Berben et al., 2019 -- The Arctic had more ice in the 20th century, than in past 9,500 years

Biomarker evidence for Arctic-region 

sea ice coverage in the northern 

Barents Sea indicates the most extensive 

sea ice conditions of the last 9,500 years 

occurred during the 20th century 

(0 cal yr BP). 

In contrast, this region was ice free 

with open water conditions during 

the Early Holocene 

( 9,500 to 5,800 years ago ).

Berben et al., 2019

"Atlantic water inflow & 

sea ice distribution 

in the northern Barents Sea: 

A Holocene palaeoceanographic 

evolution" ( The early Holocene 

ca. 9500 – 5800 cal yr BP )".
https://pdfs.semanticscholar.org/9d01/7c43133eb7e028f19d429748de055c7542a0.pdf

Relatively low IP25 concentrations 

[a proxy for sea ice presence] 

indicate reduced seasonal (spring) 

sea ice cover and longer (warmer) 

summers with open water conditions 

suitable for phytoplankton production. 

The occurrence of reduced sea ice 

cover and longer summers is consistent 

with increased planktic foraminiferal 

concentrations (reported here and 

Carstens et al., 1997) 

and with longer ice-free seasons 

and a retreated ice margin 

in the northern Barents Sea 

(Duplessy et al., 2001) as well as 

increased phytoplankton production 

in the northern Fram Strait 

(Müller et al., 2009). 

“Our proposed sea ice scenario 

suggests that water masses 

south of the study area were ice free, 

which agrees with open water conditions 

observed in the western Barents Sea 

(Berben et al., 2014) 

and the 

West Svalbard margin 

(Müller et al., 2012) 

during the early Holocene.”

“For the West Svalbard margin, 

Werner et al. (2013) associate

d high planktic foraminiferal fluxes 

ca. 8000 cal yr BP to ice-free 

or seasonally fluctuating 

sea ice margin conditions.”

“The PBIP25 index shows 

the lowest values of the record 

(0.16 – 0.40) suggesting a period 

characterized by low or variable 

seasonal sea ice cover 

and influenced substantially 

by open water conditions 

(Müller et al., 2011).”

“ ... the PBIP25 values reach 

their highest value (0.87) 

of the record at ca. 0 cal yr BP. 

( 20th century )

The Early Holocene was about 

+6-7°C warmer than today 

in this region (NW Barents Sea).