Après Nous, Le Déluge: Extreme Rainfall Rises With Global Temperatures

University of Adelaide news release

A worldwide review of global rainfall data led by the University of Adelaide has found that the intensity of the most extreme rainfall events is increasing across the globe as temperatures rise.

In the most comprehensive review of changes to extreme rainfall ever undertaken, researchers evaluated the association between extreme rainfall and atmospheric temperatures at more than 8000 weather gauging stations around the world.

Lead author Dr Seth Westra said, “The results are that rainfall extremes are increasing on average globally. They show that there is a 7% increase in extreme rainfall intensity for every degree increase in global atmospheric temperature.

“Assuming an increase in global average temperature by 3 to 5 degrees Celsius by the end of the 21st century, this could mean very substantial increases in rainfall intensity as a result of climate change.”

Dr Westra, a Senior Lecturer with the University of Adelaide’s School of Civil, Environmental and Mining Engineering” and member of the Environment Institute, said trends in rainfall extremes were examined over the period from 1900 to 2009 to determine whether they were becoming more intense or occurring more frequently.

“The results show that rainfall extremes were increasing over this period, and appear to be linked to the increase in global temperature of nearly a degree which also took place over this time.

“If extreme rainfall events continue to intensify, we can expect to see floods occurring more frequently around the world,” Dr Westra said.

The strongest increases occurred in the tropical countries, although some level of increase seems to be taking place at the majority of weather gauging stations.

Dr Westra said, “Most of these tropical countries are very poor and thus not well placed to adapt to the increased risk of flooding, which puts them in a larger threat of devastation.”

This work is being published in the Journal of Climate and can be seen online.

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7 Responses to Après Nous, Le Déluge: Extreme Rainfall Rises With Global Temperatures

  1. Chad Brick says:

    Sometimes the obvious just really is true: higher temperatures = more evaporation = more rainfall. Duh. I’d like to say it is nice to see a study confirming this, but it would actually be better for us all if somehow magically a warmer world DIDN’T have more downpours.

  2. Jim Baird says:

    Chad wouldn’t it actually be better to rectify the problem?

    First by putting the heat to work

    Second by moving the deluge to the desert.

  3. Joan Savage says:

    It’s natural to focus on increased rainfall “in countries” as human suffering is felt immediately from crop damage and flooding.

    What are also of concern, at least to me, are the effect of increased rainfall over oceans and the shift in locales of extreme rainfall, on either land or sea.

  4. Jack Burton says:

    This has been obvious where I live for over a decade or more. It rains now very rarely, even though our upper Midwest climate used to produce many rainy days, like about one in four when I was a kid. It was a rule around here when going camping in the wilderness of the boreal forest that one must be prepared for rain at least 1 in 4 days, often 1 in 3. i.e. bring good rain gear and pack all gear in water proof packs.
    No fast forward to the 2000’s. It seldom rains at all. My rain gear has not been used on a camping trip since I don’t know when. But when the rare rain event does happen! It is a downpour. Several inches in an event is now common. Last summer a 24hr rain event brought between 15 and 22 inches depending on where you were. This was unprecedented around here. No record of anything close ever happening in historical times!
    Anyone over 50 can tell you that our climate in Northern Minnesota is radically different now! Huge noticeable changes.

  5. Rabid Doomsayer says:

    More extreme rainfall and more drought, much less normal rain.

    It is hard to realize just how well behaved our weather has been and how essential that good behavior is for our grain industries.

    Averages just do not tell the story. On average we will have a little bit more rain, but not where I am.

  6. Alex says:

    Are we sure that rectifies (at least part of) the problem, or is it ‘potentially’ just moving the problem from one place to another, and messing with things we don’t entirely understand (if we’re talking large scale changes in heat distribution)?

  7. Merrelyn Emery says:

    Yep, it’s all gone unpredictable in local regions and like many southern areas of Australia, we’ve gone tropical-looking green in Feb which is really unnatural. But despite the tropical down pours, the overall out look is still heading for drought and even as I type, fires in Victoria are wiping out beautiful bushland, homes and properties, ME