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David P. Brown, Ph.D. Regional Climate Services Director NOAA Southern Region March 9, 2012 Presented at the Texas Water Conservation Association annual conference.
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U N I T E D S T A T E S D E P A R T M E N T O F C O M M E R C E
N A T I O N A L O C E A N I C A N D
A T M O S P H E R I C A D M I N I S T R A T I O N
The 2011-2012 Texas Drought: Short-Term Extremes and
Long-Term Context
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David P. Brown, Ph.D. Regional Climate Services Director
NOAA Southern Region March 9, 2012
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news
Overview
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news
Overview
In addition to record dryness,
there was also record heat
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• Driest 12-month period ever
– October 1, 2010 thru September 30, 2011
– 2011 was driest calendar year ever (in 117 years)
• Hottest summer ever (in 117 years)
– June-July-August all hottest ever (in 117 years)
• Agricultural losses ~ $6 billion
• Acres burned due to wildfire ~ 4 million
• Mandatory/voluntary water restrictions ~ 1000
What has the drought looked like?
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news
Overview
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
1. Winter season La Niña
Why did the drought happen?
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
1. Winter season La Niña
As John Nielsen-Gammon likes to say:
El Nino = EL = Extra Liquid
La Nina = LA = Less Agua
for the Southern U.S.
Why did the drought happen?
Strong
El Nino
Weak or
Neutral
Strong
La Nina
Figure courtesy of NOAA/ESRL
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
1. Winter season La Niña
2. “Missed” spring storms
Why did the drought happen?
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
1. Winter season La Niña
2. “Missed” spring rainfall
3. Summer heat
Why did the drought happen?
Figure courtesy of Texas A&M
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
Why did the drought happen?
• How 2011 summer heat affected the drought
– Dry soil due to low winter/spring precipitation
– Very little evaporation
– Fewer thunderstorms
– Drier soil
• And
– Very little evaporation less atmospheric cooling hotter temperatures more evaporation of what little water is left greater water stress/demand
• Dryness added ± 4-6 degrees F to summer heat
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
1. Winter season La Niña
2. “Missed” spring rainfall
3. Summer heat
4. Lack of tropical activity
Why did the drought happen?
Figure courtesy of Weather Underground
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news
Overview
Figure courtesy of SCIPP
Figure courtesy of Texas A&M
Figure courtesy of SCIPP
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
Was it a climate change event?
• Temperatures going up (since mid-1970s)
• Precipitation changes uncertain
• Easier to “cross the threshold” into drought
– Higher temperatures more evaporation
• Future droughts likely hotter and drier
N A T I O N A L O C E A N I C A N D A T M O S P H E R I C A D M I N I S T R A T I O N
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news
Overview
Some improvement, but much more relief still needed
U N I T E D S T A T E S D E P A R T M E N T O F C O M M E R C E
N A T I O N A L O C E A N I C A N D
A T M O S P H E R I C A D M I N I S T R A T I O N
Acknowledgements:
John Nielsen-Gammon (Texas A&M) Victor Murphy (NOAA NWS)
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David P. Brown [email protected]
