Record-wet and record-dry months increased in regions worldwide

From Eurekalert

Public Release: 12-Dec-2018

Record-wet and record-dry months increased in regions worldwide

Climate change drives rainfall extremes

Potsdam Institute for Climate Impact Research (PIK)

More and more rainfall extremes are observed in regions around the globe – triggering both wet and dry records, a new study shows. Yet there are big differences between regions: The central and Eastern US, northern Europe and northern Asia have experienced heavy rainfall events that have led to severe floods in recent past. In contrast, most African regions have seen an increased frequency of months with a lack of rain. The study is the first to systematically analyze and quantify changes in record-breaking monthly rainfall events from all over the globe, based on data from roughly 50,000 weather stations worldwide. Climate change from fossil fuel greenhouse gases has long been expected to disturb rainfall patterns.

„We took a close look at observed monthly rainfall data – if it’s not just a few days but several weeks that are record wet, this can accumulate over time and lead to large river floods, or to droughts if it is record dry,” says lead author Jascha Lehman from the Potsdam Institute for Climate Impact Research (PIK). The impacts on people’s livelihoods in the affected regions can be huge, ranging from flooded houses to endangered food security due to large-scale agricultural losses.

 

 

Downpour in parts of US, Europe, Russia – drought in parts of Africa

The US has so far seen an increase of record wet months by more than 25 percent in the Eastern and central parts over the period 1980-2013. Argentina and bordering countries have experienced an increase of 32 percent. In central and northern Europe the increase is between 19 and 37 percent. In the Asian part of Russia the increase is around 20 percent, while South East Asia shows an increase of about 10 percent.

The scientists ran strict tests for the statistical significance of observed changes. Therefore, they so far see significant changes in dry extremes just in Africa south of the Sahara and in the Sahel zone where dry records have increased by up to 50 percent. „This implies that approximately one out of three record-dry months in this regions would not have occurred without long-term climate change,” says co-author Dim Coumou from the Institute for Environmental Studies (IVM) at Vrije Universiteit Amsterdam. „A central conclusion from our study is that, generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records – this largely fits the patterns that scientists expect from human-caused climate change.”

 

 

UN climate summit decides about future rainfall extremes

The scientists compared observed wet and dry rainfall extremes to the number of extremes that would be expected in a climate without long-term changes. „We checked for new records – monthly rainfall values that have never been observed before in a given region since the beginning of systematic measurements more than a hundred years ago.” Of course one expects to see some rainfall records simply due to natural variability. „Normally, record weather events occur by chance and we know how many would happen in a climate without warming,” explains Jascha Lehmann. „It’s like throwing a dice: on average, one out of six times you get a six. But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often with severe impacts for society and the environment.”

„It is worrying that we see significant increases of such extremes already at just one degree global warming,” adds Lehmann. „Right now, governments from countries all over the world meet at the UN climate summit – if they do not agree on solutions to limit warming to well below 2 degrees, we’re headed for 3-4 degrees within this century. Physics tells us that this would boost rainfall extremes even further.”

###

Article: Lehmann, J., Mempel, F., & Coumou, D. (2018): Increased occurrence of record-wet and record-dry months reflect changes in mean rainfall. Geophysical Research Letters, 45.

Weblink to the article, once it is published: https://doi.org/10.1029/2018GL079439

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86 thoughts on “Record-wet and record-dry months increased in regions worldwide

  1. They say it “largely” fits in with what climate science expects. What sort of scientific term is “largely”. Over what timescale did they base their findings?

    • You didn’t.

      Arguably, the Goldilocks Climate Epoch was 9000 to 5000 BP ie. the Holocene Climate Optimum.

      It was warmer then. The Sahara was lush and green. link That should put paid to the notion that global warming will cause Africa to dry out.

      The thing about CAGW is that it ignores the evidence of what has happened previously when it was warmer.

      • ” … ignores the evidence …”

        Rather then attempt to explain contradictions, they ignore anything that disputes their position. This is unambiguous evidence that this whole CAGW fiasco has nothing to do with the climate and is all about power, control and money justified with fake science supported with self righteous indignation, hollow rhetoric and fear mongering.

        One sure thing is that the longer this CAGW foolishness persists, the harder the political left will crash and burn. This is why politics should never choose sides of controversial science as there’s a 50/50 chance they will choose incorrectly. This is also why the left so stubbornly holds on to its flawed position. Anyone with the least bit of scientific acumen can see how wrong they are, yet to admit this would seriously harm the rest of the left’s agenda, much of which is similarly supported.

      • That’s because it’s never ever been warmer ever, ever, ever, honest g’vnor, a tree told me.. so sayeth Mr Mann

  2. But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often with severe impacts for society and the environment.”

    Right. I’m runnin’ on empty, Doc.

  3. ”A central conclusion from our study is that, generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records – this largely fits the patterns that scientists expect from human-caused climate change.”

    These climate fraudsters think people don’t remember their previous “predictions.”
    The subtropics and tropics are wet. They were predicted to get wetter, not drier. The midand high latitudes are generally drier, and were predicted to get drier, not wetter.

    But with climate pseudo-science all possible outcomes are expected. That is what makes Climate Change pure junk science.

    • Show me the man and I’ll find you the crime (Beria.)

      Show me the weather and I’ll find you CO2 warming.

      Same motivation.

      • For some reason, I had never heard of Beria. Holy Moses! My respect for Khrushchev just went up by an order of magnitude. It’s ‘amusing’ that Khrushchev may have cooked him with the same recipe that Beria himself had used on so many others.

        Your point is well taken. The SJWs who push the global warming narrative do show a Beria-like level of ruthlessness.

        • There was a movie last year called “The Death of Stalin” which is an EXTREMELY BLACK HUMOUR version of the events around …the death of Stalin. Be warned, it is not for the faint of heart.

    • this largely fits the patterns that scientists expect from human-caused climate change.

      These ‘scientists’ do not seem to consider natural climate change at all or, alternatively, do not expect any natural climate change, ignoring all changes before CAGW began (1950?).

      Idjits

  4. Sounds like green propaganda on steroids.

    Just like here in Sydney where last month (November) an Australian Bureau of Meteorology (BoM) spokeswoman had the temerity to tell us that the 105mm of rainfall experienced on Wednesday 28 November was a “once in a hundred year” event.

    Unfortunately for her, there’s 160 years of records from Sydney’s Observatory Hill collected by her organisation (BoM), that puts the lie to her nonsense. Over that 160 year period there’s been 127 days recorded when rainfall exceeded 100 mm; and 107 days when it exceeded 105 mm.

    Now, we all know that the green-left find arithmetic a challenge, but even the dullest of them should be able to do a simple division to obtain an average that is some considerable way short of once on a hundred years.

    The truth is not in them. Believe them at your peril.

    • Skeptical Sam

      That is hilarious. Honestly, how much easier could it be to see such a lie rebutted? Using data?! Data is for rubes.

      Another bizarre claim in the article is that some “expert” knows, as in, has prescient knowledge, of how many “extreme” events and records there will be. He doesn’t have expectations, nor calculations of statistical significance, he has knowledge. Dang! I gotta get me some o’ dat larnin’.

      He even knows that the globe will warm three to four degrees C in eighty years. It will be a bit embarrassing if his zeroth-order first guess at the ECS is out by a factor of five or ten.

    • “(BoM) spokeswoman had the temerity to tell us that the 105mm of rainfall experienced on Wednesday 28 November was a “once in a hundred year” event.”

      Seems it was …. but for the RATE of rainfall and not the total.

      From:
      http://catallaxyfiles.com/2018/11/28/wednesday-forum-november-28-2018/comment-page-2/

      “Rae
      #2874803, posted on November 29, 2018 at 9:43 am
      Met says Sydney rain “worst in a century”.

      Lol. “The sky is falling, the sky is falling.” Seems this is what was actually said:
      Bureau of Meteorology (BOM) spokesman Rob Taggart described the rainfall as “phenomenal”.
      “91mm fell in 90 minutes, that’s basically the equivalent of a one-in-100-year event,” he said.

    • (if my first post turns up)
      Re”
      “Now, we all know that the green-left find arithmetic a challenge, but even the dullest of them should be able to do a simple division to obtain an average that is some considerable way short of once on a hundred years.”
      And:
      “That is hilarious. Honestly, how much easier could it be to see such a lie rebutted? Using data?! Data is for rubes.

      From:
      https://www.bbc.co.uk/news/world-australia-46366961

      “Australia’s Bureau of Meteorology said it was the region’s wettest November day since 1984.
      “The intensity of that rainfall was phenomenal – 91mm fell in 90 minutes,” forecaster Rob Taggart told the Australian Broadcasting Corporation.”

      And:
      http://catallaxyfiles.com/2018/11/28/wednesday-forum-november-28-2018/comment-page-2/

      “Bureau of Meteorology (BOM) spokesman Rob Taggart described the rainfall as “phenomenal”.
      “91mm fell in 90 minutes, that’s basically the equivalent of a one-in-100-year event,” he said.

    • You will lose that communications war. You don’t use the language of the New Majority.

      The old ways of communicating dealt with facts, reason and logic. The new ways are all about triggering emotions.

      “Once in a Hundred Years”® triggers an emotion of “this is highly unusual” given that for most people today, history begins the day they were born. Everything is relative to their own subjective experiences as seen through emotions.

      So lots of precipitation, or sun, or wind or something a few SD’s away from what is declared to be “normal”. The emotion is “OMG! OMG! OMG!” then have an experienced manipulator trigger an associative emotion of “this never happens” (due to the 100 year > age of average Millennial) this puts the subject into an emotion of unresolved angst because someone was always around to fix problems or inconveniences. So our manipulator then finishes the Truth Claim through emotional closure by saying “Climate Change”. Previous exposure to emotional triggering has already ingrained the idea that humans can control the WX, the manipulator then associates themselves with the Savior – the one who can remove the angst.

    • OK. For the record.

      Here’s the BoM’s 160 years worth of records for Observation Hill:

      http://www.bom.gov.au/climate/averages/tables/cw_066062_All.shtml

      Now, perhaps all the apologists for the BoM and its chief propagandist might like to point to the data that records Rob Taggart’s phenomenal “intensity” of rainfall excuse.

      160 years of data and the BoM’s Rob Taggart makes a one in a hundred years claim based on “intensity of the downpour. Where’s the data, A P Banton? Show us the data for the 160 years that supports intense Taggart’s nonsense.

  5. “Argentina … has seen a 32% increase in rainfall” is totally a false statement. Argentina is in the third year of a drought, with current water reserve (reservoir capacity and snowpack) at 50% of normal. I just drove over the Andes from Argentina to Chile, via the Libertador Pass, and we remarked on how there was no roadside snow, which we had never seen before at this time of year. Wherever they are getting their data it is suspect.

    • Thanks. I live in Morehead City and we’ve already had 90+ inches of rain this year. Florence brought us 25 inches in one day.

      • And, of course, Florence – and Hurricane Michael – were just weather. So eastern NC has record rainfall, due to weather.

        ‘Climate change drives rainfall extremes’ is opportunistic propaganda.

  6. Global Warming will make wet areas get wetter and dry areas get drier, and it will also make wet areas get drier and dry areas get wetter. With Global Warming all outcomes are predicted and expected and the theory cannot be falsified by any means at all. The future is certain, only the past is changing.

  7. Potsdam Institute for Climate Impact Research (PIK)

    We took a close look at observed monthly rainfall data – if it’s not just a few days but several weeks that are record wet, this can accumulate over time and lead to large river floods,

    The presence of flood control dams, power generating dams and water reservoir dams will cause rainwater to accumulate in river channels upstream from the dam, ….. but that water is not allowed to accumulate “over time” because it is constantly being released as needed or as necessary (to create “winter” pool)

    • ren – December 14, 2018 at 3:33 am

      Is the excess of ozone over the Bering Sea in the stratosphere due to the increase in CO2?

      Ren , the graphic you cited describes it as portraying … TOTAL OZONE December 15, 2018

      Given the December date, I think maybe you should have been asking “what was all that ozone doing congregated high in the stratosphere over western Canada and Alaska” ……. with NONE to very little ozone south of the Tropic of Cancer, ….. given the fact that there is very little to nil UV radiation (or Sunshine) entering the far northern atmosphere during the winter months.

  8. Over-use of the word ‘extreme’
    If I jumped up now and ran a marathon 0.1 seconds faster tan anyone else ever did, does that make me ‘extreme’?

    Also, can we please please dump the (wild) speculation?
    Please just present the results as you find them and let the reader make their own conclusion(s)

    Do Not treat your reader as dumb & stupid and then coerce them via Appeals to Authority into what you personally, or others, imagine to be the cause of what you’ve found.
    Do try to remember that, what should be, The Ultimate Authority here is your reader = the guy who votes for the politicians = the guy who pays taxes = the guy who pays your salary

    e.g. If I call in a plumber to fix a blocked drain, I want the drain clearing. I do NOT want a barrage of belching about how ‘extreme’ the blockage is, how you’ve *never* seen anything like it nor to hear that it was because I ate a beef-steak for dinner last nite instead of a bowl of (stomach churning) Polenta.
    (It may actually have been me pushing the polenta down the sink’s plughole wot did it. sorreeeeee)

    Nor do I want to hear your friend’s opinion on it or on what I should eat for my dinner tonite.
    If I want their opinion I’ll ask them myself.

    thank you

    • And doesn’t change your predictive power of your analysis which stays at a dubious correlation. You have decadal and multi decadal variations both in the historic reconstructions and actual real data which is explained with some hand waving.

    • Now if you want to be taken seriously prediction for average temperature at 415, 425, 440, 450 ppm CO2 please.

    • How can records be digitized when said records were “lost” in the mid-1990’s during office moves? I smell lots of bullcarp.

    • Steven, as you mention the UK, see this paper: https://www.clim-past-discuss.net/cp-2018-27/cp-2018-27.pdf . Take home message:” Thus, one cannot reach any clear conclusions about precipitation changes in warmer or colder background climates during the past centuries. ”
      Neither the ERAint reanalysis ( 1979 to now) nor longer records from the UK bolster the results ot the paper in question. Seems to me “prosa” 🙂

  9. Potsdam claims to have run strict statistical studies to derive this”study”.
    😜
    Now that is really funny.
    Almost like modifying (ahem) past temp data, or using tree rings as thermometers, erasing the MWP, ignoring past rain, drought and temperature records be when reporting weather.

    • Good point, why would they need to “use a comprehensive statistical tool” (whatever that is) to determine something as simple as 30 year running average precipitation?

  10. If I would have been a reviewer I would have a look at the best available data for precipation, ERAint with the help of the KNMI climate explorer.
    They state:
    “A central conclusion from our study is that, generally, land regions in the tropics and sub-tropics have seen more dry records…”
    https://i.imgur.com/HgEskZ4.jpg
    (The figure shows the monthly minimum data for land 0…35°N)…)

    “…and the northern mid- to high-latitudes more wet records-…”
    https://i.imgur.com/0Xgsh82.jpg
    (The figure shows monthly maximum data for land 35…55°N)

    and as a reviewer I would not be amused 🙂

  11. ‘Climate change drives rainfall extremes’

    ‘Climate change’ is not a force*. It can’t ‘drive’ anything.

    *It’s not clear what ‘climate change’ actually is. It is usually just sloganeering, as in this case.

    • “Climate change” is the result of a long-lasting change in the weather of a region. It is not a force that causes a change in the long-term weather. That would be like saying wet sidewalks cause rain.

      • But the only place on earth experiencing generalized weather change is the Sahel. Ipso facto, there is no climate change.

        At least ‘global warming’ could be real if we looked at Global Mean Temperature. The switch to ‘climate change’ (OH MY!) took reality out of the discussion.

  12. I have not looked at the “study”.
    What is the time period covered. My guess it is similar to the Arctic Ice – covers part of a cycle. So it is meaningless except good for fear mongering the false conclusions.

  13. Not being a climate scientist but only a simple physicist, I don’t have enough interest in this paper to spend much time on it, but I did spend about 15 minutes searching for rain gauge instrumentation over the past century. It would be vaguely interesting to see how much time the paper spends examining bias and error in the transition from mechanical tipping bucket rainfall measurements to more modern instrumentation over the past century and regional differences in that instrumentation. I am reluctant to spend much time examining extremal data from changing instrumentation in a field other than my own, particularly when I can’t put my hands on the details of the historical instrumentation. In my opinion, climate science could learn a lot from spending some time reading Galileo’s works.

  14. How much of the increased reporting of heavy rain in the US is from a change in rain gauge technology around 2003? Before then, most US rain gauges were of the tipping bucket type, which reads low in heavy rain. There is an algorythm that can be used to mostly correct for this, but it has to be applied differently over each .01″ “tick” /”tip” to properly correct recordings of unsteady heavy rain. After 2003, most rain gauges in the US have been AWPAGs, which are more accurate in heavy rain.

  15. „It is worrying that we see significant increases of such extremes already at just one degree global warming,”

    The assumptions are strong in this one! There is the assumption that the observed changes in rainfall are all the result of one degree of global warming. There is the assumption that the one degree of global warming is entirely the result of human emissions of CO2. In other words, there is the gross assumption that there is no such thing as natural climate variability. If CO2 concentrations in the atmosphere are stable and constant, than climate does not change one bit, which is clearly a false and ridiculous assumption.

    Since the assumptions are false, the conclusion is meaningless and invalid. It is just as equally possible that increasing CO2 has muted the observed changes and reduced the number of extremes that would have happened otherwise, or that the change in CO2 concentration has had no discernable impact at all. The ‘science’ cannot say one way or the other, even if the scientists cannot stop saying it.

    And again we have the use of the word ‘already’ where the word ‘finally’ is clearly warranted.

  16. This is record keeping and torturing data with statistics, but I see no science done here and the conclusions are mere speculation and arm waving.

    In fact, they don’t even say in the abstract the time period observed but instead say “Sparse rainfall data, however, have made it difficult to answer the question of whether robust changes can already be seen in the short observational time period.”

    • Ron, it seems they took individual rainfall data for particular months (The more unreliable the further back you go.) and calculated the long-term averages. They defined some greater or lesser numbers as “extreme” and applied them to fit their meme.

    • In other words: “You can’t see our data, methods or computer programs.”

      I am WOKE to their methods.

  17. “The scientists compared observed wet and dry rainfall extremes to the number of extremes that would be expected in a climate without long-term changes.”

    And what method did they use to determine what would be expected without long-term changes? The phony IPCC “with and without CO2” model runs?

  18. “It is worrying that we see significant increases of such extremes already at just one degree global warming.”

    If global temperature causes global weather, then how is it that global weather does not repeat when temperatures rise or fall to the levels they have been at previously? If you believe BEST or HADCRUT 4, then the temperature spike that occurred around 1876 was nearly matched in the early 1940s, and then again around 1980, after which temperatures continued to go up by an additional 0.5C or more. And yet, the horrific global drought and bizarre meteorological conditions that obtained in the 1870s (e.g. Minnesota farmers ploughing fields in December of 1878) were never repeated, either in the 1940’s, the 1980s, or thereafter.

    The same goes with the freakish weather of the 1930s, the global temperature of which was supposedly matched and exceeded in the latter half of the 20th century, yet without any similar weather phenomena emerging.

    Does this not suggest that either:
    a) the temperature series on which we compare past to present are wildly incorrect; or
    b) meteorological conditions, such as rain and drought, do not emerge from “global temperature” at all but are simply local phenomena and unrelated to global temperature?

    Additionally, if CO2 is well mixed in the atmosphere globally, and if small increases in global heat cause local weather phenomena to change, then is it to be supposed that those changes, having taken place, become immutable? If, for example, a 0.2C increase in global temp has somehow caused more rain clouds to form over the area where I live, then is it not equally possible that an additional 0.2C increase might cause those clouds to move somewhere else? Perhaps even move somewhere, God forbid, that could use a bit more rain?

    On what basis is it even possible to say that increasing CO2 / temp will cause a particular area to become wetter or drier, if that prediction is not made in specific reference to a particular concentration of CO2 or a specified global average temperature? Has it been determined that weather in each location can change as a result of CO2 increasing from 350 to 400ppm, but that from that point onward all changes are either immutable or only allowed to become “even more so” but not “even less so”? Seems to make very little sense.

  19. Of course you will see increasing records over time in some areas. Just like you will see decreasing records in other areas.

    What you are measuring is variability, not climate. The same result would be found regardless of CO2.

  20. we know how many would happen in a climate without warming
    =≠=======
    Actually you don’t, because you don’t have data from an earth that wasn’t warming.

    What you have is an earth that has been warming since 1850 and rainfall data for the same period.

    You do not have a record of what would happen without warming. All you have is a statistical guesstimate.

  21. After reading the abstract and supporting information, I am still wondering the size of each instance of a record. Was it a single weather station, a grid cell or a part of a continent? There are no comparisons which would indicate the statistical size of each “record setting event”. If the event is half a continent, then that is more alarming than the results of individual weather stations. In fact statistically, wet/dry events from individual stations are not significant.

    One graph does indicate that most of the data is from areas with high population densities. The Amazon basin had almost no data sources, but was included with coastal Brazil by infilling (I believe).

  22. When I saw this …

    “over the period 1980-2013”

    I knew it was nothing but cherry picking. Was is sad is there are some people who think these paper are science.

  23. If both were occuring in the same locations, it would be a different story. Shifts from one region to anothet are…well, “normal.”

  24. It would be interesting to understand what would happen if a clean air act was introduced in China. Would the increased insolation in the east change the jetstream and hence the track of precipitation? Would the associated warming be attributed to CO2?

  25. “if they do not agree on solutions to limit warming to well below 2 degrees, we’re headed for 3-4 degrees within this century. ”

    Wow, that is catastrophic!

    There can be no argument over that My poor grandchildren

    Regards

    M

  26. I find it difficult to believe they have accurate rainfall records going back a hundred years for most of Africa if they don’t even have proper temperature records. I suspect ‘modelling’.

  27. In Sweden they said we would face severe flooding from increased precipitation due to more evaporation from the warming.
    Then we had an unusual drought this Summer (I avoid using words like extreme or unprecedented) instead.

    Since there was an election in November, the Greens then changed it to attribute all “extreme weather” to global warming. Including drought.
    Some more honest scientists admitted they were surprised.
    Then they said this was “the worst drought since 1955”.
    Which made me think they just admitted it has nothing to do with CO2 then – or why was it so much dryer in 1955?
    They were almost voted out of parliament, so people are on to them I guess.
    The media, however, is not.

  28. Here in Aus we, apparently, have had two 100 year wet events in the last few weeks. It has been wet, thanks to to Tim Flannery, who predicted there would be no more rain.

  29. Bigger or more frequent episodes of heavy rain are to be expected with global warming. I think it is commonly agreed that this will put more water vapour into the atmosphere, which will make for greater precipitation. However, this will come with less draught. Which is why the Sahara was green 7000 years ago, and why it has always been bigger during glaciations and smaller during interglacials. Those that tell that we will have both more extreme rains and also more terrible draughts are lying, and the data does not support what they claim.

  30. That is the most severe case of near sightedness, reported as something new, that I have ever seen! It’s like they don’t even know ice cores exist. Of course climate has extremes now and then. If it didn’t, studying ice cores would be the epitome of boring “boring”research!

  31. Given how short the record is, and given how many places are monitored around the world. Just random variation would cause thousands of new records to be set every year.

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