The astounding western North America heat wave of 2021 broke records by tens of degrees, killed more than 1,000 people and sparked catastrophic wildfires. A new study affirms that it was driven largely by climate change, and for the first time comprehensively elucidates the multiple mechanisms — some strictly climate-related, others more in the realm of disastrous coincidences — that led to the mind-bending temperatures.The astounding western North America heat wave of 2021 broke records by tens of degrees, killed more than 1,000 people and sparked catastrophic wildfires. A new study affirms that it was driven largely by climate change, and for the first time comprehensively elucidates the multiple mechanisms — some strictly climate-related, others more in the realm of disastrous coincidences — that led to the mind-bending temperatures.