Heavy rainfall from Cyclone Daniel, the deadliest and costliest Mediterranean tropical-like cyclone in recorded history, led to catastrophic flooding and destruction in Libya a few weeks ago. Thousands of people died, with 10,000 more still missing. However, it wasn’t just the heavy rainfall that led to flooding. Human factors also contributed, such as aging infrastructure, which led to the collapse of two dams, and the building of homes in low-lying areas, subject to flooding.

The cyclone gained energy from the unusually warm waters of the Mediterranean Sea. This is a pattern we’ve seen all summer in the Northern Hemisphere – unusually warm waters. That fueled a hurricane in another unlikely place last month: California. Overall, today’s climate is around 1.2 degrees Celsius warmer than pre-industrial levels. Scientific research has long linked climate change to more intense rainfall and studies have found that for every 1 degree Celsius (1.8 degree Fahrenheit) of warming, the air can hold around 7% more moisture.

The World Weather Attribution initiative was founded in 2015 with a core team of researchers from several institutions across Europe, the USA and India, to understand these types of weather events. Each study tries to answer how climate change influenced the intensity and likelihood of an event occurring, as well as how pre-existing vulnerability worsened the impacts of the event. In the case of Libya, scientists found that planet-warming pollution made the rainfall 50 times more likely to occur and 50% worse. Extreme rainfall also hit Greece, Turkey and Bulgaria. In those regions, human-induced climate change made the extreme rainfall up to 10 times more likely. The destruction there included dozens of deaths and damage to large stretches of farmland.


The collision of the climate crisis with high levels of vulnerability will continue to lead to these types of humanitarian disasters. Thus, reducing vulnerability and increasing resilience are key to surviving these extreme weather events, now and in the future. Learn more about how water moves in the atmosphere and natural hazards and risks, in these two modules I’ve co-authored for Visionlearning. The website is supported by The National Science Foundation and U.S. Department of Education, with content written for introductory undergraduate classes.


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