support to help reduce and eliminate mercury, a heavy metal affecting the health of millions of people worldwide from Guyana and Kiribati, to Uganda and Japan.

As the mercury falls in Geneva with the advent of autumnal chills, the world is for the first time gathering to deal with the rising health impacts of the toxic chemical.