Thursday, December 15, 2011

Cotton: "Texas Drought Could be Extended by Rare Third Year of La Niña"

The current drought is being compared to the great drought of the 1950's but it is probably worse, some of the literature points up the drought of 1789 as the best comp, that's going back a long ways. In Texas the 1950's drought was more severe than the Dust Bowl of the 1930's:

From the Southwest Farm Press (Dec. 1):
  • NOAA forecasters are saying there is a 40-percent chance for an even rarer third round of the Pacific Ocean phenomenon next year.
  • Could add to the devastating $5.2 billion in losses to state agriculture.
  • Often an El Niño follows a La Niña event, and traditionally this brings exceptionally wet weather to the region.
 Two consecutive years of La Niña events in the Southern Hemisphere, an unusual development, are credited with causing the worst drought in Texas history. But NOAA forecasters are saying there is a 40-percent chance for an even rarer third round of the Pacific Ocean phenomenon next year and that could add to the devastating $5.2 billion in loses to state agriculture....MORE
I've pointed out that we reentered the cool phase of the Pacific Decadal Oscillation. One of the correlations associated with a cool PDO is an ENSO pattern where La Nina is twice as common as during the warm phase.

The PDO is a quasi-periodic warming and cooling of a huge swath of the North Pacific, the periodicity ranging from 22 to 35 years, centering around an average of 30 years.
In 1977 we entered the warm phase and in 2007, after some fits and starts entered the cool phase.
During this period the El Nino/Southern Oscillation was dominated by the warmer El Nino:

Since 2007 we have seen more of the cooler La Nina, and may have entered a period similar to the last PDO cool phase, 1947-1977. The official stats on PDO Sea Surface Temperature anomalies are kept by the University of Washington, the discoverers of the periodicity, who found the pattern while trying to figure out where the salmon went back in the 1990's.

That's a long introduction, here's the current state of affairs, released this morning:
 US Drought Monitor, December 13, 2011
Despite all the destruction visited on Texas last year that may only have been the beginning.
From ClimateWire via the New York Times (Oct. 3):
Some Climatologists Worry That Texas' Mega-Drought Could Endure for Years
Texas State Climatologist John Nielsen-Gammon made headlines last week when he predicted his state's devastating drought could last until 2020.

That's yet another heaping helping of bad news for Texas, where unusually dry conditions this year have caused $5.2 billion in damages to the state's agriculture sector.

But the prediction is also notable because scientists don't forecast drought years in advance. The federal government's latest drought outlook only extends through December.

So is it even possible to predict whether Texas will be locked into drought in 2015, let alone 2020?
Nielsen-Gammon, a professor of atmospheric sciences at Texas A&M University, admits it's more of an art than a science. But he sees a lot of similarities between conditions now and the worst recorded drought in Texas history, which lasted from 1950 to 1957.

Scientists have put much of the blame for the current drought on La Niña, a weather phenomenon signaled by unusually cool surface waters in the tropical Pacific Ocean.

"Drought in the southern Great Plains tend to be very much linked to La Niña conditions," said Siegfried Schubert, a senior research scientist in the Global Modeling and Simulation Office at NASA's Goddard Space Flight Center. "But there are issues of times when the drought will persist longer than La Niña conditions, and there are questions about what other oceans perhaps are playing a role."
Atlantic Ocean may play a role
A strong La Niña emerged last fall and fizzled in early summer. Now a new La Niña is emerging, setting Texas up for another dry winter, said David Miskus, a drought specialist at the National Oceanic and Atmospheric Administration's Climate Prediction Center.

But Nielsen-Gammon says there's another factor at play -- unusually warm surface waters in the tropical Atlantic Ocean, which also factored into the historic 1950s drought.

He believes those warm waters are a product of a long-term climate pattern, the Atlantic Multidecadal Oscillation (AMO), now in a "warm" phase that could last for another 15 years.
 "Unfortunately, if you go back to that record [of the 1950s], it's pretty similar to what's going on right now," he said. "That's the only time in the past 100 years when [the ocean conditions] had a similar configuration to how they are today."...MORE
For risk modelers the AMO most associated with hurricane frequency (more frequent in warm phase), here are the PDO/AMO drought correlations:

...This is typical of cold PDO and warm Atlantic Multidecadal Oscillation combinations, as we saw in our April 2008 post "Um, folks, um, maybe we should start thinking about rebuilding our grain reserves.":

...North American Drought
Drought over north America has been correlated to the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation.
North American drought frequency
The relationship between drought in the continental US and the phases of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). The most severe droughts occur when the PDO is in a negative phase, and the AMO is in a positive phase.
From McCabe (2004).

Here is the table of monthly AMO values, we'll see how it pans out.

So what does it mean for investors?
Back in September we posted "Pray for Texas (and maybe buy some cotton futures): 'Historic La Nina imminent?". Since then cotton futures have drifted lower:


but the trade is definitely worth being aware of. A reasonable target would be the bottom of the chart gap in the 130 area a ~50% move from this morning's 85.680.

We'll have more next week. Here's NOAA's Diagnostic Discussion:

A majority of the models predict a weak or moderate strength La Niña to continue through the Northern Hemisphere winter (Fig. 6) and then gradually weaken after peaking during the December – January period.  The models are roughly split between those that predict La Niña to remain weak (3-month average in the Nino-3.4 region between -0.5 and -0.9°C) and those that predict a stronger episode. Over the last half-century, La Niña events that were preceded by ENSO-neutral conditions during the Northern Hemisphere summer (May-August) were less likely to attain strong amplitude (stronger than –1.5°C) the following winter.  This observation, in combination with the model forecasts, favors a weak-to-moderate strength La Niña during the Northern Hemisphere winter, likely weakening with the onset of northern spring....