Are extreme rainfall events just random or are they increasingly more likely due to global warming? This presentation argues for the latter and provides some suggestions on how towns and cities across the world should address this. This was presented during a panel discussion held in Chennai, India in the aftermath of the devastating rainfall and flooding in Chennai in Nov/Dec 2015.

1. T. R. Ramachandran
23 January 2016
Extreme Rainfall
Presented during “Chennai’s Legacy: A conversation on
governance, environment and society following the 2015 floods”

2. “Freak Weather”
“Perfect Storm”

3. 3
The highest daily rainfall in a century.
Freak weather conditions on one day.
The hottest-ever Indian Ocean.
The strongest-ever El Niño.
The hottest year on record.
The bad news is that a perfect storm of
meteorological conditions combined to create
Chennai’s worst-ever deluge last week,
exacerbated in no small part by civic
infrastructure pushed to its limit and systemic
dysfunction

4. A Question

5. How Many States in the US had Monthly
Record-Breaking Rainfall in 2015?
5

6. 2015: Record Monthly Rainfall in US
# State Town/City Record Broken in Highest In ~
1 North Carolina Charlotte Nov 137 years
2 Texas
Dallas/Fort-Worth & others +
State
May, Nov, Full Yr 117 years
3 Oklahoma Oklahoma City + State May, Nov 120 years
4 New Jersey Millville Jun 120 years
5 Illinois State Jun 120 years
6 Missouri St. Louis, Springfield + State Jun, Nov, Dec, Full Yr 141 years
7 South Carolina Charleston + other towns Oct 125 years
8 Maryland Baltimore Jun 142 years
9 Minnesota Many towns May 130 years
10 Iowa Sioux City Nov 100 years
11 California Los Angeles, San Diego Jul 138 years
12 Colorado Boulder, Col. Springs + State Feb, May 121 years
6

7. 2015: Record Monthly Rainfall in US
# State Town/City Record Broken in Highest In ~
13 Nebraska Lincoln May 100 years
14 Arkansas Fort Smith + others May, Dec, Full Yr 133 years
15 Vermont Montpelier, Mt. Mansfield Jun 120 years
16 Ohio Several towns Jun 120 years
17 Hawaii Honolulu August 138 years
18 Massachusetts Boston, Worcester Feb, Winter 142 years
19 Indiana Fort Wayne + State Jun 120 years
20 Oregon Portland Dec 75 years
21 Florida Miami-Dade Dec 83 years
- Contiguous US Entire country May 121 years
7
Source: http://www.kanvz.com/trr/canvas/1444143085761

8. 2015: Record Monthly Rainfall in US
# State Town/City Record Broken in Highest In ~
1 North Carolina Charlotte Nov 137 years
2 Texas
Dallas/Fort-Worth & others +
State
May, Nov, Full Yr 117 years
3 Oklahoma Oklahoma City + State May, Nov 120 years
4 New Jersey Millville Jun 120 years
5 Illinois State Jun 120 years
6 Missouri St. Louis, Springfield + State Jun, Nov, Dec, Full Yr 141 years
7 South Carolina Charleston + other towns Oct 125 years
8 Maryland Baltimore Jun 142 years
9 Minnesota Many towns May 130 years
10 Iowa Sioux City Nov 100 years
11 California Los Angeles, San Diego Jul 138 years
12 Colorado Boulder, Col. Springs + State Feb, May 121 years
8
Eliminated extreme drought of past 5 years
35T gallons, ~27 yrs drinking water for world
Eliminated extreme drought of past 5 years
Across NJ, 4th wettest Jun after 3rd driest May
Eliminated drought in several parts of state
Wettest months usually Jan-Mar, more rain in 1 day in Jul
than all of Jan after worst drought in > a century
Wettest month usually Mar
Wettest months usually Sep-Nov
Wettest month usually Jun
Wettest months usually Aug-Sep
Wettest month usually May
Wettest months usually Jul-Aug
Sixth “1-in-1000 year” event since 2010

9. Should We Keep Assuming
These Are Just “Freak” Events?

10. A Global Data Set from MunichRe
10
Source

11. Extreme Rainfall Events in the US
11
Source
nca2014.globalchange.gov

12. A Key Factor
12

13. Annual Average Worldwide T
13
Source

14. Averages are Misleading - I
14

15. Increasing Likelihood of Extreme Events
15

16. Averages are Misleading - II
16

17. Worldwide T Anomalies (2015)
17
Source

18. Local T Anomalies
18

19. Averages are Misleading - III
19

20. Here’s What is Happening in the Oceans –
That Cover 70% of Earth’s Surface
20
Source
The Vast Majority of Warming is Actually
Occurring in Our Oceans

21. Staggering Level of Ocean Warming Has
Widespread Consequences
21
Source
The Heat Trapped in Our Oceans Since
Recorded History Has Doubled Since 1997
How
Much
Heat?

22. What is Causing Global
Warming?

23. Predominantly CO2 (with some CH4)
23
Source

24. We’ve Changed Our Atmosphere Radically
Since the Industrial Revolution
24
Source

25. But Isn’t El Nino The Cause of
Anomalous Warming?

26. El Nino and La Nina
26
Source

27. El Nino and La Nina
27
Source

28. In Short
Less “Freak”, Less “Perfect Storm”
More “Climate Change”

29. So, Where is the Excess CO2
Coming From?

30. Emissions
30
Source

31. What We Need to Do

32. Takeaways
1. Focus more aggressively on switching from coal, oil,
gas to solar, wind, hydro (and if needed, nuclear)
 Collective effort required, driven by government
 Balance needs of development with needs of survival and livelihoods
2. Make the soil around our homes and buildings
strongly water-absorbent – esp. in towns and cities
 The right soil, the right vegetation, the right trees for the location
 Allows water to seep through and get distributed slowly to water respositories
 Ideally, do not build near large water bodies or low lying areas
3. Listen to experts when it comes to making and
enforcing laws that impact the world around us
 Tap into wealth of research and learning worldwide
32