For those that confess, with no apparent shame, they don’t really understand rudimentary climate science — like Sen. Joni Ernst — it must be comforting to believe the ruinous flooding Iowans endured this year is simply part of a natural “ebb and flow” of extreme climate events. However, for those that don’t derive bliss from sciolism, the reality is an anthropogenic rise in the concentration of greenhouse gases in the atmosphere has led to radiative forcing that is mostly to blame for these deviations in the hydrological cycle.
Indeed, due to warmer temperatures, the annual level of precipitation has increased in the Midwest since 1991, which is part of a feedback that involves higher levels of saturation vapor pressure and more substantial rates of condensation and evaporation. As a consequence, there’s considerably more soil saturation, which is either not absorbed, or frozen, without the insulation of snow, to a state where there’s very limited permeability. This is then exacerbated by a warmer stratosphere that allows for more of an outbreak of arctic air because of disruptions in the polar vortex and conditions where the heaviest snowfall is unusually segmented at later parts in the winter. When accompanied by heavy rain, though, the penetration of the snow banks accelerate the melting process and, as a result, the acuity and frequency of flooding become markedly more pronounced.
For this to change, we need more than half-measures, but I expect little from Ernst because, as Oliver Goldsmith observed, “every absurd delusion has its defender.”