"Make no mistake, the tragedy unfolding in Australia is climate-change-based," Russell, who was born in New Zealand, but has lived in Australia for most of his life, said in the speech.
"We need to act based on science, move our global workforce to renewable energy and respect our planet for the unique and amazing place it is. That way we all have a future."
Joaquin Phoenix, Ellen DeGeneres and Patricia Arquette also spoke out during their speeches, while Cate Blanchett said she was "very grateful for the callouts to our fellow compatriots".
"When one country faces a climate disaster, we all face a climate disaster," the Australian actor said.
At least 24 people have died since the fires began in September.
Other Aussie stars like Nicole Kidman, who donated $500,000 to the crisis, spoke from the red carpet.
"Our family is safe, but obviously many families have been put under enormous stress and duress right now," she said, according to Variety.
"We’re so deeply upset and worried. There’s enormous strength in the country right now in terms of camaraderie and helping each other."
Kidman’s husband, Keith Urban added: "There’s a lot of people who have lost so much down there already and there’s more to come, too. We’re not out of the woods. This is just really the beginning of summer, but people are doing amazing work down there."