When Secretary of the Navy Richard Spencer told the media last week that “the damn thing melted,” he wasn’t talking about an ice cream cone. As the Arctic faces unprecedented levels of open water, Spencer and other naval leaders recently testified to Congress about the U.S. Navy’s strategy, which is changing as quickly as the Arctic itself. 

Plastics. From the devastating effects of plastic pollution on our oceans, to the news that plastic bottles likely pollute the drinking water they contain, plastic pollution—the theme of this year’s Earth Day—has been a highly visible issue, and we’ve seen some notable progress on fighting the plastic battle.  

The Lanjiang river in Eastern Zhejiang, China, reached its peak water level of 100 feet the night of June 25, 2017. Lanxi residents remember this day as “6.25,” marking the worst flood since 1955. Elsewhere in China that month, 7.3 million people were affected by floods, landslides, and heavy rains in northwestern Sichuan Province alone. Northern Guangxi suffered direct economic losses of 2.9 billion RMB (US$460 million). In the autonomous regions, 92,000 people were relocated. Flash floods caused the deaths of 10 people and forced 76,800 people to evacuate from Shanxi Province.

To further its goals to strengthen the global economy, China has already invested $300 billion of its pledged $1 trillion towards its Belt and Road Initiative—a massive infrastructure investment plan that spans 60 countries across Southeast Asia, Central Asia, Africa, South Asia, the Middle East, and Eastern Europe. China’s initiative will shift the world’s political, environmental, and economic landscape.

Just days before the 2016 Summer Olympics began in Rio de Janeiro, the Brazilian city faced an unsavory problem: how to handle its overwhelming sewage. Nearly half of Rio’s municipal wastewater flowed untreated into Guanabara Bay, where the waters were so polluted by sludge that direct contact was deemed a health hazard to Olympic athletes.

Every year, millions of shorebirds migrate to the Arctic to breed—some coming from as far away as Australia and New Zealand—and then head back again. Nearly all of the birds making this journey spend time in the food-rich intertidal mudflats of the Yellow Sea ecoregion, on the east coast of China and the west coasts of the Korean peninsula. But as China’s economy has grown, around 70 percent of the intertidal mudflats in the Yellow Sea area have disappeared—the land drained and “reclaimed” for development. All of the more than 30 species of shorebirds that rely on the mudflats are declining, and those that stop there twice a year are declining at a faster rate than those that stop only once. If the current trajectory continues, the Yellow Sea—once known as the cradle of China—will become the epicenter of extinction.

I pulled my horse to a stop along the banks of a little stream, which was wedged between two grassy hills speckled with wildflowers and pika holes, to admire the view of the Tibetan-Qinghai Plateau’s rolling hills evolving into snowcapped mountains.

Sewage—refuse liquids or waste matter usually carried off by sewers—is at the front lines of a global movement for clean energy. Innovative U.S. cities are digging into their dirtiest depths to create new sources of power that optimize economic benefits, generate clean energy, and control pollution. This wastewater-to-power movement is just beginning to catch on in China. But with some of the largest and most densely populated cities in the world, the country could be poised to lead a sludge-to-energy revolution.