CICERO Research Archive (CICERO Senter for klimaforskning)
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A multi-model comparison of meteorological drivers of surface ozone over Europe
Get PDFThe implementation of European emission abatement strategies has led to a significant reduction in the emissions of ozone precursors during the last decade. Ground-level ozone is also influenced by meteorological factors such as temperature, which exhibit interannual variability and are expected to change in the future. The impacts of climate change on air quality are usually investigated through air-quality models that simulate interactions between emissions, meteorology and chemistry. Within a multi-model assessment, this study aims to better understand how air-quality models represent the relationship between meteorological variables and surface ozone concentrations over Europe. A multiple linear regression (MLR) approach is applied to observed and modelled time series across 10 European regions in springtime and summertime for the period of 2000–2010 for both models and observations. Overall, the air-quality models are in better agreement with observations in summertime than in springtime and particularly in certain regions, such as France, central Europe or eastern Europe, where local meteorological variables show a strong influence on surface ozone concentrations. Larger discrepancies are found for the southern regions, such as the Balkans, the Iberian Peninsula and the Mediterranean basin, especially in springtime. We show that the air-quality models do not properly reproduce the sensitivity of surface ozone to some of the main meteorological drivers, such as maximum temperature, relative humidity and surface solar radiation. Specifically, all air-quality models show more limitations in capturing the strength of the ozone–relative-humidity relationship detected in the observed time series in most of the regions, for both seasons. Here, we speculate that dry-deposition schemes in the air-quality models might play an essential role in capturing this relationship. We further quantify the relationship between ozone and maximum temperature (mo3 − T, climate penalty) in observations and air-quality models. In summertime, most of the air-quality models are able to reproduce the observed climate penalty reasonably well in certain regions such as France, central Europe and northern Italy. However, larger discrepancies are found in springtime, where air-quality models tend to overestimate the magnitude of the observed climate penalty.publishedVersio
Concentrations and radiative forcing of anthropogenic aerosols from 1750 to 2014 simulated with the Oslo CTM3 and CEDS emission inventory
Get PDFWe document the ability of the new-generation Oslo chemistry-transport model, Oslo CTM3, to accurately simulate present-day aerosol distributions. The model is then used with the new Community Emission Data System (CEDS) historical emission inventory to provide updated time series of anthropogenic aerosol concentrations and consequent direct radiative forcing (RFari) from 1750 to 2014. Overall, Oslo CTM3 performs well compared with measurements of surface concentrations and remotely sensed aerosol optical depth. Concentrations are underestimated in Asia, but the higher emissions in CEDS than previous inventories result in improvements compared to observations. The treatment of black carbon (BC) scavenging in Oslo CTM3 gives better agreement with observed vertical BC profiles relative to the predecessor Oslo CTM2. However, Arctic wintertime BC concentrations remain underestimated, and a range of sensitivity tests indicate that better physical understanding of processes associated with atmospheric BC processing is required to simultaneously reproduce both the observed features. Uncertainties in model input data, resolution, and scavenging affect the distribution of all aerosols species, especially at high latitudes and altitudes. However, we find no evidence of consistently better model performance across all observables and regions in the sensitivity tests than in the baseline configuration. Using CEDS, we estimate a net RFari in 2014 relative to 1750 of −0.17 W m−2, significantly weaker than the IPCC AR5 2011–1750 estimate. Differences are attributable to several factors, including stronger absorption by organic aerosol, updated parameterization of BC absorption, and reduced sulfate cooling. The trend towards a weaker RFari over recent years is more pronounced than in the IPCC AR5, illustrating the importance of capturing recent regional emission changes.publishedVersio
Småkraft
Get PDFCategory: Second Opinion, Sector: Energy, Issuer type: Corporate, Shading: Dark GreenpublishedVersio
Clemens Craft AS
No full textCategory: Second Opinion, Sector: Energy, Issuer type: Corporate, Shading: Dark GreenpublishedVersio
Blocking and its Response to Climate Change
Get PDFPurpose of Review Atmospheric blocking events represent some of the most high-impact weather patterns in the mid-latitudes, yet they have often been a cause for concern in future climate projections. There has been low confidence in predicted future changes in blocking, despite relatively good agreement between climate models on a decline in blocking. This is due to the lack of a comprehensive theory of blocking and a pervasive underestimation of blocking occurrence bymodels. This paper reviews the state of knowledge regarding blocking under climate change, with the aim of providing an overview for those working in related fields. Recent Findings Several avenues have been identified by which blocking can be improved in numerical models, though a fully reliable simulation remains elusive (at least, beyond a few days lead time). Models are therefore starting to provide some useful information on how blocking and its impacts may change in the future, although deeper understanding of the processes at play will be needed to increase confidence in model projections. There are still major uncertainties regarding the processes most important to the onset, maintenance and decay of blocking and advances in our understanding of atmospheric dynamics, for example in the role of diabatic processes, continue to inform the modelling and prediction efforts. Summary The term ‘blocking’ covers a diverse array of synoptic patterns, and hence a bewildering range of indices has been developed to identify events. Results are hence not considered fully trustworthy until they have been found using several different methods. Examples of such robust results are the underestimation of blocking by models, and an overall decline in future occurrence, albeit with a complex regional and seasonal variation. In contrast, hemispheric trends in blocking over the recent historical period are not supported by different methods, and natural variability will likely dominate regional variations over the next few decades.Blocking and its Response to Climate ChangepublishedVersio
Policy Entrepreneurship Curbed by Member State Preferences: DG Climate Action and the Effort Sharing Policy
Get PDFEfforts to reduce greenhouse gas emissions from the European Union (EU) are divided between two sector overreaching policy frameworks, the Emissions Trading Scheme and the Effort Sharing policy. The Effort Sharing policy distributes national targets to all member states to reduce emissions from transport, buildings, agriculture, waste-management and small industry. A central feature of the Effort Sharing policy framework is the much-disputed flexibility mechanisms. These flexibility mechanisms contribute to increase the cost-efficiency in efforts to reduce emissions from these sectors but might also contribute to delay action where the costs of reducing emissions are high. The European Council, the European Parliament and the European Commission had diverging opinions on what is the right level of flexibility in the Effort Sharing policy. Thus, the flexibility mechanism took centre stage under the review of the Effort Sharing policy framework.
This study investigates to what extent the Directorate-General (DG) for Climate Action acted as a policy entrepreneur to influence the level of flexibilities in the review of the European Union’s Effort Sharing policy for the 2021-2030 period. It draws on policy entrepreneurship theory and historical institutionalism and makes use of process tracing of the review of the Effort Sharing policy. Empirical data is collected from official EU documents and in-depth interviews. Due of the contextual conditions that constrained the room for policy entrepreneurship, it was least likely that the Commission would be able to act as a policy entrepreneur. The conditions for entrepreneurship were restricted by the asymmetrical preferences among the member states under the review process of the Effort Sharing policy from 2013-2016. However, the evidence suggests that even under such constraints, DG Climate Action is able to act as a policy entrepreneur. In response to the constraining conditions, DG Climate Action used entrepreneurial strategies to block attempts to increase the flexibilities in the Effort Sharing policy framework, thus acted as a status quo policy entrepreneur under the review of the Effort Sharing policy.publishedVersio
Industrial Bank Co (IB)
No full textCategory: Second Opinion, Sector: Banking, Issuer type: Financial Institution, Shading: Dark GreenpublishedVersio
EUs energi- og klimaunion: En analyse av et utvidet klimasamarbeid mellom Norge og EU
Get PDFDette arbeidsnotatet gir en kort gjennomgang av norsk klimapolitisk debatt anno 2018. Det redegjøres for hvordan EUs energi- og klimapolitikk etterhvert er blitt stadig mer integrert, og hvordan EUs energiunion vil ha betydning også for Norge. Regjeringen Solberg la i juni 2017 frem Stortingsmelding 41 (2016-2017) Klimastrategi for 2030 – norsk omstilling i europeisk samarbeid. Denne bygget videre på regjeringens første klimamelding fra 2015, hvor regjeringen foreslo å samarbeide med EU om å oppfylle det norske Parismålet. Regjeringen Solberg er nå i forhandlinger med EU om et tettere klimasamarbeid. Notatet diskuterer hvilke områder som berøres av et utvidet klimasamarbeid, og mulige forhandlingsutfall.
Norge har gjennom Parisavtalen forpliktet seg til å redusere utslippene med 40 prosent innen 2030. Parismålet og Norges deltakelse i EUs kvotesystem vil bestå uansett om Norge velger å gå fullt inn i en klimaunion eller et løsere klimasamarbeid. Avtaleformen (union eller samarbeid) kan ha konsekvenser for eventuelt nye klimamål og oppfølgingen av disse. Som fullverdig medlem av en klimaunion, vil Norges klimamål kunne komme til å følge av EUs nye mål. I et løsere klimasamarbeid, vil Norge sette egne målsettinger. Notatet diskuterer også eventuelle konsekvenser for Norges oppfyllelse av bidraget til Parisavtalen dersom EU og Norge ikke skulle lykkes med å komme til enighet om et tettere klimasamarbeid.publishedVersio
Climate sensitivity estimates - Sensitivity to radiative forcing time series and observational data
Get PDFInferred effective climate sensitivity (ECSinf) is estimated using a method combining radiative forcing (RF) time series and several series of observed ocean heat content (OHC) and near-surface temperature change in a Bayesian framework using a simple energy balance model and a stochastic model. The model is updated compared to our previous analysis by using recent forcing estimates from IPCC, including OHC data for the deep ocean, and extending the time series to 2014. In our main analysis, the mean value of the estimated ECSinf is 2.0 ∘C, with a median value of 1.9 ∘C and a 90 % credible interval (CI) of 1.2–3.1 ∘C. The mean estimate has recently been shown to be consistent with the higher values for the equilibrium climate sensitivity estimated by climate models. The transient climate response (TCR) is estimated to have a mean value of 1.4 ∘C (90 % CI 0.9–2.0 ∘C), and in our main analysis the posterior aerosol effective radiative forcing is similar to the range provided by the IPCC. We show a strong sensitivity of the estimated ECSinf to the choice of a priori RF time series, excluding pre-1950 data and the treatment of OHC data. Sensitivity analysis performed by merging the upper (0–700 m) and the deep-ocean OHC or using only one OHC dataset (instead of four in the main analysis) both give an enhancement of the mean ECSinf by about 50 % from our best estimate.Climate sensitivity estimates - Sensitivity to radiative forcing time series and observational datapublishedVersio