From a paper by the same title published in AGU’s journal “Water Resources Resarch” and also “Commentaries on Hydrology and Earth Surface” h/t to CTM
It is now well established that rising temperatures are increasing precipitation extremes. This has led many to believe that flood magnitude and hence risk are also increasing, while observational evidence suggests otherwise. This commentary outlines the reasons for this dichotomy and presents mechanisms that may be contributing to it. The implications of increasing precipitation extremes leading to reducing flood magnitudes are discussed, and an argument is made that understanding this changing link between the two is deserving of increased attention.
Abstract
Despite evidence of increasing precipitation extremes, corresponding evidence for increases in flooding remains elusive. If anything, flood magnitudes are decreasing despite widespread claims by the climate community that if precipitation extremes increase, floods must also. In this commentary we suggest reasons why increases in extreme rainfall are not resulting in corresponding increases in flooding. Among the possible mechanisms responsible, we identify decreases in antecedent soil moisture, decreasing storm extent, and decreases in snowmelt. We argue that understanding the link between changes in precipitation and changes in flooding is a grand challenge for the hydrologic community and is deserving of increased attention.
Summary:
There is a clear dichotomy between observed increases in precipitation extremes and the lack of corresponding increases in floods, with reduced flood magnitudes observed in many cases. Despite the conceptual arguments we’ve made, there remains a good deal of uncertainty in the relationships between changes in precipitation and flood magnitude across the spectrum of catchment, storm, and antecedent hydrologic conditions. Although changes in flood magnitude are unlikely to be explainable by precipitation changes alone, this has largely been the focus to date in the climate literature. Moving forward, along with a better characterization of changes in floods not directly driven by precipitation increases, we argue for a focus on the complexity of the relationships among the entire suite of variables (including precipitation extremes) that lead to the generation of flood extremes. In our view, the foremost among these are as follows:
- Changes to antecedent hydrologic conditions and their impact on flood response;
- Changes in the proportion and persistence of storms arising from different causative mechanisms, such as an increased proportion and frequency of convective extremes;
- Interaction among catchment size and geometry and changing storm characteristics including extent, intensity, and duration;
- Snow cover and snow volume changes and their changing contributions to flood extremes in a warmer climate;
- The role of land cover change (especially, but not only, urbanization) and the interaction of land cover change with climatic factors.
The full paper is open access at:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018WR023749
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Most rain gauges monitored by the National Weather Service, at least the usual automated ones at airports, were changed in/around 2003 from a tipping bucket type to the more accurate AWPAG. Tipping bucket rain gauges read low in heavy rain. There is a correction algorithm, but it is cumbersome for unsteady heavy rain, and I don’t know how much and how well it is used.
The plot thickens! 🙂
It is now well established that rising levels of climate indoctrination are increasing hysterical outbursts and behavioural extremes by activists. This has led many to believe that bad weather and hence risk are also increasing, while observational evidence suggests otherwise.
Here are three centuries of precipitation records for Paris, from 1680 to 2001 (with a large gap in the 18th century)
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2001GL014302
There is a slight upward linear trend in the data, varying by season, up to 10% per century. The plot is mostly cyclic, rolling hills and valleys, with occasional extreme spike every half century or so.
The article was keen on pointing out that the year 2000 was a very wet year
Where I live, inland south-eastern Australia, precipitation extremes are increasing, but at the lower end – rainfall from 1 Jan – 21 Apr 2019: 9mm, and the Darling River (Australia’s second biggest) is dry. So here the precipitation extreme is definitely reducing flooding.
On the other hand, in northern Australia…https://en.wikipedia.org/wiki/2019_Townsville_flood.
I think you’re making an unwarranted statement. There is no evidence that increased precipitation extremes — if they are increasing — is reducing flooding; it’s just not causing INCREASED flooding.
There’s a big difference in those two statements.
My comment was motivated by the post and comments talk about precipitation extremes (plural) but then only consider one extreme – higher precipitation.
I stand by my comment that extreme decreases in rainfall, resulting in longer droughts, reduces the amount of flooding. That’s different from ‘not causing increased flooding’. There are circumstances where flooding is valuable – to water and replenish floodplain.
There was a big burst of quake activity on the West Coast today, including a moderate quake up by Port Hardy Canada, after a lull for several days. The Phillippines had a strong quake as well. … https://earthquake.usgs.gov/earthquakes/map/#%7B%22autoUpdate%22%3A%5B%22autoUpdate%22%5D%2C%22basemap%22%3A%22satellite%22%2C%22feed%22%3A%221day_m25%22%2C%22listFormat%22%3A%22default%22%2C%22mapposition%22%3A%5B%5B-82.89698689394206%2C-5.9765625%5D%2C%5B82.85338229176081%2C408.1640625%5D%5D%2C%22overlays%22%3A%5B%22plates%22%5D%2C%22restrictListToMap%22%3A%5B%22restrictListToMap%22%5D%2C%22search%22%3Anull%2C%22sort%22%3A%22newest%22%2C%22timezone%22%3A%22utc%22%2C%22viewModes%22%3A%5B%22list%22%2C%22map%22%5D%2C%22event%22%3Anull%7D
UK floods have increased since 2000…
somewhere like Carlisle/Cumbria has had repeated 1 in 100 year record floods (exceeding twice the previous early 1800s record). The second set of floods went over the flood defences designed to cope with another outbreak like the first…
The UK has seen record new rainfall levels from slow moving depressions and indeed an increase in damaging storms and tidal surges.
It may not be evident in the USA, but the UK climate has certainly changed.
Please do try and make sense Ms Griff. Are the floods increasing since 2000, or since the early 1800’s? Clearly you have no real clue, and you are only here to make wild unsubstantiated claims to keep funding pseudoscience instead of feeding poor brown people. You never have told me why you hate poor brown people so very much.
The comment seems quite clear, that the post 2000 floods have been bigger that the previous floods, including the previous 1800s record high. The following gives some un-wild substantiation, easy to find on-line. There’s no doubt a final report available.
Carlisle Flood Investigation Report Final Draft – Cumbria
https://www.cumbria.gov.uk/eLibrary/Content/Internet/536/6181/… · PDF file
The city has a long history of flooding with notable floods in 1771, 1822, 1856, 1925, 1968 and more recently in 2005. The 2015 flood level on the River Eden was 0.6m higher than in..
No pseudoscience, just data. Even if you disagree with it, there’s no need to be uncivil.
So alarmism is civil? Even when it results in millions of starved children? I never knew. Silly me.
It helps to recognize that there are many different kinds of flooding.
The IPCC’s special report on extreme weather claimed that short periods of intense rainfall had become more common. This is the kind of rainfall that produces flash floods.
Other floods are caused by weather fronts that remain stationary to an unusually long period of time. This is sometimes called blocking, and causes day after day of rainfall in one particular region.
For somewhat similar reasons, Hurricane Harvey stalled over Houston and produced extraordinary flooding.
Another reason for flooding is a sudden melting of accumulated winter snow.
In some locations, flooding is caused by “atmospheric rivers” delivering a large amount of moisture from the tropics to temperate zones.
Although intense rainfall has become modestly more frequent (as predicted), none of the other causes of flooding has been observed OR predicted to increase.
The biggest reason for changes in flooding is man: We dammed rivers, built levees along long stretches of rivers, and shaped then in many other ways. Man contributes in some way to all modern flooding, but usually not through burning fossil fuels.
We changed the way we measured precipitation – in the past rain gauges could not measure large rainfall nor measure the rate of fall in short cloudbursts. We can now. I think the supposed “change” is purely down to instrumentation changes.