Tim Garrett University of Utah

1. Can we provide thermodynamic constraints for the long-term coupled evolution of the economy and the atmosphere? Tim Garrett University of Utah

2. SRES Emissions Scenarios out to 2100 All scenarios are considered equally probable CO2 Emissions 2100

3. Range of possible futures depends as much on societal trajectories as climate physics

4. But historically, the problem looks tightly constrained… R2=0.90 Atmospheric CO2 Perturbation (ppmv)

6. Cullenwardet al. 2011 Climatic Change xkcd.com

7. The atmosphere is an open thermodynamic system Material and energetic flow sunlight Available potential energy density atmosphere dissipation to space

8. …so is the global economy Material and energetic flow fuel Available potential energy density civilization dissipation to space

9. A child grows because it dissipates less energy than it consumes Energy efficient consumption is central to a positive feedback driving growth

10. Wealth is a fiscal measure of our capacity to enable the consumptive flow of primary (potential) energy. This flow enables all civilization activities. The convergence of energetic and material flows is what we fiscally quantify as the real GDP. By growing civilization, convergence grows our capacity to consume by expanding access to new energy reservoirs. This is what we implicitly value as economic production or the GDP. POSITIVE FEEDBACK fuel Wealth ($) civilization GDP ($/yr) dissipation to space

11. Power of money constant • Energy consumption rate is global economic wealth • Wealth is an accumulation of past real economic production. The GDP is a convergence of flows. • Key point:  is hypothesized to be a constant coefficient: the power of money • Hypothesis is testable and falsifiable Current rate of energy consumption Past world real GDP Wealth

12. Hypothesis evaluation Inflation-adjusted wealth is an implicit measure of the rate of energy consumption by civilization C = Global Wealth a = Global energy consumption rate a/C = Power per dollar  = 9.7 ± 0.3 mW per 1990 US dollar

13. IPCC:“Future greenhouse gas (GHG) emissions are the product of very complex dynamic systems, determined by driving forces such as demographic development, socio-economic development, and technological change. Their future evolution is highly uncertain.”

14. non-SRES global CO2 Emissions Identity Power of money constant Current rate of energy consumption Past world real GDP Wealth

15. non-SRES global CO2 Emissions Identity carbonization of energy supply Emissions Past real GDP Energy consumption rates wealth of civ. • Without decarbonizing, emissions cannot be reduced without destruction of global wealth • Current wealth is tied to the past history of real GDP, which cannot be destroyed

18. CThERM Multi-decadal coupled hindcasts Hindcast initialized with current state in 1985 Dashed: observations Color: hindcasts Gross World Product (trillions 1990 $/yr) Carbon Dioxide Concentrations Initialization

19. Forecasts to 2100 No switch from fossil fuels 3.7 - 8.3 ºC Civilization divergence 1.9 - 4.4 ºC SRES Models get an unphysically high GDP per [CO2] because they assume that energy consumption can be decoupled from the economy through efficiency gains

20. Conclusions • Civilization’s future is tied to its past consumption. • Wealth, energy consumption and CO2 emissions are coupled through a constant • Energy efficiency gains accelerate growth of wealth and CO2 emissions • The negative feedback on emissions and wealth is resource depletion and environmental disasters. • Shouldn’t SRES models appeal foremost to physics if they are to be coupled to GCMs?