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Extreme Rain and Drought Trends in California.

October 9, 2020

By Paul Homewood



 Further to yesterday’s post on extremely hot days in California, NOAA also produce this graph for extreme rainfall for California:





Clearly, rainfall is not becoming more extreme there, despite claims to the contrary.

There is also this very interesting graph on drought trends since 1000 AD:





Current drought trends are little different to most of the 20thC. Looking further back in time, California has suffered much more severe droughts for most of the last millennium.

  1. October 9, 2020 10:16 am

    Here’s the ‘US drought monitor’ which says:

    Since 2000, the longest duration of drought (D1-D4) in California lasted 376 weeks beginning on December 27, 2011 and ending on March 5th, 2019.

  2. jack broughton permalink
    October 9, 2020 10:45 am

    interesting to note that on the drought index there are about 20 distinct peaks and troughs over the last 1000 years which is in line with the rule of thumb that climate cycles are about 50 years long, rather than the 30 claimed by the WMO as the basis for climate rather than weather.

    I wonder where they got the historical data from …. before Columbus arrived even.

    • ThinkingScientist permalink
      October 9, 2020 12:44 pm

      Good point about cycles being longer than 30 yrs. Same is true of world temps – there is an approximately 60 yr cycle. Using 30 yrs as the definition automatically creates trends over 30 yr periods.

    • ThinkingScientist permalink
      October 9, 2020 12:56 pm

      Demonstration of the difference between 35 yr and 70 yr linear regression using Hadcrut4 at WoodForTrees.

      The green line (period 1910-1945) is the pre-AGW warming. The slope is almost indistinguishable from the warming 1980-2015 (blue line, supposedly all anthropogenic). The IPCC forcings for the second period are over 3x larger than the first period, yet the warming trend is almost identical.

      The magenta line is the trend from the 1910 – 1980, twice the period of the other two lines. The slope is clearly substantially lower and would represent an underlying trend less influence by the periodic behaviour. This would be interpreted perhaps as closer to a much slower long term trend.

      In any time series of natural data this ambiguity is very pronounced and is related to the stationarity assumption. Periods longer than data series could of course give the false impression of a warming trend when they are in fact part of long period cycle (say > 150 – 300 yrs).

    • October 9, 2020 10:28 pm

      See figure 7 – historical ‘indirect’ data mainly from tree rings.

    • Nancy & John Hultquist permalink
      October 10, 2020 5:25 am

      30 is a number from Statistics 101.
      30 year weather averages (Climate Normals) have nothing to do with climate, and were not intended to.

  3. MrGrimNasty permalink
    October 9, 2020 12:29 pm

    With the endless stream of fake climate alarmism stories rapidly becoming an inexhaustible supply of chip wrappers, it’s easy to forget all these declared ‘endless droughts’, ‘new normals’ etc.

    SA was running short of water a little while back as a result of perfectly to be expected weather combined with incompetence/mismanagement/politics. So what happened?

  4. Broadlands permalink
    October 9, 2020 1:16 pm

    Far from California in July of 1921 the news was reported:

    “BRITISH ISLES: London, July 10. England is sweltering and suffering the worst drought in a century. Today was the seventy-eighth virtually rainless day. For the third successive day temperatures have exceeded 100. The rainfall for the year is less than one-third normal to date.”

    CO2 was pre-industrial.

    • Mack permalink
      October 9, 2020 9:38 pm

      A bit like the mid 1660s. If it happened now in the U.K. we’d all be in ‘climate lockdown’!

  5. C Lynch permalink
    October 9, 2020 3:09 pm

    It’s not hard to see why a 30 year cycle is preferred – it’s far more conducive towards generating an Alarmist narrative.

  6. mardington permalink
    October 9, 2020 3:25 pm

    Proxy data is usually sketchy on any side of a query or argument. Nevertheless, what alarmists almost never consider -let alone have a grasp of- is TIME. TIME, TIME!!

    In my own narrow window of 1971 to present, working as a forester and forest pathologist, I was an environmental extremist from about 71-85. From 85-2000 there was a bit of a waffling/adjustment period as I was gaining more objectivity and observing phenomena contrary to my brainwashing, AND working outside of government circles. (Make NO mistake about it, academia in the earth sciences is overwhelmingly biased)

    Keep doing what you’re doing. I call it exposing a more probable truth. At the very least, seeds of doubt will be cast among the acolytes.

    M A Ardington Forest Sampling Systems 98501

    On Fri, Oct 9, 2020 at 1:26 AM NOT A LOT OF PEOPLE KNOW THAT wrote:

    > Paul Homewood posted: “By Paul Homewood Further to yesterday’s post > on extremely hot days in California, NOAA also produce this graph for > extreme rainfall for California: > Clearly, rai” >

  7. NeilC permalink
    October 9, 2020 3:54 pm

    It is 30 years since this whole AGW started (MBH98). Given the PDO and AMO have 60 year cycles (30 warm and 30 cold.

    The warming narrative has been on their side. However with both the PDO now in cold phase and AMO soon to become cold phase, the solar cycle 25 weak so far and a weak La Nina. The AGW nonsense will soon end.

    • Adam Gallon permalink
      October 9, 2020 6:50 pm

      AGW started before 1998, MBH98 & 99, were created to support it. Remember the first Earth Day was in 1970, Rio Earth Summit in 1992, along with the IPCC’s FAR.

  8. Robin Guenier permalink
    October 9, 2020 5:54 pm

    This might be relevant: ‘The Weaponization of Weather in the Phony Climate War‘ by Joe Bastardi.

  9. I_am_not_a_robot permalink
    October 9, 2020 9:45 pm

    Graphs like the one above combining measured and supposedly proxy values are a bit of a worry, as has been noted by many in the past.
    How are tree rings etc. given values in terms of degrees C or centimetres of precipitation?
    Supposedly in these studies proxies are ‘calibrated’ but that invites the use of artful statistical techniques by ‘activist scientists’, procedures such as proxy sample selection on the dependent variable employed to get a desired result as shown by Steve McIntyre and others.

    Why not show proxy data for the entire period up to the present?

    • October 10, 2020 2:44 am

      Good point by “not a robot”.
      Also not necessary to dig all the way back beyond the data to look for proxies.

      But I think the real issue here is circular reasoning and confirmation bias. If climate science contains a drought effect of warming they should predict it BEFORE it happens and not after it happens.

      They did make such a prediction for “the American Southwest” but it didn’t happen.

      Here’s the data. Actual measurements. Not proxies. Both PDSI and PHDI

  10. markl permalink
    October 10, 2020 3:36 am

    The MSM supports alarmist climate claims that ignore history and ignores skeptics when they reference history.

  11. MrGrimNasty permalink
    October 10, 2020 9:44 am

    Monty Don got his ‘BBC mandated’ climate change mention in yet again last night.

    Grass needs mowing much later in the year because climate change has made Autumn so much milder he said. As usual Monty’s casual climate alarmism is short on detail.

    The trend line shows English Autumns stopped warming 15 years ago.

    As for it being man-made? Well in the whole time series, the warming before the supposed influence of man’s CO2 (prior 1950/60) is about the same as since.

    There have been 3 exceptionally warm Autumns since 2000, but this could just be pure random weather. All other years are within the 100 year limits of variability.

    More importantly, today, the CET shows Autumn 2020 (September/October to date) is marginally colder than the mean compared to the ‘cold’ 1961-1990 climate reference period preferred by the Met Office!

    • NeilC permalink
      October 10, 2020 11:37 am

      Should they not be using 1981-2010 as a reference as per WMO rules. Using the cold period 1961-1990 is deceitful.

      • MrGrimNasty permalink
        October 10, 2020 1:47 pm

        Both are ‘within their rules’. Justification:-

        “Also under the WMO Technical Regulations, recognising the need for a stable base for long-term climate change and variability assessment, a fixed reference period is defined as the 30-year period 1 January 1961 to 31 December 1990. This period should be used to compare climate change and variability across all countries relative to this standard reference period. It will remain fixed in perpetuity, or until there is a sound scientific reason to change it.”

        4.8.1 in ******

  12. A C Osborn permalink
    October 11, 2020 9:58 am

    The graph that really stood out in that summary was warm nights.
    CO2 or UHI?
    The other item to note was the rcrzy projections for the next 80 years, they looked nothing like the trend for that last 80 years.

    • MrGrimNasty permalink
      October 11, 2020 10:48 am

      It’s a bit like what we’ve seen with pandemic model projections of deaths, action is being based on these forecasts that deviate so far from current and previous trends, no sane person could consider them even a remote possibility.

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