Steve Greenberg: 'As CO2 levels rise to a record 400 ppm, it is clear a pending environmental catastrophe is upon us, which makes it even more alarming that the world's leaders are not taking significant action, based on their own self-centered economic desires.'

This cartoon is selected for our project About Freedom. An important part of freedom is the freedom to choose how you want to live your life.

This cartoon is selected for our project About Freedom. A traumatic experience can keep you captive long after you we're subjected to the experience.

Cartoon selected for our project About Freedom. The meaning of freedom becomes truly apparent when you experience oppression. This cartoon is available as a t-shirt design in our webshop.

This cartoon is selected for our project About Freedom. Freedom is living without fear of attacks or arrests.

This cartoon is selected for our project About Freedom. Your own problems in life can get in the way of your freedom. The cartoon is available as a t-shirt design in our webshop.

This cartoon is selected for our project About Freedom. In our modern, free society, we can feel imprisoned by fear of crime.

Free media will always be victorious over corrupt leaders that do not want the truth to be known. Check out more cartoons on press freedom here. This cartoon is available as a t-shirt design in our webshop.

Each year, an estimated 100 million sharks and rays, and 300,000 whales, dolphins and porpoises are caught by mistake.

Another general strike is underway today in Greece against the tough austerity measures imposed by the government. Check out more cartoons about the crisis in Greece here.