| 1. |
- Gagen, Mary, et al.
(författare)
-
Cloud response to summer temperatures in Fennoscandia over the last thousand years
- 2011
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 38, s. L05701-
-
Tidskriftsartikel (refereegranskat)abstract
- Cloud cover is one of the most important factors controlling the radiation balance of the Earth. The response of cloud cover to increasing global temperatures represents the largest uncertainty in model estimates of future climate because the cloud response to temperature is not well-constrained. Here we present the first regional reconstruction of summer sunshine over the past millennium, based on the stable carbon isotope ratios of pine treerings from Fennoscandia. Comparison with the regional temperature evolution reveals the Little Ice Age (LIA) to have been sunny, with cloudy conditions in the warmest periods of the Medieval at this site. A negative shortwave cloud feedback is indicated at high latitude. A millennial climate simulation suggests that regionally low temperatures during the LIA were mostly maintained by a weaker greenhouse effect due to lower humidity. Simulations of future climate that display a negative shortwave cloud feedback for high-latitudes are consistent with our proxy interpretation. Citation: Gagen, M., E. Zorita, D. McCarroll, G. H. F. Young, H. Grudd, R. Jalkanen, N. J. Loader, I. Robertson, and A. Kirchhefer (2011), Cloud response to summer temperatures in Fennoscandia over the last thousand years, Geophys. Res. Lett., 38, L05701, doi:10.1029/2010GL046216.
|
|
| 2. |
|
|
| 3. |
- Loader, Neil J., et al.
(författare)
-
Spring temperature variability in northern Fennoscandia AD 1693–2011
- 2011
-
Ingår i: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 26:6, s. 566-570
-
Tidskriftsartikel (refereegranskat)abstract
- A reconstruction of spring (April–May) temperature for northern Fennoscandia developed from the Tornionjoki (Tornio river) long cryophenological record of ice break-up dates, back to AD 1693, is presented. The record is strongly climatically sensitive and explains 67% of the variance in the instrumental data over the last 150 years. The record exhibits a stepped decrease in the duration of the river's ice cover by 14 days, equivalent to an increase in April–May mean temperature of approximately 2.5°C over the last three centuries. The relationship between the date of ice break-up, and accumulated daily mean temperatures (>0°C) is investigated. Uncertainty in the observation of ice break-up is also considered in addition to the potential of this time series for regional climate model validation.
|
|
| 4. |
- Mccarroll, Danny, et al.
(författare)
-
A critical evaluation of multi-proxy dendroclimatology in northern Finland
- 2011
-
Ingår i: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 26:1, s. 7-14
-
Tidskriftsartikel (refereegranskat)abstract
- Twentieth-century summer (July-August) temperatures in northern Finland are reconstructed using ring widths, maximum density and stable carbon isotope ratios (delta(13)C) of Scots pine tree rings, and using combinations of these proxies. Verification is based on the coefficient of determination (r(2)), reduction of error (RE) and coefficient of efficiency (CE) statistics. Of the individual proxies, delta(13)C performs best, followed by maximum density. Combining delta(13)C and maximum density strengthens the climate signal but adding ring widths leads to little improvement. Blue intensity, an inexpensive alternative to X-ray densitometry, is shown to perform similarly. Multi-proxy reconstruction of summer temperatures from a single site produces strong correlations with gridded climate data over most of northern Fennoscandia. Since relatively few trees are required (<15) the approach could be applied to long sub-fossil chronologies where replication may be episodically low.
|
|
| 5. |
- Saurer, Matthias, et al.
(författare)
-
Spatial variability and temporal trends in water-use efficiency of European forests
- 2014
-
Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 20:12, s. 3700-3712
-
Tidskriftsartikel (refereegranskat)abstract
- The increasing carbon dioxide (CO2) concentration in the atmosphere in combination with climatic changes throughout the last century are likely to have had a profound effect on the physiology of trees: altering the carbon and water fluxes passing through the stomatal pores. However, the magnitude and spatial patterns of such changes in natural forests remain highly uncertain. Here, stable carbon isotope ratios from a network of 35 tree-ring sites located across Europe are investigated to determine the intrinsic water-use efficiency (iWUE), the ratio of photosynthesis to stomatal conductance from 1901 to 2000. The results were compared with simulations of a dynamic vegetation model (LPX-Bern 1.0) that integrates numerous ecosystem and land-atmosphere exchange processes in a theoretical framework. The spatial pattern of tree-ring derived iWUE of the investigated coniferous and deciduous species and the model results agreed significantly with a clear south-to-north gradient, as well as a general increase in iWUE over the 20th century. The magnitude of the iWUE increase was not spatially uniform, with the strongest increase observed and modelled for temperate forests in Central Europe, a region where summer soil-water availability decreased over the last century. We were able to demonstrate that the combined effects of increasing CO2 and climate change leading to soil drying have resulted in an accelerated increase in iWUE. These findings will help to reduce uncertainties in the land surface schemes of global climate models, where vegetation-climate feedbacks are currently still poorly constrained by observational data.
|
|
| 6. |
- Treydte, Kerstin, et al.
(författare)
-
Recent human-induced atmospheric drying across Europe unprecedented in the last 400 years
- 2024
-
Ingår i: NATURE GEOSCIENCE. - 1752-0894 .- 1752-0908. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- The vapor pressure deficit reflects the difference between how much moisture the atmosphere could and actually does hold, a factor that fundamentally affects evapotranspiration, ecosystem functioning, and vegetation carbon uptake. Its spatial variability and long-term trends under natural versus human-influenced climate are poorly known despite being essential for predicting future effects on natural ecosystems and human societies such as crop yield, wildfires, and health. Here we combine regionally distinct reconstructions of pre-industrial summer vapor pressure deficit variability from Europe's largest oxygen-isotope network of tree-ring cellulose with observational records and Earth system model simulations with and without human forcing included. We demonstrate that an intensification of atmospheric drying during the recent decades across different European target regions is unprecedented in a pre-industrial context and that it is attributed to human influence with more than 98% probability. The magnitude of this trend is largest in Western and Central Europe, the Alps and Pyrenees region, and the smallest in southern Fennoscandia. In view of the extreme drought and compound events of the recent years, further atmospheric drying poses an enhanced risk to vegetation, specifically in the densely populated areas of the European temperate lowlands. The atmosphere has dried across most regions of Europe in recent decades, a trend that can be attributed primarily to human impacts, according to tree ring records spanning 400 years and Earth system model simulations.
|
|
| 7. |
- Ytreberg, Erik, 1980, et al.
(författare)
-
EMERGE deliverable 6.1. Baltic and North Sea report
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Shipping is responsible for a range of different pressures affecting air quality, climate, and the marine environment. However, most social and economic analysis of shipping have focused on air pollution assessment and how shipping may impact climate change and human health. This risks policies to be biased towards air pollution and climate change, while trading off impacts on the marine environment. One example is the IMO’s global sulphur cap, which requires shipowners to use a compliant fuel with a sulphur content of 0.5% (0.1% in SECA regions) or use alternative compliance options (scrubbers) that are effective in reducing sulphur oxide (SOX) emissions to the atmosphere. The scrubber process results in large volumes of acidic discharge water. Although regulations primarily target SOX removal, other pollutants such as polycyclic aromatic hydrocarbons (PAHs) and metals are transferred from the exhausts to the wash water and subsequently discharged to the marine environment. The aim of this deliverable has therefore been to develop a holistic framework to evaluate the impacts of shipping emissions, particularly those related to scrubbers, on the marine environment, human health, climate, and economy. The structure of this deliverable follows the well-established DAPSIR (Driver-Activity-Pressure-State-Impact-Response) framework, under which information, findings and conclusions from previous work packages are synthesized and integrated, including experiments of direct emissions from shipping to the marine environment (WP2) and the atmosphere (WP3), assessment of marine environmental impacts (WP2, WP4 and WP6), as well as human health and climate change impacts (WP5 and WP6). Finally, this deliverable provides recommendations and guidance for stakeholders and policymakers. The assessment is performed using a baseline scenario (year 2018) and three future scenarios (for year 2050) based on different projected future developments of shipping transport volumes and considering the development of ships regarding fuel efficiency and ship size. In this deliverable, we focused primarily on two of the different future scenarios, scenario 3 (high scrubber pressure) and scenario 8 (high use of liquefied natural gas (LNG) and methanol). The marine environmental risk assessment, performed in the Öresund region for the baseline scenario (2018), showed unacceptable risks when ships in the area were using open loop scrubbers. In the assessment, modelled predicted environmental concentrations (PECs) of open loop scrubber discharge water exceeded the tolerable marine threshold value (predicted no-effect concentration, PNEC) in almost the entire Öresund region. The PEC value was derived based on ship activity and discharges of scrubber water in 2018, while the PNEC value was derived based on the ecotoxicological assays performed within the EMERGE project. Notably, the modelling of open loop scrubber discharge water was performed using the ship traffic activity in 2018 when less than 200 ships in the Baltic Sea used scrubbers, collectively releasing 192 million tonnes of discharge water. By 2022 there were approximately 800 ships equipped with scrubbers in the Baltic Sea. In the high scrubber future scenario (S3) in 2050 this led to an assumption of the considerably higher scrubber water discharge (1740 million tonnes), representing almost one order of magnitude higher compared to our baseline scenario in 2018. In addition, our impact assessment, following Marine Environment Protection Committee (MEPC) guidelines, shows that a ban on discharge water from scrubbers should be considered in the entire Baltic and North Sea region, since all sea basins in the region fail to reach good environmental status (GES) as defined by the EU Marine Strategy Framework Directive (Directive 2008/56/EC). However, the costs of such a measure for the shipping sector (banning discharges from scrubbers, i.e., in practice a ban on scrubbers) have been questioned within the International Maritime Organisation (IMO). Therefore, EMERGE also focused on analysing to what extent the global scrubber fleet has reached break-even on their scrubber installations and the potential monetary gain of using Heavy Fuel Oil (HFO) as compared to the more expensive Marine Gas Oil (MGO) or Very Low Sulphur Fuel Oil (VLSFO). Our results showed that 51% of the global scrubber fleet had reached break-even by the end of 2022, resulting in a summarised balance of 4.7 billion €2019. In addition, the marine ecotoxicity damage cost, by not restricting scrubbers in the Baltic Sea Area, accumulated to >680 million €2019 from 2015 to end of 2022. For air quality, both future scenarios showed a decrease in shipping contribution to PM2.5 exposure by a factor of 2 to 3 compared to our baseline scenario in 2018. Scenario 8 is somewhat more efficient in decreasing the shipping originated PM2.5 than scenario 3. Using the Greenhouse gas and Air pollution Interactions and Synergies (GAINS) model for human health impact assessment in scenario 3 revealed the loss of life expectancy in most areas around the Baltic Sea, when considering all sources, to be limited to two to four months. However, the differences in life shortening between Scenarios 3 and 8 are two to three orders of magnitude lower when compared to human health impacts resulting from all sources, indicating that scrubbers alone have a minor impact on human health in the Baltic region from air quality perspective. For Öresund case the shipping-related health impacts from PM2.5 represented approximately 10% of the total burden of air pollution, in 2050 scenario simulations this burden decreased to 7-9%. Important improvement of air quality in the scenario simulations come also from reduction of NO2 which is a criteria pollutant regulated by the Air Quality Directive, where the decrease is 3 to 5-fold. In relative terms the shipping contribution to NO2 concentration levels, however, maintains similar, approximately 25%, as the land emissions are also expected to decrease. The GAINS health impact assessment for the Baltic Sea was compared to the Solent region using a statistical technique. The latter study showed that a relatively small fraction of all premature deaths in Southampton, Portsmouth, Poole, Christchurch & Bournemouth are attributable to air pollution from shipping, corroborating the conclusion that the deployment scrubbers alone has a minor impact on human life shortening through atmospheric transport.
|
|
