Heartland Conference on Climate Change Chicago May Indian Monsoon Variability & Global Warming Madhav Khandekar CANADA Expert Reviewer IPCC 2007 Climate Change

Heartland Conference on Climate Change Chicago May Abstract An analysis of Indian Summer Monsoon Rainfall (ISMR) reveals that droughts and floods have occurred irregularly throughout a 200-year long excellent dataset with NO Link to “global warming OR climate change” at this point in time. An analysis of Indian Summer Monsoon Rainfall (ISMR) reveals that droughts and floods have occurred irregularly throughout a 200-year long excellent dataset with NO Link to “global warming OR climate change” at this point in time.

Heartland Conference on Climate Change Chicago May Monsoon: General Notes Indian/Asian monsoon is the largest seasonal abnormality in the global climate system Indian/Asian monsoon is the largest seasonal abnormality in the global climate system Indian/Asian monsoon affects about 4 billion people of south Asia. Timely arrival and well distributed rainfall during the summer season (May-October) is critical for agriculturally dominated countries of south Asia. Indian/Asian monsoon affects about 4 billion people of south Asia. Timely arrival and well distributed rainfall during the summer season (May-October) is critical for agriculturally dominated countries of south Asia. Climate models have achieved only a limited success so far in simulating many features of global and regional monsoon. Most climate models project monsoon circulation to intensify in a warmer future climate. In reality, Monsoon circulation has weakened in the last fifty years. Climate models have achieved only a limited success so far in simulating many features of global and regional monsoon. Most climate models project monsoon circulation to intensify in a warmer future climate. In reality, Monsoon circulation has weakened in the last fifty years.

Heartland Conference on Climate Change Chicago May Basic Facts on Indian Summer Monsoon 1. Summer (June-September) rains most important for whole of India for agriculture & water supply 2. Mean rainfall ~90 cm; On west coast ( Mumbai-Goa-Kerala Coast)~ cm; central India ~ cm; northwest India ~50 cm 3. Monsoon onset on west coast tip of India ~June 7 th 4. Despite year-to-year variability, this onset date is robust: Over Bay of Bengal & northeast, monsoon arrival ~1-12 June 5. By 25 June, monsoon spreads over most of India

Heartland Conference on Climate Change Chicago May

Highest/Lowest Rainfall Highest One Year Rainfall: Cherrapunji 2646 cm Highest One Year Rainfall: Cherrapunji 2646 cm Aug July 1861 Aug July 1861 Highest One Month Rainfall: Cherrapunji 930 cm Highest One Month Rainfall: Cherrapunji 930 cm July 1861 Highest 2-day Rainfall: 41 in ( ~105 cm) Mumbai Highest 2-day Rainfall: 41 in ( ~105 cm) Mumbai July 2005 Lowest seasonal Rainfall: 33mm (1918), 49mm (1899) in West Rajasthan: Both the years ( 1899 &1918 ) were severe drought years over whole of India Lowest seasonal Rainfall: 33mm (1918), 49mm (1899) in West Rajasthan: Both the years ( 1899 &1918 ) were severe drought years over whole of India

Heartland Conference on Climate Change Chicago May Major drought years 1868, 1877, 1899, 1918, 1951, 1972, 1987 Major Flood Years 1892, 1917, 1933, 1961, 1970, 1975

Heartland Conference on Climate Change Chicago May Large-scale controls of Indian Monsoon ENSO phase in the equatorial Pacific (El Nino linked to drought) ENSO phase in the equatorial Pacific (El Nino linked to drought) Eurasian snow cover, previous winter (Heavy snow cover weakens monsoon) Eurasian snow cover, previous winter (Heavy snow cover weakens monsoon) Equatorial stratospheric wind oscillation (QBO: quasi-biennial oscillation) Equatorial stratospheric wind oscillation (QBO: quasi-biennial oscillation) Indian Ocean Dipole (IOD) Indian Ocean Dipole (IOD) These large-scale controls and their various phases, produce major droughts/floods in summer monsoon

Heartland Conference on Climate Change Chicago May Depressions traveling along Monsoon trough Regional controls of Monsoon Low Pressures strengthen westcoast rain Axis of Monsoon trough Western Ghats

Heartland Conference on Climate Change Chicago May ENSO (El Nino-Southern Oscillation) phases in the equatorial Pacific

Heartland Conference on Climate Change Chicago May The 1997/98 El Nino structure at about Sep 1997

Heartland Conference on Climate Change Chicago May Equatorial stratospheric wind oscillation (QBO) at ~20-22 km level with about 26-month (east-west) period.

Heartland Conference on Climate Change Chicago May A schematic of Indian Ocean Dipole (IOD) Positive phase: warmer SSTs in west equatorial ocean Negative phase: warmer SSTs in east equatorial ocean

Heartland Conference on Climate Change Chicago May Eurasian winter snow cover Blanford (1884) first identified adverse impact of heavy winter snow cover on subsequent monsoon rains Blanford (1884) first identified adverse impact of heavy winter snow cover on subsequent monsoon rains Sir Gilbert Walker used snow cover as one of the important parameters Sir Gilbert Walker used snow cover as one of the important parameters Barnett et al (1989) simulated snow/monsoon adverse relationship using climate models Barnett et al (1989) simulated snow/monsoon adverse relationship using climate models In general, heavier snow cover produces weaker monsoon and vice-versa In general, heavier snow cover produces weaker monsoon and vice-versa

Heartland Conference on Climate Change Chicago May This jet (peak winds ~100 knots at 15 km level) is due to reversal of north-south temperature gradient. The jet disappears by October.

Heartland Conference on Climate Change Chicago May Indian monsoon exhibits decadal variability and is not influenced by Global Warming at this time Indian Monsoon Rainfall standardized values (Top) Cramer’s t-statistic for 11-year running mean depicting decadal variability and epochs (Bottom)

Heartland Conference on Climate Change Chicago May Major floods/droughts ( ) FLOODS FLOODS 1818 (1036 mm) 1818 (1036 mm) 1861 (1051 mm) 1861 (1051 mm) 1874 (1033 mm) 1874 (1033 mm) 1878 (1039 mm) 1878 (1039 mm) 1892 (1050 mm) 1892 (1050 mm) 1894 (1032 mm) 1894 (1032 mm) 1916 (1034 mm) 1916 (1034 mm) 1917 (1079 mm) 1917 (1079 mm) 1933 (1042 mm) 1933 (1042 mm) 1942 (1037 mm) 1942 (1037 mm) 1956 (1007 mm) 1956 (1007 mm) 1961 (1088 mm)— Most Severe Flood 1961 (1088 mm)— Most Severe Flood 1971 (1002 mm) 1971 (1002 mm) 1988 (1047 mm) 1988 (1047 mm) DROUGHTS DROUGHTS 1823 (795 mm) 1823 (795 mm) 1824 (770 mm) 1824 (770 mm) 1832 (775 mm) 1832 (775 mm) 1840 (774 mm) 1840 (774 mm) 1844 (788 mm) 1844 (788 mm) 1848 (688 mm) 1848 (688 mm) 1851 (744 mm) 1851 (744 mm) 1860 (733 cm) 1860 (733 cm) 1864 (748 mm) 1864 (748 mm) 1868 (777 mm) 1868 (777 mm) 1877 (609 mm)—Most Severe Drought 1877 (609 mm)—Most Severe Drought 1899 (695 mm) 1899 (695 mm) 1918 (661 mm) 1918 (661 mm) 1920 (786 mm) 1920 (786 mm) 1941 (785 mm) 1941 (785 mm) 1965 (741 mm) 1965 (741 mm) 1972 (708 mm) 1972 (708 mm) 1979 (723 mm) 1979 (723 mm) 1982 (788 mm) 1982 (788 mm) 1986 (780 mm) 1986 (780 mm) 1987 (739 mm) 1987 (739 mm) 2002 (715 mm) 2002 (715 mm) 2009 (698 mm) 2009 (698 mm) Mean 1041mmMean 739 mm

Heartland Conference on Climate Change Chicago May IPCC 2007: Global temperature declined between , present Warming since 1980 to 2005

Heartland Conference on Climate Change Chicago May Summer Monsoon Variability: vs floods, 3 droughts 4 floods, 3 droughts Mean rainfall:917 mm Mean rainfall:917 mm Only 8 years below normal Only 8 years below normal floods, 4 droughts 2 floods, 4 droughts Mean rainfall:888 mm Mean rainfall:888 mm 12 years below normal 12 years below normal 2 years close to normal 2 years close to normal Summer monsoon was stronger during , weaker in recent years in a warming climate

Heartland Conference on Climate Change Chicago May IOD Indian Ocean Dipole Positive phase IOD Indian Ocean Dipole Negative phase Drought Flood

Heartland Conference on Climate Change Chicago May Severe Drought

Heartland Conference on Climate Change Chicago May Floods in Pakistan and NW India

Heartland Conference on Climate Change Chicago May Summary & Conclusions Indian Monsoon is a robust system and its inter-annual variability is governed by large-scale atmosphere-ocean patterns. Indian Monsoon is a robust system and its inter-annual variability is governed by large-scale atmosphere-ocean patterns. Droughts/floods have occurred irregularly throughout a 200-year long dataset. Droughts/floods have occurred irregularly throughout a 200-year long dataset. Indian Monsoon appears to exhibit a decadal variability with approximately 30-year period of above/below rainfall. Indian Monsoon appears to exhibit a decadal variability with approximately 30-year period of above/below rainfall. Indian (and by extension Asian) monsoon is NOT impacted at this time by the modest warming of the earth’s climate. Indian and global monsoon circulations have weakened, in general, in the last 30 years or so. Indian (and by extension Asian) monsoon is NOT impacted at this time by the modest warming of the earth’s climate. Indian and global monsoon circulations have weakened, in general, in the last 30 years or so. A conceptual drought/flood model of Indian Monsoon based on selected large-scale indices can help predict future droughts and floods with a lead time of few weeks A conceptual drought/flood model of Indian Monsoon based on selected large-scale indices can help predict future droughts and floods with a lead time of few weeks