How Can One Separate Seasonal Weather From Climate?

[JMJones0424]

This is an entirely selfish question. I am at a point in my life where I must decide to continue living where I am or move to a more opportune location. Don't get me wrong, I love being a Texan, and all you other mf'ers that have no clue what it is to be a Texan can go on living your pitiful lives not knowing what your missing. That being the case, there seems to be some pretty worrisome developments in the weather over the last few years. I have witnessed the driest March on record during the month that is supposed to be the wettest. At the same time, I have witnessed more instances of snowfall during the winter over the last five years than I remember experiencing from the late 60's to the mid 80's. I am afraid that I may be confusing weather with climate, and am looking for any excuse to remain invested in the land I currently own. However, I can not overlook the bizarre weather that I have seen over the last decade, and I wonder if I wouldn't be better off cutting ties and establishing myself somewhere that rainfall is more predictable. Basically, the question I'm asking is: Has anyone done predictive modeling of rainfall pattern changes due to global warming that agrees with current observations? Am I wrong to be worried that I may be clinging onto the next great desert?

[Essay]

...somewhere that rainfall is more predictable. Basically, the question I'm asking is: Has anyone done predictive modeling of rainfall pattern changes due to global warming that agrees with current observations?

 

Am I wrong to be worried that I may be clinging onto the next great desert?

NOPE! [see ref. to ITCZ below]

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I just finished a 100 level "science of climate change" class, and one section was on what the models show about precipitation. The models are pretty good at predicting general trends globally and for continents and oceans, but they break down at the regional level because of mountain ranges and coastal effects which can't be modeled yet. They don't even include small scale features such as rivers, lakes and hurricanes, or long-term features such as ice sheet dynamics.

 

Climate models aren't why we predict global warming either. GW is just simple physics (radiative forcing caused by CO2). The models about climate change are used only to predict the magnitude of feedbacks such as temperature, pressure, humidity, precipitation, winds, etc., caused by that extra heating (extra radiative forcing caused by extra CO2). ...Thought that was an interesting semantic distinction.

 

Check out:

http://ats150.atmos.colostate.edu/Lectures.html

 

Basically the gist is that wet areas will get wetter and dry areas will get drier... globally. For the U.S., it's generally hotter and drier, especially for the Central and SW, but the Rockies make specifics unpredictable. We'll spend the next century approaching the 5-11 degrees F heating predicted for [uS] 2100 [& +15 F. in the Arctic!]. This means less soil moisture and increased runoff from that less predictable precipitation. And speaking of "less predictable precipitation" ...increasingly extreme events (droughts and floods) are predicted, as well as increasingly FREQUENT extreme events.... That includes record-breaking precipitation/drought events as well as temperature events such as "# of days above 100" or any given temperature, or "streak" of days....

...and... Earlier and longer growing seasons, fewer days with frost, and more increased warmth at night that during the day are general overall trends too.

 

One easy exercise from the class was just to imagine your city/region with the climate of a similar place 400-700 miles to the south, such as Denver with the climate of Amarillo, Grand Junction with the climate of Tucson, or Illinois with the climate of Mississippi.

 

Globally.... Higher latitudes (and altitudes) will get more of the extra atmospheric moisture, while lower latitudes and altitudes will trend drier. But the models don't have any reliable predictions for regional-type mountain snow cover.

 

...And we are still on track to exceed even the highest emission scenario that currently informs that "11 degrees F" temperature predicted by the models.

 

Weather can be anything on any given day, but climate should be about how you make plans. Traditionally, the climate has been much more predictable than the weather.

Unfortunately, one of the biggest problems with climate change is the "change" part.

 

Especially in a complex, multivariate, nonlinear system with multiple positive and negative feedbacks... each change causes many unpredictable effects. So asking for the predictability of weather in any specific place, during a time of climate adjustment, is asking for a very lucky break... or in other words....

Some places will be lucky and have a reasonably predictable pattern of weather, but it'll be hard to predict where those places will be.

 

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Not from the class... but the Inter-Tropical Convergence Zone [iTCZ] is now as far north as it was during the Medieval Warm Period... and if it continues moving northward (as it has since the end of the Little Ice Age) those global bands of desert climate around 30 deg.North & South (caused by the ITCZ) should start moving farther northward also.

 

...Maybe a network of locales could mutually survive the vagueries of future changes better than any one place.

 

~ :)

 

p.s. for some maps of precip. changes (projections and comparisons of models with measures) see:

http://ats150.atmos.colostate.edu/Lectures_files/14.FutureClimate.pdf

Edited May 11, 2011 by Essay