Abstract
Carbon dioxide emissions, global average temperature, atmospheric CO2 concentrations, and surface ocean mixed layer acidity are extrapolated using analyses calibrated against extensive time series data for nine global regions. Extrapolation of historical trends without policy-driven limitations has China responsible for about half of global CO2 emissions by the middle of the twenty-first century. Results are presented for three possible actions taken by China to limit global average temperature increase to levels it considers to be to its advantage: (1) Help develop low-carbon energy technology broadly competitive with unbridled carbon emissions from burning fossil fuels; (2) Entice other countries to join in limiting use of what would otherwise be economically competitive fossil fuels; (3) Apply geo-engineering techniques such as stratospheric sulfur injection to limit global average temperature increase, without a major global reduction in carbon emissions. Taking into account China’s expected influence and approach to limiting the impact of anthropogenic climate change allows for a narrower range of possible outcomes than for a set of scenarios that are not constrained by analysis of likely policy-driven limitations. While China could hold back on implementing geoengineering given a remarkable amount of international cooperation on limiting fossil carbon burning, an outcome where geoengineering is used to delay the perceived need to limit the atmospheric CO2 concentration may be difficult to avoid.
Highlights
How much will global average temperature increase in the twenty-first century? This is an important and as yet unanswered question for those who have to plan for the effects of climate change but cannot control it
(1) Help develop low-carbon energy technology broadly competitive with unbridled carbon emissions from burning fossil fuels; (2) Entice other countries to join in limiting use of what would otherwise be economically competitive fossil fuels; (3) Apply geo-engineering techniques to limit global average temperature increase, without a major global reduction in combustion of fossil carbon
For this example, based on the analysis described in Appendix E, the global average temperature increase over its preindustrial value to 3 ◦ C until after 2200 is limited by enough sulfur injection to sufficiently reduce net effective insolation proportional to S = 1/[1 + e−(ty −2065)/10 )] + 0.925/[1 + e−(ty −2150)/25 )], where ty is in Julian years
Summary
How much will global average temperature increase in the twenty-first century? This is an important and as yet unanswered question for those who have to plan for the effects of climate change but cannot control it. Either such outcome suggests that China’s preference for the eventual level of global average temperature increase will strongly influence the actual outcome. To examine the consequences of the above three options, we couple extrapolations of historical energy use trends with global heat and carbon balance analyses. The following section gives an example of how China might limit the increase of global average temperature over is preindustrial average to 3 ◦ C without any substantial cooperation from other countries on limiting carbon emissions until the twenty-third century. The section after that examines an alternative where China promptly begins to engage the rest of the world in a cooperative effort to limit carbon burning
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