The leader of B.C.'s Green Party drew a crowd in Vernon.
On Thursday, Andrew Weaver spoke to more than 200 people at the Schubert Centre.
"His message was clear. The scientists have done their job, the science on climate change is absolutely conclusive," said Keli Westgate, with the Sustainable Environment Network Society.
"He gave a short history of climate change that clarified that scientists have known about the greenhouse effect since at least 1936."
Weaver gave examples of economic activity that puts the climate at risk.
"He then showed the challenges we face as well as the opportunities presented that we are continuing to miss," said Westgate.
"When asked how such a small quantity of gas as carbon in the atmosphere can have such a huge effect he likened it to the well-known impact that ozone, also a small part of the atmosphere, has. Overall, Dr. Weaver's presentation left people more sure than ever that action at all levels of governments are required urgently and will happen if people understand the urgency and demand action."
Weaver has a degree in applied mathematics, has taught and worked in atmospheric and ocean sciences around the world and, prior to being elected to the Legislature, was the Canada Research Chair in climate modelling and analysis at the University of Victoria. He was a lead author in the International Panel on Climate Change assessments which received a Nobel Peace Prize in 2007.