The demand for ivory, especially in Asia, and the greed of those who profit from this gruesome trade means that poachers kill one elephant every 15 minutes. In the past decade, more than one-fourth of the world's elephants have been slaughtered for their ivory.

And it's not just the elephants that suffer. Millions of tourists every year flock to see these giant animals, bringing vital jobs and income to some of the poorest communities on Earth. Kill an elephant and you rob people of their livelihoods. This senseless killing must stop, and it must stop now.

That's why I'm supporting a new United Nations campaign against the illegal trade in wildlife, which is pushing many species－not just elephants－to the brink of extinction in every corner of the world. Under the banner "Wild for Life", this campaign serves to raise awareness about the illegal trade in wildlife and embolden everyone to take action against these crimes, which destroy forests, fuel corruption, breed insecurity and divert money away from governments struggling to improve healthcare and education for their people.

The illegal trade in wildlife thrives on ignorance and indifference. That is why knowledge serves as such a powerful weapon against these crimes. Armed with knowledge, we can shop carefully to avoid buying illegally sourced products like ivory; we can report crimes using mobile devices and national hotlines; and we can support conservation initiatives that press authorities to combat wildlife crime.

If we take away the demand for ivory then the killing of elephants will end. That is why it's vital that we don't buy anything made from ivory no matter how intricately it is carved.

The terrible truth is that an elephant's blood has been spilt and entire families have been torn apart. This is the awful truth that we need to megaphone across the world. It's a truth that you can help spread.

It is not enough to weep for the countless animals that have been killed. The time for tears is over. The time for action is upon us.

The author is an actress and a goodwill ambassador for the United Nations Environment Programme.