Energy and Industry Emissions🔗

The Energy and Industry Emissions sector captures the historical and projected CO₂ fossil fuel (FF) emissions for nations or regions and aggregates those emissions into the global CO₂ fossil fuel emissions parameter that serves as input into the carbon cycle sub-model of C-ROADS. The CO₂ Fossil Fuel Emissions variable is the final output of this sector and feeds into the carbon cycle sector. It is determined either by Historical Emissions or Projected CO₂ FF emissions, depending upon the simulated year. The emissions sector has two primary functions within the C-ROADS simulator.

• It aggregates national or regional fossil fuel CO₂ emissions into a single global emissions parameter to feed into the carbon sector sub-model.
• It allows the user to graphically view and compare global CO₂ fossil fuel emissions trajectories and national or regional per capita CO₂ emissions under different scenarios.

Population projections are driven by UN projections; GDP projections are driven by population and GDP per capita; and emissions are driven by GDP and emissions per GDP.Parameters are set so that projections are consistent with the NGFS Current Policies, which are also consistent with the IPCCs AR5 SSP2 RF 6.0.

Reference Scenario Calculation🔗

Population projections also exogenously use those from the UN's medium fertility scenarios for each region.

Projections of GDP are determined by the projected GDP per capita. GDP per capita projections assume growth rates continue from what they are in the period leading up to the last historic year but decrease over time, converging to 1.5% through 2100. GDP is also subject to aggregate economic impact of climate change. Extensive research into the literature shows the vast disparity between estimates of damage at varying temperature changes. We assessed the very low estimates (Nordhaus, 2007, 2013, and 2016; Weitzman, 2012), ranging from 1% at 2 degrees, 2-3 % at 3 degrees, and 4-9% at 4 degrees, and 6-25% at 5 degrees, to be unrealistic. C-ROADS uses the function fitting the Burke et al., (2018) relationship, although the user may turn off the damage effect.

Projections of Baseline emissions, i.e., the Baseline emissions before any actions are implemented, are determined by the projections of emissions per GDP. This structure applies to RS CO₂ FF, CH₄, N₂O, SF₆, PFCs, and HFCs, each with its own starting and convergence rates and times to converge. CO₂ emissions from land use, land use change, and forestry (LULUCF) are detailed in Land Use, Land Use Change, and Forestry and Terrestrial Biosphere Carbon Cycle

Changes to Emissions🔗

Fossil fuel CO₂ emissions grow at the RS rate until a year specified by the user when the growth of emissions stops. Emissions are then held constant until another specified year, when emissions are reduced at an annual rate designated by the user. This allows for the testing of simple scenarios in which the growth, peak, and decline of regional emissions is controlled by the user. The proportional change from the Baseline applies to the Baseline emissions of each GHG.

LULUCF emissions are changed by setting the target action reduce deforestation and degradation. This type of action reduces the land changed or used, which then affects the emissions.

The percent of potential afforestation sets the land converted from other land to forests. Net emissions account for the increase in land removals of CO₂ from the atmosphere.