How climate change denial is threatening our planet, destroying our politics, and driving us crazy. With the election of Donald Trump to the Presidency of the United States, it now seems climate change denial has reached into the most powerful political office in the world. In this special Sydney Ideas public lecture, world-renowned climate scientist Professor Michael Mann provides a somewhat light-hearted take on a very serious issue—the threat of human-caused climate change and what to do about it. Based on his recent collaboration with Washington Post editorial cartoonist Tom Toles, Professor Mann will review the scientific evidence of climate change, the reasons we should care, and the often absurd efforts by special interests and partisan political figures to confuse the public and attack the science. Despite the monumental nature of the challenge this poses to human civilization, and the seeming inability of political leadership to respond to the climate crisis, Professor Mann highlights ways forward in mitigating future harm and reasons for cautious optimism.