Climate Impacts Droughts, Floods and Hurricanes

Climate change is and will continue to amplify droughts, floods and increase the strength of tropical storms and hurricanes.  

Precipitation

Warmer air can hold more water than colder air.  Thus, as air temperature warm, we expect and are seeing both more extreme droughts and floods. These seems like a paradox, but let's examine this infographic to understand the changes.  It's easy to see how  higher temperatures lead to more evaporation of water and therefore bigger storm systems (clouds are just water vapor). But what is not as obvious, is that this means that water  is being dumped in one place, and that is usually robbing water from somewhere else- ie where there will be a drought. 

More extreme droughts can occur because the warmer air masses will hold onto water, causing less rain. More extreme flooding is predicted because when it does rain, that air mass will likely hold more water and precipitate more.  In addition, we've seen some storms that are surprisingly sluggish - they don't move, but rather sit over one region and rain for longer periods of time than would otherwise be expected.  

For example, in 2016, a flood event in Louisiana received over 31" of rain in one week, and Hurricane Harvey in 2017 dropped four feet of rain in two days in Houston.

Accessible text for How Climate Change Impacts Weather image (Word doc) 

Hurricanes

Warm ocean temperatures are linked to increases in storm intensity for tropical storms, hurricanes, and typhoons.  Learn more about the link between hurricanes, ocean temperatures, and climate change in the 4-minute video below.  

California- Climate Whiplash 

What about California?  This research predicted that California is headed for a future of extreme swings between drought years and flood years:  

Research by UCLA climate scientists, published today in Nature Climate Change, projects that the state will experience a much greater number of extremely wet and extremely dry weather seasons — especially wet — by the end of the century. The authors also predict that there will be a major increase in the likelihood of severe flooding events, and that there will be many more quick changes from one weather extreme to the other. (Study forecasts a severe climate future for California, 2018) 

That was published in 2018 and seems like a good description of what we are experiencing.  Here are the important points from this research

Yearly Precipitation 

• • • There will be more extreme dry years
    • There will be more extremely wet years
    • If you average the amount of rainfall, the two extremes will cancel each other out. This gives the impression that there isn't any change. 
    • But if you live in California, it means that you will experience very wet years with high risk of flooding and also extremely dry years when there isn't enough water and we have severe droughts. 

Change in Start of Rainy Season 

• • • Our rainy season used to start in October and November
    • Wet weather will start later in the winter and be more concentrated
    • Spring and Fall storms will be less frequent

Climate Whiplash and Fire

All of this increases the conditions for wildfires. Plants dry out over the summer, and the longer the dry season, the more likely it will overlap with the dry warm winds that happen in the fall. Furthermore the yearly extremes, mean that there are more plants that have died due to drought. All of this adds up to more fuel for wildfires. 

California- The Great Flood 

In 1862 there was so much rain that the floodwaters in the Central Valley were 30 feet deep, 300 miles long and 60 miles wide. Sacramento flooded so badly that the governor at the time, Leland Stanford, rowed to his inauguration. 

"From the Sierra Nevada to the Coast Range is apparently one sheet of yellow rippling water,” the Marysville Appeal wrote.  There were 500,000 people living in California and 4,000 of them died, 1/3 of a taxable property (buildings) were destroyed, 1/4 of the cattle died, eggs cost the equivalent of $79/each. 

Today our population is 40 million. And this type of an event could happen again with unimaginably worse  outcomes. The USGS  calls this ''The Other Big One'' referring to the idea that the big earthquake that we all worry about. The cause of this Great Flood was a very high snowpack followed by warm rains in an atmospheric river. This lead to enormous amounts of water flooding down out of the Sierra Nevada.