When you're an environmental activist, every day is Earth Day, not just April 22. In many places around the globe, being an environmental activist can literally mean putting your life on the line.

More than 900 environmental and land-rights activists were killed around the world between 2002 and 2013, according to a new report by the watchdog group Global Witness.

The numbers are "shocking," says co-author Oliver Courtney. These are people "who have been killed in the line of protecting their rights to land and the environment ... often some of the poorest and most vulnerable people in the world."

"What's perhaps even more shocking," Courtney says, "is that all the signs point to a vast number of cases which are going unmonitored and unrecognized."

Courtney says two-thirds of the cases Global Witness documented in their report, Deadly Environment: the Dramatic Rise in Killings of Environmental and Land Defenders, involved conflicts over who has the right to particular tracts of land "and whether or not people who've been living on that land for generations can really assert their rights."

In particular, he says, the vast majority of those case have involved "resistence to the operations of mining or logging or agribusiness companies."

The report also found that very few of the killings are being prosecuted.

"One percent of the cases that we have documented (involve) a known killer who has been brought to justice," Courtney says.

Among the worst places for deadly environmental conflicts, the report found, is Latin America, which includes five of the six countries with the largest number of killings — Brazil, Honduras, Peru, Colombia and Mexico.

One of the common themes in this region, Courtney says, is a combination of concentration of land ownership in the hands of a few, very powerful land owners with a very large percentage of the population that remains poor and reliant on the land.

"That dynamic sparks conflict," Courtney says.

Courtney says governments need to do much more to monitor and prosecute threats and crimes against environmental and land-rights activists, but he says the responsibility for the problem doesn't stop there.

Mining, logging and agribusiness companies doing business around the world "have a responsibility to make sure that they aren't involved with or sponsoring this kind of abuse," he says.

And he says there's a role for consumers.

"This problem is ultimately driven by consumption in the rich world," Courtney says. "So that's something we have to consider ourselves on a day to day basis, and our governments have to legislate for."