Influence of the representation of convection on the mid-Holocene West African Monsoon Climate of the Past DOI 10.5194/cp-17-1665-2021 15 September 2021 This paper investigates the impact of explicitly resolving convection on the mid-Holocene West African Monsoon rain belt by employing the ICON climate model in high resolution. While the spatial distribution and intensity of the precipitation are improved by this technique, the monsoon extents further north and the mean summer rainfall is higher in the simulation with parameterized convection. Read more
Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales Climate of the Past DOI 10.5194/cp-17-1025-2021 2 July 2021 The Mediterranean Sea turned repeatedly into an oxygen-deprived basin during the geological past, as evidenced by distinct sediment layers called sapropels. We use here records of the last sapropel S1 retrieved in front of the Nile River to explore the relationships between riverine input and seawater oxygenation. We decipher the seasonal cycle of fluvial input and seawater chemistry as well as the decisive influence of primary productivity on deoxygenation at millennial timescales. Read more
On the phenomenon of the blue sun Climate of the Past DOI 10.5194/cp-17-969-2021 18 June 2021 This study investigates the physical processes leading to the rare phenomenon of the sun appearing blue or green. The phenomenon is caused by anomalous scattering by, e.g., volcanic or forest fire aerosols. Unlike most other studies, our study includes a full treatment of the effect of Rayleigh scattering on the colour of the sun. We investigate different factors and revisit a historic example, i.e. the Canadian forest fires in 1950, that led to blue sun events in different European countries. Read more
Snapshots of mean ocean temperature over the last 700 000 years using noble gases in the EPICA Dome C ice core Climate of the Past DOI 10.5194/cp-17-843-2021 9 June 2021 Using the temperature-dependent solubility of noble gases in ocean water, we reconstruct global mean ocean temperature (MOT) over the last 700 kyr using noble gas ratios in air enclosed in polar ice cores. Our record shows that glacial MOT was about 3 °C cooler compared to the Holocene. Interglacials before 450 kyr ago were characterized by about 1.5 °C lower MOT than the Holocene. In addition, some interglacials show transient maxima in ocean temperature related to changes in ocean circulation. EPICA Dome C ice core">Read more
Cryptotephra from the Icelandic Veiðivötn 1477 CE eruption in a Greenland ice core: confirming the dating of volcanic events in the 1450s CE and assessing the eruption’s climatic impact Climate of the Past DOI 10.5194/cp-17-565-2021 23 March 2021 Volcanic eruptions are a key source of climatic variability, and reconstructing their past impact can improve our understanding of the operation of the climate system and increase the accuracy of future climate projections. While many chronological mismatches have been resolved, the precise timing and climatic impact of two major sulfate-emitting volcanic eruptions during the 1450s CE, including the largest atmospheric sulfate-loading event in the last 700 years, have not been constrained. Here we explore this issue through a combination of tephrochronological evidence and high-resolution ice-core chemistry measurements from a Greenland ice core, the TUNU2013 record. Read more
Lower oceanic δ13C during the last interglacial period compared to the Holocene Climate of the Past DOI 10.5194/cp-17-507-2021 17 March 2021 The last time in Earth’s history when high latitudes were warmer than during pre-industrial times was the last interglacial period (LIG, 129–116 ka BP). Since the LIG is the most recent and best documented interglacial, it can provide insights into climate processes in a warmer world. However, some key features of the LIG are not well constrained, notably the oceanic circulation and the global carbon cycle. Here, we use a new database of LIG benthic δ13C to investigate these two aspects. Read more
Long-term global ground heat flux and continental heat storage from geothermal data Climate of the Past DOI 10.5194/cp-17-451-2021 11 March 2021 Here, we provide new global estimates of changes in ground surface temperature, ground surface heat flux, and continental heat storage derived from geothermal data using an expanded database and new techniques. Read more
In situ cosmogenic 10Be–14C–26Al measurements from recently deglaciated bedrock as a new tool to decipher changes in Greenland Ice Sheet size Climate of the Past DOI 10.5194/cp-17-419-2021 9 March 2021 Sometime during the middle to late Holocene (8.2 ka to ∼ 1850–1900 CE), the Greenland Ice Sheet (GrIS) was smaller than its current configuration. Contemporary retreat of the GrIS from its historical maximum extent in southwestern Greenland is exposing a landscape that holds clues regarding the configuration and timing of past ice-sheet minima. Read more
Greenland climate simulations show high Eemian surface meltwhich could explain reduced total air content in ice cores Climate of the Past DOI 10.5194/cp-17-317-2021 16 February 2021 This study presents simulations of Greenland surface melt for the Eemian interglacial period (∼130,000 to 115, 000 years ago) derived from regional climate simulations with a coupled surface energy balance model. Read more
The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons Climate of the Past DOI 10.5194/cp-17-269-2021 15 February 2021 We find that CO2 forcing involving a large decrease in CO2 of ca. 40 % (∼325 ppm drop) provides the best fit to the available proxy evidence,with ice sheet and palaeogeographic changes playing a secondary role. Read more
