Technologies to harness the power of water are crucial for a low-emissions future, but hydropower can cause serious damage.
Only about half of the heavy metal in the sea results from rainfall. The other half comes from gaseous sources.
German scientists say the July floods were about more than rain, and climate models need to adjust for factors rarely seen in Central Europe.
Water rights activist Óscar Eyraud Adams died in Mexico. 12 wildlife defenders died in DR Congo. Some 227 global activists died last year.
Unregulated sand mining has been documented in 70 countries and linked with several associated conflicts.
"When you can't irrigate your crops, you can't have a city of 40,000, like some of the Maya cities were."