Global Zero Emissions Scenarios: Assessment of Climate Change Mitigations and their Costs. (August 2015) - Tokimatsu, Koji
Abstract: This study investigated various zero emissions scenarios under A1T of IPCC-SRES (Intergovernmental Panel on Climate Change – Special Report of Emissions Scenarios) that allowed economic growth in particularly technological progress. We used our global modeling including a simplified climate model, whose supply costs of sectors in energies, materials, biomass and foods were minimized by linear programming from 2010 to 2150 in order to draw various zero emissions scenarios. In this study, we focused on various scenarios of CO2 zero emissions from the sectors and their climate change mitigations and their costs. Inclusion of Non CO2 greenhouse gases (NCGHG) can be chosen. We set following four scenarios. First one is Business As Usual (BAU) without any climate policy intervention. Second one is denoted as "350 ppm zero", whose emissions trajectories are zero in the latter half of this century, which can be achieved by giving cumulative emissions of WRE 350 (Wigley Richels Edmonds) from 2010 to 2150 as emissions constraint. Caveating that this scenario add on the allowed WRE 350 emissions after 2010. Third one is denoted as "net zero", whose cumulative emissions from 2010 to 2150 is zero. This does not mean keep the emissions level zero in the time horizon; allowing positive emissions in several decades while negative emissions achieved by large deployment of BECCS (biomass energy carbon capture and storage). Fourth one is keeping the emissions level after 2100 is zero emissions, which is denoted as "2100 zero". We considered several patterns of carbon accounting for BECCS, such as carbon neutral, gross accounting, and net accounting. We also considered that two patterns of storage options for BECCS, one is only forest sink, the other one is allowing the captured CO2 into both the forest sink and geological storage. Following results when adding NCGHG emissions are obtained. Global mean temperature rise up to 2150 below 2 degree Celsius (DC) can be achieved in the "net zero" scenario, while "350 ppm zero" scenario leached 2.3 DC. The "2010 zero" scenario leached 4 DC while BAU about 5 DC.