la actual mega-sequía en chile central: llegó el futuro?la megasequía 2010-2015 • moderada...
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La actual Mega-Sequía en Chile Central: Llegó el futuro?
René D. Garreaud + grupo de Sequía CR2Department of Geophysics, Universidad de ChileCenter for Climate and Resilience Research, CR2
IV Congreso Nacional de Oceanografía Fìsica y MeteorologíaPUCV 1u-Noviembre-2015
Mirando el futuro: Escenarios de emisiones (CO2, etc) + Modelos de Circulación General (Atmos+Ocean)
20+ GCMs
Mirando el futuro: Escenarios de emisiones (CO2, etc) + Modelos de Circulación General (Atmos+Ocean)
IPCC-AR5
Impactos Regionales del Cambio Climático• Aumento de temperatura 2.5-3.5ºC (*)• Disminución de precipitación 25-35% (*)(*) Proyección a fin de siglo bajo escenario A2
Estudio DGF/UCh-CONAMA 2007 empleando PRECIS
La megasequía 2010-2015
• Moderada (20-40% déficit anual)• Larga (5-6 años) e ininterrumpida• Extensa (30-40°S)• Cálida (+0.5 – 1°C)• Alta demanda hídrica
Recurrencia en el siglo XX• 2-3 casos similares en centro-norte• 2-3 casos similares en centro-norte• <1 caso en centro-sur• También es inusual en reconstrucción Paleo
Impactos:• Hidrología sfc y subterranea• Vegetación natural• Regimen de incendios• Sociales y economicos
La Megasequía 2010-2015
% con respectoa climatología
+40%
+20%
0
Norte Chico Centro Centro-sur
Período de retorno del año más seco durante la MS (años)
7 15 >30
Recurrencia de eventos secos (>30%) de 4 o mas años
4-6 2-3 1?
-20%
-40%
1967-1970 2010-2014
Valparaiso
La Serena% con respectoa climatología
Grandes sequías contemporáneas
+40%
+20%
Concepción
Valdivia
0
-20%
-40%
Una mirada al pasado
Reconstrucción dendroclimática (1000-2000 años d.C.) de la precipitación en Chile central
Sequía y calor
Promedio anual de la temperatura máxima en Santiago (DMC)
Impactos en Hidrología
Impactos en Hidrología
(a) Promedio (b) Anomalía MS
Copiapo
La Serena
Desierto
Índice de Vegetación Mejorada (EVI)Julio-Agosto-Septiembre
(b) Anomalía Megaseqia
0 – 55 – 1010 – 1515 – 3030 – 50
La Serena
Talca
Santiago
Salamanca
Nieve
Veg
etac
ión
+50
- 5Seq
ued
adFuente de datos: NASA (producto MODIS MOD13A3)
Mapas producidos por David Lopez, CEAZA
Santiago
MODIS-TERRA08 Enero 2014
11:55 Hora Local
During the current DroughtLess number of forest firesLarger burned areaExtended fire season
Talca
Constitución
Curicó
60 km
Mauro Gonzalez, Antonio Lara, et. al.
DéficitPluviométrico(2010-2014)
DéficitPluviométrico(2010-2014)
La Megasequía 2010-2015
Gastos en Camiones Aljibes
(Mill$)
Gastos en Camiones Aljibes
(Mill$)
Seq
ued
ad
Apariciones en prensa escrita
(2014)
Apariciones en prensa escrita
(2014)
Seq
ued
ad
Deterioro vegetación
Agosto 2010-2015
Deterioro vegetación
Agosto 2010-2015
Incendios forestales de
magnitud
Incendios forestales de
magnitud
Transportede sedimentos
en invierno
Transportede sedimentos
en invierno
2008
2013
©GdG
No
dat
a
La Megasequía 2010-2015:Una lección para el futuro
www.cr2.cl/megasequia
Next Decade
100%
90%
80%
0%
10%
20%
Rai
nfa
ll an
om
aly
wrt
19
70
-20
00 R
ainfall d
eficit wrt
19
70????
Precipitación en Chile CentralEl desafío de la próxima década
1995 2005 2015 2025 2080
Far Future
RCP8.5
Mega
Drought
Recent
Past
80%
70%
20%
30%
Mid Future
RCP8.5
Rai
nfa
ll an
om
aly
19
70
-20
00
????
100%
90%
80%
0%
10%
20%
Rai
nfa
ll an
om
aly
wrt
19
70
-20
00 R
ainfall d
eficit wrt
19
70
Next Decade
Precipitación en Chile CentralEl desafío de la próxima década
1995 2005 2015 2025 2080
Far Future
RCP8.5
Mega
Drought
Recent
Past
80%
70%
20%
30%
Mid Future
RCP8.5
Rai
nfa
ll an
om
aly
19
70
-20
00
Rainfall (GCPC) Z500 (NNR) SST (NCEP-OI)
Drought Composite
Large-scale context for central Chile droughts
Cold
1967,68,64,73,76,85,96,87,03,07
-50 0 +50 m -1 0 +1°C-60 0 +60 mm/month
ColdHigh
Warm
Large-scale context for central Chile droughts
Cen
tral
Chi
le w
inte
r ra
infa
ll an
omal
y
La Niña El Niño
r ≈ 0.6
MJJAS Niño3.4 index [°C]
Cen
tral
Chi
le w
inte
r ra
infa
ll an
omal
y
Mea
n Q
N A
nn
ual
Pre
cip
itat
ion
[mm
/yea
r]
1900-10
1915-22
1926-42
1977-90
1991-2003
The error bars indicate the dispersion in the mean values when the initial or final year of each period is changed ±1 year
Warm PDO periodsCold PDO periods
The grey circles are 10-year synthetic PDO cold or warm periods
The blue circles are the composites using tree-rings reconstructions.
The 2010-2015 drought in Central Chile
Mean PDO Index
Mea
n Q
N A
nn
ual
Pre
cip
itat
ion
[mm
/yea
r]
1900-10
1942-57
1961-75
2007-2014
Long term mean
PDO Index
Year
Large-scale context for central Chile droughts
Cen
tral
Ch
ile R
ain
fall
An
om
aly
r ≈ -0.6
Cen
tral
Ch
ile R
ain
fall
An
om
aly
Z500 difference
Rainfall Z500 SST
DroughtComposite
The 2010-2015 drought in Central Chile
ColdHigh
Warm
1967,68,64,73,76,85,96,87,03,07
2010-2014Average
-50 0 +50 m -1 0 +1°C-60 0 +60 mm/month
High
Warm
Cen
tral
Chi
le w
inte
r ra
infa
ll an
omal
y
La Niña El Niño
The 2010-2015 drought in Central Chile
2010
2014
2013
2012
2011
2009
MJJAS Niño3.4 index [°C]
Cen
tral
Chi
le w
inte
r ra
infa
ll an
omal
y
+
2015????
Monte Carlo Experiment:5000 samples of 4 randomly chosen ENSO-neutral years
Central Chile Rainfall Anomaly
The 2
01
0-2
01
5 d
rou
ght in
Cen
tral Ch
ile
r≈
0.6
Central Chile Rainfall Anomaly
Z50
0 d
ifference
5800
5750
5700
5650
Subtropical box
NNRMMM
(hist+RC85)
Geo
po
ten
tial
hei
ght
[m]
The 2010-2015 drought in Central Chile
5300
5250
5200
5150
5000
5600
Midlatitude Box
MMM(hist+RC85)
NNR
Geo
po
ten
tial
hei
ght
[m]
Evidence for anthropogenic forcing
Climate simulation family
Attribution of the 2010-2015 mega drought
AMIP simulations: Global Circulation Model (GCM) forced by
• Observed SST
• Observed Sea Ice Distribution
• Observed or past Radiative Forcing (CO2, aerosols, O3,…)
Ensemble AMIP simulationsEnsemble AMIP simulations
• 10-30 “runs” of several decades long with slightly different initial conditions
• Ensemble mean reveals the SST forced response
• Ensemble spread reveals impact of internal variability (weather)
SST forcing includes natural variability (e.g., ENSO) but also anthropogenic impact
Ensemble mean with past radiative forcing excludes direct anthropogenic impact
Rainfall deficit
CAM4 (20) ECHAM5 (30)
May-September, 2010-2014
-50 0 +50 %
GPCP
Observations AMIP (Obs .SST, Obs. Rad.Forc.)
Z500 anomaly
-50 0 +50 m
NNR
SST variability + Obs. Rad. Forcing during 2010-2014 accounts about half of theobserved Z and P anomalies. Remaining anomaly can due to “bad luck”
(a) Nat-Hist forcing / Obs SST (b) Obs. Rad. Forcing / Obs. SST
Winter (MJJAS) rainfall anomaly 2010-2014LBNL CAM 5.1 AMIP simulations (50 runs)
-300 0 300 mm/year
-10% -20%
AMIP ORF AMIP NH CMIP-5
Ran
ifal
l an
om
aly
(% w
rt 1
98
0 -
20
10
)
Central Chile (33-36°S) winter (MJJAS) rainfallanomalies during mega drought (2010-2014)
P50
P25
P75
Observedanomaly
ECHAM5
(30)
CAM4
(20)
CAM5.1
(50)
CAM5.1
(50)MultiModel
(23)
CESM1
(3)
Ran
ifal
l an
om
aly
(% w
rt 1
98
0
P25
The Next Decade Challenge
Next Decade
100%
90%
80%
0%
10%
20%
Rai
nfa
ll an
om
aly
wrt
19
70
-20
00 R
ainfall d
eficit wrt
19
70????
1995 2005 2015 2025 2080
Far Future
RCP8.5
Mega
Drought
Recent
Past
80%
70%
20%
30%
Mid Future
RCP8.5
Rai
nfa
ll an
om
aly
19
70
-20
00
????
The Next Decade Challenge
100%
90%
80%
0%
10%
20%
*
**
Rai
nfa
ll an
om
aly
wrt
19
70
-20
00 R
ainfall d
eficit wrt
19
70
Next Decade
Unlikely
Unlikely
Likely
1995 2005 2015 2025 2080
Far Future
RCP8.5
Mega
Drought
Recent
Past
80%
70%
20%
30%
Mid Future
RCP8.5
MD Forcing
(*) Anthropogenic
(**) Natural (ENSO, PDO, Internal)
Rai
nfa
ll an
om
aly
19
70
-20
00
Very unlikely
Unlikely
Conclusions
• Current multi-year drought (MD) in central Chile is a very infrequent event in the historical record (100 years) and paleo-record (1000 years). It occurs during the warmest decade on record and much increased water demands.
• The uninterrupted sequence of 5 (6) dry years occurred during mostly ENSO-neutral conditions, a very unlikely situation.mostly ENSO-neutral conditions, a very unlikely situation.
• Roughly speaking, half of the current MD rainfall deficit can be attributed to concurrent SST state (cold-phase of PDO).
• Thus, anthropogenic climate change, mediated by circulation anomalies, is already influencing central Chile hydro-climate.
• So, we are not fully into the “future”, but this is how it will be…warm and dry.
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