The G20 summit comes amid tensions over trade, climate, and refugee policy and increased uncertainty over the U.S. commitment to multilateral institutions.

International efforts, such as the Paris Agreement, aim to reduce greenhouse gas emissions. But experts say countries aren’t doing enough to limit dangerous global warming.

The sprawling U.S. water system is central to the nation’s economy, but chronic underinvestment, increasing demand, and the consequences of climate change have revealed the system’s weaknesses.  

The dizzying rise of bitcoin and other cryptocurrencies has created new challenges for governments and central banks. Increasing popularity and high levels of market volatility have raised the stakes…