The Early to Mid‐Holocene Thermal Optimum in the North Atlantic

Jansen, Eystein; Andersson, Carin; Moros, Matthias; Nisancioglu, Kerim H.; Nyland, Birgitte F.; Telford, Richard J.

doi:10.1002/9781444300932.ch5

Cited by 58 publications

(58 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This east-west contrast has been explained by a stronger cooling impact by postglacial sea ice and melt water in the west before 8.5 ka BP, leading to a clearer expression of the early Holocene warming influence by insolation in the east (Andersen et al, 2004). However, it has been argued by Koç et al (1993) and other studies (Kaufman et al, 2004;Jansen et al, 2008;Risebrobakken et al, 2011) that these warmer temperatures cannot be due to insolation alone. Eastern SSTs reconstructed from alkenones (Calvo et al, 2002) show a behaviour similar to the orbital trend, but are considerably lower at the thermal maximum (by 2-3 K) and yield a later HTM (i.e.…”

Section: Introductionmentioning

confidence: 74%

“…In the early Holocene a period of relatively warm climate, the Holocene thermal maximum (HTM), has been associated with the orbitally forced Northern Hemisphere summer insolation maximum at approximately 10 ka BP (Jansen et al, 2008). Indeed, detailed analyses of proxy data and model results have confirmed that orbital forcing is the dominant long-term forcing considering temperature response at the scale of the Arctic (Renssen et al, 2009).…”

Section: Introductionmentioning

confidence: 74%

“…Moreover, at the same site, SST reconstructions based on foraminifera and radiolarians also lack this early HTM suggested by diatoms (Risebrobakken et al, 2003(Risebrobakken et al, , 2011Cortese et al, 2005;Dolven et al, 2002). Jansen et al (2008) suggest that the SST maximum recorded in proxy data above the seasonal thermocline (diatoms, alkenones) is forced by the summer insolation maximum and that deeper dwelling species (foraminifera and radiolarians) are not influenced. Andersson et al (2010) support this hypothesis in a comparison with climate model simulations of the 6 ka BP climate performed with the CCSM3 model.…”

Section: Introductionmentioning

confidence: 95%

See 2 more Smart Citations

The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere–sea-ice–ocean model

Blaschek¹,

Renssen²

2013

Clim. Past

View full text Add to dashboard Cite

Abstract. The relatively warm early Holocene climate in the Nordic Seas, known as the Holocene thermal maximum (HTM), is often associated with an orbitally forced summer insolation maximum at 10 ka BP. The spatial and temporal response recorded in proxy data in the North Atlantic and the Nordic Seas reveals a complex interaction of mechanisms active in the HTM. Previous studies have investigated the impact of the Laurentide Ice Sheet (LIS), as a remnant from the previous glacial period, altering climate conditions with a continuous supply of melt water to the Labrador Sea and adjacent seas and with a downwind cooling effect from the remnant LIS. In our present work we extend this approach by investigating the impact of the Greenland Ice Sheet (GIS) on the early Holocene climate and the HTM. Reconstructions suggest melt rates of 13 mSv for 9 ka BP, which result in our model in an ocean surface cooling of up to 2 K near Greenland. Reconstructed summer SST gradients agree best with our simulation including GIS melt, confirming that the impact of the early Holocene GIS is crucial for understanding the HTM characteristics in the Nordic Seas area. This implies that modern and near-future GIS melt can be expected to play an active role in the climate system in the centuries to come.

show abstract

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere–sea-ice–ocean model

Blaschek¹,

Renssen²

2013

Clim. Past

View full text Add to dashboard Cite

show abstract

“…This transition has been recorded by a wide range of climate proxies (e.g. Kaufman et al, 2004;Jansen et al, 2009;Seppä et al, 2009;Bartlein et al, 2011) and has been related to different biosphere feedbacks and potentially to a decay of the remaining Laurentide Ice Sheet (Renssen et al, 2009). All proxies from the Hachlaf sequence as well as the reconstructed climate variables have recorded marked changes during that period of time.…”

Section: Discussionmentioning

confidence: 99%

Climate change and ecosystems dynamics over the last 6000 years in the Middle Atlas, Morocco

et al. 2016

View full text Add to dashboard Cite

Abstract. The present study aims at reconstructing past climate changes and their environmental impacts on plant ecosystems during the last 6000 years in the Middle Atlas, Morocco. Mean January temperature (T jan ), annual precipitation (P ann ), winter (P w ) and summer (P s ) precipitation, and a seasonal index (SI) have all been quantified from a fossil pollen record. Several bio-and geo-chemical elements have also been analysed to evaluate the links between past climate, landscape, and ecosystem changes.Over the last 6000 years, climate has changed within a low temperature and precipitation range with a trend of aridity and warming towards the present. T jan has varied within a ca. 2 • C range, and P ann within less than 100 mm yr −1 . The longterm changes reconstructed in our record between 6 ka cal BP and today are consistent with the aridity trend observed in the Mediterranean basin. Despite the overall limited range of climate fluctuation, we observe major changes in the ecosystem composition, the carbon isotopic contents of organic matter (δ 13 C), the total organic carbon and nitrogen amount, and the carbon to nitrogen ratio (C / N) after ca. 3750 cal BP. The main ecosystem changes correspond to a noticeable transition in the conifer forest between the Atlas cedar, which expanded after 3750 cal BP, and the pine forest. These vegetation changes impacted the sedimentation type and its composition in the lake.Between 5500 and 5000 cal BP, we observe an abrupt change in all proxies which is coherent with a decrease in T jan without a significant change in the overall amount of precipitation.

show abstract

“…In the Arctic-subarctic areas, diatoms often relate to a spring bloom, whereas alkenones are produced by coccolithophorids, which develop during the warmest part of the summer (e.g., Andruleit, 1997). Divergence between alkenone and diatom records was also observed during the Holocene and was related to sensitivity to different depths (Jansen et al, 2008;Hessler et al, 2014).…”

Section: Long-term Tendenciesmentioning

confidence: 99%

Climate variability in the subarctic area for the last 2 millennia

et al. 2018

View full text Add to dashboard Cite

Abstract.To put recent climate change in perspective, it is necessary to extend the instrumental climate records with proxy data from paleoclimate archives. Arctic climate variability for the last 2 millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many types of proxy data archived in the Arctic 2k database v1.1.1. In the North Atlantic and Alaska, the major climatic trend is characterized by long-term cooling interrupted by recent warming that started at the beginning of the 19th century. This cooling is visible in the Siberian region at two sites, warming at the others. The cooling of the Little Ice Age (LIA) was identified from the individual series, but it is characterized by wide-range spatial and temporal expression of climate variability, in contrary to the Medieval Climate Anomaly. The LIA started at the earliest by around AD 1200 and ended at the latest in the middle of the 20th century. The widespread temporal coverage of the LIA did not show regional consistency or particular spatial distribution and did not show a relationship with archive or proxy type either. A focus on the last 2 centuries shows a recent warming characterized by a well-marked warming trend parallel with increasing greenhouse gas emissions. It also shows a multidecadal variability likely due to natural processes acting on the internal climate system on a regional scale. A ∼ 16-30-year cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation, whereas ∼ 20-30-and ∼ 50-90-year periodicities characterize the North Atlantic climate variability, likely in relation with the Atlantic Multidecadal Oscillation. These regional features are probably linked to the sea ice cover fluctuations through ice-temperature positive feedback.

show abstract

The Early to Mid‐Holocene Thermal Optimum in the North Atlantic

Cited by 58 publications

References 22 publications

The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere–sea-ice–ocean model

The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere–sea-ice–ocean model

Climate change and ecosystems dynamics over the last 6000 years in the Middle Atlas, Morocco

Climate variability in the subarctic area for the last 2 millennia

Contact Info

Product

Resources

About