scholarly journals Anthropogenic aerosol drives uncertainty in future climate mitigation efforts

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. J. L. Larson ◽  
R. W. Portmann
Keyword(s):  
Climate Models ◽  
Ghg Emissions ◽  
Paris Agreement ◽  
Climate Mitigation ◽  
Mathematical Framework ◽  
Emission Rates ◽  
Anthropogenic Aerosol ◽  
Greenhouse Gasses ◽  
Near Term ◽  
Aerosol Emissions

Abstract The 2016 Paris agreement set a global mean surface temperature (GMST) goal of not more than 2 degrees Celsius above preindustrial. This is an ambitious goal that will require substantial decreases in emission rates of long-lived greenhouse gasses (GHG). This work provides a mathematical framework, based on current state of the art climate models, to calculate the GHG emissions consistent with prescribed GMST pathways that meet the Paris agreement goal. The unique capability of this framework, to start from a GMST timeseries and efficiently calculate the emissions required to meet that temperature pathway, makes it a powerful resource for policymakers. Our results indicate that aerosol emissions play a large role in determining the near-term allowable greenhouse gas emissions that will limit future warming to 2 °C, however in the long term, drastic GHG emissions reductions are required under any reasonable aerosol scenario. With large future aerosol emissions, similar to present day amounts, GHG emissions need to be reduced 8% by 2040 and 74% by 2100 to limit warming to 2 °C. Under a more likely low aerosol scenario, GHG emissions need to be reduced 36% and 80% by 2040 and 2100, respectively. The Paris agreement Intended Nationally Determined Contributions are insufficient to meet this goal.

Climate effects of changing aerosol emissions over the coming decades

2021 ◽  
Author(s):  
Bjorn H. Samset ◽  
Camilla W. Stjern ◽  
Marianne T. Lund
Keyword(s):  
Global Scale ◽  
Mitigation Strategies ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Surface Temperature Change ◽  
Temperature And Precipitation ◽  
Large Ensembles ◽  
Near Term ◽  
Aerosol Emissions

<div>Emissions of anthropogenic aerosols strongly influence the climate, by modulating global and regional temperature, and by affecting precipitation, extremes, circulation patterns and other local-to-global scale features. This influence has been continually changing over previous decades, and will continue to change at least until 2050. It is also highly heterogeneous, in space and time. Hence, a deeper look at the potential role of anthropogenic aerosol emissions in shaping climate change over the coming decades is crucial for both adaptation and mitigation strategies. </div><div> </div><div>Here, we discuss three techniques to bound the potential near-term role of aerosols: (i) The influence on local and global rates of warming, relative to natural variability, using simplified models in combination with Large Ensembles, (ii) an overall constraint on the precipitation influence of absorbing aerosols, combining recent emission projections with results from several multi-model intercomparison projects, and (iii) changes to regional distributions of daily temperature and precipitation as function of the level of aerosol emissions and global warming, leveraging the statistics available through Large Ensembles. </div><div> </div><div>Overall, we find that while greenhouse gas emissions will continue to dominate the global mean climate evolution, by driving surface temperature change and its associated feedbacks, aerosol emissions may still hold a key - or even dominating - influence on changes to regional weather and climate. </div>

scholarly journals Negative emissions technologies and carbon capture and storage to achieve the Paris Agreement commitments

2018 ◽  
Vol 376 (2119) ◽  
pp. 20160447 ◽  
Author(s):  
R. Stuart Haszeldine ◽  
Stephanie Flude ◽  
Gareth Johnson ◽  
Vivian Scott
Keyword(s):  
Carbon Capture ◽  
Low Cost ◽  
Carbon Capture And Storage ◽  
Paris Agreement ◽  
Small Scale ◽  
Climate Mitigation ◽  
Emission Rates ◽  
Negative Emissions ◽  
Warming World ◽  
And Storage

How will the global atmosphere and climate be protected? Achieving net-zero CO 2 emissions will require carbon capture and storage (CCS) to reduce current GHG emission rates, and negative emissions technology (NET) to recapture previously emitted greenhouse gases. Delivering NET requires radical cost and regulatory innovation to impact on climate mitigation. Present NET exemplars are few, are at small-scale and not deployable within a decade, with the exception of rock weathering, or direct injection of CO 2 into selected ocean water masses. To keep warming less than 2°C, bioenergy with CCS (BECCS) has been modelled but does not yet exist at industrial scale. CCS already exists in many forms and at low cost. However, CCS has no political drivers to enforce its deployment. We make a new analysis of all global CCS projects and model the build rate out to 2050, deducing this is 100 times too slow. Our projection to 2050 captures just 700 Mt CO 2  yr −1 , not the minimum 6000 Mt CO 2  yr −1 required to meet the 2°C target. Hence new policies are needed to incentivize commercial CCS. A first urgent action for all countries is to commercially assess their CO 2 storage. A second simple action is to assign a Certificate of CO 2 Storage onto producers of fossil carbon, mandating a progressively increasing proportion of CO 2 to be stored. No CCS means no 2°C. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

scholarly journals Methane and the Paris Agreement temperature goals

2021 ◽  
Vol 380 (2215) ◽  
Author(s):  
Michelle Cain ◽  
Stuart Jenkins ◽  
Myles R. Allen ◽  
John Lynch ◽  
David J. Frame ◽  
...  
Keyword(s):  
Climate Model ◽  
Climate Science ◽  
Paris Agreement ◽  
Climate Mitigation ◽  
Emission Rates ◽  
Global Mean Temperature ◽  
Policies And Measures ◽  
Net Zero ◽  
Nationally Determined Contributions

Meeting the Paris Agreement temperature goal necessitates limiting methane (CH 4 )-induced warming, in addition to achieving net-zero or (net-negative) carbon dioxide (CO 2 ) emissions. In our model, for the median 1.5°C scenario between 2020 and 2050, CH 4 mitigation lowers temperatures by 0.1°C; CO 2 increases it by 0.2°C. CO 2 emissions continue increasing global mean temperature until net-zero emissions are reached, with potential for lowering temperatures with net-negative emissions. By contrast, reducing CH 4 emissions starts to reverse CH 4 -induced warming within a few decades. These differences are hidden when framing climate mitigation using annual ‘CO 2 -equivalent’ emissions, including targets based on aggregated annual emission rates. We show how the different warming responses to CO 2 and CH 4 emissions can be accurately aggregated to estimate warming by using ‘warming-equivalent emissions', which provide a transparent and convenient method to inform policies and measures for mitigation, or demonstrate progress towards a temperature goal. The method presented (GWP*) uses well-established climate science concepts to relate GWP100 to temperature, as a simple proxy for a climate model. The use of warming-equivalent emissions for nationally determined contributions and long-term strategies would enhance the transparency of stocktakes of progress towards a long-term temperature goal, compared to the use of standard equivalence methods. This article is part of a discussion meeting issue ‘Rising methane: is warming feeding warming? (part 2)’.

scholarly journals Atmospheric SO2: Principal Control Knob Governing Earth's Temperatures

2018 ◽  
Author(s):  
Burl Henry
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
So2 Emissions ◽  
Anthropogenic Aerosol ◽  
Volcanic Origin ◽  
Greenhouse Gasses ◽  
Earth’S Atmosphere ◽  
Clean Air ◽  
Earth's Atmosphere ◽  
Aerosol Emissions

An examination of the effects of SO2 aerosols in the Earth's atmosphere shows that they are responsible for all of the changes that have occurred in Earth's temperatures since the Roman warming period. and, by extension, the cause of all of the Ice Ages throughout Earth's history. They are primarily of volcanic origin, but since circa 1950, anthropogenic aerosol emissions began rising, peaking at ~ 136 Megatons in 1979, and, because of their cooling effect, fears of a return to Little Ice Age conditions. However, because of Acid Rain and Health concerns, global Clean Air efforts to reduce SO2 emissions were instituted in the early 1970's, and temperatures began to rise because of the cleaner, less polluted air.This warming was attributed to the accumulation of CO2 in Earth's atmosphere, but the analysis presented in this paper shows that the expected warming from the reduction in SO2 aerosol emissions precisely matches the actual rise in average global temperatures, leaving NO room for any of the hypothesized warming from "greenhouse" gasses. The warming is simply an unfortunate side effect of global Clean Air efforts.

Exploring the impact of aerosol radiative forcing uncertainty on shifts in ITCZ position and tropical rainfall in the near-term future

2020 ◽  
Author(s):  
Amy Peace ◽  
Ben Booth ◽  
Ken Carslaw ◽  
Leighton Regayre ◽  
Lindsay Lee ◽  
...  
Keyword(s):  
Energy Balance ◽  
Northern Hemisphere ◽  
Radiative Forcing ◽  
Anthropogenic Aerosol ◽  
Tropical Rainfall ◽  
Aerosol Radiative Forcing ◽  
Tropical Precipitation ◽  
Near Term ◽  
Aerosol Emissions ◽  
Aerosol Radiative

<p>Anthropogenic aerosol emissions over the industrial period have caused a negative but highly uncertain radiative forcing. This negative radiative forcing has had a cooling effect mainly over the northern hemisphere, affecting the atmospheric interhemispheric energy balance. Consequently aerosols have been linked to observed dynamical responses over the industrial period that depend on the atmospheric interhemispheric energy balance, such as changes in the position of the Intertropical Convergence Zone (ITCZ) and resultant tropical precipitation shifts. However, over the course of the 21<sup>st</sup> century anthropogenic aerosol emissions are predicted to decline. The reduction in anthropogenic aerosol emissions will cause a positive radiative forcing relative to present day, creating a warming effect in the northern hemisphere. Hence, if the strength of aerosol radiative forcing modulates the magnitude of shifts in the ITCZ, then the large uncertainty in aerosol radiative forcing will limit our understanding of how tropical precipitation will shift in the near-term future.</p><p>We use a perturbed parameter ensemble (PPE) of a global coupled climate model to investigate the link between aerosol radiative forcing and ITCZ and tropical rainfall shifts in the near-term future. The PPE consists of 20 simulations of the UK Met Office’s GC3.05 model with parameters perturbed from a range of model schemes. The ensemble was designed to sample uncertainties in future changes, and as a result spans a range of aerosol radiative forcings.</p><p>The PPE reveals both northward and southwards shifts in the ITCZ position across the ensemble in the latter half of the 20<sup>th</sup> century and first half of the 21<sup>st</sup> century, as well as changes in width and intensity of the ITCZ. We find a correlation between the shift in the ITCZ position and the magnitude of aerosol radiative forcing and AOD trends. However, the correlations in our ensemble are not as strong as those cited in previous studies that use multi-model ensembles. The potential causes of this difference are investigated. We also compare our model output to aerosol, cloud and radiation observations in attempt to identify the most plausible future aerosol-driven climate responses.</p>

scholarly journals The role of the European small ruminant dairy sector in stabilising global temperatures: lessons from GWP* warming-equivalent emission metrics

2021 ◽  
pp. 1-8
Author(s):  
Agustin del Prado ◽  
Pablo Manzano ◽  
Guillermo Pardo
Keyword(s):  
Small Ruminant ◽  
Ghg Emissions ◽  
Small Ruminants ◽  
Feed Additives ◽  
Dairy Goat ◽  
Emission Rates ◽  
Animal Products ◽  
Ghg Reduction ◽  
Mitigate Climate Change ◽  
Climate Neutrality

Abstract Recent calls advocate that a huge reduction in the consumption of animal products (including dairy) is essential to mitigate climate change and stabilise global warming below the 1.5 and 2°C targets. The Paris Agreement states that to stabilise temperatures we must reach a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases (GHG) in the second half of this century. Consequently, many countries have adopted overall GHG reduction targets (e.g. EU, at least 40% by 2030 compared to 1990). However, using conventional metric-equivalent emissions (CO2-e GWP100) as the basis to account for emissions does not result in capturing the effect on atmospheric warming of changing emission rates from short-lived GHG (e.g. methane: CH4), which are the main source of GHG emissions by small ruminants. This shortcoming could be solved by using warming-equivalent emissions (CO2-we, GWP*), which can accurately link annual GHG emission rates to its warming effect in the atmosphere. In our study, using this GWP* methodology and different modelling approaches, we first examined the historical (1990–2018) contribution of European dairy small ruminant systems to additional atmosphere warming levels and then studied different emission target scenarios for 2100. These scenarios allow us to envision the necessary reduction of GHG emissions from Europe's dairy small ruminants to achieve a stable impact on global temperatures, i.e. to be climatically neutral. Our analysis showed that, using this type of approach, the whole European sheep and goat dairy sector seems not to have contributed to additional warming in the period 1990–2018. Considering each subsector separately, increases in dairy goat production has led to some level of additional warming into the atmosphere, but these have been compensated by larger emission reductions in the dairy sheep sector. The estimations of warming for future scenarios suggest that to achieve climate neutrality, understood as not adding additional warming to the atmosphere, modest GHG reductions of sheep and goat GHG would be required (e.g. via feed additives). This reduction would be even lower if potential soil organic carbon (SOC) from associated pastures is considered.

scholarly journals Pathways of China's PM2.5 air quality 2015–2060 in the context of carbon neutrality

2021 ◽  
Author(s):  
Jing Cheng ◽  
Dan Tong ◽  
Qiang Zhang ◽  
Yang Liu ◽  
Yu Lei ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Critical Role ◽  
Climate Mitigation ◽  
Air Pollution Control ◽  
Carbon Neutrality ◽  
Climate Action ◽  
Clean Air ◽  
Near Term ◽  
Who Guideline

ABSTRACT Clean air policies in China have substantially reduced PM2.5 air pollution in recent years, primarily by curbing end-of-pipe emissions. However, further reaching the WHO guideline may instead depend upon the air quality co-benefits of ambitious climate action. Here, we assess pathways of Chinese PM2.5 air quality from 2015 to 2060 under a combination of scenarios which link Global and China's climate mitigation pathways (i.e. global 2°C- and 1.5°C-pathways, NDC pledges, and carbon neutrality goals) to local clean air policies. We find that China can achieve both its near-term climate goals (peak emissions) and PM2.5 air quality annual standard (35 μg/m3) by 2030 by fulfilling its NDC pledges and continuing air pollution control policies. However, the benefits of end-of-pipe control reductions are mostly exhausted by 2030, and reducing PM2.5 exposure of the majority of the Chinese population to below 10 μg/m3 by 2060 will likely require more ambitious climate mitigation efforts such as China's carbon neutrality goals and global 1.5°C-pathways. Our results thus highlight that China's carbon neutrality goals will play a critical role in reducing air pollution exposure to the WHO guideline and protecting public health.

scholarly journals Cities Exacerbate Climate Warming

Urban Science ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 27
Author(s):  
Lahouari Bounoua ◽  
Kurtis Thome ◽  
Joseph Nigro
Keyword(s):  
Surface Temperature ◽  
Land Surface ◽  
Large Scale ◽  
Climate Models ◽  
Warming Trend ◽  
Climate Mitigation ◽  
Temperature Changes ◽  
Surface Warming ◽  
The Us

Urbanization is a complex land transformation not explicitly resolved within large-scale climate models. Long-term timeseries of high-resolution satellite data are essential to characterize urbanization within land surface models and to assess its contribution to surface temperature changes. The potential for additional surface warming from urbanization-induced land use change is investigated and decoupled from that due to change in climate over the continental US using a decadal timescale. We show that, aggregated over the US, the summer mean urban-induced surface temperature increased by 0.15 °C, with a warming of 0.24 °C in cities built in vegetated areas and a cooling of 0.25 °C in cities built in non-vegetated arid areas. This temperature change is comparable in magnitude to the 0.13 °C/decade global warming trend observed over the last 50 years caused by increased CO2. We also show that the effect of urban-induced change on surface temperature is felt above and beyond that of the CO2 effect. Our results suggest that climate mitigation policies must consider urbanization feedback to put a limit on the worldwide mean temperature increase.

scholarly journals Evaluating the Uncertainty Induced by the Virtual Salt Flux Assumption in Climate Simulations and Future Projections

2010 ◽  
Vol 23 (1) ◽  
pp. 80-96 ◽  
Author(s):  
Jianjun Yin ◽  
Ronald J. Stouffer ◽  
Michael J. Spelman ◽  
Stephen M. Griffies
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Ocean Model ◽  
Salt Flux ◽  
Freshwater Flux ◽  
Unexpected Result ◽  
Geophysical Fluid Dynamics Laboratory ◽  
External Forcing ◽  
Future Evolution ◽  
Near Term

Abstract The unphysical virtual salt flux (VSF) formulation widely used in the ocean component of climate models has the potential to cause systematic and significant biases in modeling the climate system and projecting its future evolution. Here a freshwater flux (FWF) and a virtual salt flux version of the Geophysical Fluid Dynamics Laboratory Climate Model version 2.1 (GFDL CM2.1) are used to evaluate and quantify the uncertainties induced by the VSF formulation. Both unforced and forced runs with the two model versions are performed and compared in detail. It is found that the differences between the two versions are generally small or statistically insignificant in the unforced control runs and in the runs with a small external forcing. In response to a large external forcing, however, some biases in the VSF version become significant, especially the responses of regional salinity and global sea level. However, many fundamental aspects of the responses differ only quantitatively between the two versions. An unexpected result is the distinctly different ENSO responses. Under a strong external freshwater forcing, the great enhancement of the ENSO variability simulated by the FWF version does not occur in the VSF version and is caused by the overexpansion of the top model layer. In summary, the principle assumption behind using virtual salt flux is not seriously violated and the VSF model has the ability to simulate the current climate and project near-term climate evolution. For some special studies such as a large hosing experiment, however, both the VSF formulation and the use of the FWF in the geopotential coordinate ocean model could have some deficiencies and one should be cautious to avoid them.

The local and remote atmospheric impacts of Africa’s 21st century aerosol emission trajectory

2021 ◽  
Author(s):  
Chris Wells ◽  
Apostolos Voulgarakis
Keyword(s):  
Regional Climate ◽  
Emission Region ◽  
Anthropogenic Aerosol ◽  
Remote Locations ◽  
Aerosol Emission ◽  
Radiation Fluxes ◽  
The World ◽  
Aerosol Emissions ◽  
The Impact ◽  
Lower Biomass

<p>Aerosols are a major climate forcer, but their historical effect has the largest uncertainty of any forcing; their mechanisms and impacts are not well understood. Due to their short lifetime, aerosols have large impacts near their emission region, but they also have effects on the climate in remote locations. In recent years, studies have investigated the influences of regional aerosols on global and regional climate, and the mechanisms that lead to remote responses to their inhomogeneous forcing. Using the Shared Socioeconomic Pathway scenarios (SSPs), transient future experiments were performed in UKESM1, testing the effect of African emissions following the SSP3-RCP7.0 scenario as the rest of the world follows SSP1-RCP1.9, relative to a global SSP1-RCP1.9 control. SSP3 sees higher direct anthropogenic aerosol emissions, but lower biomass burning emissions, over Africa. Experiments were performed changing each of these sets of emissions, and both. A further set of experiments additionally accounted for changing future CO<sub>2</sub> concentrations, to investigate the impact of CO<sub>2</sub> on the responses to aerosol perturbations. Impacts on radiation fluxes, temperature, circulation and precipitation are investigated, both over the emission region (Africa), where microphysical effects dominate, and remotely, where dynamical influences become more relevant. </p>

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