• Energy Research

Cladosporium spp. and Alternaria spp. spores are dominating the airspora of Denmark. Currently, little is known about the influence of climate change on the fungal spore abundance in the air. The aim of this study was to examine temporal changes in airborne Alternaria and Cladosporium spores over 26 years. This is the first report of long-term airborne Cladosporium spore occurrence in Denmark. Air spore concentrations were obtained with a Burkard volumetric spore sampler placed in Copenhagen, Denmark, during June–September, 1990–2015. The highest monthly Spore integrals (SIn) for Alternaria were measured in August, whereas for Cladosporium July SIn was nearly as high as August SIn. Average Alternaria seasonal spore integral (SSIn) was 8615 Spores day m−3, while average 3-month (July–September) Cladosporium SIn was 375,533 Spores day m−3. Despite increasing annual temperature and decreasing relative humidity, we found a decreasing trend for Alternaria seasonal SIn (Slope = − 277, R2 = 0.38, p < 0.05), Alternaria (Slope = − 31, R2 = 0.27, p < 0.05) and Cladosporium (Slope = − 440, R2 = 0.23, p < 0.05) annual peak concentrations. We did not find any statistically significant trends for airborne Alternaria seasonal characteristics and duration, and likewise for Cladosporium 3-month SIn and peak concentration dates. Mean temperature was the main meteorological factor affecting daily spore concentrations. However, effect of meteorological parameters on daily spore concentrations was stronger for Cladosporium (R2 = 0.41) than for Alternaria (R2 = 0.21). Both genera had diurnal peaks during the day hours, earlier for Cladosporium (11:30–14:30) and later for Alternaria (15:00–19:00). Although Alternaria and Cladosporium daily concentrations were moderately correlated (Spearman’s correlation coefficient: rs = 0.55, p < 0.05), their overall annual indices were different, which indicates different sources and different factors determining spore release. We explain temporal decreasing trends in Alternaria SSIn by growing urbanisation around Copenhagen and by changes in agricultural practices.

Many international policies encourage a switch from fossil fuels to bioenergy based on the premise that its use would not result in carbon accumulation in the atmosphere. Frequently cited bioenergy goals would at least double the present global human use of plant material, the production of which already requires the dedication of roughly 75% of vegetated lands and more than 70% of water withdrawals. However, burning biomass for energy provision increases the amount of carbon in the air just like burning coal, oil or gas if harvesting the biomass decreases the amount of carbon stored in plants and soils, or reduces carbon sequestration. Neglecting this fact results in an accounting error that could be corrected by considering that only the use of ‘additional biomass’ – biomass from additional plant growth or biomass that would decompose rapidly if not used for bioenergy – can reduce carbon emissions. Failure to correct this accounting flaw will likely have substantial adverse consequences. The article presents recommendations for correcting greenhouse gas accounts related to bioenergy. Energy Policy, 45 ISSN:0301-4215

Existing descriptions of bi-directional ammonia (NH 3 ) land–atmosphere exchange incorporate temperature and moisture controls, and are beginning to be used in regional chemical transport models. However, such models have typically applied simpler emission factors to upscale the main NH 3 emission terms. While this approach has successfully simulated the main spatial patterns on local to global scales, it fails to address the environment- and climate-dependence of emissions. To handle these issues, we outline the basis for a new modelling paradigm where both NH 3 emissions and deposition are calculated online according to diurnal, seasonal and spatial differences in meteorology. We show how measurements reveal a strong, but complex pattern of climatic dependence, which is increasingly being characterized using ground-based NH 3 monitoring and satellite observations, while advances in process-based modelling are illustrated for agricultural and natural sources, including a global application for seabird colonies. A future architecture for NH 3 emission–deposition modelling is proposed that integrates the spatio-temporal interactions, and provides the necessary foundation to assess the consequences of climate change. Based on available measurements, a first empirical estimate suggests that 5°C warming would increase emissions by 42 per cent (28–67%). Together with increased anthropogenic activity, global NH 3 emissions may increase from 65 (45–85) Tg N in 2008 to reach 132 (89–179) Tg by 2100.

In recent years, residential wood combustion (RWC) has become a major source of ambient particulate matter (PM) in many developed countries, and in some of these countries even the largest source of primary particle emissions. While other sources of PM have been regulated intensively during the past decades, RWC has been subject to only minor regulation despite of its impact on climate and health. This review covers recent research publications on RWC contributions to ambient PM in different regions of Europe, North America and Australasia, and on key species associated with RWC. Furthermore, factors governing emissions from wood stoves (as the typical appliance used in residential heating) are evaluated. State-of-the-art methods for estimating RWC as a source of ambient PM are discussed. We conclude by highlighting important areas for future research and policies.