The Paris Agreement on Climate Change comes into force tomorrow and local initiatives here, such as Trees That Count, are encouraging people to get involved in combating climate change. That initiative aims at planting 4.7 million native trees next year, that's one tree for every New Zealander. But there is potential for our forests to do even more. Scientists from NIWA are looking at the potential for our forests to act as carbon sinks, and they say they could play an even bigger role than we thought. NIWA researcher, Dr Sara Mikaloff-Fletcher, explains.