Plant Wax signaling Wetter Monsoon seasons for the Southwest ..and Southern California... ahead??

[Silas_Sancona]

We may be a month into N.H. Winter ( I use the meteorological definition ) but, as always, always looking ahead to the best of seasons here in the Southwest.

Sometime ago, i'd mentioned how the UofAZ was involved in undertaking a large study to get a better grasp on what the North American Monsoon cycle might do in a warming world, and see what clues  warmer episodes in the region's climate past might offer.   checking in for winter weather- related info from a couple local climatologists, i stumbled upon an article related to recent findings that study is tarting to shed light on, which follow thoughts i myself have had, and go against some other wisdom on what drives ..or drove.. water abundance / scarcity, and summer climatology here, and in California..

In my own rambling thoughts on the subject, i've always envisioned that the overall climate across this corner of the world fluctuated between one that was winter rain dominant -during cooler climate periods, ( when vegetation in the low desert might have resembled modern day Sedona / middle- elevation New Mexico ) and times the rain cycle was more summer dominant, much more so than it is presently... ( When tropical stuff, now present in Southern Sonora, would have been more common here )

Some research i have followed through the years regarding summer rainfall patterns here is highly conflicting.. For example, a few papers discussing the subject  had suggested that the monsoon was wetter during cooler times, which, to me,  wouldn't make sense since..

For one, during cooler eras, ..say when year round ice coverage is more extensive in the higher latitudes, weather patterns associated with that would have likely suppressed both the "4 corners subtropical High" that helps initiate the overall summertime pattern, and kept sea surface temps off California, Baja ..and in the Gulf of CA. much cooler.  Those would be the same eras where the polar jet would also hang out further south in the winter, promoting a cooler / wetter climate at that time.. Cooler water off California ( and Baja / in the Gulf of CA ) help keep the atmosphere above in a stable state, which isn't conductive for promoting convection ( why coastal CA. doesn't see much summer thunderstorm activity ). Same pattern also produces lots of dry, sinking air, which also suppresses potential convection..  Simply put, cold, dry, and stable air ain't conductive for thunderstorm development..

Other research discussions pointed out the opposite, more realistic  idea that ..to generate a healthy monsoon, the 4 corners high has to be strong ( less snow pack to melt off in the spring promotes that ) and displaced north of where it likely set up during cooler eras ( probably directly over AZ, or further south over N. Mexico ), SSTs have to be favorable ( ..The discussions i've shared regarding how summer temps in the GOC / E. Pac. can influence the Monsoon ) and other factors that are conductive to storm development have to exist ( plentiful humid, warm unstable  air, for one )

The bigger questions which the on-going study will likely answer  -more clearly at least-  relate to how ENSO and hyper active East Pacific hurricane cycles play(ed) a part, let alone just how far north ..and/or.. west the heart of the North American Monsoon may have extended in the past, and how intense it may have been,  ..and could be in the years to come..

While some have suggested that a strong El Nino might suppress the NAM, both of these research papers turn a few of those "thoughts" on their side a bit..  And contradict some "ideas" that the southwest was dusty, and bone dry, during the summer, during warmer times ( ..note the mention of lakes in both papers )

In a modern world, there are both positives and negative implications to the possibility of the southwest getting wetter in the summer..   Biggest obvious impact could mean less and less winter rainfall / snowfall..  That said, if planned out right, water capturing infrastructure could collect rainfall generated by a more intense and longer extended monsoon, which might offset some of the winter time precip. losses..  Obviously, more rainfall / intense rainfall events could mean more flash flood dangers / damage..  Again, proper planning and awareness could mitigate some of those threats..

As has been seen here the last couple summers, more rain / rain days could mean having to deal with less  extreme heat, ...or perhaps "Nuclear Season" gets squeezed into a shorter period, similar to what occurs further south in Sonora..  By the same token, if these studies show what i'm thinking they might, Southern CA. < Study is focused on the monsoon's presence / influence there also > ( ..and more of CA. in general, because, if S. Cal. gets wetter, moisture would waft further north at times, esp. along the Sierras ) could see more summer rainfall, which ..if planned for, could also lessen whatever loss of wintertime precip. might occur. ( There are many studies on what may occur w/ winter rainfall patterns in CA. in the future also )  Summers may become hotter / more humid, with more ..and longer lasting... Marine Heatwaves though..  GREAT for tropical stuff, right, lol..



While nothing in the future is certain, and the outcomes of two seemingly identical eras will never match perfectly,  this study is fascinating, especially since some of the results being noted were made using " Plant Wax"    ..A substance which covers the leaves of all living plants, ..is then shed when plants die,  and ends up being deposited in both Marine and Terrestrial soil deposits.. Fossil records like this are very hard to disprove, and more reliable than computer-generated thoughts.. Will be following the overall study / any others generated by it to what else is uncovered.. let alone to see what counter-discussions come about.

  Another aspect that has been discussed previously by researchers, which this study may be shedding more light on, is the possibility that ..in a warmer world, the Eastern Pacific may enter a prolonged "El Nino"-like state,  which in turn may mean more tropical cyclone activity, that generates a feedback loop, which generates ..more tropical activity -in the entire basin,  and more potential for storms -of some level of intensity-  to reach California and the Pac. N.W.  ( Pole-ward shift of tropical storm activity / how far north legit tropical systems may reach )..  In the suggested, earlier " thoughts", Hawaii may experience more hurricane activity than we've seen in recent times, as may the S.E. Pacific, off northern S. America south of the Equator, a region that is pretty much void of tropical activity currently. This study may add to those ideas also.

Again, some very interesting research that may have widespread outcomes..   Even if i won't be alive long enough to experience more than a taste of what may occur.. ( California hurricane, ..or two.. Please.. )

https://www.wired.com/story/pliocene-like-monsoons-are-returning-to-the-american-southwest/?utm_brand=wired&utm_social-type=owned&mbid=social_twitter

2022-11-monsoons-climate-conditions-future.pdf


Wetter, w/ less extreme heat during the summers, ~more often than not here~?   Yes, Please!..😁