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The potential role of negative CO 2 emissions in solving climate problem

The potential role of negative CO 2 emissions in solving climate problem. A.Revokatova and A.Ryaboshapko , Institute of Global Climate and Ecology, Moscow , Russia. Approaches to solving climate problem :. Reduction of CO 2 emission

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The potential role of negative CO 2 emissions in solving climate problem

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  1. The potential role of negative CO2 emissions in solving climate problem A.Revokatova and A.Ryaboshapko, Institute of Global Climate and Ecology, Moscow, Russia

  2. Approaches to solving climate problem: Reduction of CO2 emission Removing of CO2 from the atmosphere - negative CO2 emission by CDR technologies (passive influence on Earth climate system) Solar radiation management - SRM (active influence on Earth climate system)

  3. Introduction • It is very likely that only emissions reduction techniques can not solve the climate problem • SRM methods cause a priori rejection of society, based on the idea of ​​undue influence on the nature and uncertainty about who will manage the process Goal: to estimate the potential of different CDR methods. Question: Is it possible to solve climatic problem by a combination of “emission reduction” methods and methods of negative emissions without application of SRM?

  4. During the industrial period in the Earth's atmosphere has received about 1,400 Gt CO2. RCP8.5 – radiative forcing =8.5 W/m2 in 2100 RCP6.0 – radiative forcing =6 W/m2 in 2100 550 ppm ~ Δ2ᵒC Δ2ᵒC – acceptable increment

  5. For climate projections it is important to calculate cumulativeemissionto the atmosphere - the accumulated amount of CO2over a long period. • Cumulative negative emission- accumulated amount of removed CO2from the atmosphere. • Humankind can archive negative emission by using CDR. But for visible result CDR methods must be applied during decades. • Global task - removal 1200 GtCO2(24 GtCO2/ year for 50 years) from the atmosphere, to end up with a CO2 concentration of 350 ppm (McLaren, 2012)

  6. Potentials of CO2 conservation

  7. Categories of negative emissions methods I – Terrestrial or oceanic methods that have a high potential and are not limited by the presence of the used components (CO2 conservation in coal;BECCS; Direct Air Capture; Electrolytic capture ofСО2; Soil mineralization; Ocean mineralization; Cultivation of algae in the ocean; Intensification of vertical transport in the ocean). II– Methods are limited by the presence of the used components (Afforestation and reforestation; Biomass conservation in the deep ocean; Biomass conservation in the mires and land; Landuseadaptation and improving restoration of peatlands). III – Others methods with low CO2 capture potential (less then 1 Gt СО2/year)(Increasing of wood used in construction CO2 capture from seawater Production of magnesium-silicate cement).

  8. Scenarios of “negative emissions” methods application Scenarios for 13 the most potential CDR methods • Potential of CO2 capture • Readiness to application • Technological inertia • Absence of experience • Transport infrastructure for delivery of CO2 to the storage place Changing of negative emission speed and cumulative negative emission values ​​were traced up to 2300. Start-time and duration of the deployment were evaluated with dependence of the complexity of technology and the degree of readiness for widespread use.

  9. General scheme of negative emission technology Air without CO2 Air+ CO2 Re - emission of CO2 CDR Воздух CO2 conservation Резервуар захоронения СО2 Reservoir of СО2 conservation

  10. Calculation of cumulative negative emission (CNE) • S – current speed of CO2 capture,GtCO2/year • CNE– CO2mass in the reservoir, GtCO2 • Re-emission-reverse flux from reservoir is proportional to CO2 mass in reservoir The exponential growth of the NE speed from the beginning of the deployment (S0 = 0) up to achievement of the estimated maximum value (Smax) was set for most of the methods. An exception is the aforestation, for which linear growth of NE speed was set in the deployment phase. CDR Воздух Si Amount of current annual NE = Si = exp (k1 * Ni) – 1 Smax = exp (k1 * Nmax) – 1 (Nmax– number of years for S= Smax ) k1 = ln (Smax +1) / Nmax linear growth: Si = Smax/ Nmax Резервуар захоронения СО2 CNE Re-emission

  11. CNE (cumulative negative emission) = CS(i) CS(i+1)at each time step is calculated as: CS(i+1) = CSi + Si – (CSi + Si) * k2 re-emission k2 - describe the process of re-emission; K2=1/, where  - the average lifetime of CO2in the reservoir Si = Smax The second phase of NE emission method deployment: CS(i+1) = CSi + Smax – (CSi + Smax) * k2.

  12. CO2 conservation in charcoal Scenario of deployment: - Maximum annual NE - 10 Gt CO2/ year (*)- Start of the application - 2030 - The exponential growth until 2120 - Sustainable use of the method to 2300 - The lifetime of coal in soils - 450 years (**) • (*) • IPCC, IPCC Expert Meeting on Geoengineering. 2012 • Lenton T.M. and Vaughan N.E., The radiative forcing potential of different climate geoengineering options. 2009 • McGlashan N.R., Workman M.H.W., Caldecott B., Shah N., Negative Emission Technologies, 2012 • McLaren D., A comparative global assessment of potential negative emissions technologies. 2012 • Meadowcroft J., Exploring negative territory carbon dioxide removal and climate policy initiatives. 2013 • Woolf D., Amonette J. E., Street-Perrott F. A., et al., Sustainable biochar to mitigate global climate change. 2010 • (**) • Jaffé R., Yan Ding, Niggemann J. et al., Global Charcoal Mobilization from Soils via Dissolution and Riverine Transport to the Oceans. 2013 • Lehmann J., Gaunt J. and Rondon M., Bio-char sequestration in terrestrial ecosystems – a review. 2006

  13. CO2 conservation in charcoal Annual NE flux Cumulative negative emission

  14. Afforestation and reforestation Limited factor – free areas Scenario of deployment: - Maximum NE of 1.5 Gt CO2 (*)- Afforestation from 2030 to 2050. - Annual uptake of 1.5 Gt of CO2 from 2050 to 2150 years. - After 2150 emission flux is equal to absorption • (*) • CanadellJ.P. and Raupach M.R., Managing Forests for Climate Change Mitigation. 2008 • McLaren D., A comparative global assessment of potential negative emissions technologies. 2012 • NingZeng, King A.W., Zaitchik B., Wullschleger S.D., et al., Carbon sequestration via wood harvest and storage: An assessment of its harvest potential. 2012 • Smith L.J. and Torn M.S., Ecological limits to terrestrial biological carbon dioxide removal. 2013 • Sitch S., Brovkin V., von Bloh W., et al., Impacts of future land cover changes on atmospheric CO2 and climate. 2005

  15. Afforestation and reforestation Cumulative negative emission Annual NE flux

  16. Total negative emission of the all considered NE methods Cumulative negative emission Annual NE flux Max  60 GtСО2/year 2300 KNE 13000 Gt СО2

  17. Contribution of each method to total negative emission

  18. RCP8.5 combined with all methods of negative emission Blue line - CO2concentration pathway (ppm(v)) according to RCP8.5 scenario. When all possible CDR techniques are applied, CO2 concentration in the atmosphere rises more slowly and begins to decline in about 2180(red line). Yellow line- CO2concentration level which corresponds to acceptable global temperature rise (+2C at 550 ppm(v)). Colored area indicates “dangerous” period, when global temperature will exceed the acceptable level.

  19. RCP6.0 combined with all methods of negative emission

  20. Results are too optimistic… • It is very unlikely that all methods will be deployed simultaneously • The thermal inertia of the ocean "stretchs" zone of dangerous excess CO2 • Imbalance between the reservoir and source-reservoir runoff ("recoil" effect) • It is necessary to consider the totality of greenhouse gases

  21. Conclusions • According to our simulations since 2050 and up to 2280 even the totality of CDR methods (or "negative emissions") cannot provide the stabilization of global temperature at an acceptable level while the most dangerous scenario of CO2 concentration increase is considered (RCP8.5). • Similar results were obtained when RCP6.0 scenario is used, but duration of “dangerous” period would be much less – about 50 years. • Only SRM techniques will be able to solve the problem during this period. Thus mankind will have to be ready to use all three approaches (emission reduction, CDR and SRM) to prevent the risk of inadmissible global temperature rise since the middle of this century.

  22. Thank you for your attention!

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