Being a climate scientist sometimes feels like being an astrophysicist in one of those 90s asteroid impact disaster movies...
except instead of coming to together to save humanity, the people in power shrug & point out how sending rockets might increase inflation. #ClimateChange
I was once, coincidentally, seated on a flight next to a @NASAJPL scientist who described his job as "taming near-Earth asteroids" from a planetary protection perspective. This is a person who would actually be called to the White House in scenarios portrayed in Hollywood films.
The JPL near-Earth object specialist made it clear that he was more concerned about #ClimateChange than an asteroid impact--not because latter wouldn't be devastating, but because the odds were low in our lifetime & "we would actually do something about it, if it ever came."
After last couple of years, some might well question even the second premise. But climate change, on the other hand, is already here. The odds are...100%. And yet, even though there has some progress, we are still pushing the Earth toward very rapid change in the coming decades.
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California, on statewide basis, is now experiencing its worst drought in observational record going back to late 1800s--narrowly beating out peak of last drought in 2014-15 (as measured by PDSI, a metric that takes into account both precip & temperature). #CAwx#CAfire#CAwater
There is a clear trend toward increasing aridity in California--and yet little trend in mean precipitation. How can this be? A very strong warming trend due to #ClimateChange means same the amount of water falling from sky just doesn't go as far as it used to. #CAwx#CAwater
We explored this phenomena in research published in 2015 (finding that rising temps are the main factor behind increasing CA drought severity): pnas.org/content/112/13…
2/The "extreme precipitation-flood paradox" arises from fact that despite abundant evidence for increasing rainfall extremes due to #ClimateChange, there is not (yet) a correspondingly clear & systematic increase in flood magnitude. nature.com/articles/s4324…
3/To address this conundrum, we use a high-resolution regional hydrologic model coupled to a high-resolution (single model) regional climate large ensemble (collectively, a "hydroSMILE") centered on hydrologic Bavaria (including parts of Germany, Austria, & Switzerland).
Dry lightning event of *some* magnitude is now looking increasingly likely across *some portions* of CA on Sun/Mon. Details to come. But first, some thoughts on potential wildfire risks posed if this comes to fruition. (Thread) #CAwx#CAfire
Usually, fewer than 1 in 10 lightning strikes actually ignites a wildland fire. These numbers can be higher if lightning is not accompanied by precip, or if lightning occurs under unusually dry conditions in dense vegetation. But in general, lightning ignition *rate* is low-ish.
A big problem thus arises when there are a very large number of dry lightning strikes. This occurred during the extraordinary and historic Aug 2020 event in Northern CA, where 10,000+ strikes were observed (and subsequently *hundreds* of fires were ignited).
Posting as heads-up to weather modeling world (not as a realistic prediction of future conditions): the (new) GFS has occasionally been spitting out completely absurd surface temperatures for CA's Central Valley. 18z run today shows 128-130F. Anyone know what's up?
An intense and very possibly record-breaking heatwave is indeed possible in that interval, but not "hottest temperature in modern history" hot. I'm assuming it's the surface scheme, but then again, the 850mb temps are absurdly high also (though maybe feedback from sfc?).
Seems as if the ECMWF is now doing something similar. Either both models share some kind of similar surface scheme bias/error that involves sporadic positive/self-reinforcing surface temp feedback during extreme events (still by far most likely), or...hmm.
Correction to give more accurate context: vegetation dryness & flammability metrics (1000hr fuel moisture & ERC, respectively) are indeed exceeding record levels for *calendar* date over most of Sierra Nevada, but *not* records for *any date.* (Phew!) (1/4) #CAwx#CAfire
For those interested, the confusion apparently arose due to a differing period of record for NorCal vs. SoCal data via the NorthOps/SouthOps GACCs. In SoCal, period of record is only ~10 years, so "any date" records less meaningful. So: data not wrong, but context is missing.
This really doesn't change the overall picture: there's still an exceptionally severe drought across all of Northern California and vegetation is still exceptionally dry--even relative to extreme values of recent years. But it's important to get the details right! (3/4)
@MichaelWWara@jtemple As I've been emphasizing recently, the *predictable* aspects of Fire Season 2021 (soil moisture/vegetation dryness) are as bad or worse as any observed historically. The level of landscape flammability--especially in denser brush & forests--is genuinely scary. BUT... (1/2)
@MichaelWWara@jtemple ...A big part of what makes certain fire seasons exceptionally severe (from lives lost, homes burned, & ecosystems damaged perspective) has substantial random component. Do ignitions primarily occur during extreme fire wx? Do we see many heatwaves/wind/dry lightning events? (2/3)
@MichaelWWara@jtemple Latter aspects are largely not predictable in advance (except perhaps frequency of heatwaves--which are indeed expected to be elevated). In 2020, we were very unlucky w/all the unpredictable elements. I hope we won't be in 2021...but that's not a good management plan! (3/3)