CLIMATE CHANGE AND MONSOON
CLIMATE CHANGE AND MONSOON Rupa Kumar Kolli Indian Institute of Tropical Meteorology Pune 411008 Email: [email protected]
AAMP7, Irvine, USA, June 18-19, 2005
South Asia : Population Pressure on Resources n n n
Total land area: 3.0% of global Population (present): 21.3% of global Population (projected-2025): 23.6% of global
AAMP7, Irvine, USA, June 18-19, 2005
Indian monsoon in a changing world n n n n n n n n n
We know the earth’s atmosphere is undergoing unprecedented warming Much of the warming is convincingly attributed to human activities How does the monsoon behave in a warmer atmosphere-ocean coupled system ? More atmospheric moisture Ë More intense hydrological cycle Ë More intense monsoon ? More intense/frequent ENSO anomalies ? More monsoon variability ? Which are the sub-regions likely to be affected ? Are land-use and land-cover changes associated with monsoon changes ? How do we distinguish between natural and anthropogenic changes in monsoon patterns ? Do we have global/regional policy options to deal with perceived monsoon changes ?
AAMP7, Irvine, USA, June 18-19, 2005
How monsoon can change… n Spatio-temporal
patterns of rainfall n Frequency of extreme seasonal anomalies n Monsoon onset/withdrawal n Timing and duration of active/break periods n Frequency of severe rainstorms n Teleconnections (e.g., ENSO-Monsoon) n Predictability of monsoon AAMP7, Irvine, USA, June 18-19, 2005
Indian Monsoon : Palaeoclimatic Setting n n
n
n
Cold periods in climatic history have winter-like circulation, whereas warm periods are characterized by a strong summer monsoon flow. Multidisciplinary evidence on climate during the Holocene period from the northwest regions indicate that the period between 10ka to 4.5ka BP experienced a warm and humid climate associated with relatively frequent floods. Around 3.5ka BP, a trend towards aridity set in over the entire northwest Indian region. However, aridity seemed to have been more active in the early part, followed by semiarid and arid conditions with present day vegetation. There are indications that the northern edge of the monsoon reaching the desert margins of northwest India underwent wide fluctuations leading to impermanent human civilizations to appear and disappear from the region.
AAMP7, Irvine, USA, June 18-19, 2005
Dendroclimatic Reconstruction of All India summer monsoon rainfall series during 1602-1960. (Indirect reconstruction based on Southern Oscillation Index estimated from tree-rings) 105 100
Rainfall (Cm)
95 90 85 80 75 70 1600
1650
1700
1750
1800
Year2005 AAMP7, Irvine, USA, June 18-19,
1850
1900
1950
The Long-Term Stability of the Indian Summer Monsoon
AAMP7, Irvine, USA, June 18-19, 2005
Long-term regional trends in Indian summer rainfall Small significant increasing/decreasing trends < +/- 0.1%/yr
Trend in %/100yr
AAMP7, Irvine, USA, June 18-19, 2005
% exp. variance
All-India Mean Surface Temperatures (1901-2000) Based on a constant network of 31 stations welldistributed over India
AAMP7, Irvine, USA, June 18-19, 2005
Diurnal Asymmetry of Temperature Trends over India
AAMP7, Irvine, USA, June 18-19, 2005
Sea Surface Temperature Trends in the Indian Ocean
AAMP7, Irvine, USA, June 18-19, 2005
Rainfall Variability over Indo-Gangetic Plains Region (IGPR) SUMMER MONSOON RAINFALL: 1844-1999
mm Eastern IGPR 1227 1175 1123
Central IGPR mm 977 895 813 mm Western IGPR 741 665 589
1841
1861
1881
1901
1921
AAMP7, Irvine, USA, June 18-19, 2005
1941
1961
1981
The 1941 Severe Rainstorm In the Indian sub-continent, the 13 July 1941 rainstorm is the most severe rainstorm of this region. Also considered to be one of the most severe rainstorms of the tropical regions of the world.
1-day rainfall (cm) AAMP7, Irvine, USA, June 18-19, 2005
Major Rainstorm Centres
AAMP7, Irvine, USA, June 18-19, 2005
Severe Rainstorms, 1891-2000 60
46
50
36
40
30 30 20
17
16
20
24 17
11
13
11
10
AAMP7, Irvine, USA, June 18-19, 2005
1991-2000
1981-1990
1971-1980
1961-1970
1951-1960
1941-1950
1931-1940
1921-1930
1911-1920
1901-1910
1891-1900
0
Changing Frequency of Cyclonic Disturbances during the Monsoon Season
AAMP7, Irvine, USA, June 18-19, 2005
Depressions/ Cyclonic storms n
Not a single monsoon depression or cyclonic storm formed during Monsoon 2002 and 2003.
Year
Number of depressions/ cyclonic storms
1997
5
1998
3
1999
2
2000
2
2001
1
2002
0
2003
0
2004
2
AAMP7, Irvine, USA, June 18-19, 2005
Weakening of ENSO-Monsoon relationship
AAMP7, Irvine, USA, June 18-19, 2005
Northeast Monsoon over South Asia
AAMP7, Irvine, USA, June 18-19, 2005
Recent strengthening of ENSO-Northeast Monsoon relationship
AAMP7, Irvine, USA, June 18-19, 2005
Modelling Monsoon Changes n n
n n n
Atmosphere-Ocean coupled models have made rapid strides over the past decade Global models are relatively better in reproducing large-scale monsoon features, but problems with regional details are yet to be overcome Regional models provide good tools to downscale global model predictions High-resolution climate change scenarios for the monsoon are available for impact assessments Yet, human behaviour being the most unpredictable forcing factor for climate change, models can only be used for policy guidance, and NOT to PREDICT future changes AAMP7, Irvine, USA, June 18-19, 2005
Annual Cycles of All-India mean rainfall in the control simulations of coupled AOGCMs
AAMP7, Irvine, USA, June 18-19, 2005
Global models provide inadequate and even inaccurate information on regional scales, more strikingly in the case of the Indian summer monsoon variability patterns. Summer Monsoon Rainfall (mm/day) Simulation by AOGCMs Observed
AAMP7, Irvine, USA, June 18-19, 2005
A qualitative description of the SRES scenarios
AAMP7, Irvine, USA, June 18-19, 2005
AOGCM Scenarios of allIndia summer monsoon rainfall and mean annual surface temperature
AAMP7, Irvine, USA, June 18-19, 2005
Annual Cycles of All-India mean rainfall and Temperature in the 20th Century simulations of coupled AOGCMz (IPCC AR4)
AAMP7, Irvine, USA, June 18-19, 2005
20th Century Climate Change of Rainfall and Temperature over the Indian Region (5:30N, 65:95E) based on 19 coupled AOGCMs (IPCC AR4)
AAMP7, Irvine, USA, June 18-19, 2005
Future Climate Change Scenarios of Rainfall and Temperature over the Indian Region (5:30N, 65:95E) based on 14 coupled AOGCMs (IPCC AR4)
AAMP7, Irvine, USA, June 18-19, 2005
ENSO-Monsoon Correlations – Observations & Modelling
AAMP7, Irvine, USA, June 18-19, 2005
Projected Changes in ENSO-Monsoon Relationships due to Transient increase in Greenhouse Gas Concentrations (ECHAM4/OPYC3)
AAMP7, Irvine, USA, June 18-19, 2005
Present-day Monsoon Precipitation (Coupled vs Forced Experiments using CNRM Climate Model)
AAMP7, Irvine, USA, June 18-19, 2005
Observed and Simulated Annual Cycles of Indian Summer Monsoon Indices
AAMP7, Irvine, USA, June 18-19, 2005
Simulated Summer Monsoon Response (Coupled vs Forced Experiments)
AAMP7, Irvine, USA, June 18-19, 2005
Simulated Changes in Annual Cycles of Indian Summer Monsoon Indices
AAMP7, Irvine, USA, June 18-19, 2005
Joint Indo-UK Collaborative Programme on Climate Change Impacts in India : Scenario Development n
n
n
n
Evaluation of Regional Climate Model simulations for Indian climate Estimation of uncertainties in model-based predictions Development of future climate scenarios for India during the 21st century Preparation of climate change scenario products for impact assessments
AAMP7, Irvine, USA, June 18-19, 2005
GCMs to Regional Adaptive Responses : Modelling Path
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS n n n n
n n
n
Providing REgional Climates for Impacts Studies High-resolution limited area model driven at its lateral and sea-surface boundaries by output from HadCM PRECIS runs on a Linux PC (horizontal resolutions currently available: 50 x 50 and 25 x 25 km). Needs data for the selected domain on lateral boundary conditions (LBC) from the driving GCM (e.g., HadCM3/HadAM3) and the associated ancillary files (e.g., sea surface temperatures, vegetation, topography, etc.). Hadley Centre, UK has been providing PRECIS as well as the driving data to several regional groups. Baseline (1961-90), A2 and B2 scenarios (2071-2100). Reanalysisdriven runs provide comprehensive regional data sets representing current conditions, which can assist model evaluation as well as assessment of vulnerability to current climate variability. Ensembles to estimate model-related uncertainties. AAMP7, Irvine, USA, June 18-19, 2005
Model Orography HadCM3
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS
PRECIS Runs at IITM n n n
n
Evaluation experiment using LBCs derived from ERA-15 (1979-93) Several scenario runs of PRECIS performed simultaneously on an array of PCs The LBCs have a length of 31 years, and are available for Baseline (1960-90), A2 and B2 scenarios (2070-2100), with and without the sulphur cycle Scenarios for intermediate time slices by pattern scaling approaches
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS captures important regional information on summer monsoon rainfall missing in its parent GCM simulations.
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Simulations of Present Climate Mean Annual Cycles of All-India Rainfall and Temperature
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Simulations of Future Climate Mean Annual Cycles of All-India Rainfall and Temperature
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Surface Temperature, A2-Baseline, 2071-2100
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Precipitation, A2-Baseline, 2071-2100
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Projected Change in Rainydays
AAMP7, Irvine, USA, June 18-19, 2005
Applications in Impact Assessment Models n
n n
n
n
PRECIS generates comprehensive regional climate information, physically consistent among all the variables. Can be directly plugged into impact assessment models Used with water balance models and river water routing algorithms, PRECIS data enables more realistic representation of the processes affecting water resources, even in smaller river basins. PRECIS generates all the required information to drive crop-weather models, to estimate impacts on agriculture. Regional vegetation models like BIOME can be run with PRECIS data to estimate changes in forest cover.
AAMP7, Irvine, USA, June 18-19, 2005
To sum up… n n n n n n n
Global warming is happening NOW, with unambiguous regional signatures, and may have implications for the monsoon Observed data indicates that the Indian summer monsoon has been stable as a large-scale system over the past 200 years Most models simulate enhanced monsoon precipitation in a global warming scenario Large uncertainties still persist in future projections of monsoon. More work needed to understand local manifestations of monsoon changes and the possible role of land-surface changes/processes Regional models are quite useful in generating more detailed regional information, seem to inherit some of the biases seen in the driving GCMs. The robustness of monsoon projections based on time-slice experiments is constrained by the lack of air-sea interactions in the Indian Ocean. High-resolution coupled GCMs, at least incorporating a slab ocean model, are essential to regionalize the impact of global warming over the monsoon region.
AAMP7, Irvine, USA, June 18-19, 2005
AAMP7, Irvine, USA, June 18-19, 2005
South Asia : Population Pressure on Resources n n n
Total land area: 3.0% of global Population (present): 21.3% of global Population (projected-2025): 23.6% of global
AAMP7, Irvine, USA, June 18-19, 2005
Indian monsoon in a changing world n n n n n n n n n
We know the earth’s atmosphere is undergoing unprecedented warming Much of the warming is convincingly attributed to human activities How does the monsoon behave in a warmer atmosphere-ocean coupled system ? More atmospheric moisture Ë More intense hydrological cycle Ë More intense monsoon ? More intense/frequent ENSO anomalies ? More monsoon variability ? Which are the sub-regions likely to be affected ? Are land-use and land-cover changes associated with monsoon changes ? How do we distinguish between natural and anthropogenic changes in monsoon patterns ? Do we have global/regional policy options to deal with perceived monsoon changes ?
AAMP7, Irvine, USA, June 18-19, 2005
How monsoon can change… n Spatio-temporal
patterns of rainfall n Frequency of extreme seasonal anomalies n Monsoon onset/withdrawal n Timing and duration of active/break periods n Frequency of severe rainstorms n Teleconnections (e.g., ENSO-Monsoon) n Predictability of monsoon AAMP7, Irvine, USA, June 18-19, 2005
Indian Monsoon : Palaeoclimatic Setting n n
n
n
Cold periods in climatic history have winter-like circulation, whereas warm periods are characterized by a strong summer monsoon flow. Multidisciplinary evidence on climate during the Holocene period from the northwest regions indicate that the period between 10ka to 4.5ka BP experienced a warm and humid climate associated with relatively frequent floods. Around 3.5ka BP, a trend towards aridity set in over the entire northwest Indian region. However, aridity seemed to have been more active in the early part, followed by semiarid and arid conditions with present day vegetation. There are indications that the northern edge of the monsoon reaching the desert margins of northwest India underwent wide fluctuations leading to impermanent human civilizations to appear and disappear from the region.
AAMP7, Irvine, USA, June 18-19, 2005
Dendroclimatic Reconstruction of All India summer monsoon rainfall series during 1602-1960. (Indirect reconstruction based on Southern Oscillation Index estimated from tree-rings) 105 100
Rainfall (Cm)
95 90 85 80 75 70 1600
1650
1700
1750
1800
Year2005 AAMP7, Irvine, USA, June 18-19,
1850
1900
1950
The Long-Term Stability of the Indian Summer Monsoon
AAMP7, Irvine, USA, June 18-19, 2005
Long-term regional trends in Indian summer rainfall Small significant increasing/decreasing trends < +/- 0.1%/yr
Trend in %/100yr
AAMP7, Irvine, USA, June 18-19, 2005
% exp. variance
All-India Mean Surface Temperatures (1901-2000) Based on a constant network of 31 stations welldistributed over India
AAMP7, Irvine, USA, June 18-19, 2005
Diurnal Asymmetry of Temperature Trends over India
AAMP7, Irvine, USA, June 18-19, 2005
Sea Surface Temperature Trends in the Indian Ocean
AAMP7, Irvine, USA, June 18-19, 2005
Rainfall Variability over Indo-Gangetic Plains Region (IGPR) SUMMER MONSOON RAINFALL: 1844-1999
mm Eastern IGPR 1227 1175 1123
Central IGPR mm 977 895 813 mm Western IGPR 741 665 589
1841
1861
1881
1901
1921
AAMP7, Irvine, USA, June 18-19, 2005
1941
1961
1981
The 1941 Severe Rainstorm In the Indian sub-continent, the 13 July 1941 rainstorm is the most severe rainstorm of this region. Also considered to be one of the most severe rainstorms of the tropical regions of the world.
1-day rainfall (cm) AAMP7, Irvine, USA, June 18-19, 2005
Major Rainstorm Centres
AAMP7, Irvine, USA, June 18-19, 2005
Severe Rainstorms, 1891-2000 60
46
50
36
40
30 30 20
17
16
20
24 17
11
13
11
10
AAMP7, Irvine, USA, June 18-19, 2005
1991-2000
1981-1990
1971-1980
1961-1970
1951-1960
1941-1950
1931-1940
1921-1930
1911-1920
1901-1910
1891-1900
0
Changing Frequency of Cyclonic Disturbances during the Monsoon Season
AAMP7, Irvine, USA, June 18-19, 2005
Depressions/ Cyclonic storms n
Not a single monsoon depression or cyclonic storm formed during Monsoon 2002 and 2003.
Year
Number of depressions/ cyclonic storms
1997
5
1998
3
1999
2
2000
2
2001
1
2002
0
2003
0
2004
2
AAMP7, Irvine, USA, June 18-19, 2005
Weakening of ENSO-Monsoon relationship
AAMP7, Irvine, USA, June 18-19, 2005
Northeast Monsoon over South Asia
AAMP7, Irvine, USA, June 18-19, 2005
Recent strengthening of ENSO-Northeast Monsoon relationship
AAMP7, Irvine, USA, June 18-19, 2005
Modelling Monsoon Changes n n
n n n
Atmosphere-Ocean coupled models have made rapid strides over the past decade Global models are relatively better in reproducing large-scale monsoon features, but problems with regional details are yet to be overcome Regional models provide good tools to downscale global model predictions High-resolution climate change scenarios for the monsoon are available for impact assessments Yet, human behaviour being the most unpredictable forcing factor for climate change, models can only be used for policy guidance, and NOT to PREDICT future changes AAMP7, Irvine, USA, June 18-19, 2005
Annual Cycles of All-India mean rainfall in the control simulations of coupled AOGCMs
AAMP7, Irvine, USA, June 18-19, 2005
Global models provide inadequate and even inaccurate information on regional scales, more strikingly in the case of the Indian summer monsoon variability patterns. Summer Monsoon Rainfall (mm/day) Simulation by AOGCMs Observed
AAMP7, Irvine, USA, June 18-19, 2005
A qualitative description of the SRES scenarios
AAMP7, Irvine, USA, June 18-19, 2005
AOGCM Scenarios of allIndia summer monsoon rainfall and mean annual surface temperature
AAMP7, Irvine, USA, June 18-19, 2005
Annual Cycles of All-India mean rainfall and Temperature in the 20th Century simulations of coupled AOGCMz (IPCC AR4)
AAMP7, Irvine, USA, June 18-19, 2005
20th Century Climate Change of Rainfall and Temperature over the Indian Region (5:30N, 65:95E) based on 19 coupled AOGCMs (IPCC AR4)
AAMP7, Irvine, USA, June 18-19, 2005
Future Climate Change Scenarios of Rainfall and Temperature over the Indian Region (5:30N, 65:95E) based on 14 coupled AOGCMs (IPCC AR4)
AAMP7, Irvine, USA, June 18-19, 2005
ENSO-Monsoon Correlations – Observations & Modelling
AAMP7, Irvine, USA, June 18-19, 2005
Projected Changes in ENSO-Monsoon Relationships due to Transient increase in Greenhouse Gas Concentrations (ECHAM4/OPYC3)
AAMP7, Irvine, USA, June 18-19, 2005
Present-day Monsoon Precipitation (Coupled vs Forced Experiments using CNRM Climate Model)
AAMP7, Irvine, USA, June 18-19, 2005
Observed and Simulated Annual Cycles of Indian Summer Monsoon Indices
AAMP7, Irvine, USA, June 18-19, 2005
Simulated Summer Monsoon Response (Coupled vs Forced Experiments)
AAMP7, Irvine, USA, June 18-19, 2005
Simulated Changes in Annual Cycles of Indian Summer Monsoon Indices
AAMP7, Irvine, USA, June 18-19, 2005
Joint Indo-UK Collaborative Programme on Climate Change Impacts in India : Scenario Development n
n
n
n
Evaluation of Regional Climate Model simulations for Indian climate Estimation of uncertainties in model-based predictions Development of future climate scenarios for India during the 21st century Preparation of climate change scenario products for impact assessments
AAMP7, Irvine, USA, June 18-19, 2005
GCMs to Regional Adaptive Responses : Modelling Path
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS n n n n
n n
n
Providing REgional Climates for Impacts Studies High-resolution limited area model driven at its lateral and sea-surface boundaries by output from HadCM PRECIS runs on a Linux PC (horizontal resolutions currently available: 50 x 50 and 25 x 25 km). Needs data for the selected domain on lateral boundary conditions (LBC) from the driving GCM (e.g., HadCM3/HadAM3) and the associated ancillary files (e.g., sea surface temperatures, vegetation, topography, etc.). Hadley Centre, UK has been providing PRECIS as well as the driving data to several regional groups. Baseline (1961-90), A2 and B2 scenarios (2071-2100). Reanalysisdriven runs provide comprehensive regional data sets representing current conditions, which can assist model evaluation as well as assessment of vulnerability to current climate variability. Ensembles to estimate model-related uncertainties. AAMP7, Irvine, USA, June 18-19, 2005
Model Orography HadCM3
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS
PRECIS Runs at IITM n n n
n
Evaluation experiment using LBCs derived from ERA-15 (1979-93) Several scenario runs of PRECIS performed simultaneously on an array of PCs The LBCs have a length of 31 years, and are available for Baseline (1960-90), A2 and B2 scenarios (2070-2100), with and without the sulphur cycle Scenarios for intermediate time slices by pattern scaling approaches
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS captures important regional information on summer monsoon rainfall missing in its parent GCM simulations.
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Simulations of Present Climate Mean Annual Cycles of All-India Rainfall and Temperature
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Simulations of Future Climate Mean Annual Cycles of All-India Rainfall and Temperature
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Surface Temperature, A2-Baseline, 2071-2100
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Precipitation, A2-Baseline, 2071-2100
AAMP7, Irvine, USA, June 18-19, 2005
PRECIS Projected Change in Rainydays
AAMP7, Irvine, USA, June 18-19, 2005
Applications in Impact Assessment Models n
n n
n
n
PRECIS generates comprehensive regional climate information, physically consistent among all the variables. Can be directly plugged into impact assessment models Used with water balance models and river water routing algorithms, PRECIS data enables more realistic representation of the processes affecting water resources, even in smaller river basins. PRECIS generates all the required information to drive crop-weather models, to estimate impacts on agriculture. Regional vegetation models like BIOME can be run with PRECIS data to estimate changes in forest cover.
AAMP7, Irvine, USA, June 18-19, 2005
To sum up… n n n n n n n
Global warming is happening NOW, with unambiguous regional signatures, and may have implications for the monsoon Observed data indicates that the Indian summer monsoon has been stable as a large-scale system over the past 200 years Most models simulate enhanced monsoon precipitation in a global warming scenario Large uncertainties still persist in future projections of monsoon. More work needed to understand local manifestations of monsoon changes and the possible role of land-surface changes/processes Regional models are quite useful in generating more detailed regional information, seem to inherit some of the biases seen in the driving GCMs. The robustness of monsoon projections based on time-slice experiments is constrained by the lack of air-sea interactions in the Indian Ocean. High-resolution coupled GCMs, at least incorporating a slab ocean model, are essential to regionalize the impact of global warming over the monsoon region.
AAMP7, Irvine, USA, June 18-19, 2005
