Environmental progress
E. Somanathan
Fellow, Center for Advanced Study in the Behavioral Sciences, Stanford, &
Professor of Economics, Indian Statistical Institute, Delhi
The India Dialog, Feb 23-24, 2023
Panel on “Integration of Economic Growth and Social Progress”

Three points
• Tremendous opportunity for economic and environmental progress at
the local (districts/cities/towns/villages) level.
• Great opportunity for environmental progress at the state & national
levels.
• Great danger at the global level

Protection from climate change – a global
public good
• India is vulnerable because it has a large population living in one of
the hottest habitable parts of the earth.

Black areas have mean annual temp > 29 C today. Shaded areas will be above this in 2070
if emissions continue along the RCP8.5 scenario. From Xu, Chi, et al. "Future of the human climate niche."
Proceedings of the National Academy of Sciences (2020).

Economic impacts in India already observed
• Wheat yields 5% lower than they would have been absent
temperature increase in 1981-2009. Gupta, Somanathan, & Dey, Climatic Change 2016.

• Rice production is also a few percentage points lower.
Auffhammer, Ramanathan, & Vincent, PNAS 2006

• The impacts on crop yields not huge, a few percent each.
• Losses faced by the poor are in percentage terms 3 to 6 times greater
than the first-order impact on production. (Gupta, Ramaswami, & Somanathan,
Econ. of Disasters & Clim. Change, 2021)

Manufacturing output falls by 2% per degree rise in
temperature. Somanathan, Somanathan, Sudarshan, & Tewari, J. Polit. Econ. 2021.

Sample: 396
informal-sector
workers, Delhi,
summer 2019.
Numbers on the
axis are fraction of
income/expenditure
gained (lost if
negative) per
degree Celsius rise
in temperature.
Das & Somanathan (in
preparation)

Source: The
Hindu Kush
Himalaya
assessment:
mountains,
climate
change,
sustainability
and people.
ICIMOD,
2019.
Chapter 7.

Sea level rise

Policy responses
• Adaptation possibilities are limited
• Emission reduction followed by carbon dioxide removal will have
effects too late to protect us in this century.
• Bottom line:
• Warming will double or triple in this century
• Damages will much more than double or triple.

• The only possible protection left:
• research, deploy, and optimize one or more solar radiation
modification (SRM) technologies.

• Two SRM technologies
• marine cloud brightening,
• and stratospheric aerosol injection (SAI).

Stratospheric aerosol injection
US Geological Survey
https://pubs.usgs.gov/fs/1997/fs113-97/
“Nearly 20 million tons of sulfur dioxide
were injected into the stratosphere in
Pinatubo's 1991 eruptions, and dispersal of
this gas cloud around the world caused
global temperatures to drop temporarily
(1991 through 1993) by about 1°F (0.5°C).”

SAI will be very cheap to implement.
Cooling the planet by a degree will cost only
2/10,000ths of world income annually.
Still, can only be done by large countries

Downsides
• there will be changes in rainfall and other weather patterns that could
be adverse in some times and places.
• Recovery of the ozone layer could be slowed but not by much.

The more serious
problem is that nearly
everyone thinks like
Bart rather than like
Homer Simpson.

• India should invest much more in climate science and research into
SRM,
• And take the lead on an international organization to conduct
research on SRM