| HN Mirror

I have a family member that works in the field, and it's pretty crazy how little attention we pay to weather extremes. Not only do we not plan on dry years, we also don't plant on wet years.

We tend to make very optimistic views of weather cycles, then plan for best. Where he works in California, a large portion of the total rainfall occurs during El Niño cycles, which means once a decade or so, they'll get a year or two with several times the rainfall of the other years in the rest of decade. They take the average of the whole decade, and plan that as the baseline. This means that under normal weather cycles, they expect most years to be far wetter than data shows they will be, and the remaining years are treated as extreme rainfall, despite it being regular and predictable.

On top of that, they only have ~200 years of data, but most of the data points only cover half that time. They use the newer data to create their models, because it has more data points, despite knowing the whether was much worse in some of the earlier data, with extremes like a hurricane that hit San Diego in 1858 and the worst-ever-recorded flood in 1862.

The only way to handle weather extremes is to design around future expected variations when building infrastructure. Whether we tried to use all of humanities resources to change course, or there were no anthropogenic effects at all on the climate, the glaciers would be melting and lakes would be drying up. There's nothing we can do to control these weather extremes in any meaningful way, but we are pretty good at figuring out what extremes to expect.

To put in in perspective, in the Late Pleistocene era, glaciers covered almost the entire US/Canada boarder and all of the great lakes, but California, Nevada, and Utah had their own great lakes. At the other extreme, before that ice age started, there was liquid ocean at the North Pole. This cycle occurs over hundreds of thousands of years, so infrastructure for any given lifetime needn't be planned around it. At the other end, we also have weather cycles that occur multiple times within the design life of any given piece of infrastructure, and we should design for those.