Today California is getting speared from two directions: flood water is surging over a landscape that has been parched by a continuing drought.
The drought makes California’s land surface more impervious to water. This was illustrated in the “Great Flood of 1861–1862”, caused by weeks-long sequences of winter storms coming after a dry spell. It produced widespread catastrophic flooding across virtually all of California’s lowlands. It transformed the interior Sacramento and San Joaquin valleys into a temporary but vast inland sea nearly 300 miles in length and inundating much of the now densely populated coastal plain in present-day Los Angeles and Orange counties.
California is graced with mountain ranges, whose rock surfaces unfortunately limit rain-water absorption. But in addition to the parched landscape and rocky ranges, absorption limits have also decreased drastically because of the relatively recent establishment of major urban areas, which do not hold water back. Water floods through the cities in special channels, with no time for absorption as groundwater.
Recent estimates suggest that floods equal to or greater in magnitude to those in 1862 occur five to seven times per millennium.
Climate change has already doubled the likelihood of an event capable of producing catastrophic flooding, with even larger increases likely to come due to continued warming.
Overall, global weather is wild. New Year’s eve saw Easterners wearing shirtsleeves right after an Arctic blast create a Christmas Snow dump for the mid-West. Record high temperatures hit Europe. And all this is riding on top of a long-term drought that is affecting all the Western American states.
And much of it — if not all of it — is due to human-sparked climate change.
At this point let us address the cactus in the room: is climate change real? I defer to our Medium colleague David Gamble who wrote an excellent article on the reality of climate change. He noted that in the UK — a country without any push-back from U.S. industrial interests…