Gov. Brown's letter to Dr. Ben Carson on Climate Change

[eyewall]

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[Eskimo Joe]

Love this  

[donsutherland1]

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Well-written letter.

[stadiumwave]

NOAA study concludes that California heat & drought is natural variation & not AGW:

http://www.usatoday.com/story/weather/2014/12/08/california-drought-cause-noaa/20095869/

[ORH_wxman]

NOAA study concludes that California heat & drought is natural variation & not AGW:

http://www.usatoday.com/story/weather/2014/12/08/california-drought-cause-noaa/20095869/

 

 

The letter from Gov. Brown didn't mention this drought as being anthropogenic in nature, so I thought it was fine. I basically just said to referr to the IPCC AR5.

 

That said, Carson's statement also has an element of truth to it...in that you will often see or hear politicians and/or media jump all over weather events as human-caused when the scientific evidence just is not there to make such conclusions.

[skierinvermont]

NOAA study concludes that California heat & drought is natural variation & not AGW:

http://www.usatoday.com/story/weather/2014/12/08/california-drought-cause-noaa/20095869/

 

That study was not peer-reviewed and was criticized by many notable scientists. I just read through the key parts of it and I agree there are two significant flaws.

 

First of all, it treats the attribution of the drought to AGW as an all or nothing proposition. I don't think that is a meaningful approach from an impacts or policy perspective. If AGW made the drought even 5% worse, that is a significant impact.

 

Second, and perhaps more importantly, it does not include any impact from increasing evaporation May to October. For some reason, the authors chose only to look at the months of November to April. They calculate precipitation (P) minus evaporation (E) for November to April. However, evaporation in the summer months, which has significantly increased, surely has a significant effect on both water supply and demand. 

 

Third, they seem to ignore the southern portion of California where the drying signal from climate models is stronger.

 

 

Here is the study: http://cpo.noaa.gov/sites/cpo/MAPP/Task%20Forces/DTF/californiadrought/california_drought_report.pdf

[stadiumwave]

That study was not peer-reviewed and was criticized by many notable scientists. I just read through the key parts of it and I agree there are two significant flaws.

First of all, it treats the attribution of the drought to AGW as an all or nothing proposition. I don't think that is a meaningful approach from an impacts or policy perspective. If AGW made the drought even 5% worse, that is a significant impact.

Second, and perhaps more importantly, it does not include any impact from increasing evaporation May to October. For some reason, the authors chose only to look at the months of November to April. They calculate precipitation (P) minus evaporation (E) for November to April. However, evaporation in the summer months, which has significantly increased, surely has a significant effect on both water supply and demand.

Third, they seem to ignore the southern portion of California where the drying signal from climate models is stronger.

Here is the study: http://cpo.noaa.gov/sites/cpo/MAPP/Task%20Forces/DTF/californiadrought/california_drought_report.pdf

When the NOAA hiatus busting study came out where you quick to point out that it wasn't peer-reviewed yet?

[stadiumwave]

The letter from Gov. Brown didn't mention this drought as being anthropogenic in nature, so I thought it was fine. I basically just said to referr to the IPCC AR5.

That said, Carson's statement also has an element of truth to it...in that you will often see or hear politicians and/or media jump all over weather events as human-caused when the scientific evidence just is not there to make such conclusions.

Oh I agree...I posted it because Gov. Brown has basically become the political poster child because he believes heat/drought there is totally a carbon footprint. Other politicians, METS, & media outlets have said the same.

While AGW is absolutely real, it drives me bonkers when natural events are pointed to as evidence.

[salbers]

I think the main points to consider include that AGW is likely to intensify both droughts and floods - is this really controversial? California has a special concern overall since any warming will decrease the storage of water in the snowpack for summer use.

[ORH_wxman]

I think the main points to consider include that AGW is likely to intensify both droughts and floods - is this really controversial? California has a special concern overall since any warming will decrease the storage of water in the snowpack for summer use.

 

I don't think that by itself is controversial...but rather, the natural variability in intensity of droughts/floods in California is well beyond the magnitude of AGW. At least based on the body of evidence we have right now. Consider the multi-decade droughts (and even multi-century) they had previously. The 20th century may have been one of the most benign centuries in that region over the past 1,000 years.

 

This doesn't mean AGW shouldn't be taken seriously, but it is very important to understand the baseline climatology and variability. We can stop AGW dead in its tracks and return to pure natrual variability and California is still going to get absolutely smoked by intense droughts and terrible floods...likely much worse than what we saw in the past century. Perhaps the impact may be just the tiniest bit more benign in a 1975 climate vs 2015.

 

I think a much more important aspect of AGW to focus on is SLR. That's where most of the threat of economic stress really is and a much stronger attribution lies there than in extreme weather events.

[aslkahuna]

I don't know how benign the 20th Century was in terms of drought in CA-from 1949 through 1960 only three winters had normal or above normal rainfall-1951-52, 1955-56 and 1957-58 with the first and last being ENSO warm phase winters and the middle one being dry in SOCA. In parts of TX and NM the drought of te 50's was worse than the '30s. Droughts of varying intensity have occurred at approximately 20 year intervals for a very long time. What has changed in CA and especially down south has been a massive influx of people mostly incapable or unwilling to practice basic water conservation in an arid and semi-arid region. Regardless of what role AGW might play, the simple fact is that the population of CA has long since passed the point of sustainably from a frequntly unreliable water supply from Nature and no one is willing to give wastrels any of their water and Las Vegas in NV is even worse off.

Steve

[skierinvermont]

When the NOAA hiatus busting study came out where you quick to point out that it wasn't peer-reviewed yet?

 

Deflection. In general, peer-review is better than not peer-review would you not agree? This is true regardless of the study, and is only one of several points I made to consider about the study.

 

It seems like a fatal flaw to not include dramatically increased evaporation May to October. Those months also seem most likely to experience any decrease in precipitation (especially the shoulder months of May and October).

[skierinvermont]

The IPCC projects dramatically reduced surface moisture (which increases demand for irrigation and increases the risk of wildfire) and modestly reduced surface runoff, especially for the Colorado River Basin which supplies close to 10% of California's water.

 

It is therefore likely that this drought was at least slightly to modestly exacerbated by AGW.

 

As a river runner, the decline of western rivers is simply a fact of life and it's only going to get worse. We will never see another 1983 on western rivers again.

[salbers]

Whether the increased evaporation wins out or the more intense precip wins out is a good question. Individual precip events may be stronger but total precip shouldn't be changed too much. So the ground should get drier overall. It's more clear that warmer temps will reduce the snowpack and water supply from the Sierra in summer.

 

This winter though the El Nino could be a spectacular drought buster. 

[Msalgado]

Its not just about evaporation. Its also about more rain falling as opposed to snow.  You can't build the capacity to store water the way the snowpack does.  I don't think the El Nino is going to do much for California.  The effects there aren't nearly as large as they are usually made out to be:

 

https://www.climate.gov/news-features/blogs/enso/fun-statistics-el-ni%C3%B1o-and-california-rainfall

 

We'll see.  Either way, I think its undeniable that warmer temps have a huge evaporative effect so its pretty undeniable that every drought is made worse by AGW.  Its not about cause, but rather how its effected.  

[salbers]

Agreed - as I had mentioned with the snowpack being reduced.

 

Interesting scatter plots in the link above. Even though there is scatter, the El Nino years do look to trend (e.g. having higher mean values) with more precip, particularly in Southern Cal.