Bummer: USGS Blows Up SC 1000 Year Flood Meme, Denies ‘Climate Change’ Link

Many, many hyperventilating news outlets yammered on about the “1000 year flood” after the days and days and days of rain in in the Carolinas, especially South Carolina (I was supposed to join my parents in Hilton Head next week. They cancelled the vacation due to the extreme detours necessary to get there). Super-Warmists Eric Holthaus even took it up a notch and called the floods “Biblical”

“Biblical” Flooding Devastates South Carolina

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Sadly, this is exactly the type of event we can expect to see more of as the planet warms. One of the most straightforward responses to climate change is a quickening of the hydrologic cycle: Warmer air speeds evaporation and can cause rain to fall with greater intensity. This supercharges the atmosphere, and boosts the likelihood of devastating floods. What’s less clear is how many of these events it will take—major floods also hit China, France, and Guatemala over the last week, with more than 100 dead—before we start bending the global emissions curve away from a worst-case climate scenario.

Biblical! And, of course, blamed on ‘climate change’, and he, like the rest, mean mostly/solely the fault of Mankind.

What does the United States Geological Survey say?

Is this flooding in South Carolina truly a 1000-year flood?

While this certainly was a catastrophic flood with lots of damage and tragic loss of life, USGS provisional data and preliminary analysis show NO indication that a 1000-year flood discharge occurred at any USGS streamgages. However, based on that analysis, it does appear that the USGS streamgage on the Black River at Kingstree, SC and the one on the Smith Branch at Columbia, SC both measured peak floods in the neighborhood of a 500-year flood. Currently, there appear to be a few more streamgages experiencing a 25-year to 50-year flood, but the majority of USGS streamgages had flood peaks that were less than 10-year floods. USGS will have more accurate estimates of the flood probabilities out in the coming months, as the engineers and scientists in South Carolina take time to do more careful analysis of the statistics.

Oops. Look, even if it was, it doesn’t mean that this is all your fault for driving a fossil fueled vehicle, purchasing Chilean Sea Bass, keeping your AC at 72, using a hair dryer and ice maker, etc and so on. Weather events happen. And the climate changes over time. That’s the nature of the Earth.

Is this flood due to climate change?

USGS research has shown no linkage between flooding (either increases or decreases) and the increase in greenhouse gases. Essentially, from USGS long-term streamgage data for sites across the country with no regulation or other changes to the watershed that could influence the streamflow, the data shows no systematic increases in flooding through time.

A much bigger impact on flooding, though, is land use change. Without proper mitigation, urbanization of watersheds increases flooding. Moreover, encroachment into the floodplain by homes and businesses leads to greater economic losses and potential loss of life, with more encroachment leading to greater losses.

Double oops. Now, this doesn’t mean that changes in the climate (remember, climate is simply the long term averages of weather) might not mean lots and lots of flooding in specific areas in the future. But, this doesn’t prove anthropogenic causation. And, that is what the debate is about: causation.

Notice the second paragraph: land use. I’ve noted time and time again that Mankind does, in fact, have an effect on the climate. A small effect, but an effect nonetheless. A tiny influence through greenhouse gases, including CO2 and Methane. But, CO2 is not the “temperature knob”, and is not the main cause of all changes. I’ve noted the Urban Heat Island Effect (UHI). And I’ve noted land use. Land use can cause what was normal to change. Cut down a forest and the winds and humidity change. Even Al Gore’s Climate Reality had to admit, in their own Cult of Climastrology manner

Some scientists believe the retreat of Mount Kilimanjaro’s glacier can be attributed in part to a reduction in snow caused by deforestation or land-use change. Cutting down forests allows winds to sweep up the mountain, which in turn can affect cloud formation, and therefore the amount of rainfall. But more research is required to assess the extent to which deforestation is affecting Mount Kilimanjaro’s glacier.

In fact, most scientists have said “it’s the deforestation“. And when the forests were replanted, the glaciers grew.

But it seems like the 100-year flood is getting larger through time at a site near me, so you are saying that this is not necessarily from climate or land-use change?

Climate variability (dry cycles to wet cycles) plays a large role. There is a large amount of uncertainty around the flood quantile estimates (the value of discharge corresponding to the 100-year flood), particularly if there isn’t a long record of observed data at a stream location. For example, if there is only 25 years of data and a statistical analysis was done on that data to estimate the 100-year flood, uncertainty around the estimate would be quite large. It can look like flooding at that particular location is getting worse if there are 2 or 3 floods in a short period that exceed that estimate of the 100-year flood. However, if there were 700 years of data, it might show that what had been called a 100-year flood when there was only 25 years of data was really only a 10-year flood.

In other words, the Cult of Climastrology needs to ease up on their apoplexy and doomsaying.

Crossed at Pirate’s Cove. Follow me on Twitter @WilliamTeach.

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