This work is dedicated to the study of the composition, structure and dynamics of the Arctic sea ice ecosystem. It considers the permanent Arctic sea ice cover as an integral steady-state ecological system.

The book on sea ice ecology is the ecology of sea ice algae and other microorganism as bacteria, meiofauna, and viruses residing inside or at the bottom of the sea ice, called the sympagic biota. Organisms as seals, fish, birds, and Polar bears relies on sea ice but are not part of this biota. A distinct feature of this ecosystem, is the disappearance (melt) every summer and re-establishing in autumn and winter. The book is organized seasonally describing the physical, optical, biological, and geochemical conditions typical of the seasons: autumn, winter, and spring. These are exemplified with case studies based on author’s fieldwork in Greenland, the Arctic Ocean, and Antarctica but focused on Arctic conditions. The sea ice ecosystem is described in the context of climate change, interests, and effects of a decreasing summer ice extent in the Arctic Ocean. The book contains an up to date description of most relevant methods and techniques applied in sea ice ecology research. This book will appeal to university students at Masters or PhD levels reading biology, geosciences, and chemistry.

Ten years ago Polar Biology published the book, Weddell Sea Ecology, containing the European "Polarstern" study EPOS in the Weddell Sea and Peninsula waters 1988/89. In certain respects, the present collection of papers, first published in Polar Biology in 2001, is a follow-up as it combines papers partly based on three "Polarstern" expeditions to the same region. Further articles relate to both land-based and shipborne studies, again primarily in the Atlantic sector and around the Antarctic Peninsula. The SCAR programme, "Ecology of the Antarctic Sea Ice Zone" (EASIZ), served as an umbrella for a truly international cooperation. Although funding came exclusively from national sources, 40% of the scientists on board "Polarstern" were foreigners. Out of the 35 papers of the present volume not less than 14 papers have multinational authorship. The scope of EASIZ is wider ilian the Southern Ocean Studies in JGOFS and GLOBEC. The Contents reflect emphasis on the study of benthos, which hitherto had not received the necessary attention in the attempt to understand key questions of evolution and zoogeography of fauna from the Southern Hemisphere. The information collected under EASIZ enhanced greatly our recognition of the rather high biodiversity of ilie Antarctic shelf benthos. In order to extend these studies to ilie deeper continental slopes and the deep sea, "Polarstern" is presently on her way for ilie first international survey of deep-sea benthos in the Atlantic sector of ilie Southern Ocean.

Over the past 20 years the study of the frozen Arctic and Southern Oceans and sub-arctic seas has progressed at a remarkable pace. This third edition of Sea Ice gives insight into the very latest understanding of the how sea ice is formed, how we measure (and model) its extent, the biology that lives within and associated with sea ice and the effect of climate change on its distribution. How sea ice influences the oceanography of underlying waters and the influences that sea ice has on humans living in Arctic regions are also discussed. Featuring twelve new chapters, this edition follows two previous editions (2001 and 2010), and the need for this latest update exhibits just how rapidly the science of sea ice is developing. The 27 chapters are written by a team of more than 50 of the worlds’ leading experts in their fields. These combine to make the book the most comprehensive introduction to the physics, chemistry, biology and geology of sea ice that there is. This third edition of Sea Ice will be a key resource for all policy makers, researchers and students who work with the frozen oceans and seas.

The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years. The melting is accelerating, and researchers were unable to identify natural processes that might slow the deicing of the Arctic. Such substantial additional melting of Arctic and Antarctic glaciers and ice sheets would raise the sea level worldwide, flooding the coastal areas where many of the world's population lives. Studies, led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Arizona, show that greenhouse gas increases over the next century could warm the Arctic by 3-5°C in summertime. Thus, Arctic summers by 2100 may be as warm as they were nearly 130,000 years ago, when sea levels eventually rose up to 6 m higher than today.

Investigators from a number of countries have been studying the ice community and experimental information is now available from a number of geographic areas. This includes ecological data as well as community and species specific physiological information. The literature on ice biota is scattered, being found in scientific journals, research and technical reports, symposia proceedings, M. S. theses and Ph.D. dissertations, meeting abstracts, and books on topics ranging from algal ecology to regional oceanography. Much of the material has not been published and some is available only in proprietry or difficult to obtain reports. The purpose of this book is to bring the data and references together in one place and to provide state of the art information on these little known, but ecologically important, polar communities.

This report reviews evidence that overshooting 1.5°C may push the earth over several tipping points, leading to irreversible and severe changes in the climate system. If triggered, tipping point impacts will rapidly cascade through socio-economic and ecological systems, leading to severe effects on human and natural systems and imposing important challenges for human adaptation.

The Topic Editors Paul F. J. Wassmann, dorte Krause-Jensen, Markus A. Janout, and Bodil Annikki Bluhm declare that they are collaborating with pan-arctic community.

Sea ice is an important driver of climate patterns and polar marine ecosystem dynamics. In particular, primary production by microalgae in sea ice has been postulated as a sink for anthropogenic CO2, and as a critical resource in the life cycle of Antarctic krill Euphausia superba, a keystone species. Study of the sea ice ecosystem is difficult at regional and global scales, however, because of the expense and logistical difficulties in accessing such a remote and hostile environment. Consequently, models remain valuable tools for investigations of the spatial and temporal dynamics of sea ice and associated ecology and biogeochemistry. Recent advances in model representations of sea ice have called into question the accuracy of previous studies, and allow the creation of new tools to perform mechanistic simulations of sea ice physics and biogeochemistry. To address spatial and temporal variability in Antarctic sea ice algal production, and to establish the bounds and sensitivities of the sea ice ecosystem, a new, coupled sea ice ecosystem model was developed. In the vertical dimension, the model resolves incorporated saline brine, macronutrients concentrations, spectral shortwave radiation, and the sea ice algae community at high resolution. A novel method for thermodynamics, desalination, and fluid transfer in slushy, high-brine fraction sea ice was developed to simulate regions of high algal productivity. The processes of desalination, fluid transfer, snow-ice creation, and superimposed ice formation allowed the evolution of realistic vertical profiles of sea ice salinity and algal growth. The model replicated time series observations of ice temperature, salinity, algal biomass, and estimated fluid flux from the Ice Station Weddell experiment. In the horizontal dimension, sub-grid scale parameterizations of snow and ice thickness allow more realistic simulation of the ice thickness distribution, and consequently, sea ice algal habitat. The model is forced from above by atmospheric reanalysis climatologies, and from below by climatological ocean heat flux and deep-water ocean characteristics. Areal sea ice concentration and motion are specified according to SSM/I passive microwave satellite estimates of these parameters. Sensitivity testing of different snow and ice parameterizations showed that without a sub-grid scale ice thickness distribution, mean ice and snow thickness is lower and bottom sea ice algal production is elevated. Atmospheric forcing from different reanalysis data sets cause mean and regional shifts in sea ice production and associated ecology, even when sea ice extent and motion is controlled. Snow cover represents a first-order control over ice algal production by limiting the light available to bottom ice algal communities, and changes to the regional, rather than mean, snow thickness due to the use of different ice and snow representations are responsible for large differences in the magnitude and distribution of sea ice algal production. Improved convective nutrient exchange in high-brine fraction (slush) sea ice is responsible for up to 18% of total sea ice algal production. A continuous 10-year model run using climatological years 1996-2005 produced a time series of sea ice algal primary production that varied between 15.5 and 18.0 Tg C yr-1. This study represents the first interannual estimate of Antarctic sea ice algal production that dynamically considers the light, temperature, salinity, and nutrient conditions that control algal growth. On average, 64% of algal production occurred in the bottom 0.2 m of the ice pack. Production was spatially heterogeneous, with little consistency between years when examined at regional scales; however, at basin or hemispheric scales, annual production was fairly consistent in magnitude. At a mean of 0.9 g C m-2 yr-1, the magnitude of carbon uptake by sea ice algae will not significantly affect the Southern Ocean carbon cycle. Light availability was the dominant control on sea ice algae growth over the majority of the year; however, severe nutrient limitation that occurred annually during late spring and summer proved to be the largest control over sea ice algal productivity.