"The hots are getting hotter. The dries are getting drier. Climate change is real. If you are in denial about climate change, come to California," said Governor Gavin Newsom, speaking at the Democratic National Convention last week through a short, self-shot video captured in a redwood forest about a mile from a wildfire. But are the dots between climate change and California's wildfires really that easy to connect?
But teasing out what's responsible for making natural disasters worse, and specifically to what extent climate change plays a role, can get muddled pretty quickly. For example, even as fires have become more destructive, some studies have shown a net decrease in wildfire burn area over the last 20 years. And while more people live in flood zones today than ever before, it's partly because there are simply more people than ever before that need housing.
First, that "natural disaster" is something of a misnomer. A hurricane that lands on an uninhabited strip of coastline isn't a "disaster" no matter how strong its storm surge. It takes civilization and human development to create conditions conducive to a disaster. Secondly, that climate change is only one among multiple factors that influence the frequency and severity of wildfires, severe floods, hurricanes and the like. There's simply no magic bullet.
With that in mind, let's look at what experts in the field -- climate scientists, meteorologists, statisticians -- have to say about climate change's impact on natural disasters.
Floods and storms (such as hurricanes and tornadoes) are by far the most common, accounting for as much as 70% of the world's total natural disasters, according to the World Economic Forum. Rounding out that list are earthquakes (8%), extreme hot and cold temperatures (6%), landslides (5%), drought (5%), wildfire (4%) and volcanic activity (2%). Combined, these events result in an average 60,000 deaths per year, or about 0.1% of global deaths overall.
Isn't there a difference between climate and weather?
Yes, but they're still closely linked. Weather refers to events occurring in Earth's atmosphere on a day-to-day basis. Weather concerns the short-term changes we experience, like the difference between rain and sunshine, or snow and sleet. Climate describes overall weather patterns across a much longer period of time -- like years and decades -- and over a specific area or region, like, for example, North America.
How can climate change influence both floods and droughts? And extreme hot and cold temperatures?
Water evaporates faster as temperatures warm, which means global warming causes more water to evaporate. This has changed the way water, both as rain and in the form of humidity, is distributed around the globe, meaning some areas have started having less rain than usual during certain times of the year (leading to drought), and other areas have experienced more (leading to flooding).
Earthquakes: No, the weather doesn't cause earthquakes, but there are several theories for how climate change might provoke them. Reduced atmospheric pressure might allow fault lines to shift more easily, increased rainfall following hurricanes may result in more erosion and reduces the weight on fault lines so they might shift more easily. They increased rainfall itself also might lubricate fault lines and lead to more slippage.
Extreme Temperatures: Fluctuations in temperature are ultimately a consequence of unusual changes to atmospheric pressure. Normally, what's called a "polar vortex" encircles Earth's two poles and blocks frigid air from drifting too far toward the equator. However, as air pressure fluctuates around the globe -- more wildly as a result of climate change -- those polar vortexes can become unstable, which may allow cold air to drift into typically much warmer climes, and vice versa.