COPENHAGEN—Cherelle Jackson turned a deaf ear to the threatening calls she got after publishing the first two parts of a story about a government-sponsored development project that was proceeding despite the misgivings of an environmental impact assessment. But, when someone set her office on fire a little over two years ago, the twenty-seven-year-old Samoan reporter fled to New Zealand without publishing the third part.

“In small countries it’s really easy to access people,” she said Friday at the international climate summit here, walking and talking as she rushed to a press conference about threats to environmental journalists. “Part of your job is to deal with the threat. So, I usually ignore the calls, but the burning down of my office is not easy to ignore.”

The number of environmental journalists that are being attacked and threatened is growing, according to twenty-six press freedom organizations who sponsored the press conference. A representative of Reporters Without Borders said fifteen percent of the cases that the group monitors worldwide are now linked to the environment. Other watchdog groups have also found that stories exposing environmental degradation wrought by governments, industry, mafia organizations, and even small-time polluters are increasingly risky for environmental reporters.

“The fact is that more and more journalists are being harassed and even killed for covering environmental issues,” said Jesper Hojberg, the director of International Media Support (IMS). “Without a free press and corporations will not be compelled to join the fight of global warming. Journalists must be free to investigate, and then must have access to the facts.”

Reporters Without Borders, IMS, Internews, and the International Institute for Environment and Development presented a call to action (pdf) on behalf of twenty-six international, regional, and national press freedom organizations, stating:

Media and press freedom organisations call on the world’s leaders to reaffirm their pledge to Principle 10 of the Rio Declaration and Article 19 of the Universal Declaration of Human Rights and urge all governments to practice transparency in access to information and to protect journalists reporting on environmental issues and climate change…

Efforts to combat pollution will be severely weakened if environmental journalists and activists are not free to investigate. Illegal logging will not be revealed, much less halted, if reporters are arrested when they take an interest in the story. Likewise, limiting and monitoring CO2 emissions will be difficult if not impossible if the media are not independent of vested interests and hidden agendas.

In a study (pdf) published in September, Reporters Without Borders listed the names of dozens of reporters who have faced some sort of violence for writing and reporting about the environment. Russian journalist Grogory Pako spent four years in prison for revealing that the Navy was dumping radioactive waste into the Sea of Japan. Uzbek journalist Solidzhon Abdurkakhmanov was sentenced to ten years for writing about the destruction of the Aral Sea. In Egypt, Tamer Mabrouk was sued for libel and fired from his job when he blogged that Trust Chemical Industries was dumping untreated water into the Suez Canal.

“[Threats against journalists covering the environment] are not new, but their number is growing,” said Vincent Brossel, the head of Reporters Without Borders’ Asia desk. “When the journalists are exposing companies and local governments that’s when they are in trouble. A few years back it was just a few cases per year. Now, for three years, fifteen percent of the cases we monitor around the world are linked with environmental issues [like] logging, pollution and impacts of climate change.”

In southern China, for instance, foreign journalists have been chased out of villages where most of the world’s discarded computers are stripped apart in an environmentally disastrous manner. The Reporters Without Borders study also found that local populations often support polluters because they provide jobs.

Betwa Sharma is the New York/United Nations correspondent for the Press Trust of India. She also blogs for the Huffington Post and is a freelance journalist whose work has appeared in Time.com, The Hindustan Times, The Indian Express, and The Daily Beast.