Environmental Research Letters

Journal: Environmental Research Letters

Abbreviation

Environ. Res. Lett.

Publisher

IOP Publishing

ISSN

1748-9326
1748-9318

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Publications 1 - 10 of 275

Are forest disturbances amplifying or canceling out climate change-induced productivity changes in European forests?
Reyer, Christopher P.O.; Bathgate, Stephen; Blennow, Kristina; et al. (2017)
Environmental Research Letters
Recent studies projecting future climate change impacts on forests mainly consider either the effects of climate change on productivity or on disturbances. However, productivity and disturbances are intrinsically linked because 1) disturbances directly affect forest productivity (e.g. via a reduction in leaf area, growing stock or resource-use efficiency), and 2) disturbance susceptibility is often coupled to a certain development phase of the forest with productivity determining the time a forest is in this specific phase of susceptibility. The objective of this paper is to provide an overview of forest productivity changes in different forest regions in Europe under climate change, and partition these changes into effects induced by climate change alone and by climate change and disturbances. We present projections of climate change impacts on forest productivity from state-of-the-art forest models that dynamically simulate forest productivity and the effects of the main European disturbance agents (fire, storm, insects), driven by the same climate scenario in seven forest case studies along a large climatic gradient throughout Europe. Our study shows that, in most cases, including disturbances in the simulations exaggerate ongoing productivity declines or cancel out productivity gains in response to climate change. In fewer cases, disturbances also increase productivity or buffer climate-change induced productivity losses, e.g. because low severity fires can alleviate resource competition and increase fertilization. Even though our results cannot simply be extrapolated to other types of forests and disturbances, we argue that it is necessary to interpret climate change-induced productivity and disturbance changes jointly to capture the full range of climate change impacts on forests and to plan adaptation measures.
Intensification of summer precipitation with shorter time-scales in Europe
Hodnebrog, Øivind; Marelle, Louis; Alterskjær, Kari; et al. (2019)
Environmental Research Letters
While daily extreme precipitation intensities increase with global warming on average at approximately the same rate as the availability of water vapor (~7%/°C), a debated topic is whether sub-daily extremes increase more. Modelling at convection-permitting scales has been deemed necessary to reproduce extreme summer precipitation at local scale. Here we analyze multi-model ensembles and apply a 3 km horizontal resolution model over four regions across Europe (S. Norway, Denmark, Benelux and Albania) and find very good agreement with observed daily and hourly summer precipitation extremes. Projections show that daily extreme precipitation intensifies compared to the mean in all regions and across a wide range of models and resolutions. Hourly and 10 min extremes intensify at a higher rate in nearly all regions. Unlike most recent studies, we do not find sub-daily precipitation extremes increasing much more than 7%/°C, even for sub-hourly extremes, but this may be due to robust summer drying over large parts of Europe. However, the absolute strongest local daily precipitation event in a 20 year period will increase by 10%–20%/°C. At the same time, model projections strongly indicate that summer drying will be more pronounced for extremely dry years.
Meteorological and hydrological dry-to-wet transition events are only weakly related over European catchments
Brunner, Manuela I; Anderson, Bailey; Muñoz-Castro, Eduardo (2025)
Environmental Research Letters
Transitions from dry to wet states challenge water management and can lead to severe impacts. While meteorological transitions from dry-to-wet spells are well studied, it is yet unclear how, and if, they propagate to hydrological transitions. Here, we study where and why seasonal meteorological transitions propagate to drought-to-flood transitions in Europe using a large-sample dataset of hydro-meteorological observations. Our analysis shows that the relationship between meteorological and hydrological transitions is weak, with only 10% and 25% of the meteorological transitions propagating to the hydrosphere at monthly and annual time scales, respectively. Transition propagation is limited by the propagation of wet spells, in particular those with small precipitation intensities and volumes but favored in catchments with a direct link between precipitation and streamflow and limited storage influences. As hydrological and meteorological transitions are only weakly related, changes in meteorological transitions are a relatively poor proxy for future changes in drought-to-flood transitions.
Snow drought propagation and its impacts on streamflow drought in the Alps
Chartier-Rescan, Corentin; Wood, Raul R.; Brunner, Manuela (2025)
Environmental Research Letters
Snow droughts, that is negative anomalies in annual snow storage, challenge water resources management in snow-rich catchments and their downstream regions because they can lead to succeeding streamflow droughts in the following melt season. Under continued global warming, snow droughts are expected to become more frequent and intense, which likely increases the occurrence of succeeding streamflow droughts. However, we still know little about the rate at which snow droughts propagate to subsequent streamflow droughts, the spatial patterns of these concurrent events, the influence of snow drought characteristics on the occurrence, deficit, and duration of streamflow droughts, and temporal changes in snow drought propagation. To address these research gaps, we developed a novel dynamic bi-directional snow-to-streamflow drought propagation scheme, that resulted in a unique dataset of concurrent snow and streamflow droughts for 207 catchments in Switzerland and Austria. We found that in the period from 1961 to 2020, 18% of the snow droughts propagated to a streamflow drought, and that 21% of the spring/summer streamflow droughts were preceded by a snow drought. Snow-to-streamflow droughts are most common in catchments at high elevations without glaciers and among the snow droughts with the largest deficits and longest durations. In general, snow droughts lead to streamflow droughts with higher deficits, longer durations, and earlier occurrences. In the last six decades, the number of snow droughts has increased, which resulted in a doubling of snow-to-streamflow drought events in 1991-2020 compared to 1961-1990. As snow droughts are expected to further increase due to climate change, the propagation of snow-to-streamflow droughts will likely increase in medium to high elevation catchments and lead to more frequent and intense spring and summer droughts in the Alps.
Biomass heat storage dampens diurnal temperature variations in forests
Meier, Ronny; Davin, Edouard Léopold; Swenson, Sean C.; et al. (2019)
Environmental Research Letters
Observational evidence suggests that compared to non-forested areas, forests have a cooling effect on daytime land surface temperature (LST) and a warming effect on nighttime LST in many regions of the world, thus implying that forests dampen the diurnal temperature range. This feature is not captured by current climate models. Using the Community Land Model 5.0 (CLM5.0), we show that this diurnal behavior can be captured when accounting for biomass heat storage (BHS). The nighttime release of energy absorbed by the vegetation biomass during the day increases both nighttime LST and ambient air temperature in forested regions by more than 1 K. The daytime cooling is weaker than the nighttime warming effect, because the energy uptake by the biomass is compensated by a reduction in the turbulent heat fluxes during day. This diurnal asymmetry of the temperature response to BHS leads to a warming of daily mean temperatures, which is amplified during boreal summer warm extremes. Compared to MODIS, CLM5.0 overestimates the diurnal LST range over forested areas. The inclusion of BHS reduces this bias due to its dampening effect on diurnal LST variations. Further, BHS attenuates the negative bias in the nighttime LST difference of forest minus grassland and cropland, when compared to MODIS observations. These results indicate that it is essential to consider BHS when examining the influence of forests on diurnal temperature variations. BHS should thus be included in land surface models used to assess the climatic consequences of land use changes such as deforestation or afforestation.
Sensitivity of inferred climate model skill to evaluation decisions: A case study using CMIP5 evapotranspiration
Schwalm, Christopher R.; Huntinzger, Deborah N.; Michalak, Anna M.; et al. (2013)
Environmental Research Letters
Confrontation of climate models with observationally-based reference datasets is widespread and integral to model development. These comparisons yield skill metrics quantifying the mismatch between simulated and reference values and also involve analyst choices, or meta-parameters, in structuring the analysis. Here, we systematically vary five such meta-parameters (reference dataset, spatial resolution, regridding approach, land mask, and time period) in evaluating evapotranspiration (ET) from eight CMIP5 models in a factorial design that yields 68 700 intercomparisons. The results show that while model–data comparisons can provide some feedback on overall model performance, model ranks are ambiguous and inferred model skill and rank are highly sensitive to the choice of meta-parameters for all models. This suggests that model skill and rank are best represented probabilistically rather than as scalar values. For this case study, the choice of reference dataset is found to have a dominant influence on inferred model skill, even larger than the choice of model itself. This is primarily due to large differences between reference datasets, indicating that further work in developing a community-accepted standard ET reference dataset is crucial in order to decrease ambiguity in model skill.
Patterns of organic acids exuded by pioneering fungi from a glacier forefield are affected by carbohydrate sources
Brunner, Ivano; Goren, Asena; Schlumpf, Alessandro (2014)
Environmental Research Letters
Can designs inspired by control theory keep deployment policies effective and cost-efficient as technology prices fall?
Nuñez-Jimenez, Alejandro; Knoeri, Christof; Hoppmann, Joern; et al. (2020)
Environmental Research Letters
Deployment policies based on economic incentives are among the most effective tools for speeding up the diffusion of clean energy technologies. Policy instruments such as feed-in tariffs have played a critical role in driving the growth of solar photovoltaics, and could accelerate the uptake of other technologies that are key to the decarbonization of energy systems. Historical experiences, however, show that failing to adjust economic incentives to falling technology prices can fundamentally undermine these policies' effectiveness and cost-efficiency. This paper addresses this challenge by assessing three novel policy designs. Based on control-theory principles, the proposed mechanisms modify incentives in response to changes in deployment, policy costs, or profitability for adopters. We assess the outcomes that each policy design would have achieved when applied to Germany's feed-in tariff for solar photovoltaics between 2000 and 2016. For this purpose, we developed an agent-based model that allows us to simulate the adoption decisions of individual households and medium-sized and large firms, as well as the evolution of technology prices. Our results show that responsive designs inspired by control theory might produce policies that follow their targets more closely, and at a lower cost. In addition, our analysis suggests that the studied designs could greatly reduce uncertainty over policy outcomes and windfall profits. This research also highlights the role of the temporal distribution of policy targets, and identifies policy design tradeoffs, drawing relevant implications for the design of future deployment policies.
An effort to distinguish the effects of cloud cover and aerosols on the decadal variations of surface solar radiation in the Northern Hemisphere
Jiao, Boyang; Su, Yucheng; Li, Zichen; et al. (2024)
Environmental Research Letters
Surface solar radiation (SSR) serves as the primary energy source on Earth. However, a relative lack of research systematically quantifies long-term SSR variations and their driving factors based on complete and reliable baseline data. This paper presents a new assessment of the Northern Hemisphere/regional SSR variations and the influence of total cloud cover (TCC) on these variations, based on the latest reconstructed SSR gridded dataset. We also address multicollinearity among multiple aerosol types and quantify the effects of multiple aerosol/precursors on SSR variability using a partial least squares regression model. The results indicate that TCC is not the predominant driver of longer-term SSR variations, known as ‘dimming’ and ‘brightening’. The variations of NH3 and SO2 primarily drive inter-decadal SSR variations in North America, while the variations of SO2 and NO X mainly influence inter-decadal SSR variations in Europe.
Spatial assessment of maize physical drought vulnerability in sub-Saharan Africa: Linking drought exposure with crop failure
Kamali, Bahareh; Abbaspour, Karim C.; Lehmann, Anthony; et al. (2018)
Environmental Research Letters
Crop yields exhibit known responses to droughts. However, quantifying crop drought vulnerability is often not straightforward, because components of vulnerability are not defined in a standardized and spatially comparable quantity in most cases and it must be defined on a fine spatial resolution. This study aims to develop a physical crop drought vulnerability index through linking the drought exposure index (DEI) with the crop sensitivity index (CSI) in sub-Saharan Africa. Two different DEIs were compared. One was derived from the cumulative distribution functions fitted to precipitation and the other from the difference between precipitation and potential evapotranspiration. DEIs were calculated for one, three, six, nine, and twelve-month time scales. Similarly, CSI was calculated by fitting a cumulative distribution function to maize yield simulated using the Environmental Policy Integrated Climate model. Using a power function, curves were fitted to CSI and DEI relations resulting in different shapes explaining the severity of vulnerability. The results indicated that the highest correlation was found between CSI and DEI obtained from the difference between precipitation and potential evapotranspiration in one, three, and six-month time scales. Our findings show that southern African countries and some regions of the Sahelian strip are highly vulnerable to drought due to experiencing more water stress, whereas vulnerability in Central African countries pertains to temperature stresses. The proposed methodology provides complementary information on quantifying different degrees of vulnerabilities and the underlying reasons. The methodology can be applied to different regions and spatial scales.

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Journal: Environmental Research Letters

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