EHN editors picked China's smog plans, Canada's oilsands and coal's slipping grip as the top topics of 2013.
Several recent skyscrapers have had large-scale wind turbines designed into their structure to generate energy. But are they effective?
London Zoo conducts its annual animal census.
Why 2014's wearable tech needs to get smarter
An operation begins in Antarctica to rescue passengers from the research vessel Akademik Shokalskiy, trapped in ice for more than a week.