Salty Atlantic waters may have been seeping into the Arctic since the early 20th century, several decades earlier than previously believed. The Arctic is warming faster than any other part of the world and the increasing influence of water from the Atlantic Ocean, which is on average warmer and saltier than the Arctic Ocean, is likely to be leading to further ice loss.
This effect is known as “Atlantification”, says Tesi Tommaso at the Italian National Research Council Institute of Polar Sciences. But it is hard to quantify because we only have 20 years of confirmed data about the interaction between these waters, he adds.
He and his colleagues studied the Fram Strait in the Arctic Ocean between Greenland and the Norwegian archipelago Svalbard. They collected a 112-centimetre sediment core from the bottom of one of Svalbard’s inlets to reconstruct the history of the strait.
“The rock is in the ocean,” says Tommaso. “What we see is a reflection of the water’s properties.”
The layers of the core correspond to sediments laid down over the past 800 years, which hold clues to the time they were deposited. “Every centimetre gave us climate information for about four to five years,” says Tommaso.
The team found that for the earliest 700 years or so, nothing changed in the composition of organic matter in the sediment. But in samples corresponding to the year 1907, they saw a sudden change in the oxygen isotopes in the organic matter. “This change suggests the waters became a lot warmer and saltier,” says Tommaso.
The team is unsure what caused this dramatic shift in temperature. “It could be a natural event that propagated from the subpolar regions to the gate of the Arctic Ocean,” says Tommaso.
More data and modelling are needed to gain a clearer picture of what caused this sudden change, he says.
“This early Atlantification is important as it will have pre-conditioned the Arctic to be susceptible to the more rapid change seen today,” says Yueng-Djern Lenn at Bangor University, UK.
Understanding the history of this effect can tell us about how the ecosystem may respond in the future, says Marie Porter at the Scottish Association for Marine Science. “The process of Atlantification continues across the Atlantic-Arctic under post-industrialisation climate change.”
Science Advances DOI: 10.1126/sciadv.abj2946
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Maji ya bahari ya Atlantiki ya chumvi huenda yalitiririka katika eneo la Aktiki tangu mwanzoni mwa karne ya 20, miongo kadhaa mapema kuliko ilivyodhaniwa hapo awali. "Arctic ni joto haraka kuliko sehemu nyingine yoyote ya dunia na kuongezeka kwa ushawishi wa maji kutoka Bahari ya Atlantiki, ambayo kwa wastani ni joto na chumvi kuliko Bahari ya Aktiki, ni uwezekano wa kusababisha zaidi ya kupoteza barafu. """ Athari hii inajulikana kama "Atlantification", anasema Tesi Tommaso katika Taasisi ya Sayansi ya Polar ya Baraza la Kitaifa la Utafiti la Italia. "Lakini ni vigumu kuamua kwa sababu tuna miaka 20 tu ya data iliyothibitishwa juu ya mwingiliano kati ya maji haya, ""aliongeza." Yeye na wenzake walichunguza Mlango-Bahari wa Fram katika Bahari ya Aktiki kati ya Greenland na visiwa vya Svalbard vya Norway. Watafiti hao walichunguza mchanga wa sediment wenye urefu wa sentimita 112 kutoka chini ya moja ya vijito vya Svalbard ili kuunda upya historia ya mfereji huo. "Mwamba uko baharini", asema Tommaso. "Kile tunachoona ni mwangaza wa sifa za maji. ""Mipaka ya msingi inalingana na sediments iliyowekwa zaidi ya miaka 800 iliyopita, ambayo inashikilia vidokezo vya wakati walipowekwa." "Kila sentimeta ilitupa habari za hali ya hewa kwa miaka minne hadi mitano", anasema Tommaso. Watafiti hao waligundua kwamba katika miaka 700 ya kwanza, hakuna mabadiliko yoyote katika muundo wa vitu vya kikaboni katika mchanga. Katika sampuli zilizochukuliwa mwaka 1907, wanasayansi waligundua mabadiliko makubwa katika viwango vya oksijeni katika chembe za urithi. "Mabadiliko haya yanaonyesha kwamba maji yakawa yenye joto na chumvi zaidi", anasema Tommaso. Timu hiyo haijui ni nini kilichosababisha badiliko hilo kubwa la halijoto. "Inaweza kuwa tukio la asili ambalo lilitangazwa kutoka mikoa ya chini ya mviringo hadi mlango wa Bahari ya Aktiki", anasema Tommaso. "Tuna mahitaji ya data zaidi na modeling kupata picha wazi ya nini kusababisha mabadiliko haya ya ghafla. """ "Kutokea kwa Atlantiki mapema ni muhimu kwa sababu itakuwa imeweka hali ya Arctic kuwa nyeti kwa mabadiliko ya haraka zaidi yanayoonekana leo, "Yueng-Djern Lann anasema katika Chuo Kikuu cha Bangor, Uingereza." "Kufahamu historia ya athari hii kunaweza kutuambia jinsi mazingira yanaweza kujibu katika siku zijazo, ""anasema Marie Porter katika Chama cha Scotland cha Sayansi ya Bahari." "Kama ilivyoelezwa hapo juu, ""Mapinduzi ya Sayansi"" (Science Advances DOI: 10.1126.sciadv.abj2946) ni jarida la bure la ""Fix the Planet"" ambalo linatuma maoni mazuri ya hali ya hewa moja kwa moja kwenye sanduku lako la barua kila Alhamisi."