Based on my previous reading, having the frozen tundra warm is a worst-case situation since there is an abundance of carbon trapped in the frozen ground. When it thaws, there will be a massive release of carbon that can hyper-feed the rate of climate change throughout the world. I guess there will be those who point to that event as being naturally occurring and not connected to humans.
But then there is this article on how attitudes toward the cause of climate change may be finally changing here in the United States, see Americans increasingly see climate change as a crisis, poll shows.