Surface temperature response to regional black carbon emissions: do location and magnitude matter?

Abstract

Abstract. Aerosol radiative forcing can influence climate both locally and far outside the emission region. Here we investigate black carbon (BC) aerosols emitted in four major emission areas and evaluate the importance of emission location and magnitude as well as the concept of the absolute regional temperature-change potentials (ARTP). We perform simulations with a climate model (NorESM) with a fully coupled ocean and with fixed sea surface temperatures. BC emissions for year 2000 are increased by factors of 10 and 20 in South Asia, North America, and Europe, respectively, and by 5 and 10 in East Asia (due to higher emissions there). The perturbed simulations and a reference simulation are run for 100 years with three ensemble members each. We find strikingly similar regional surface temperature responses and geographical patterns per unit BC emission in Europe and North America but somewhat lower temperature sensitivities for East Asian emissions. BC emitted in South Asia shows a different geographical pattern in surface temperatures, by changing the Indian monsoon and cooling the surface. We find that the ARTP approach rather accurately reproduces the fully coupled temperature response of NorESM. Choosing the highest emission rate results in lower surface temperature change per emission unit compared to the lowest rate, but the difference is generally not statistically significant except for the Arctic. An advantage of high-perturbation simulations is the clearer emergence of regional signals. Our results show that the linearity of normalized temperature effects of BC is fairly well preserved despite the relatively large perturbations but that regional temperature coefficients calculated from high perturbations may be a conservative estimate. Regardless of emission region, BC causes a northward shift of the ITCZ, and this shift is apparent both with a fully coupled ocean and with fixed sea surface temperatures. For these regional BC emission perturbations, we find that the effective radiative forcing is not a good measure of the climate response. A limitation of this study is the uncertainties in BC–cloud interactions and the amount of BC absorption, both of which are model dependent.

Comparable sulfate climate impacts by consumption of developed and developing countries

“…This highlights the complex response of the nonlinear climate system to not only the magnitude but also the spatial pattern of aerosols. This nding is broadly consistent with previous E p based, idealized model simulations [8][9][10][11][12][13] , although our results are based on realistic E c emissions. For climate policy considerations and international negotiations, a climate change attribution assessment based on fully coupled model simulations driven by realistic, regionally detailed emissions is important.…”

“…For aerosols, which are short-lived, the spatial distribution of consumption associated emissions determines the distribution of their atmospheric loadings and thus exerts spatially inhomogeneous forcing 6,7 to the nonlinear climate system. Emerging evidence has suggested strong nonlinearity in the climate response to the magnitude 8,9 and location [10][11][12][13] of aerosols ─ for example, one study suggests that a given amount of aerosol emissions released in Western Europe cause 14 times as much global average cooling as when emitted in India 11 . These studies are solely based on idealized model experiments by scaling the emissions with an arbitrary factor or by putting the same amount of emissions to different locations.…”

Estimating Arctic Temperature Impacts From Select European Residential Heating Appliances and Mitigation Strategies

“…The 43.2 Gg of BC emissions were responsible for 5.8 millikelvin (mK) of Arctic warming (13.4 mK of warming per 100 Gg emitted). This result is comparable to that from Sand et al (2020), in which 10 mK of warming per 100 Gg emitted was modeled in a scenario where baseline European BC emissions were perturbed by a factor of 10. Snow and ice deposition were responsible for 64% of warming influence from BC.…”

“…The regional temperature response approach developed by Sand et al (2015) does have some limitations. In particular, the Arctic temperature responses were developed using very large emissions changes in order to create a signal, and recent research has suggested nonlinearities with the size of the emissions change (Sand et al, 2020; Yang et al, 2019), with Arctic temperature responses generally being larger per ton of emission change for smaller emission changes. However, it remains the best approach available for examining the Arctic temperature impacts of aerosol emissions perturbations, as direct modeling would be computationally prohibitive and not sufficiently sensitive for perturbations of the magnitude examined in this manuscript.…”

Aerosol Direct Radiative Effects under Cloud-Free Conditions over Highly-Polluted Areas in Europe and Mediterranean: A Ten-Years Analysis (2007–2016)

“…For instance, in 2004, Johnson et al [49] demonstrated the warming effect of absorbing particles within the mixing layer. Recently, Sand et al [50] found a non-linear relationship between emissions rate and temperature variation at ground level: the higher is the BC emission rate, the lower is the air temperature sensitivity because the convection in the lower atmospheric levels promote convection and turbulent motion moving BC from the surface to the mixing layer top. In other words, the net motion results in enhancing aerosol upward vertical transport.…”