scholarly journals GLOBAL CHANGES IN THE SEA ICE COVER AND ASSOCIATED SURFACE TEMPERATURE CHANGES

2016 ◽  
Vol XLI-B8 ◽  
pp. 469-479 ◽  
Author(s):  
Josefino C. Comiso
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Surface Temperature ◽  
Ice Cover ◽  
Rate Of Change ◽  
The Arctic ◽  
Global Changes ◽  
Data Set ◽  
Time Period ◽  
The Antarctic

The trends in the sea ice cover in the two hemispheres have been observed to be asymmetric with the rate of change in the Arctic being negative at −3.8 % per decade while that of the Antarctic is positive at 1.7 % per decade. These observations are confirmed in this study through analyses of a more robust data set that has been enhanced for better consistency and updated for improved statistics. With reports of anthropogenic global warming such phenomenon appears physically counter intuitive but trend studies of surface temperature over the same time period show the occurrence of a similar asymmetry. Satellite surface temperature data show that while global warming is strong and dominant in the Arctic, it is relatively minor in the Antarctic with the trends in sea ice covered areas and surrounding ice free regions observed to be even negative. A strong correlation of ice extent with surface temperature is observed, especially during the growth season, and the observed trends in the sea ice cover are coherent with the trends in surface temperature. The trend of global averages of the ice cover is negative but modest and is consistent and compatible with the positive but modest trend in global surface temperature. A continuation of the trend would mean the disappearance of summer ice by the end of the century but modelling projections indicate that the summer ice could be salvaged if anthropogenic greenhouse gases in the atmosphere are kept constant at the current level.

scholarly journals GLOBAL CHANGES IN THE SEA ICE COVER AND ASSOCIATED SURFACE TEMPERATURE CHANGES

2016 ◽  
Vol XLI-B8 ◽  
pp. 469-479
Author(s):  
Josefino C. Comiso
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Surface Temperature ◽  
Ice Cover ◽  
Rate Of Change ◽  
The Arctic ◽  
Global Changes ◽  
Data Set ◽  
Time Period ◽  
The Antarctic

The trends in the sea ice cover in the two hemispheres have been observed to be asymmetric with the rate of change in the Arctic being negative at −3.8 % per decade while that of the Antarctic is positive at 1.7 % per decade. These observations are confirmed in this study through analyses of a more robust data set that has been enhanced for better consistency and updated for improved statistics. With reports of anthropogenic global warming such phenomenon appears physically counter intuitive but trend studies of surface temperature over the same time period show the occurrence of a similar asymmetry. Satellite surface temperature data show that while global warming is strong and dominant in the Arctic, it is relatively minor in the Antarctic with the trends in sea ice covered areas and surrounding ice free regions observed to be even negative. A strong correlation of ice extent with surface temperature is observed, especially during the growth season, and the observed trends in the sea ice cover are coherent with the trends in surface temperature. The trend of global averages of the ice cover is negative but modest and is consistent and compatible with the positive but modest trend in global surface temperature. A continuation of the trend would mean the disappearance of summer ice by the end of the century but modelling projections indicate that the summer ice could be salvaged if anthropogenic greenhouse gases in the atmosphere are kept constant at the current level.

scholarly journals A spurious jump in the satellite record: has Antarctic sea ice expansion been overestimated?

2014 ◽  
Vol 8 (4) ◽  
pp. 1289-1296 ◽  
Author(s):  
I. Eisenman ◽  
W. N. Meier ◽  
J. R. Norris
Keyword(s):  
Sea Ice ◽  
Ice Cover ◽  
Current Data ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Data Set ◽  
Antarctic Sea Ice ◽  
Ice Retreat ◽  
Bootstrap Algorithm ◽  
The Antarctic

Abstract. Recent estimates indicate that the Antarctic sea ice cover is expanding at a statistically significant rate with a magnitude one-third as large as the rapid rate of sea ice retreat in the Arctic. However, during the mid-2000s, with several fewer years in the observational record, the trend in Antarctic sea ice extent was reported to be considerably smaller and statistically indistinguishable from zero. Here, we show that much of the increase in the reported trend occurred due to the previously undocumented effect of a change in the way the satellite sea ice observations are processed for the widely used Bootstrap algorithm data set, rather than a physical increase in the rate of ice advance. Specifically, we find that a change in the intercalibration across a 1991 sensor transition when the data set was reprocessed in 2007 caused a substantial change in the long-term trend. Although our analysis does not definitively identify whether this change introduced an error or removed one, the resulting difference in the trends suggests that a substantial error exists in either the current data set or the version that was used prior to the mid-2000s, and numerous studies that have relied on these observations should be reexamined to determine the sensitivity of their results to this change in the data set. Furthermore, a number of recent studies have investigated physical mechanisms for the observed expansion of the Antarctic sea ice cover. The results of this analysis raise the possibility that much of this expansion may be a spurious artifact of an error in the processing of the satellite observations.

scholarly journals Correlation and trend studies of the sea-ice cover and surface temperatures in the Arctic

2002 ◽  
Vol 34 ◽  
pp. 420-428 ◽  
Author(s):  
Josefino C. Comiso
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Ice Cover ◽  
The Arctic ◽  
Temperature Anomalies ◽  
Ice Concentration ◽  
Arctic Ice ◽  
Highly Correlated ◽  
Surface Ice ◽  
Perennial Ice

AbstractCo-registered and continuous satellite data of sea-ice concentrations and surface ice temperatures from 1981 to 2000 are analyzed to evaluate relationships between these two critical climate parameters and what they reveal in tandem about the changing Arctic environment. During the 19 year period, the Arctic ice extent and actual ice area are shown to be declining at a rate of –2.0±0.3% dec –1 and 3.1 ±0.4% dec–1, respectively, while the surface ice temperature has been increasing at 0.4 ±0.2 K dec–1, where dec is decade. The extent and area of the perennial ice cover, estimated from summer minimum values, have been declining at a much faster rate of –6.7±2.4% dec–1 and –8.3±2.4% dec–1, respectively, while the surface ice temperature has been increasing at 0.9 ±0.6K dec–1. This unusual rate of decline is accompanied by a very variable summer ice cover in the 1990s compared to the 1980s, suggesting increases in the fraction of the relatively thin second-year, and hence a thinning in the perennial, ice cover during the last two decades. Yearly anomaly maps show that the ice-concentration anomalies are predominantly positive in the 1980s and negative in the 1990s, while surface temperature anomalies were mainly negative in the 1980s and positive in the 1990s. The yearly ice-concentration and surface temperature anomalies are highly correlated, indicating a strong link especially in the seasonal region and around the periphery of the perennial ice cover. The surface temperature anomalies also reveal the spatial scope of each warming (or cooling) phenomenon that usually extends beyond the boundaries of the sea-ice cover.

scholarly journals Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

2014 ◽  
Vol 14 (7) ◽  
pp. 10929-10999 ◽  
Author(s):  
R. Döscher ◽  
T. Vihma ◽  
E. Maksimovich
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
Climate System ◽  
Arctic Climate ◽  
The Arctic ◽  
Atlantic Sector ◽  
Sea Ice Decline ◽  
Arctic Sea

Abstract. The Arctic sea ice is the central and essential component of the Arctic climate system. The depletion and areal decline of the Arctic sea ice cover, observed since the 1970's, have accelerated after the millennium shift. While a relationship to global warming is evident and is underpinned statistically, the mechanisms connected to the sea ice reduction are to be explored in detail. Sea ice erodes both from the top and from the bottom. Atmosphere, sea ice and ocean processes interact in non-linear ways on various scales. Feedback mechanisms lead to an Arctic amplification of the global warming system. The amplification is both supported by the ice depletion and is at the same time accelerating the ice reduction. Knowledge of the mechanisms connected to the sea ice decline has grown during the 1990's and has deepened when the acceleration became clear in the early 2000's. Record summer sea ice extents in 2002, 2005, 2007 and 2012 provided additional information on the mechanisms. This article reviews recent progress in understanding of the sea ice decline. Processes are revisited from an atmospheric, ocean and sea ice perspective. There is strong evidence for decisive atmospheric changes being the major driver of sea ice change. Feedbacks due to reduced ice concentration, surface albedo and thickness allow for additional local atmosphere and ocean influences and self-supporting feedbacks. Large scale ocean influences on the Arctic Ocean hydrology and circulation are highly evident. Northward heat fluxes in the ocean are clearly impacting the ice margins, especially in the Atlantic sector of the Arctic. Only little indication exists for a direct decisive influence of the warming ocean on the overall sea ice cover, due to an isolating layer of cold and fresh water underneath the sea ice.

scholarly journals Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

2014 ◽  
Vol 14 (24) ◽  
pp. 13571-13600 ◽  
Author(s):  
R. Döscher ◽  
T. Vihma ◽  
E. Maksimovich
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
Climate System ◽  
Arctic Climate ◽  
The Arctic ◽  
Central Component ◽  
Atlantic Sector ◽  
Sea Ice Decline

Abstract. Sea ice is the central component and most sensitive indicator of the Arctic climate system. Both the depletion and areal decline of the Arctic sea ice cover, observed since the 1970s, have accelerated since the millennium. While the relationship of global warming to sea ice reduction is evident and underpinned statistically, it is the connecting mechanisms that are explored in detail in this review. Sea ice erodes both from the top and the bottom. Atmospheric, oceanic and sea ice processes interact in non-linear ways on various scales. Feedback mechanisms lead to an Arctic amplification of the global warming system: the amplification is both supported by the ice depletion and, at the same time, accelerates ice reduction. Knowledge of the mechanisms of sea ice decline grew during the 1990s and deepened when the acceleration became clear in the early 2000s. Record minimum summer sea ice extents in 2002, 2005, 2007 and 2012 provide additional information on the mechanisms. This article reviews recent progress in understanding the sea ice decline. Processes are revisited from atmospheric, oceanic and sea ice perspectives. There is strong evidence that decisive atmospheric changes are the major driver of sea ice change. Feedbacks due to reduced ice concentration, surface albedo, and ice thickness allow for additional local atmospheric and oceanic influences and self-supporting feedbacks. Large-scale ocean influences on Arctic Ocean hydrology and circulation are highly evident. Northward heat fluxes in the ocean are clearly impacting the ice margins, especially in the Atlantic sector of the Arctic. There is little indication of a direct and decisive influence of the warming ocean on the overall sea ice cover, due to an isolating layer of cold and fresh water underneath the sea ice.

scholarly journals Positive Trend in the Antarctic Sea Ice Cover and Associated Changes in Surface Temperature

2017 ◽  
Vol 30 (6) ◽  
pp. 2251-2267 ◽  
Author(s):  
Josefino C. Comiso ◽  
Robert A. Gersten ◽  
Larry V. Stock ◽  
John Turner ◽  
Gay J. Perez ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Climate Models ◽  
Ice Cover ◽  
Southern Annular Mode ◽  
Positive Trend ◽  
Growth Season ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract The Antarctic sea ice extent has been slowly increasing contrary to expected trends due to global warming and results from coupled climate models. After a record high extent in 2012 the extent was even higher in 2014 when the magnitude exceeded 20 × 106 km2 for the first time during the satellite era. The positive trend is confirmed with newly reprocessed sea ice data that addressed inconsistency issues in the time series. The variability in sea ice extent and ice area was studied alongside surface ice temperature for the 34-yr period starting in 1981, and the results of the analysis show a strong correlation of −0.94 during the growth season and −0.86 during the melt season. The correlation coefficients are even stronger with a one-month lag in surface temperature at −0.96 during the growth season and −0.98 during the melt season, suggesting that the trend in sea ice cover is strongly influenced by the trend in surface temperature. The correlation with atmospheric circulation as represented by the southern annular mode (SAM) index appears to be relatively weak. A case study comparing the record high in 2014 with a relatively low ice extent in 2015 also shows strong sensitivity to changes in surface temperature. The results suggest that the positive trend is a consequence of the spatial variability of global trends in surface temperature and that the ability of current climate models to forecast sea ice trend can be improved through better performance in reproducing observed surface temperatures in the Antarctic region.

scholarly journals Satellite-observed variability and trend in sea-ice extent, surface temperature, albedo and clouds in the Arctic

2001 ◽  
Vol 33 ◽  
pp. 457-473 ◽  
Author(s):  
Josefino C. Comiso
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Ice Cover ◽  
Warming Trend ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
North American Continent ◽  
The North ◽  
Ice Surface

AbstractRecent observations of a decreasing ice extent and a possible thinning of the ice cover in the Arctic make it imperative that detailed studies of the current Arctic environment are made, especially since the region is known to be highly sensitive to a potential change in climate. A continuous dataset of microwave, thermal infrared and visible satellite data has been analyzed for the first time to concurrently study in spatial detail the variability of the sea-ice cover, surface temperature, albedo and cloud statistics in the region from 1987 to 1998. Large warming anomalies during the last four years (i.e. 1995−98) are indeed apparent and spatially more extensive than previous years. The largest surface temperature anomaly occurred in 1998, but this was confined mainly to the western Arctic and the North American continent, while cooling occurred in other areas. The albedo anomalies show good coherence with the sea-ice concentration anomalies except in the central region, where periodic changes in albedo are observed, indicative of interannual changes in duration and areal extent of melt ponding and snow-free ice cover. The cloud-cover anomalies are more difficult to interpret, but are shown to be well correlated with the expected warming effects of clouds on the sea-ice surface. The results from trend analyses of the data are consistent with a general warming trend and an ice-cover retreat that appear to be even larger during the last dozen years than those previously reported.

scholarly journals Influence of sea surface temperature in the tropics on the Antarctic sea ice under global warming

2019 ◽  
Vol 59 (2) ◽  
pp. 213-221 ◽  
Author(s):  
G. V. Alekseev ◽  
N. I. Glok ◽  
A. E. Vyasilova ◽  
N. E. Ivanov ◽  
N. E. Kharlanenkova ◽  
...  
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Polar Front ◽  
Global Climate Models ◽  
The Arctic ◽  
Antarctic Polar Front ◽  
Sea Ice Extent ◽  
Low Latitudes ◽  
The Antarctic ◽  
Sst Anomalies

Sea ice fields in the Antarctic, in contrast to the Arctic ones, did not show a reduction in observed global warming, whereas the global climate models indicate its certain decrease. The purpose of the study is to explain this climatic phenomenon on the basis of the idea of joint dynamics of oceanic structures in the Southern Ocean – the Antarctic polar front and the margin of the maximum distribution of sea ice. We used data from the ERA/Interim and HadISST as well as the database on the sea ice for 1979–2017. Relationship between the SST-anomalies in low latitudes of the Northern hemisphere and positions of the Antarctic polar front and maximum sea-ice extent was investigated. It was found that locations of these structures changed under the influence of the SST anomalies in low latitudes. The results obtained confirm existence of the opposite trends in changes in the sea ice extent in the Arctic and Antarctic under the influence of the SST anomalies in the central North Atlantic Ocean. When positive, the anomalies cause a shift of the Intertropical Convergence Zone (ITCZ) and the Hadley circulation to the North, while, on the contrary, the negative anomaly promotes the corresponding shift of the Antarctic polar front, followed by the boundary of sea ice.

scholarly journals Satellite Passive Microwave Sea-Ice Concentration Data Set Intercomparison: Closed Ice and Ship-Based Observations

2019 ◽  
Author(s):  
Stefan Kern ◽  
Thomas Lavergne ◽  
Dirk Notz ◽  
Leif Toudal Pedersen ◽  
Rasmus Tage Tonboe ◽  
...  
Keyword(s):  
Sea Ice ◽  
The Arctic ◽  
Data Sets ◽  
Sea Ice Concentration ◽  
Data Set ◽  
Group I ◽  
Ice Concentration ◽  
Data Products ◽  
Group Ii ◽  
The Antarctic

Abstract. Accurate sea-ice concentration (SIC) data are a pre-requisite to reliably monitor the polar sea-ice covers. Over the last four decades, many algorithms have been developed to retrieve the SIC from satellite microwave radiometry, some of them applied to generate long-term data products. We report on results of a systematic inter-comparison of ten global SIC data products at 12.5 to 50.0 km grid resolution for both the Arctic and the Antarctic. The products are compared with each other with respect to differences in SIC, sea-ice area (SIA), and sea-ice extent (SIE), and they are compared against a global winter-time near-100 % reference SIC data set for closed pack ice conditions and against global year-round ship-based visual observations of the sea-ice cover. We can group the products based on the observed inter-product consistency and differences of the inter-comparison results. Group I consists of data sets using the self-optimizing EUMETSAT-OSISAF – ESA-CCI algorithms. Group II includes data using the NASA-Team 2 and Comiso-Bootstrap algorithms, and the NOAA-NSIDC sea-ice concentration climate data record (CDR). The standard NASA-Team and the ARTIST Sea Ice (ASI) algorithms are put into a separate group III because of their often quite diverse results. Within group I and II evaluation results and intra-product differences are mostly very similar. For instance, among group I products, SIA agrees within ±100 000 km2 in both hemispheres during maximum and minimum sea-ice cover. Among group II products, satellite- minus ship-based SIC differences agree within ±0.7 %. Standing out with large negative differences to other products and evaluation data is the standard NASA-Team algorithm, in both hemispheres. The three CDRs of group I (SICCI-25km, SICCI-50km, and OSI-450) are biased low compared to the 100 % reference SIC with biases of −0.4 % to −1.0 % (Arctic) and −0.3 % to −1.1 % (Antarctic). Products of group II appear to be mostly biased high in the Arctic by between +1.0 % and +3.5 %, while their biases in the Antarctic only range from −0.2  to +0.9 %. The standard deviation is smaller in the Arctic for the quoted group I products: 1.9 % to 2.9 % and Antarctic: 2.5 % to 3.1 %, than for group II products: Arctic: 3.6 % to 5.0 %, Antarctic: 4.5 % to 5.4 %. Products of group I exhibit larger overall satellite- minus ship-based SIC differences than group II in both hemispheres. However, compared to group II, group I products’ standard deviations are smaller, correlations higher and evaluation results are less sensitive to seasonal changes. We discuss the impact of truncating the SIC distribution, as naturally retrieved by the algorithms around the 100 % sea-ice concentration end. We show that evaluation studies of such truncated SIC products can result in misleading statistics and favour data sets that systematically overestimate SIC. We describe a method to re-construct the un-truncated distribution of SIC before the evaluation is performed. On the basis of this evaluation, we open a discussion about the overestimation of SIC in data products, with far-reaching consequences for, e.g., surface heat-flux estimations in winter. We also document inconsistencies in the behaviour of the weather filters used in products of group II, and suggest advancing studies about the influence of these weather filters on SIA and SIE time-series and their trends.

scholarly journals Autumn Sea Ice Cover, Winter Northern Hemisphere Annular Mode, and Winter Precipitation in Eurasia

2012 ◽  
Vol 26 (11) ◽  
pp. 3968-3981 ◽  
Author(s):  
Fei Li ◽  
Huijun Wang
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Northern Hemisphere ◽  
Ice Cover ◽  
Winter Precipitation ◽  
The Arctic ◽  
Northern Eurasia ◽  
Laptev Sea ◽  
Annular Mode ◽  
Northern Hemisphere Annular Mode

Abstract This paper examines the impacts of the previous autumn sea ice cover (SIC) on the winter Northern Hemisphere annular mode (NAM) and winter precipitation in Eurasia. The coherent variations among the Kara–Laptev autumn SIC, winter NAM, and Eurasian winter precipitation appear after the year 1982, which may prove useful for seasonal prediction of winter precipitation. From a physical point of view, the Kara–Laptev SIC and sea surface temperature (SST) anomalies develop in autumn and remain in winter. Given that winter NAM is characterized by an Arctic–midlatitude seesaw centered over the Barents Sea and Kara–Laptev Seas, it is closely linked to the Arctic forcing that corresponds to the Kara–Laptev sea ice increase (reduction) and the associated surface temperature cooling (warming). Moreover, based on both model simulations and observations, the diminishing Kara–Laptev sea ice does induce positive sea level pressure (SLP) anomalies over high-latitude Eurasia in winter, which is accompanied by a significant surface warming in northern Eurasia and cooling south of the Mediterranean. This surface air temperature (SAT) anomaly pattern facilitates increases of specific humidity in northern Eurasia with a major ridge extending southward along the East Asian coast. As a result, the anomalous Eurasian winter precipitation has a more zonal band structure.

Sign in / Sign up

Export Citation Format

Share Document