She went shopping. With her five kids, four of them girls. Two answers started to appear — "go local" and "no new stuff."

China has grand plans to green its buildings.

Coastal deltas are becoming more at risk of flooding due to land subsidence, or the gradual sinking of the Earth’s surface, and sea-level rise.

No single person could hope to count the world’s trees.

You often hear about renewable energy success stories in cities in the developed world — such as Vancouver, which has committed to get 100 percent of its energy from renewable sources before 2050, or San Diego, which has promised to obtain 100 percent renewable electricity by 2035.

The mission is ambitious, the motivations are myriad and the methods are many. What's more, the progress is notoriously difficult to measure.

"We are still in." On June 5, with these four words a group of U.S. businesses and investors with a combined annual revenue of $1.4 trillion sent a powerful message to the world

You'll be forgiven for missing it. You may have been enjoying what now seems to have been the last gasp of summer — having a long weekend on the beach or snatching the last couple of days with the children before they headed back to school.

By 2030, the target date for the United Nation's Sustainable Development Goals, the number of youth aged 15 to 24 years will reach nearly 1.3 billion globally, up 7 percent from 2015.

A warning: At the end of this article, I will raise some uncomfortable questions about sustainable development ...