How climate change contributed to Harvey

Penn State scientist Michael Mann posted a short primer on Facebook that describes the connection between the devastating storm and global warming. While climate change didn't "cause" the storm, it's worsening the impact in several ways, he says.

• Rising waters: Sea level rise attributable to climate change (some is due to coastal subsidence due to human disturbance, e.g. oil drilling) is more than half a foot over the past few decades. "That means that the storm surge was a half foot higher than it would have been just decades ago, meaning far more flooding and destruction."
• Warmer waters: The rise in sea surface temperatures in the region by about a half-degree celsius in recent decades has led to a roughly 3% rise in atmospheric moisture content. "That large amount of moisture meant the potential for much greater rainfalls and greater flooding," Mann writes.