Abstract: . Climate change is a growing concern that is attracting international efforts. India, as a developing country, has committed to reducing its emission intensity of GDP up to 30 %–35 % by 2030. The emission intense sectors would be targeted to achieve climate commitment. One of the emission intense sector is construction raw material manufacturing that contributes 10 % share in the total emissions making it one of the potential mitigation sector. The study examines emissions from the construction raw materials namely, cement, steel, and brick manufacturing and presents two emission scenarios up to 2050. Energy efficient scenario (S2) is compared with a reference scenario (S1) developed based on a bottom-up approach. The results indicate that a moderate energy efficiency improvements and technological shifts lead to a decrease in emissions of 72 MT CO2 by 2030 and 137 MT CO2 by 2050. Further, the steel industry has the highest reduction potential, as the current technologies are energy inefficient. Similarly, the current dependency on fired bricks may be shifted to cement setting blocks leading to emission reductions. Cement manufacturing, on the other hand, shows limited scope for emission reduction that may be achieved through energy efficiency improvements. Efforts towards energy efficiency improvements in construction raw material manufacturing would result in reductions beyond the existing commitment of the Paris Agreement for India by 2030.

Abstract: The transient climate response (TCR) is defined to be the warming after 70 years of a 1% per year increase in atmospheric CO₂. It is one of the important metrics in climate science because it plays a key role in determining how much warming we will experience in the future. Previous work has found that TCR inferred from observed warming over the 20th century tends to be lower than TCR in climate models. This has been used by suggest that climate models are overpredicting future warming. We use a large number of climate model runs to investigate the methodology of this comparison. We find that TCR estimated from the 20th century simulations may indeed be much lower than the model’s true TCR. This arises from biases in the methodology of estimating TCR from 20th century warming, as well as biases in the construction of the observational temperature data sets. We therefore find no evidence that models are overestimating TCR.

Abstract: The potential of climate engineering to substitute or complement abatement of greenhouse gas emissions has been increasingly debated over the last years. The scientific assessment is driven to a large extent by assumptions regarding its effectiveness, costs, and impacts, all of which are profoundly uncertain. We investigate how this uncertainty about climate engineering affects the optimal abatement policy in the near term. Using a two period model of optimal climate policy under uncertainty, we show that although abatement decreases in the probability of success of climate engineering, this relationship is concave implying a rather ‘flat’ level of abatement as the probability of climate engineering becomes a viable policy option. Using a stochastic version of an integrated assessment model, the results are found to be robust to a wide range of specifications. Moreover, we numerically evaluate different correlation structures between climate engineering and the equilibrium climate sensitivity.