by K. Richard, Apr 6, 2021 in ClimateChangeDispatch
In contrast to alarming claims about rare, 100-year flood events now occurring every few years due to global warming, scientists have determined the exact opposite is more likely true.
Not only have flood frequencies declined globally in the last 50 years, but the probability of a 100-year flood event is now so rare it has only been occurring once every 358 years on average since 1970.
According to the IPCC, there has been no clear evidence of a global-scale increase in flood magnitude or frequency in the last century (Hodgkins et al., 2017).
A new study (Slater et al., 2021) suggests that claims of flood magnitude, frequency, and probability dramatically increasing with global warming can be “misleading” if they use a stationary calculation approach instead of continually updating significant changes over time.
These scientists, using “observed annual maximum daily streamflow” records and a “nonstationary approach,” concluded there has been no obvious global-scale trend in 20-, 50-, and 100-year flood magnitude since 1970, with 100-year flood events defined as “flows of a given exceedance probability in each year.”