И.И. Борзенкова (2016) История оледенения Арктического бассейна: взгляд из прошлого для оценки возможных изменений в будущем. Лёд и Снег, Т. 56, № 2

Быстрое сокращение площади морских льдов в Арктике в последние десятилетия обусловлено их реакцией на повышение глобальной температуры. Морские льды – прекрасный индикатор состояния глобальной климатической системы как в историческое время, так и в отдалённом прошлом. Анализ исторических данных показывает, что современное сокращение площади и толщины морских льдов в Арктике беспрецедентно за последние 1450  лет. На основе синтеза морских, континентальных и других косвенных данных рассматривается история образования морского оледенения Арктики за последние 65 млн лет, от раннего палеогена до голоцена. Сокращение площади морских льдов в Арктике, уменьшение их толщины и увеличение площади одногодичного льда свидетельствуют, что запущен механизм замещения многолетних льдов сезонными. Это  – естественное состояние перехода от сезонных льдов к следующему этапу – безлёдной Арктики.

Summary

The process of the sea ice formation in the Arctic Ocean is analyzed for the period of the last 65 million years, i.e. from
the Paleocene to the present time. Appearance of sea ice in the high latitudes is demonstrated to be caused by the negative
trend in global temperatures due to decreasing of the CO2 concentration in the ancient atmosphere. Formation of seasonal
and perennial ice cover in the limited area near the Pole could take place during the mid-Neogene period, about
12–13 Ma ago. However, areas of the sea icing could be obviously changed for this time during periods of the climate warming
and cooling. Permanent sea ice had been formed in the early Pleistocene, i.e. about 2.0–1.8 Ma ago only. Paleoclimatic
reconstructions, based on the indirect data and modeling simulation for the Holocene optimum (10–6 ka ago) and for the
Last Interglacial period (the isotopic substage in the marine cross-section 5e, about 125–127 ka ago) had shown that rising
of global temperatures by 1.0–1.5 °C resulted in strong decreasing of the sea ice area, and the perennial ice cover became
the seasonal one. Relatively small changes in the incoming solar radiation originating during the spring-summer time due
to the orbital factors played the role of a trigger for onset of the melting process. Further on, the process could be enhanced
owing to difference in the albedo between the ice cover and open water. Recently, the rapid shortening of the sea ice area is
noted, and in some parts of the Arctic Ocean the area is twice cut down as compared with the normal. In 2015, the record
low area of the winter sea ice was observed, and therewith the maximum of the ice area shifted to the earlier period (by
15 days) as compared with the period of 1981–2010. The winter fluctuations of the sea ice areas are as much important as
the summer ones, since they are the best indicators of the present-day global warming. Thus, it can be supposed that some
mechanism of replacing the perennial sea ice by the seasonal ones has been started up, that is the natural process of transition
from seasonal ices to the next stage that is the ice-free Arctic. On the assumption that increasing of the CO2 concentration
will continue despite the efforts to reduce emissions of greenhouse gases into the atmosphere, and the radiation forcing
will approach to doubling of the CO2 content, one of the scenarios of the past can be realized now.

citation: 
И.И. Борзенкова (2016) История оледенения Арктического бассейна: взгляд из прошлого для оценки возможных изменений в будущем. Лёд и Снег, Т. 56, № 2
Topics: 
publication_date: 
февраля, 2016