Earth System Engineering A Way Out of Trouble or a Cure Worse than Disease

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Earth System Engineering - A Way Out of Trouble
or a Cure Worse than Disease?

• K. Kasturirangan
• Member
• Planning Commission
• Government of India
• New Delhi

Foundation Day Lecture Ministry of Earth
Sciences Government of India New Delhi July 27,
2009
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Earth System Engineering A Way Out of Trouble
or a Cure Worse Than Disease?

• Describes proposals to deliberately manipulate
  the earths climate to counter-act the effects of
  global warming from Green House Gas emissions.
• These are not suggested as alternative to
  emissions control but rather an accompanying
  strategy.
• Current surge of interest in this area arises
  from the fact that global warming could be both
  real and dangerous.
• Notably a complex discipline requiring collation
  of knowledge in
• Scientific disciplines including Atmospheric
  Chemistry, Ecology, Meteorology and Plant
  Biology.
• Engineering disciplines including Aeronautical
  Engineering, Naval Architecture Ballistics.
• Management and control disciplines such as risk
  management and operational research.

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Source IPCC AR4 Ch.6
The rate of increase of population in the last
2000 years (right) is very similar to the rate of
increase in the radiative forcing due to
greenhouse gases (inset).
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Systems Approach Interactions among components,
feedbacks, affecting the total system
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Comparison between temperature rise as derived
from models and observations since the year 1860
Inference The effect of external forcings cannot
be ignored these are unpredictable and may
hinder geoengineering efforts
Source IPCC AR4
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Systems Approach

• Interactions and feedbacks among components and
  these affect the whole system
• Known feedbacks ice-albedo(), vegetation (-),
  cloud-solar radiation(-) cloud-terrestrial
  radiation () Water vapour() CO2 -weathering
  (-) aerosol-clouds-precipitation
• Both external and internal forcings must be taken
  into account
• Non-linear responses/Thresholds have to be
  identified and quantified

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Inadequacy of models

• Models solve partial differential equations that
  are sensitive to the initial conditions small
  differences in initial conditions may lead to
  widely different solutions.
• Models do not parameterize all the feedbacks in
  the Earth System. Models have low spatial
  resolution.
• Most feedbacks require accurate quantification
  before they can be incorporated in the models.
• The more sophisticated the model, the more is the
  requirement for field data (specifically over
  tropics).
• Illustration with Paleocene Eocene Thermal
  Maximum (PETM).

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• Palaeoanalogue of Global change?
• Models unable to predict the warming in high
  latitudes clouds that form in high CO2
  atmosphere could be different?
• PETM ?T 10 to 30ka atmospheric warming of 5 to
  6C

Source IPCC AR4 Ch.6
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Geoengineering ideas proposed

• Carbon Sequestration
• (i) Afforestation (ii) Direct CO2 capture
• (iii) Petrification of CO2 (iv) Ocean
  fertilization
• Changing the Earths effective Albedo
• (i) Space mirrors (ii) Stratospheric sulphur
  aerolsols (iii) stratospheric balloons with
  alumina aerosols (iv) Low stratospheric dust/soot
  (iv) stimulation of white clouds (v) cool roofs
• Removal of atmospheric CFCs

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The advantages of global warming include
intensifictaion of the hydrological Cycle by
water vapour feedback increased monsoon is
expected, and fertilization of plants. Attennuatio
n of insolation might adversely impact these
benefits, e.g. Monsoons, a concern for Asian
countries on the other hand, they might benefit
by reduction in extreme weather events
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SSTs have increased in the recent years (blue)
and so have the destructive power of cyclones
(green).
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Partition of Anthropogenic Carbon Emissions into
Sinks
2000-2006
45 of all CO2 emissions accumulated in the
atmosphere
Atmosphere
The Airborne Fraction
The fraction of the annual anthropogenic
emissions that remains in the atmosphere
55 were removed by natural sinks
Land removes 30
Ocean removes 24
Canadell et al. 2007, PNAS
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45 of annual carbon flux is processed by
phytoplankton
THE BIOLOGICAL PUMP

• Plankton grow, mature and dietaking carbon with
  them to the deep ocean
• They have a larger effect on climate than any
  single other process or group of organisms.
• Of the 750 billion tons of CO2 that turn over
  annually, plankton process 45
• 99 of marine life relies on planktonthey form
  the base of the marine food chain.

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Conclusions about the ocean sink from the
Global Carbon Project

• The efficiency of natural sinks has decreased by
  10 over the last 50 years (and will continue to
  do so in the future), implying that the longer we
  wait to reduce emissions, the larger the cuts
  needed to stabilize atmospheric CO2.
• All of these changes characterize a carbon cycle
  that is generating stronger climate forcing and
  sooner than expected.

Canadell et al. 2007, PNAS
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Causes of the decrease in efficiency of the
ocean sink

• Part of the decline is attributed to up to a 30
  decrease in the efficiency of the Southern Ocean
  sink over the last 20 years.
• This sink removes annually 0.7 Pg of
  anthropogenic carbon.
• The decline is attributed to the strengthening of
  the winds around Antarctica which enhances
  ventilation of natural carbon-rich deep waters.
• The strengthening of the winds is attributed to
  global warming and the ozone hole.

Credit N.Metzl, August 2000, oceanographic
cruise OISO-5
Le Quéré et al. 2007, Science
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Iron experiments in world Ocean from 1993-2005
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An oceanic phytoplankton bloom in the South
Atlantic Ocean, off the coast of Argentina.
Encouraging such blooms with iron fertilization
could lock up carbon on the seabed Source
Moderate Resolution Imaging Spectroradiometer
(MODIS) on NASAs Aqua satellite
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duration of experiment in days
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How much CO2 can the biological pump sequester
in the Southern Ocean?

• If ALL the nitrate in the mixed layer (150m)
  were converted into phytoplankton biomass,
• and if all this biomass sank out of the mixed
  layer
• and if all the resultant CO2 deficit were
  compensated by uptake from the atmosphere
• then
• The maximum amount of CO2 that could be
  sequestered would amount to about 1 (one)
  Gigatonne of CO2
• Equivalent to 15 of annual input by humans
• This maximum amount could be removed about once
  every 4 years.
• SourceVictor Smetacek

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Ocean acidification affects the growth of
calcifying organisms Calcification and shell
growth rates coccolithophoridae. The efficiency
of the oceans for uptake of CO2 is thus reduced
significantly.
Courtesy Zondervan et al 2001
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Change in sea surface pH caused by anthropogenic
CO2 between the 1700s and the 1990s. This ocean
acidification will still be a major problem
unless atmospheric CO2 is reduced. Source
Global Ocean Data Analysis Project World Ocean
Atlas Climatologies
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Varying Photosynthetic response of biota in the
sea Some of these may be more effective in
removing CO2 from the atmosphere. The relative
geographical distribution of various species and
the overall efficiency for CO2 removal is yet to
be quantified.
Courtesy Rost and Riebesell 2004, (Springer)
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Conclusions

• Viable options
• (i) Use alternative energy sources,
  fuel-efficient engines to control emissions,
  prevent direct emissions (ii) afforestation
  (land) and fertilization (ocean) to scavenge CO2
  from the atmosphere (iii) Peterification of CO2
  by reaction with peridotite.
• Coordinated research to precisely quantify
  various feedbacks (e.g. soil carbon residence
  times, extreme weather events)

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Thank you