Fant 10464 publikasjoner. Viser side 396 av 419:
2025
2025
Removal Processes of the Stratospheric SO2 Volcanic Plume From the 2015 Calbuco Eruption
Abstract We analyze the volcanic plume from the April 2015 Calbuco eruption over a 35‐day period using simulations from Meso‐NH, a non‐hydrostatic mesoscale atmospheric model. A dedicated parameterization of the deep injection of the plume into the stratosphere ensures a realistic representation when compared to Infrared Atmospheric Sounding Interferometer satellite observations. During the first 12 hr of the eruption, on 22 April 2015, SO 2 mixing ratio reached 29 ppmv between 15 and 18 km for the first eruption pulse, and 38 ppmv between 12 and 16 km for the second. Most SO 2 was injected directly into the stratosphere, with a stratospheric load reaching 308 ktS (kilotons of atomic sulfur, i.e. 616 kilotons of SO 2 ) after the eruption. After 1 month, both stratospheric and tropospheric SO 2 loads returned to near‐background levels. During analysis, the chemical conversion of SO 2 into H 2 SO 4 removed a part of SO 2 from the stratosphere. During the long‐range advection, the co‐location between the subtropical jet stream and the Calbuco plume led to three significant stratospheric intrusions on 24, 26 and 28 April 2015. These events transferred stratospheric SO 2 into the troposphere, SO 2 mixing ratios in the upper troposphere reaching 15 ppmv, 26 and 15 ppbv, respectively. SO 2 is gradually oxidized into H 2 SO 4 , with up to 5 ktS of gaseous H 2 SO 4 in the stratosphere on 30 April, but dynamical processes dominate the SO 2 atmospheric budget over chemical transformations. This study demonstrates that stratospheric intrusions can play a critical role in the removal of volcanic material from the stratosphere following a major eruption.
2025
Extremt varmt i stan? Köp en vit bil
Global uppvärmning och extremvärme i städerna är ett växande problem. Nu lanserar forskarna en ny och helt oväntad lösning.
2025
NILU og Akvaplan-niva har et felles overvåkingsprosjekt rundt Hammerfest LNG på Melkøya. I perioden 2025 – 2028 skal overvåkingen omfatte bly (Pb), kvikksølv (Hg) og PAH i nedbør, vegetasjon, jord, ferskvann, ferskvannsfisk og ferskvannssediment, samt kvikksølv i luft. For de fleste komponenter og prøvemedier er verdiene lave.
NILU
2025
2025
Carbonaceous aerosols (CA), composed of black carbon (BC) and organic matter (OM), significantly impact the climate. Light absorption properties of CA, particularly of BC and brown carbon (BrC), are crucial due to their contribution to global and regional warming. We present the absorption properties of BC (bAbs,BC) and BrC (bAbs,BrC) inferred using Aethalometer data from 44 European sites covering different environments (traffic (TR), urban (UB), suburban (SUB), regional background (RB) and mountain (M)). Absorption coefficients showed a clear relationship with station setting decreasing as follows: TR > UB > SUB > RB > M, with exceptions. The contribution of bAbs,BrC to total absorption (bAbs), i.e. %AbsBrC, was lower at traffic sites (11–20 %), exceeding 30 % at some SUB and RB sites. Low AAE values were observed at TR sites, due to the dominance of internal combustion emissions, and at some remote RB/M sites, likely due to the lack of proximity to BrC sources, insufficient secondary processes generating BrC or the effect of photobleaching during transport. Higher bAbs and AAE were observed in Central/Eastern Europe compared to Western/Northern Europe, due to higher coal and biomass burning emissions in the east. Seasonal analysis showed increased bAbs, bAbs,BC, bAbs,BrC in winter, with stronger %AbsBrC, leading to higher AAE. Diel cycles of bAbs,BC peaked during morning and evening rush hours, whereas bAbs,BrC, %AbsBrC, AAE, and AAEBrC peaked at night when emissions from household activities accumulated. Decade-long trends analyses demonstrated a decrease in bAbs, due to reduction of BC emissions, while bAbs,BrC and AAE increased, suggesting a shift in CA composition, with a relative increase in BrC over BC. This study provides a unique dataset to assess the BrC effects on climate and confirms that BrC can contribute significantly to UV–VIS radiation presenting highly variable absorption properties in Europe.
2025
Previous Common Era (i.e., the past 2000 years) climate reconstructions from Fennoscandia have focused on northern and central areas, with scarce data from the southern areas. Using varved sediments from Lake Sagtjernet in southeastern Norway, we developed a hydrogen isotope record from sedimentary leaf waxes (n-alkanes) as a proxy for hydrogen isotopes in precipitation, which we interpret as an indicator of temperature variability over the past 2000 years. The climate reconstruction provides high, decadal resolution for the period 360–770 CE, allowing critical evaluation during the Dark Ages Cold Period (around 300–800 CE) and a cooling during the 6th century, previously suggested as the coldest period of the Common Era. Our results reveal that the most rapid drop in temperature occurred from 536 to 545 CE (+74/-90 years), corresponding in time to the 536 and 540 CE volcanic eruptions. We also document an inferred cold interval that persisted from around 650 to 710 CE (+72/-90 years). While past studies have suggested prolonged cooling during the Dark Ages Cold Period, our findings show that, on average, the climate during 360–770 CE was similar to the Common Era average in the Lake Sagtjernet record. To explore socio-environmental interactions throughout the past 2000 years, we present a pollen-based environmental reconstruction and integrate it with archaeological evidence from around Lake Sagtjernet. These analyses reveal significant societal activities such as land clearing, cereal cultivation, and large-scale iron production, which drastically altered the landscape in the Viking Age (around 800–1050 CE) and the first half of the Norwegian Middle Ages (around 1050–1350 CE). Modern cultivation practices following the Black Death (1349–1350 CE) were first established around 1470 CE and increased continuously until around 1940 CE. Intensification of societal activities through the past millennium, including iron production and modern cultivation, occurred during both warmer (Medieval Climate Anomaly; 950–1250 CE) and colder (Little Ice Age; 1450–1850 CE) periods.
2025
2025
2025
2025
Marine plastic litter is subject to different abiotic and biotic forces that lead to its degradation, the main driver being UV-induced photodegradation. Since UV-exposure leads to both physical and chemical degradation of plastic, leading to a release of micro- and nanoplastics as well as leaching of chemicals and degradation products – it is expected to have radical impacts on plastics fate and effects in the marine environment. The number of laboratory studies investigating the mechanisms of plastic UV-degradation in seawater has increased significantly in the past 10 years, but are the exposures designed in a manner that allow observations to be extrapolated to environmental fate? Most studies to date focus on quantifying plastic fragmentation and surface changes, but is this relevant for impact assessments? Here, we provide a review of the current scientific literature on UV-degradation of plastic under marine conditions. Plastic fragmentation processes and surface changes as well as implications of UV-degradation of plastics on additive leaching and the toxicity of UV-weathered versus non-weathered plastics are highlighted. Furthermore, experimental set-ups are critically inspected and recommendations for future studies are issued.
2025
Screening Program 2024. Substances in electronic waste facilities and wastewater treatment
The 2024 Screening Programme investigated emerging and legacy contaminants in e-waste facilities and wastewater treatment. LCD substances, flame retardants, plasticizers, and their metabolites were found in air, dust, and water near e-waste sites. Bisphenol-related compounds and follow-up substances were detected in wastewater, particularly in sludge and particles. The findings highlight environmental dispersion, treatment efficiency, and the need for continued monitoring.
NILU
2025
2025
Rest of World News: Ocean carbon removal, touted as a climate solution, faces significant hurdles. A new EU report cautions that these unproven technologies lack evidence
2025
The report provides the annual update of the European air quality concentration maps and population and vegetation exposure estimates for human health related indicators of pollutants PM10 (annual average, 90.4 percentile of daily means), PM2.5 (annual average), ozone (93.2 percentile of maximum daily 8-hour means, peak season average of maximum daily 8-hour means, SOMO35, SOMO10), NO2 (annual average) and benzo(a)pyrene (annual average), and vegetation related ozone indicators (AOT40 for vegetation and for forests) for the year 2023. The report contains also maps of Phytotoxic ozone dose (PODY) for selected crops (wheat, potato and tomato) and trees (spruce and beech) and NOx annual average map for the same year 2023. The trends in exposure estimates in the period 2005-2023 are summarized. The analysis for 2023 is based on the interpolation of the annual statistics of the 2023 observational data reported by the EEA member and cooperating countries and other voluntary reporting countries and stored in the Air Quality e-reporting database, complemented, when needed, with measurements from additional sources. The mapping method is the Regression – Interpolation – Merging Mapping (RIMM). It combines monitoring data, chemical transport model results and other supplementary data using linear regression model followed by kriging of its residuals (residual kriging). The report presents the mapping results and gives an uncertainty analysis of the interpolated maps. It also presents concentration change in 2023 in comparison to the 5-year average 2018-2022 using the difference maps and exposure estimates.
European Topic Centre on Human Health and the Environment (ETC HE)
2025
Evaluating the Combined Effect of Land and Marine CDR
With the global annual mean temperature in 2024 exceeding 1.5°C above preindustrial levels, the world faces increasing risks from climate impacts. Achieving the long-term temperature goals of the Paris Agreement will require not only deep emission reductions but likely also large-scale deployment of carbon dioxide removal (CDR). However, major uncertainties remain regarding the Earth system’s response to CDR, its efficacy under overshoot conditions, and the potential of CDR to reverse warming beyond net-zero emissions.
Here, we use emission-driven simulations with activity-driven implementation of CDR in the Norwegian Earth System Model (NorESM2-LM) to assess the carbon sequestration efficacy and climate response of two CDR methods, Bioenergy with Carbon Capture and Storage (BECCS) and Ocean Alkalinity Enhancement (OAE), deployed individually and in combination. Our scenarios follow a high-overshoot trajectory (SSP5-3.4-OS) combined with ramped-up deployment of CDR. Additional CDR amounted to 5.2 million km² of bioenergy feedstock for BECCS in addition to the BECCS already present in the SSP5-3.4-OS and a CaO deployment rate of 2.7 Gt/year for OAE, derived from life cycle analysis. OAE is applied across the exclusive economic zones of Europe, the United States, and China. BECCS alone accounts for a 16 ppm reduction using 5.2 million km² of bioenergy crops, while OAE contributes 7 ppm reduction with a cumulative addition of 82.3 Gt of CaO, yielding a CDR effectiveness of 0.08 ppm per Gt of CaO. During the overshoot phase (2050–2060), the combined simulation shows a gross atmospheric CO₂ reduction of 2-4 ppm, increasing to a reduction of 23 ppm by 2100, indicating nearly additive contributions from the two methods.
Despite the substantial CO₂ drawdown and a net reduction of anthropogenic emissions by 5.4 GtCO₂/year by 2100 through additional CDR, the global temperature response remains modest and indistinguishable from internal variability. This highlights the importance of designing robust, scalable CDR portfolios along with ambitious emission cuts. Our results also call for better integration of CDR pathways into IAMs scenarios so that we can have them in ESMs to fully capture biogeophysical feedback and Earth system constraints in overshoot scenarios.
2025