航空愿景2050：气候中和增长的潜力

The potential for climate-neutralgrowth XINYI SOLA ZHENG, JAYANT MUKHOPADHAYA PH.D., JONATHAN BENOIT,SUPRAJA N. KUMAR, DAN RUTHERFORD PH.D., DENIZ RHODE, DANIEL SITOMPUL ACKNOWLEDGMENTS The authors thank ICCT researchers Ana Beatriz Rebouças and Gabe Alvarez for theirthoughtful feedback. We are also grateful to the external reviewers—Tim Johnson(Transport & Environment), Marc Shapiro (Breakthrough Energy), Tom Opderbeckand Sarah Chou (American Airlines), and Jerrold Cline (GE Aerospace Research)—fortheir valuable inputs. This work was conducted with generous support from ClimateImperative Foundation. International Council on Clean Transportation1500 K Street NW, Suite 650Washington, DC 20005 communications@theicct.org|www.theicct.org|@TheICCT EXECUTIVE SUMMARY Aviation is a growing contributor to climate change, with effects extending beyondcarbon dioxide (CO2) emissions to include short-lived climate pollutants (SLCPs) suchas nitrogen oxides, black carbon, and contrail cirrus. In 2022, the International CivilAviation Organization agreed to achieve net-zero CO2emissions by 2050, but theindustry is not on track to deliver the scale of fuel efficiency improvements, sustainableaviation fuel (SAF) uptake, and zero-emission aircraft development required to meetthat goal. Recent advances in the scientific understanding of SLCPs have attractedattention to the potential rapid reductions in aviation-attributable warming throughcontrail mitigation. But no deep decarbonization roadmaps for aviation have beenupdated to reflect SLCP controls. This report updates the ICCT’sVision 2050decarbonization roadmap for the aviationsector by quantifying how SLCP mitigation can complement greenhouse gas (GHG)strategies to align aviation with the Paris Agreement. Using a high-fidelity 2023 flightemission inventory (JETSTREAM), an emission projection model (PACE 2.0), and asimplified climate model (FaIR), the report estimates aviation’s warming potentialthrough 2050 across five scenarios that span the full range of GHG and SLCPcontrol: Historical Trends, Current Commitments, GHG Forward, SLCP Forward, andFull Breakthrough. The Paris Agreement, adopted in 2015, commits countries to limit global warming towell below 2 °C and to pursue efforts to limit the temperature increase to 1.5 °C abovepre-industrial levels. This report compares aviation’s warming contributions to theremaining 1.7 °C warming budget, reflecting recent findings that global warming islikely to surpass the 1.5 °C threshold before 2030. As shown in Figure ES1, under the Historical Trends scenario, we project an additional60 millidegrees Celsius (mC), or 0.06 °C, of warming from aviation activity between2025 and 2050, which is double its contribution to temperature change over its entirehistory from 1940 to 2024. The Current Commitments scenario, which accounts forpolicies to curb aviation GHG emissions announced to date, projects an 11 mC (19%)reduction in warming by mid-century. The GHG Forward case, which models maximumlevels of GHG mitigation through SAF uptake, zero-emission planes (ZEPs), andimproved fuel efficiency, is projected to cut future warming by 29 mC, or 48% belowthe Historical Trends case. However, aviation would double its historical 4% share ofglobal warming, to 9% of the remaining 1.7 °C budget, under this scenario. Figure ES1 Aviation’s projected contribution to global warming by scenario, 1940 to 2050 Larger reductions are modeled via the SLCP Forward scenario, which adds contrailavoidance, fuel quality improvements, and advanced engines to the CurrentCommitments scenario; in this scenario, additional warming is reduced by 46 mC, or76% below Historical Trends. The SLCP Forward scenario keeps aviation to a 4% shareof the remaining 1.7 °C climate budget until 2050, but the share will likely increasebeyond 2050 as unmitigated GHG emissions continue to drive warming. In the FullBreakthrough scenario, which blends maximum GHG and SLCP mitigation, aviation’scontribution to global warming is cut by 91% below the Historical Trends scenario andlimits aviation’s share of additional contribution to the remaining 1.7 °C budget to 2%. By comparing the Historical Trends and Full Breakthrough scenarios, we cancharacterize the relative contribution that different mitigation levers may play incurbing aviation’s climate impact. Table ES1 summarizes the relative contribution ofeach mitigation lever to avoidable warming in 2050. The share of total warming bymitigation lever is shown at the far right; the breakdown of GHG versus SLCP control isshown at the bottom of the table. Table ES1 As shown in the table, contrail avoidance contributes the largest share (23 mC,or more than 40%) of all potential avoidable warming. That includes a small (0.07mC) temperature increase due to the fuel burn penalty of rerouting. The use ofSAF contributes 21% of avoided temperature increase, the second largest amount.Hydrotreating and operational efficiency are the third