- The paper uses a feedback-free radiation model to estimate an averted warming of 0.0084°C (U.S.) to 0.070°C (global) by achieving net zero CO2 emissions by 2050.
- The authors derive an equilibrium climate sensitivity of 0.75°C, contrasting sharply with the IPCC’s 3.0°C estimate and highlighting uncertainties in climate feedbacks.
- Comparisons with the MAGICC model underscore the paper's challenge to mainstream mitigation strategies, urging a reassessment of climate policy priorities.
Analysis of "Net Zero Averted Temperature Increase"
The paper "Net Zero Averted Temperature Increase" by R. Lindzen, W. Happer, and W. A. van Wijngaarden presents a critical assessment of the estimated temperature reduction resulting from achieving net zero carbon dioxide (CO2) emissions by the year 2050, both in the United States and globally. The authors employ a fundamental, feedback-free model for calculating the temperature response, leveraging basic principles of radiation transfer without resorting to complex climate models.
At the core of the analysis is the equilibrium climate sensitivity (ECS), defined as the global mean surface temperature change due to a doubling of atmospheric CO2 concentration. The authors posit an ECS of 0.75°C, based on simplified physics. This value contrasts starkly with the Intergovernmental Panel on Climate Change's (IPCC) more conventional value of 3.0°C, which incorporates positive feedback mechanisms. Employing these assumptions, the paper concludes that efforts towards net zero CO2 emissions by 2050 would have a minimal impact on global temperatures.
The authors quantify that eliminating U.S. CO2 emissions by 2050 would result in an averted temperature increase of approximately 0.0084°C. If applied globally, under the same assumptions, the anticipated temperature rise mitigation would be only 0.070°C. The authors also present a scenario considering a fourfold increase in the climate sensitivity factor, according to IPCC estimates. Under these conditions, the averted temperature changes rise modestly—to 0.034°C for the U.S. and 0.28°C globally.
For a practical perspective, the authors compare their feedback-free results with those generated by the MAGICC model, a well-established integrated assessment tool frequently referenced in policy dialogues. MAGICC suggests that U.S.-only net zero emissions by the year 2100 might result in a temperature decrease of 0.173°C. This scenario incorporates a higher ECS and presumes a longer timeframe for evaluating the averted warming.
The theoretical implications of the paper are significant, as they challenge mainstream climatological estimates regarding the benefits of achieving net zero emissions. The authors assert that most natural feedback processes are negative, opposing common assumptions about positive climate feedbacks that amplify warming. This position invites further scrutiny about the intrinsic uncertainties associated with climate feedbacks and their implications for policy-driven mitigation measures.
Practically, the paper suggests a reconsideration of the economic and policy priorities associated with global net zero initiatives, given the purportedly limited temperature reductions presented. This perspective could influence international climate policy, especially in the allocation of resources towards alternative climate resilience strategies, such as adaptation or geoengineering.
Given its implications, this analysis could inspire future inquiry into refining methodologies for estimating climate sensitivity and feedback processes. Additionally, it underscores the importance of a rigorous appraisal of the costs and absolute benefits derived from ambitious greenhouse gas mitigation actions. This scholarly work indeed invites ongoing debate and further empirical investigation in climate science and policy development contexts.