If you Google “arcane bureaucratic tool” the Department of Defense Directive (DODD) should be high on the results list. That said, these little-known directives can be very influential in how the Pentagon conducts its day-to-day business. Late last week, Deputy Secretary of Defense Robert Work signed out a DODD that may just be the most meaningful climate-related document the Department of Defense has released.

China’s “strictest air protection law” yet took effect on January 1, 2016, promising to bring big changes to its smog-filled cities. But some municipal governments have been ahead of the curve, working to clean up the air through experimentation and innovation. Shenzhen, China’s first special economic zone and which recently passed its neighbor Hong Kong to lead China’s most competitive cities, is one of these.

Climate change is the world’s greatest environmental threat. It is also increasingly understood as a threat to domestic and international peace and security – recognized by the Department of Defense as a “threat multiplier,” by Secretary of State John Kerry as “perhaps the world’s most fearsome weapon of mass destruction,” and by President Obama, in an address to graduates of the United States Military Academy, as “a creeping national security crisis.” The Supreme Court’s temporary blocking of the Clean Power Plan highlights the Federal-State divide over how to address climate change, but because of its national security dimension, climate change also raises unique separation of powers issues between the president and Congress with regard to how the military can respond.

It is “not sufficient to look at history for lessons on how we should prepare for and prevent future security risks in a climate change world,” said Swathi Veeravalli, research scientist at the U.S. Army Corps of Engineers’ Geospatial Research Laboratory, at the Wilson Center on January 14. Climate change and the extreme weather events it brings pose an “unprecedented” threat to human security. [Video Below]

In December 2015, Beijing issued its first-ever “red alert” for smog, its highest air pollution warning, which closed schools and restricted the number of cars on the road. Less than two weeks later, it issued its second.

Around the world, urbanization and climate change are transforming societies and environments, and the stakes could not be higher for the poor and marginalized. The 2015 UN climate conference in Paris (COP-21) highlighted the need for coordinated action to address the profound injustice of the world’s most disadvantaged people bearing the greatest costs of climate impacts. Among those at the COP were mayors from around the world advocating for the important role of cities in these efforts.

This fall, the National Intelligence Council released an intelligence community assessment of the extent to which factors such as climate change, severe weather, conflict, resource scarcity, disease, poor governance, and environmental degradation will impact peoples’ purchasing power and food availability over the next decade. They found “the overall risk of food insecurity in many countries of strategic importance to the United States will increase.”