Every year since 1972 the UN has hosted World Environment Day to encouraging people to treat the environment more kindly and realise that it's everyone's responsibility to make the change ... because it's not just us that our actions on the world affects — it will have an impact on all our future generations too.
Although World Environment Day activities happen year round they culminate on 5 June every year, with the aim of enabling everyone to realize not only their responsibility, but also their power to become agents for change in support of sustainable and equitable development. It is also a day for people from all walks of life to come together to ensure a cleaner, greener and brighter outlook for themselves and future generations.
This year's theme is Think.Eat.Save — an anti-food waste and food loss campaign that encourages people to reduce their "foodprint". According to the UN Food and Agriculture Organization (FAO), every year 1.3 billion tonnes of food is wasted; the equivalent of food production in the whole of sub-Saharan Africa. While this is happening around 15% of the world's population is under-fed or staving.
That is an enormous imbalance in lifestyles and which also has serious effects on the environment. So the Think.Eat.Save theme is intended to encourage you to become more aware of the environmental impact of the food choices you make and empower you to make informed decisions.
As I've said before, in my view there also needs to be root and branch reform of our whole environmental practice as well as of agriculture (for instance see here and here) — but that's really a whole other debate.
As always there is a whole raft more information on the World Environment Day website at http://www.unep.org/wed/, including a list of activities by country.