The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280-315 nm) radiation through 1850-2005 is evaluated using an Earth system model. Responses of UV-B dose to ...anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N-60° N and 120° E-150° E), where the effect of aerosols (ca. 70%) dominates the total UV-B change.
Changes in atmospheric ozone have occurred since the preindustrial era as a result of increasing anthropogenic emissions. Within ACCENT, a European Network of Excellence, ozone changes between 1850 ...and 2000 are assessed for the troposphere and the lower stratosphere (up to 30 km) by a variety of seven chemistry-climate models and three chemical transport models. The modeled ozone changes are taken as input for detailed calculations of radiative forcing. When only changes in chemistry are considered (constant climate) the modeled global-mean tropospheric ozone column increase since preindustrial times ranges from 7.9 DU to 13.8 DU among the ten participating models, while the stratospheric column reduction lies between 14.1 DU and 28.6 DU in the models considering stratospheric chemistry. The resulting radiative forcing is strongly dependent on the location and altitude of the modeled ozone change and varies between 0.25 Wm−2 and 0.45 Wm−2 due to ozone change in the troposphere and −0.123 Wm−2 and +0.066 Wm−2 due to the stratospheric ozone change. Changes in ozone and other greenhouse gases since preindustrial times have altered climate. Six out of the ten participating models have performed an additional calculation taking into account both chemical and climate change. In most models the isolated effect of climate change is an enhancement of the tropospheric ozone column increase, while the stratospheric reduction becomes slightly less severe. In the three climate-chemistry models with detailed tropospheric and stratospheric chemistry the inclusion of climate change increases the resulting radiative forcing due to tropospheric ozone change by up to 0.10 Wm−2, while the radiative forcing due to stratospheric ozone change is reduced by up to 0.034 Wm−2. Considering tropospheric and stratospheric change combined, the total ozone column change is negative while the resulting net radiative forcing is positive.
Recent advances of biotechnology have laid the groundwork for potent and specific molecular-targeting therapies including RNA interference. The largest remaining hurdle for widespread use of this ...technology in skin is an effective delivery system. Here, we demonstrate an effective topical delivery system using a cream formulation containing a small-interfering RNA (siRNA) that specifically targets osteopontin (OPN). OPN is a validated target in numerous inflammatory diseases, including rheumatoid arthritis (RA). The siRNA targeting OPN was incorporated into a cream formulation GeneCream that penetrates the stratum corneum, depositing siRNA in the epidermis, dermis, and to a lesser extent, subcutaneous tissue. In addition, when the OPN siRNA cream was topically applied to the skin of a collagen antibody-induced RA mouse model, the siRNA cream prevented the occurrence of severe, irreversible damage to bone and cartilage. Thus, the siRNA cream provides effective delivery of active OPN siRNA, suggesting this formulation may represent a platform technology for delivery of siRNAs for treating various disorders including RA.
An improved spectroscopy is used to implement and optimize the retrieval strategy of ethane (C2H6) from ground-based Fourier Transform Infrared (FTIR) solar spectra recorded at the high-altitude ...station of Jungfraujoch (Swiss Alps, 46.5°N, 8.0°E, 3580m a.s.l.). The improved spectroscopic parameters include C2H6 pseudo-lines in the 2720–3100cm−1 range and updated line parameters for methyl chloride and ozone. These improved spectroscopic parameters allow for substantial reduction of the fitting residuals as well as enhanced information content. They also contribute to limiting oscillations responsible for ungeophysical negative mixing ratio profiles. This strategy has been successfully applied to the Jungfraujoch solar spectra available from 1994 onwards. The resulting time series is compared with C2H6 total columns simulated by the state-of-the-art chemical transport model GEOS-Chem. Despite very consistent seasonal cycles between both data sets, a negative systematic bias relative to the FTIR observations suggests that C2H6 emissions are underestimated in the current inventories implemented in GEOS-Chem. Finally, C2H6 trends are derived from the FTIR time series, revealing a statistically-significant sharp increase of the C2H6 burden in the remote atmosphere above Jungfraujoch since 2009. Evaluating cause of this change in the C2H6 burden, which may be related to the recent massive growth of shale gas exploitation in North America, is of primary importance for atmospheric composition and air quality in the Northern Hemisphere.
•20-year time series of C2H6 is retrieved from ground-based FTIR solar spectra.•Improved spectroscopy reduces fitting residuals and enhances information content.•Negative bias to FTIR suggests underestimated C2H6 emissions in the GEOS-Chem model.•Trend analysis reveals a sharp increase of C2H6 burden since 2009.•C2H6 upturn may be related to growth of shale gas exploitation in North America.
West Siberia contains the largest extent of wetlands in the world, including large peat deposits; the wetland area is equivalent to 27% of the total area of West Siberia. This study used inverse ...modeling to refine emissions estimates for West Siberia using atmospheric CH4 observations and two wetland CH4 emissions inventories: (1)the global wetland emissions dataset of the NASA Goddard Institute for Space Studies (the GISS inventory), which includes emission seasons and emission rates based on climatology of monthly surface air temperature and precipitation, and (2)the West Siberian wetland emissions data (the Bc7 inventory), based on insitu flux measurements and a detailed wetland classification. The two inversions using the GISS and Bc7 inventories estimated annual mean flux from West Siberian wetlands to be 2.9 ± 1.7 and 3.0 ± 1.4Tgyr − 1, respectively, which are lower than the 6.3Tgyr − 1 predicted in the GISS inventory, but similar to those of the Bc7 inventory (3.2 Tgyr − 1). The well-constrained monthly fluxes and a comparison between the predicted CH4 concentrations in the two inversions suggest that the Bc7 inventory predicts the seasonal cycle of West Siberian wetland CH4 emissions more reasonably, indicating that the GISS inventory predicts more emissions from wetlands in northern and middle taiga.
We analyze present‐day and future carbon monoxide (CO) simulations in 26 state‐of‐the‐art atmospheric chemistry models run to study future air quality and climate change. In comparison with ...near‐global satellite observations from the MOPITT instrument and local surface measurements, the models show large underestimates of Northern Hemisphere (NH) extratropical CO, while typically performing reasonably well elsewhere. The results suggest that year‐round emissions, probably from fossil fuel burning in east Asia and seasonal biomass burning emissions in south‐central Africa, are greatly underestimated in current inventories such as IIASA and EDGAR3.2. Variability among models is large, likely resulting primarily from intermodel differences in representations and emissions of nonmethane volatile organic compounds (NMVOCs) and in hydrologic cycles, which affect OH and soluble hydrocarbon intermediates. Global mean projections of the 2030 CO response to emissions changes are quite robust. Global mean midtropospheric (500 hPa) CO increases by 12.6 ± 3.5 ppbv (16%) for the high‐emissions (A2) scenario, by 1.7 ± 1.8 ppbv (2%) for the midrange (CLE) scenario, and decreases by 8.1 ± 2.3 ppbv (11%) for the low‐emissions (MFR) scenario. Projected 2030 climate changes decrease global 500 hPa CO by 1.4 ± 1.4 ppbv. Local changes can be much larger. In response to climate change, substantial effects are seen in the tropics, but intermodel variability is quite large. The regional CO responses to emissions changes are robust across models, however. These range from decreases of 10–20 ppbv over much of the industrialized NH for the CLE scenario to CO increases worldwide and year‐round under A2, with the largest changes over central Africa (20–30 ppbv), southern Brazil (20–35 ppbv) and south and east Asia (30–70 ppbv). The trajectory of future emissions thus has the potential to profoundly affect air quality over most of the world's populated areas.
Apoptotic cell death plays a pivotal role in the development and/or maintenance of several tissues including thymus. Deregulated thymic cell death is associated with autoimmune diseases including ...experimental autoimmune encephalomyelitis (EAE), a prototype murine model for analysis of human multiple sclerosis. Because Thy28 expression is modulated during thymocyte development, we tested whether Thy28 affects induction of EAE as effectively as antigen-induced thymocyte deletion using Thy28 transgenic (TG) mice. Thy28 TG mice showed partial resistance to anti-CD3 monoclonal antibody (mAb)-induced thymic cell death in vivo, as assessed by annexin V-expression and loss of mitochondrial membrane potential. The resistance to anti-CD3 mAb-induced cell death in Thy28 TG mice appeared to correlate with a decreased c-Jun N-terminal kinase phosphorylation and reduced down-regulation of Bcl-xL. Moreover, thymic hyperplasia was detected in Thy28 TG mice, although thymocyte development was unaltered. Development of peripheral lymphoid tissues including spleen and lymph nodes was also unaltered. Thy28 TG spleen T cells showed an increased production of IFN-γ, but not IL-17, in response to both anti-CD3 and anti-CD28 mAbs. Finally, Thy28 TG mice displayed accelerated induction of EAE as assessed by disease incidence, clinical score, and pathology following immunization with myelin oligodendrocyte glycoprotein compared with control WT mice. These findings suggest that modulation of Thy28 expression plays a crucial role in the determination of thymic cell fate, which may contribute to the development of EAE through proinflammatory cytokine production.
A multi-model study of the long-range transport of ozone and its precursors from major anthropogenic source regions was coordinated by the Task Force on Hemispheric Transport of Air Pollution (TF ...HTAP) under the Convention on Long-range Transboundary Air Pollution (LRTAP). Vertical profiles of ozone at 12-h intervals from 2001 are available from twelve of the models contributing to this study and are compared here with observed profiles from ozonesondes. The contributions from each major source region are analysed for selected sondes, and this analysis is supplemented by retroplume calculations using the FLEXPART Lagrangian particle dispersion model to provide insight into the origin of ozone transport events and the cause of differences between the models and observations. In the boundary layer ozone levels are in general strongly affected by regional sources and sinks. With a considerably longer lifetime in the free troposphere, ozone here is to a much larger extent affected by processes on a larger scale such as intercontinental transport and exchange with the stratosphere. Such individual events are difficult to trace over several days or weeks of transport. This may explain why statistical relationships between models and ozonesonde measurements are far less satisfactory than shown in previous studies for surface measurements at all seasons. The lowest bias between model-calculated ozone profiles and the ozonesonde measurements is seen in the winter and autumn months. Following the increase in photochemical activity in the spring and summer months, the spread in model results increases, and the agreement between ozonesonde measurements and the individual models deteriorates further. At selected sites calculated contributions to ozone levels in the free troposphere from intercontinental transport are shown. Intercontinental transport is identified based on differences in model calculations with unperturbed emissions and emissions reduced by 20% by region. Intercontinental transport of ozone is finally determined based on differences in model ensemble calculations. With emissions perturbed by 20% per region, calculated intercontinental contributions to ozone in the free troposphere range from less than 1 ppb to 3 ppb, with small contributions in winter. The results are corroborated by the retroplume calculations. At several locations the seasonal contributions to ozone in the free troposphere from intercontinental transport differ from what was shown earlier at the surface using the same dataset. The large spread in model results points to a need of further evaluation of the chemical and physical processes in order to improve the credibility of global model results.
Lightning can cause natural hazards that result in human and animal injuries and fatalities, infrastructure destruction, and wildfire ignition. Lightning-produced NOx (LNOx), a major NOx (NOx=NO+NO2) ...source, plays a vital role in atmospheric chemistry and global climate. The Earth has experienced marked global warming and changes in aerosol and aerosol precursor emissions (AeroPEs) since the 1960s. Investigating long-term historical (1960–2014) lightning and LNOx trends can provide important indicators for all lightning-related phenomena and for LNOx effects on atmospheric chemistry and global climate. Understanding how global warming and changes in AeroPEs influence historical lightning and LNOx trends can be helpful in providing a scientific basis for assessing future lightning and LNOx trends. Moreover, global lightning activities' responses to large volcanic eruptions such as the 1991 Pinatubo eruption are not well elucidated and are worth exploring. This study employed the widely used cloud top height lightning scheme (CTH scheme) and the newly developed ice-based ECMWF-McCAUL lightning scheme to investigate historical (1960–2014) lightning and LNOx trends and variations as well as their influencing factors (global warming, increases in AeroPEs, and the Pinatubo eruption) in the framework of the CHASER (MIROC) chemistry–climate model. The results of the sensitivity experiments indicate that both lightning schemes simulated almost flat global mean lightning flash rate anomaly trends during 1960–2014 in CHASER (the Mann–Kendall trend test (significance inferred as 5 %) shows no trend for the ECMWF-McCAUL scheme, but a 0.03 %yr-1 significant increasing trend is detected for the CTH scheme). Moreover, both lightning schemes suggest that past global warming enhances historical trends for global mean lightning density and global LNOx emissions in a positive direction (around 0.03 %yr-1 or 3 %K-1). However, past increases in AeroPEs exert an opposite effect on the lightning and LNOx trends (-0.07 % to -0.04 %yr-1 for lightning and -0.08 % to -0.03 %yr-1 for LNOx) when one considers only the aerosol radiative effects in the cumulus convection scheme. Additionally, effects of past global warming and increases in AeroPEs in lightning trends were found to be heterogeneous across different regions when analyzing lightning trends on the global map. Lastly, this paper is the first of study results suggesting that global lightning activities were markedly suppressed during the first year after the Pinatubo eruption as shown in both lightning schemes (global lightning activities decreased by as much as 18.10 % as simulated by the ECMWF-McCAUL scheme). Based on the simulated suppressed lightning activities after the Pinatubo eruption, the findings also indicate that global LNOx emissions decreased after the 2- to 3-year Pinatubo eruption (1.99 %–8.47 % for the annual percentage reduction). Model intercomparisons of lightning flash rate trends and variations between our study (CHASER) and other Coupled Model Intercomparison Project Phase 6 (CMIP6) models indicate great uncertainties in historical (1960–2014) global lightning trend simulations. Such uncertainties must be investigated further.
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