No Evidence Climate Change Behind Current Dry Period in Los Angeles.

Late last year, the LA Times banned letters from so-called climate skeptics (actually, it called them "climate-change deniers"). Why? Because this media outlet's management only wants to see accurate factual statements about climate science in its newspaper.

This brings us to an article in the LA Times from July 15, 2014 by Veronica Rocha -- who apparently is the "Public safety/courts reporter in Los Angeles" -- entitled "Downtown L.A. is now driest since rain records started in 1877."

In her article, Rocha states the following:

"Rainy seasons over the last two years were the driest in downtown Los Angeles since record-keeping began in 1877, and forecasters now say the El Nino that had been predicted to bring some relief may not materialize.

According to the National Weather Service, the 2012 to 2014 rainy seasons -- which are measured every July 1 to June 30 -- only brought 11.93 inches of rainfall, which is 17.93 inches below normal.

By comparison, the 1897 to 1899 seasons saw 12.65 inches of rain, or about 17.21 inches below normal for the period, according to the National Weather Service."

Okay, let us think about this statement for a bit. If the rainy seasons in Los Angeles "are measured every July 1 to June 30," when is the dry season? Last I checked, there is no period of time between June 30 and July 1, so if your rainy season goes from July 1 of Year 1 to June 30 of Year 2, that means -- by definition -- that the entire year is the rainy season. Shouldn't it raise some alarm bells as a journalist if your source is claiming the entire year is a rainy season, especially in dry southern California?

So this LA Times article -- apparently derived from a NWS press release -- is entirely messed up. The article is clearly using annual precipitation -- not "rainy season" data -- for downtown LA over the period from July 1 to June 30. How do I know? Because we can all go to the National Weather Service data archive for the downtown LA site and download the raw data.

Sure enough, the period from July 2012 through June 2014 has a precipitation total of 11.93 inches, and indeed, July 1897 through June 1899 saw 12.65 inches of rain. But these aren't the "rainy seasons," these are annual precipitation totals for the consecutive 12-month periods running from July through to the following June.

The City of Los Angeles itself has defined the rainy season for the city, which runs from October 1 through April 15. Thus, the 2012-2014 two-year "rainy season" total precipitation is 11.12 inches, not 11.93 inches as the LA Times erroneously reports. And this isn't the lowest two-year rainy season total on record. Rather, it is the third lowest. Both 1898-1899 (10.19 inches) and 1899-1900 (10.97 inches) were lower.

To finish off this dose of climate realism, there are also absolutely no significant trends in one-year July-June, two-year consecutive July-June, one-year October-April (aka, the real "rainy season"), or two-year consecutive October-April precipitation totals for downtown LA since records began in 1877. Thus, any notions out there that the current dry spell in Los Angeles is due to climate change is not supported at all by an almost 140 year long climate record.