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

Earth System Engineering – A Way Out of Trouble or a Cure Worse Than Disease? Describes proposals to deliberately manipulate the earth ’ s 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.

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).

Systems Approach: Interactions among components, feedbacks, affecting the total system

Source: IPCC AR4 Inference: The effect of external forcings cannot be ignored; these are unpredictable and may hinder geoengineering efforts Comparison between temperature rise as derived from models and observations since the year 1860

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(+); CO 2 -weathering (-); aerosol- clouds-precipitation Both external and internal forcings must be taken into account Non-linear responses/Thresholds have to be identified and quantified

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).

1.Palaeoanalogue of Global change? 2.Models unable to predict the warming in high latitudes: clouds that form in high CO 2 atmosphere could be different? 3.PETM: ΔT =10 to 30ka atmospheric warming of 5 to 6°C Source: IPCC AR4 Ch.6

Geoengineering ideas proposed Carbon Sequestration (i) Afforestation (ii) Direct CO 2 capture (iii) Petrification of CO 2 (iv) Ocean fertilization Changing the Earth ’ s 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

The advantages of global warming include intensifictaion of the hydrological Cycle by water vapour feedback: increased monsoon is expected, and fertilization of plants. Attennuation 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

SSTs have increased in the recent years (blue) and so have the destructive power of cyclones (green).

Partition of Anthropogenic Carbon Emissions into Sinks Canadell et al. 2007, PNAS Ocean removes ~ 24% Land removes ~ 30% 55% were removed by natural sinks 45% of all CO 2 emissions accumulated in the atmosphere The Airborne Fraction The fraction of the annual anthropogenic emissions that remains in the atmosphere Atmosphere [ ]

13 Plankton grow, mature and die—taking 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 plankton—they form the base of the marine food chain. THE BIOLOGICAL PUMP 45% of annual carbon flux is processed by phytoplankton

“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 CO 2.” “All of these changes characterize a carbon cycle that is generating stronger climate forcing and sooner than expected.” Conclusions about the ocean sink from the Global Carbon Project: Canadell et al. 2007, PNAS

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. Causes of the decrease in efficiency of the ocean sink Le Qu é r é et al. 2007, Science Credit: N.Metzl, August 2000, oceanographic cruise OISO-5

Iron experiments in world Ocean from

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 NASA’s Aqua satellite

17* * = duration of experiment in days

How much CO 2 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 CO 2 deficit were compensated by uptake from the atmosphere then The maximum amount of CO 2 that could be sequestered would amount to about 1 (one) Gigatonne of CO 2 Equivalent to ~15 % of annual input by humans This maximum amount could be removed about once every 4 years. Source:Victor Smetacek

Ocean acidification affects the growth of calcifying organisms: Calcification and shell growth rates – coccolithophoridae. The efficiency of the oceans for uptake of CO 2 is thus reduced significantly. Courtesy: Zondervan et al 2001

Change in sea surface pH caused by anthropogenic CO 2 between the 1700s and the 1990s. This ocean acidification will still be a major problem unless atmospheric CO 2 is reduced. Source: Global Ocean Data Analysis Project & World Ocean Atlas Climatologies

Courtesy: Rost and Riebesell 2004, (Springer) Varying Photosynthetic response of biota in the sea Some of these may be more effective in removing CO 2 from the atmosphere. The relative geographical distribution of various species and the overall efficiency for CO 2 removal is yet to be quantified.

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 CO 2 from the atmosphere (iii) Peterification of CO 2 by reaction with peridotite. Coordinated research to precisely quantify various feedbacks (e.g. soil carbon residence times, extreme weather events)