Current News

Science Activities Update - Hydroclimate Whiplash in California

Posted on Friday, June 25, 2021

The April Science Activities lecture was given by Dr. Daniel Swain, climate scientist at UCLA and an ARCS NCC Scholar Alum. His Professor at Stanford, Noah Diffenbaugh (also an NCC alum!) introduced him and moderated the Q&A. The title of his talk was “Increasing Hydroclimate Whiplash in California”.

Dr. Swain clearly described the interconnectedness of droughts and floods in CA. While this may seem contradictory, understanding the science makes it clear that warming temperatures due to climate change are accelerating and cause an increase in atmospheric demand for water (increased water vapor). That demand for water in the air causes aridification of soil and vegetation; warmer temperatures reduce snowpack. In addition, the seasons are changing in California: spring and autumn (the dry seasons) are getting longer, while winter (the rainy season) is getting shorter. It is logical that these factors increase susceptibility to wildfires. Dr. Swain gave sobering examples of the wildfires between 2015 and 2020. He then explained how increased atmospheric water vapor due to warmer temperatures results in more intense precipitation (but reduced snowpack) which in turn increases the risk of flooding and post-flooding debris flows. He noted that there is a 50% risk of a major flood in the next 40 years (think Sacramento in 1862).

Dr. Swain concluded that we need to prepare for both drought and floods. He cited the prescribed burns on the Yurok Tribal land for forest management and the Yolo Bypass near Sacramento for flood management.

Need more? Listen to this talk on the ARCS NCC YouTube channel.

And check out Dr. Swain’s website:


Daniel Swain ARCS Foundation