‘Yet another study finds little basis for attribution of extreme weather (drought-flood-storm) to human-caused climate change.’
Excerpts:
“There can be a tendency in some quarters to want to confidently attribute extremes to anthropogenic climate change in the absence of scientific consensus or to argue that it isn’t possible to link individual extreme events with anthropogenic climate change, neither of which is correct. Given that many extreme weather and climate events have occurred before substantial anthropogenic modification of the climate system has been clearly detected in many regions, an over simplistic attribution to human causes could be costly. For example, based on the occurrence of a particularly damaging extreme event, plans could made to adapt to an increasing frequency of such events in future when in fact this is not what is expected.”
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Flashback 1974: ‘Global cooling trend affects wacky weather’ – ‘Implications can only be described as disastrous’
…Obama in Malaysia: ‘You’ll See Oceans Rise…More Drought, More Flooding, Bigger Hurricanes, Typhoons’
Scientist: ‘There Is No Such Thing As A 1000-Year Flood’
Phrases like “100 year rainfalls” or floods or whatever for whatever period of time are awful. They convey an improper idea of uncertainty.
The phrase “X year event” is based on inverting the probability of the event; call that probability p. Thus “X year event” is equal to “1/p year event”, where p is the probability the event happens per year. That means a “100 year event” has a probability of 1%, and so on. A “1000 year event” sounds stupendous, and, to most ears, rarer than a 0.1% chance.
Anyway, these are all wrong.
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It’s perfectly correct to make the statements like this: “The last time a flood this size occurred was in 1945.” That statement is not, however, equivalent to (in 2015) “That was a 70 year flood.”…
Feds declare no climate link to floods – SC’s ‘1000 year flood’ only a 10 year flood! U.S. Geological Survey: ‘No linkage between flooding & increase in GHGs’
http://water.usgs.gov/floods/events/2015/Joaquin/HolmesQA.html
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.
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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.
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I heard that the river flow through downtown Columbia was 4 times the historic maximum; maybe that was close to the 1000-year flood?
The provisional peak flood flow that USGS measured for the Congaree River in Columbia was 185,000 cubic feet per second (cfs) on Sunday, October 4, 2015. The maximum recorded in history was 364,000 cfs in 1908, which is almost double what was experienced in this current flood.
In the 1930s, though, reservoirs were built in certain parts of the Congaree watershed upstream of Columbia, which makes a flood of 364,000 cfs unlikely. However, even in the 75 years since the construction of those reservoirs (see the peak record here), there have been floods that approach the 2015 flood. For example, in 1964 the peak discharge was 142,000 cfs, and in 1977 the peak discharge was 155,000 cfs.
So, if only the …
Can a Carbon Tax Save Pumpkins!? Claim: ‘Climate change could threaten your holiday slice of pumpkin pie’
…Climatologist Dr. Roy Spencer: South Carolina Flooding is NOT a 1 in 1,000 Year Event
South Carolina Flooding is NOT a 1 in 1,000 Year Event
http://www.drroyspencer.com/2015/10/south-carolina-flooding-is-not-a-1-in-1000-year-event/
There is no question that the flooding in South Carolina is exceptional, even historic. But a once on 1,000 year event? Sorry, but there is no way to determine that…there are simply not enough rainfall statistics over a long enough period of time to establish such a claim. But we do have information on previous floods over the last 100 years or so. So, let’s look at how the current event compares. The greatest multi-day rainfall reported on the CoCoRaHS cooperative rainfall monitoring website was 27 inches in Columbia, SC. The Congaree River crested at 31 ft. there on Sunday: Congaree River gage height at Columbia, SC. Here’s a photo taken about the time the river crested: Photo of Congaree River, Columbia, SC, Oct. 4, 2015, taken about the time of cresting. Now, for comparison, take a look at a bridge over the Congaree River during the record flood of 1908, when the river crested at 40 ft…about 9 ft. higher than the current flood event: Congaree River bridge in Columbia, SC, during the 1908 record flood event. Not to discount the misery and likely billions of dollars of damage caused by the current event, but when someone claims that a weather disaster is 1 in a 1,000 year event, they need to back it up. Unfortunately, there seems to be an trend toward classifying events as “1 in 1,000 years”, when there is no way of knowing such things. This is especially true for floods, where paving of urban and suburban areas causes increasing runoff, making river flooding worse for the same amount of rainfall. This is a big reason why flood events have gotten worse in the last 100 years…it has nothing to do with “climate change”. For some areas the current flood is no doubt a 1 in 100 year event, or even worse. But remember, it is perfectly normal to have a 1 in 100 year event every year…as long as they occur in different locations. That’s how weather records work.
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The Thousand Year Rainfall Fallacy: ‘Conflating odds of one individual station getting a 20 inch rain, with odds of any station getting a 20 inch rain.’
…South Carolina Floods – ‘A Thousand Year Rainfall’? Actually the worst since 1999! ‘There is nothing unprecedented about the single day rainfall this week in Charleston’
…Texas warns us that we’re unprepared for normal weather
http://fabiusmaximus.com/2015/06/01/texas-flooding-unprepared-normal-weather-85187/…