Like the grains of sand in an hour glass, 400 grains now sit at the bottom of the glass while just five grains remain at the top. The Earth's 400 ppm of atmospheric CO2 is a stark reminder of how little time we have left to act on climate and end our dependency on fossil fuels.

Anyone who has sat through UN negotiations knows that the process can be slow and frustrating. There are long stretches of inactivity followed by a day when you realize that big things can be achieved when people and countries come together to seek consensus. For those of us who have been working on climate issues in the aviation industry, last week marked the culmination of a number of years of work.

A dozen years ago sustainability was an uncommon word, and was used occasionally to describe anything that would maintain over time. Then the term gained new meaning as increasingly scientific studies were published with data relating to climate change and its impact on our planet.