The Earth’s front-line defenders are disappearing at an astonishing rate. On average three environmental activists were killed each week in 2015, according to a recent report from the United Nations special rapporteur on the situation of human rights defenders. Global Witness, an international NGO that documents natural resource extraction, corruption, and violence, reports a 59 percent increase in deaths last year compared to 2014. In total, 185 killings of environmental defenders were recorded by Global Witness in 2015.

As Syria has collapsed, spasming into civil war over the last five years, the effects have rippled far beyond its borders. Most notably, a surge of refugees added to already swelling ranks of people fleeing instability in Afghanistan, Iraq, Pakistan, and sub-Saharan Africa, leading to the highest number of displaced people since the Second World War. At the same time, scientists have noted record-breaking temperatures, a melting Arctic, extreme droughts, and other signs of climate change. For some, an obvious question is: what does one have to do with the other?

“Climate work is practical, common-sense, good development,” said Carrie Thompson, deputy assistant administrator at the Bureau for Economic Growth, Education, and Environment at the U.S. Agency for International Development (USAID). “It’s prevention, and we all know that preventative medicine is the best medicine.”

AGADEZ, Niger — The world dismisses them as economic migrants. The law treats them as criminals who show up at a nation’s borders uninvited. Prayers alone protect them on the journey across the merciless Sahara.

A roughly three-foot increase in sea level will threaten 128 coastal military installations in the United States, valued at $100 billion, according to a study from the Union of Concerned Scientists. The report, The U.S. Military on the Front Lines of Rising Seas, argues that the growing exposure to storm surge and sea-level rise puts vital infrastructure, training and testing grounds, and housing for thousands of personnel at risk.

As global climate change affects livelihoods across the world, migration patterns are also changing. In a recent study published in Global Environmental Change, Clark Gray, Valerie Mueller, and I found that since the 1970s, climatic variations have been increasing internal migration across many South American countries, with few exceptions. And many people are headed to cities.

Environmental security? Climate security? How about planetary security. Last week at the venerable Peace Palace in The Hague, nearly 300 experts from around the world met for the somewhat dramatically named Planetary Security Conference, a new initiative aimed at bringing together people working on all things related to the environment, climate change, and their security implications.

“Before the famine my life was better. I was a man in my own country,” Abdi Abdullahi Hussein, a Somali refugee living in Kenya, tells The Climate Reality Project. “When you have livestock and a farm and it all disappears, it feels like falling off a cliff.”