Evelien Van Dijk

• Smith, William McFarlane; Visioni, Daniele; Kravitz, Ben; Dijk, Evelien Van; Storelvmo, Trude & Hunt, Hugh (2026). Parallel and diverging responses across four earth system models in response to cirrus cloud thinning climate intervention experiment. Environmental Research: Climate. 5(3). doi: 10.1088/2752-5295/ae8c7a. Full text in Research Archive
• Dijk, Evelien Van; Jungclaus, Johann; Sigl, Michael; Timmreck, Claudia & Krüger, Kirstin (2024). High-frequency climate forcing causes prolonged cold periods in the Holocene. Communications Earth & Environment. 5. doi: 10.1038/s43247-024-01380-0. Full text in Research Archive Show summary

  Understanding climate variability across interannual to centennial timescales is critical, as it encompasses the natural range of climate fluctuations that early human agricultural societies had to adapt to. Deviations from the long-term mean climate are often associated with both societal collapse and periods of prosperity and expansion. Here, we show that contrary to what global paleoproxy reconstructions suggest, the mid to late-Holocene was not a period of climate stability. We use mid- to late-Holocene Earth System Model simulations, forced by state-of-the-art reconstructions of external climate forcing to show that eleven long-lasting cold periods occurred in the Northern Hemisphere during the past 8000 years. These periods correlate with enhanced volcanic activity, where the clustering of volcanic eruptions induced a prolonged cooling effect through gradual ocean-sea ice feedback. These findings challenge the prevailing notion of the Holocene as a period characterized by climate stability, as portrayed in multi-proxy climate reconstructions. Instead, our simulations provide an improved representation of amplitude and timing of temperature variations on sub-centennial timescales.

• Dijk, Evelien Van; Gundersen, Ingar Mørkestøl; Bode, Anna de; Høeg, Helge Irgens; Loftsgarden, Kjetil & Iversen, Frode [Show all 9 contributors for this article] (2023). Climate and societal impacts in Scandinavia following the 536 and 540 CE volcanic double event. Climate of the Past. ISSN 1814-9324. 19(2), p. 357–398. doi: 10.5194/cp-19-357-2023. Full text in Research Archive Show summary

  In the Northern Hemisphere, the mid-6th century was one of the coldest periods of the last 2000 years, as indicated by both proxy records and Earth System Model (ESM) simulations. This cold period was initiated by volcanic eruptions in 536 CE and 540 CE. Evidence from historical sources, archaeological findings, and proxy records suggests that the extent and severity of this volcanic induced cooling was spatially heterogeneous and that the effect on society resulted in adaptation and resilience at some locations, whereas social crisis has been indicated at others. Here, we study the effect of the volcanic double event in 536 CE and 540 CE on the climate and society in Scandinavia with a special focus on Southern Norway. Using an ensemble of Max Planck Institute ESM transient simulations for 521–680 CE, the temperature, precipitation and atmospheric circulation patterns are studied. The simulated cooling magnitude is then used as input for the growing degree day (GDD) model set-up for Southern Norway. This GDD model indicates the possible effects on agriculture for three different study areas in Southern Norway, representative of typical meteorological and landscape conditions. Pollen from bogs and archaeological records inside the study area are then analysed at high resolution (1–3 cm sample intervals) to give insights into the validity of the GDD model set-up with regard to the volcanic climate impact on the regional scale, and to link the different types of data sets. After the 536/540 CE double event, a maximum surface air cooling of up to 3.5 °C during the mean growing season is simulated regionally in Southern Norway. With a worst-case scenario cooling of 3 °C, the GDD model indicates crop failures were likely in our northernmost and western study areas, while crops were more likely to mature in the southeastern study area. These results are in agreement with the pollen records from the respective areas. During the sixth century, excavations show an abandonment of farms, severe social impact but also a continuation of occupation or a mix of those. In addition, archaeological findings from one of the excavation sites suggest wetter conditions for the mid-sixth century in Scandinavia, as simulated by individual ensemble members. Finally, we discuss the likely climate and societal impacts of the 536/540 CE volcanic double event by synthesising the new and available data sets for the whole Scandinavia.

• Dijk, Evelien Van; Jungclaus, Johann; Lorenz, Stephan; Timmreck, Claudia & Krüger, Kirstin (2022). Was there a volcanic-induced long-lasting cooling over the Northern Hemisphere in the mid-6th-7th century? Climate of the Past. ISSN 1814-9324. 18(7), p. 1601–1623. doi: 10.5194/cp-18-1601-2022. Full text in Research Archive Show summary

  Abstract. The climate of the Northern Hemisphere (NH) in the mid-6th century was one of the coldest during the last 2 millennia based on multiple paleo-proxies. While the onset of this cold period can be clearly connected to the volcanic eruptions in 536 and 540 Common Era (CE), the duration, extent, and magnitude of the cold period are uncertain. Proxy data are sparse for the first millennium, which compounds the uncertainties of the reconstructions. To better understand the mechanisms of the prolonged cooling, we analyze new transient simulations over the Common Era and enhance the representation of mid-6th to 7th century climate by additional ensemble simulations covering 520–680 CE. We use the Max Planck Institute Earth System Model to apply the external forcing as recommended in the Paleoclimate Modelling Intercomparison Project phase 4. After the four large eruptions in 536, 540, 574, and 626 CE, a significant mean surface climate response in the NH lasting up to 20 years is simulated. The 2 m air temperature shows a cooling over the Arctic in winter, corresponding to the increase in Arctic sea ice, mainly in the Labrador Sea and to the east of Greenland. The increase in sea-ice extent relates to a decrease in the northward ocean heat transport into the Arctic within the first 2 years after the eruptions and to an increase in the Atlantic meridional overturning circulation, which peaks 10 years after the eruptions. A decrease in the global ocean heat content is simulated after the eruptions that does not recover during the simulation period. These ocean–sea-ice interactions sustain the surface cooling, as the cooling lasts longer than is expected solely from the direct effects of the volcanic forcing, and are thus responsible for the multi-decadal surface cooling. In boreal summer, the main cooling occurs over the continents at midlatitudes. A dipole pattern develops with high sea level pressure and a decrease in both precipitation and evaporation poleward of 40∘ N. In addition, more pronounced cooling over land compared to ocean leads to an enhanced land–sea contrast. While our model ensemble simulations show a similar ∼20-year summer cooling over NH land after the eruptions as tree ring reconstructions, a volcanic-induced century-long cooling, as reconstructed from tree ring data, does not occur in our simulations.

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• Dijk, Evelien Van; Krüger, Kirstin; Sigl, Michael; Riede, Felix & Timmreck, Claudia (2025). The global impact of the 5624 BCE Mount Mazama eruption: The largest NH extratropical eruption of the Holocene. Full text in Research Archive
• Dijk, Evelien Van; Riede, Felix; Timmreck, Claudia; Krüger, Kirstin & Sigl, Michael (2024). Extreme climatic and compound impacts of the Mount Mazama eruption. Full text in Research Archive
• Krüger, Kirstin; Dijk, Evelien Van; Jungclaus, Johann; Sigl, Michael & Timmreck, Claudia (2024). High-frequency climate forcing causes prolonged cold periods in the Holocene. Full text in Research Archive
• Krüger, Kirstin; Fuglestvedt, Herman Fæhn; Dijk, Evelien Van; Zhuo, Zhihong; Sigl, Michael & Toohey, Matthew (2022). Modelling volcanic climate and environmental impacts and their signals in ice cores. Full text in Research Archive
• Dijk, Evelien Van; Gundersen, Ingar Mørkestøl; Loftsgarden, Kjetil; Krüger, Kirstin & Iversen, Frode (2021). Can we link volcanic impacts on the climate to a change in society in Norway? Full text in Research Archive
• Dijk, Evelien Van & Krüger, Kirstin (2021). Large volcanic eruptions as a natural hazard: The impact of the 536/540 CE double event on the atmospheric circulation, surface climate, vegetation and society in Scandinavia. Full text in Research Archive

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