Claim: Global Warming Is Increasing The Intensity Of The North American Monsoon

sun heat

New research by the Southwest Watershed Research Center and the University of Arizona department of Hydrology and Atmospheric Sciences claims that global warming is causing our monsoon season to be more intense. KGUN9 carried the story (link). You can read the whole paper, published in Geophysical Research Letters: Intensification of the North American Monsoon Rainfall as Observed From a Long-Term High-Density Gauge Network (link).

KGUN9 characterizes this news as a bad thing (and we all know that global warming produces only bad results): “The higher intensity can also spell trouble for soil, as erosion would happen more often and quicker. Infrastructure, the researchers said, is also at stake. Drains, washes, walls and bridges need to be built to withstand a higher flood capacity.”

I my opinion, the purpose of this paper was to give the authors publishing credits, because it seems to do little else.

The research paper says: “The mean of rainfall intensities exceeding the 95th percentile have been increasing during 1961–2017 period for all durations longer than 1 hr at a rate of 0.50 to 0.03 mm/hr per decade….” Does an increase in the rate of precipitation of half a millimeter per hour per decade sound troublesome? (A millimeter is about the thickness of a penny.)

The study was conducted in the Walnut Gulch Experimental Watershed which is centered on Tombstone, AZ. Data were collected from 59 rain gauges dispersed over an area of about 58 square miles. (Metropolitan Tucson covers about 237 square miles.) In my opinion, making broad claims from such a small sample base is problematic.

The intensity of monsoon storms is highly variable; so is the amount of rain in individual storms. Let’s see if/how the amount of rain varies with temperature during the monsoon season.

Here is Figure 1 from the scientific paper showing the array of rain gauges and the area temperature and precipitation. If you look at panels “c” and “d” on the right side of the figure, there seems to be no relationship between temperature and the amount of precipitation.


Looking at the broader Southwest, we see there is also no relation between temperature and precipitation during the monsoon season. Note that the region has warmed since 1970 when climate scientists were predicting an imminent return to a glacial epoch.

Regarding the Walnut Gulch Experimental Watershed, the researchers say “Average summer rainfall, May through September, over the watershed for the 1961–2017 period has been approximately 293 mm (112 to 370 mm range), which represents approximately 60% of the annual total (Figure 1a).” That amount seems much higher than the amounts shown on the graph of the broader southwestern region. Extrapolation of conclusions from the small study area may not be justified for the region as a whole.

Studies like this should be taken with a grain of salt (and perhaps with a lime wedge and Tequila).
Note to readers:

Visit my blog at:

Index with links to all my ADI articles:

My comprehensive 30-page essay on climate change:

A shorter ADI version is at


  1. When talking about climate change, the time researchers choose to use for data is to small and irrelevant when compared to the lifespan of the earth. Think about it, 40, 50, 100’s of years in the scheme of things is but a blink of an eye. My how we like to think we as humans can change the direction of the earth.

  2. If we have more rain than normal it’s because of global warming. If we have less rain than normal it’s because of global warming. If we have hotter than normal weather it’s because of global warming. If we have cooler than normal weather it’s because of global warming. See? It all makes sense.

  3. Ha ha If it Rains in May its NOT A monsoon
    If it rains in june Its only a summer rain
    If it rains in late Aug and Sept its most likey a true monsoon.

    Come on, over 25 yrs here and we have had not a summer alike
    Weather is always changing
    Thats one thing we can always count on is change
    Everyone want to blame one thing or another on this change
    There is really nothing you can do
    Except for
    Stop cutting tress down == no more houses
    Stop using oil All forms of it
    = no cars. no tractors
    No food no airplaces no landing on mars etc
    Stop all cows from living ==
    No milk Wheres the Beef no burgers
    Stop all Cell phones =
    Watch people go crazy
    Stop all hot air & smog == Politicians from talking

    Everything is connected one way or another
    Unless your ready to live Cave Man Style
    Forget about worrying about how much rain we recive or snow
    Its when darkness out lasts our sun shine or visa versa
    Or the moon or sun stops to rise
    Is when you can just kiss your abutt goodbye
    We are selfish people Over the GLOBE there is no way you can stop Brazils tree cutting or raping of other forests or the dumping in our oceans
    Oceans ,,people have alot more to do with weather change and our and the worlds disregaurd for it
    If you really want to blame anyone Blame Us all humans on this hugh planet..and your self
    And or God and mother Nature !
    To many people To many wants
    To many needs To many wars
    To late to change it now
    So sit back and enjoy the little rain you do recive or the floods

    Climate change has always have been around Do you see any dinausars ? No! I wonder why!

  4. Yet my own observation is that the storm cells are getting smaller and more intense year by year. Being smaller they cover more limited areas, as at our place in Picture Rocks. A scant inch total rain this monsoon season. Fact, not opinion.

    • 30 or 40, or even 100 years is a tiny window of time to base conclusions on when seeking to understand a phenomena which has been occurring for tens of thousands or possibly millions of years.

      Fact, not opinion.

  5. Nothing but a process whereas one entity needs to extract money to continue its bs scare tactics and fear in order to justify its existence with payrolls involved while producing squat, from a legit entity that actually produces things for these idiots to take and squander.

Comments are closed.