bluewave

5th consecutive NSIDC daily extent drop of 100k or greater. 2019 continues in first place on July 10th ahead of 2012. One of the most impressive weekly drops during the month of July. 7-10-19....7.996 7-10-12....8.130

2019 jumps into the extent lead over 2012 with a major 247k drop as of July 9th. 2019....8.098 2012....8.174

The blocking and high pressure relaxation is coming just as 2019 edges ahead of 2012 for extent. But the thing that separated 2012 from the rest of the pack was the big storm and record late season decline. 2019...8.345 2012...8.398

It will be interesting to see if 2019 can hold the area lead over 2012 if the models are correct about the polar blocking weakening. https://sites.google.com/site/cryospherecomputing/daily-data https://mobile.twitter.com/judah47/status/1147128282225287170

Yeah, probably 6-7 million sq km for September extents. But nothing close to the historic drop in recent times. https://www.carbonbrief.org/guest-post-piecing-together-arctic-sea-ice-history-1850 First, there is no point in the past 150 years where sea ice extent is as small as it has been in recent years. Second, the rate of sea ice retreat in recent years is also unprecedented in the historical record. And, third, the natural fluctuations in sea ice over multiple decades are generally smaller than the year-to-year variability. https://mobile.twitter.com/ZLabe/status/1146506078932230144?ref_src=twsrc^google|twcamp^serp|twgr^tweet New study in @AMSJCLi to model #Arctic sea ice volume since 1901: "The sea ice decline over the 1979-2010 period is pan-Arctic and 6 times larger than the net decline during the 1901-40 period."

The longer reconstructions further back in time make the last 40 years even more exceptional.

Ice has no agenda. It continues melt as the climate warms. The beauty of science is that you don’t have to believe in it for it to work.

2nd lowest June extent with the 2nd warmest Arctic temperatures. https://nsidc.org/arcticseaicenews/2019/07/melt-season-shifts-into-high-gear/ https://sites.uci.edu/zlabe/arctic-temperatures/

2019 continues to remain in the top 3 lowest extents right into early July. 7-2 2019....9.056 2012....8.971 2010....8.943

The record Chukchi SST warming has implications for the entire Arctic. https://www.newscientist.com/article/2178160-a-warm-water-time-bomb-could-spell-disaster-for-arctic-sea-ice/ The Arctic is in hot water, literally, following the discovery that heat has been accumulating rapidly in a salty layer of the Arctic Ocean 50 metres down. Currently, it’s being held at that depth by a less dense layer of freshwater overhead, but if the two layers start to mix it could melt all seasonal sea ice, accelerating the already-rapid loss of polar ice cover. Researchers discovered the heat time-bomb after analysing publicly available data on ice cover, and at different depths on sea temperature, heat content and saltiness over the past three decades. The data was gathered around the Canadian Basin, a major basin of the Arctic Ocean fed by waters from the North Chukchi Sea, just north of the Bering Strait between Alaska and Siberia. Over this timespan, the heat content of the salty layer doubled, from 200 to 400 million joules per square metre, enough to reduce overall Arctic ice thickness by 80 centimetres. The root cause is global warming, which has seen temperatures in the Arctic rise by 2 degrees from pre-industrial levels–twice the global average—leading to record-low sea ice coverage. The researchers found that with sea ice retreating, heat absorption by exposed surface waters has increased fivefold in 30 years, mainly from direct sunlight, which no longer gets reflected by ice. And with no ice in the way, strong northerly winds push these newly-warmed surface waters at the Arctic fringes down to the depths where they’re now accumulating under the Arctic. The fear is that the freshwater “lid” keeping them there could fall apart. “It could be lost through increased mechanical mixing of the water layers, especially driven by the winds,” says Mary-Louise Timmermans at Yale University and head of the team. “With continued sea-ice losses, we’d have more wind-driven mixing, and that would erode this natural barrier,” she says. Loss of a protective “freshwater” layer is already happening elsewhere around the Arctic in the Barents Sea north of Scandinavia, allowing warmer Atlantic waters to flow in and potentially destroy an entire Arctic ecosystem in the North Barents Sea within a decade.

Looks like June finished with the 2nd lowest extent on record behind 2016. https://mobile.twitter.com/ZLabe/status/1145720975402553344 Average June #Arctic sea ice extent was the 2nd lowest on record. It was 1,230,000 km² below the 1981-2010 average. https://mobile.twitter.com/AlaskaWx/status/1145790324465254400 Chukchi Sea average ice extent in June was the lowest of record in 41 years of daily passive microwave data from NSIDC. That means an additional (compared to normal) area the size of Florida was open water being heated by the sun instead of ice.

The sea ice north of Greenland is projected to be the last to go. https://ccin.ca/ccw/seaice/future

Very impressive dipole pattern continues on the models into early July. Extent has pulled slightly ahead of 2012. Overall 2nd place for the date behind 2010. 2010.....9.501 2019.....9.660 2016.....9.665 2012.....9.678

You can see why the Arctic Basin is at record low levels of extent. Blocking and record warmth focused over the Pacific sector. This is the opposite of 2012 when the harshest conditions were centered closer to the Atlantic regions. While 2019 has an Arctic Basin lead over 2012, the 2012 Atlantic extent was low enough to maintain a small overall advantage. NSIDC extent 6-26-19....9.819 6-26-12....9.712

The big story this year is the record warmth and low sea ice extent in the Pacific sector. But you can see 2012 ahead of 2019 in the Atlantic sector. Overall, 2019 is a bit behind the pace of 2012 to date. https://mobile.twitter.com/AlaskaWx/status/1143202863633448960 The northern Bering & southern Chukchi Seas are baking. Large areas away from land with ocean surface temperatures more than 5C (9F) above the 1981-2010 average. Impacts to the climate system, food web, communities and commerce https://mobile.twitter.com/AlaskaWx/status/1142829854930296832 Chukchi and Beaufort Seas combined #seaice extent remains the lowest of record ( @NSIDC passive microwave data since 1979), 21 percent below the 1981-2010 median. Lower concentration of ice will be easily moved by winds this week.

The AMO has become more amplified as the climate warmed. So even natural variability is impacted by climate change. https://www.nature.com/articles/srep40861 Amplification of the Atlantic Multidecadal Oscillation associated with the onset of the industrial-era warming North Atlantic sea surface temperatures experience variability with a periodicity of 60–80 years that is known as the Atlantic Multidecadal Oscillation (AMO). It has a profound imprint on the global climate system that results in a number of high value societal impacts. However the industrial period, i.e. the middle of the 19th century onwards, contains only two full cycles of the AMO making it difficult to fully characterize this oscillation and its impact on the climate system. As a result, there is a clear need to identify paleoclimate records extending into the pre-industrial period that contain an expression of the AMO. This is especially true for extratropical marine paleoclimate proxies where such expressions are currently unavailable. Here we present an annually resolved coralline algal time series from the northwest Atlantic Ocean that exhibits multidecadal variability extending back six centuries. The time series contains a statistically significant trend towards higher values, i.e. warmer conditions, beginning in the 19th century that coincided with an increase in the time series’ multidecadal power. We argue that these changes are associated with a regional climate reorganization involving an amplification of the AMO that coincided with onset of the industrial-era warming.

This is the lowest that CPOM has gone since they began issuing outlooks back around 2014. While their forecasts usually finish within the error bars, they are often a little too high. CPOM June forecast compared September average NSIDC extent verification Standard Deviations +/- 0.5 mill. km2 2018...F...5.30....V...4.71 2017...F...5.00.....V..4.80 2016...F...4.50......V..4.70 2015...F...5.10......V..4.63 2014..F....5.40.......V..5.30

The Pacific sector continues to experience the most hostile conditions for the sea ice. https://mobile.twitter.com/alaskawx?lang=en BREAKING CLIMATE: Utqiaġvik (Barrow) has been up to 73F (22.8C) through 7pm AKDT Thursday. This is a new all-time record high for the month of June. Previous record 72F (22.2C) on June 18, 1996. Climate obs since 1920

This is the first time since 2012 that we had such a hostile pattern from 05-15 to 6-14.

The Pacific side has gotten off to an especially rough start this year. https://mobile.twitter.com/AlaskaWx/status/1140230023636541440 Sea ice extent in the Chukchi & Beaufort Seas near Alaska at record low level for mid-June. A storm this past week pushed broken #seaice back over previously open water in the Beaufort Sea, resulting in a slight increase in extent.

This was the 2nd warmest on record in Greenland for June behind 2012. https://earther.gizmodo.com/half-of-greenlands-surface-started-melting-this-week-w-1835483363 Ruth Mottram, a climate scientist with the Danish Meteorological Institute, told Earther that the weather station at the top of the ice sheet saw temperatures reach above freezing on Wednesday and they were headed that way again on Thursday. That puts them just a degree or so away from setting the all-time heat record for June, which is currently held by June 2012. The spike in temperatures has caused a spike in melt. Roughly 45 percent of the ice sheet surface has been melting. Normally, less than 10 percent of the ice sheet surface is melting at this time of year. According to data from the National Snow and Ice Data Center, Wednesday set a daily record for the widest melt area on that date, with 275,000 square miles—an area bigger than Texas—of the ice sheet’s surface becoming a slushy, watery mess. Mottram said the much of the ice is likely to refreeze once the heat breaks, but it will be more primed to melt later in the season. https://mobile.twitter.com/RasmusTonboe/status/1139504201615237120 got the difficult task of retrieving our oceanographic moorings and weather station on sea ice in North West Greenland this year. Rapid melt and sea ice with low permeability and few cracks leaves the melt water on top.

Extent just fell below 2016 for a new record on this date. https://mobile.twitter.com/Climatologist49/status/1138471666630053888 As of June 10th, Arctic sea ice is now the lowest on record during the satellite era (1979-2019). The extent is typical for Jun 28th. As the basin scale, the Beaufort Sea ice is the big loser. It is already at a mid-August state! https://mobile.twitter.com/AlaskaWx/status/1137749983787012096 Unprecedented early #seaice loss from both Chukchi & Beaufort Seas north and west of Alaska. June 8th extent from is 1981-2010 median for Aug 01! Five lowest extents for this date are 2015 through 2019.

Looks like the earliest in the season that north of 80N went above freezing. http://ocean.dmi.dk/arctic/meant80n.uk.php

Warmest May on record for the Arctic. https://sites.uci.edu/zlabe/arctic-temperatures/

Great write-up on the conditions leading to April 2019 beating the minimum sea ice extent record set in 2016. Also an analysis on sea ice age and transport. https://nsidc.org/arcticseaicenews/2019/05/rapid-ice-loss-in-early-april-leads-to-new-record-low/ Rapid ice loss in early April leads to new record low May 2, 2019 April reached a new record Arctic low sea ice extent. Sea ice loss was rapid in the beginning of the month because of declines in the Sea of Okhotsk. The rate of ice loss slowed after early April, due in part to gains in extent in the Bering and Barents Seas. However, daily ice extent remained at record low levels throughout the month. Overview of conditions Figure 1. Arctic sea ice extent for April 2019 was 13.45 million square kilometers (5.19 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data Credit: National Snow and Ice Data Center High-resolution image Arctic sea ice extent for April 2019 averaged 13.45 million square kilometers (5.19 million square miles). This was 1.24 million square kilometers (479,000 square miles) below the 1981 to 2010 long-term average extent and 230,000 square kilometers (89,000 square miles) below the previous record low set in April 2016. Rapid ice loss occurred in the Sea of Okhotsk during the first half of April; the region lost almost 50 percent of its ice by April 18. Although sea ice was tracking at record low levels in the Bering Sea from April 1 to 12, the ice cover expanded later in the month. Elsewhere, there was little change except for small losses in the Gulf of St. Lawrence, the southern part of the East Greenland Sea, and southeast of Svalbard. In addition, open water areas developed along coastal regions of the Barents Sea. The ice edge expanded slightly east of Novaya Zemlya. Conditions in context Figure 2a. The graph above shows Arctic sea ice extent as of May 1, 2019, along with daily ice extent data for four previous years and 2012. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data. Credit: National Snow and Ice Data Center High-resolution image Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for April 2019. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures. Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division High-resolution image Air temperatures at the 925 hPa level (approximately 2,500 feet above the surface) were above average across the Arctic during the first two weeks of April, especially over the East Siberian Sea and the Greenland Ice Sheet where air temperatures were as much as 9 degrees Celsius (16 degrees Fahrenheit) above average (Figure 2b). Elsewhere, 925 hPa temperatures were between 3 to 5 degrees Celsius (5 to 9 degrees Fahrenheit) above average, including the Sea of Okhotsk where ice loss early in the month was especially prominent. These relatively warm conditions were linked to a pattern of high sea level pressure over the Beaufort Sea paired with low sea level pressure over Alaska, Siberia, and the Kara and Barents Seas. This drove warm air from the south over the East Siberian Sea. Similarly, high pressure over Greenland and the North Atlantic, coupled with low sea level pressure within Baffin Bay, helped usher in warm air over southern Greenland from the southeast. During the second half of the month, temperatures remained above average over most of the Arctic Ocean, and up to 8 degrees Celsius (14 degrees Fahrenheit) above average over the East Greenland Sea. However, temperatures were 1 to 5 degrees Celsius (2 to 9 degrees Fahrenheit) below average over the Bering Sea, and up to 8 degrees Celsius (14 degrees Fahrenheit) below average over the Canadian Arctic Archipelago. Air temperatures were slightly below average in the Kara Sea. April 2019 compared to previous years Figure 3. Monthly April ice extent for 1979 to 2019 shows a decline of 2.64 percent per decade. Credit: National Snow and Ice Data Center High-resolution image The 1979 to 2019 linear rate of decline for April ice extent is 38,800 square kilometers (15,000 square miles) per year, or 2.64 percent per decade relative to the 1981 to 2010 average. Sea ice age update Figure 4. The top maps compare Arctic sea ice age for (a) April 8 to 14, 1984, and (b) April 9 to 15, 2019. The time series (c) of mid-April sea ice age as a percentage of Arctic Ocean coverage from 1984 to 2019 shows the nearly complete loss of 4+ year old ice; note the that age time series is for ice within the Arctic Ocean and does not include peripheral regions where only first-year (0 to 1 year old) ice occurs, such as the Bering Sea, Baffin Bay, Hudson Bay, and the Sea of Okhotsk. Credit: W. Meier, NSIDC High-resolution image Younger sea ice tends to be thinner than older ice. Therefore, sea ice age provides an early assessment of the areas most susceptible to melting out during the coming summer. The Arctic sea ice cover continues to become younger (Figure 4), and therefore, on average, thinner. Nearly all of the oldest ice (4+ year old), which once made up around 30 percent of the sea ice within the Arctic Ocean, is gone. As of mid-April 2019, the 4+ year-old ice made up only 1.2 percent of the ice cover (Figure 4c). However, 3 to 4-year-old ice increased slightly, jumping from 1.1 percent in 2018 to 6.1 percent this year. If that ice survives the summer melt season, it will somewhat replenish the 4+ year old category going into the 2019 to 2020 winter. However, there has been little such replenishment in recent years. The sea ice age data products were recently updated through 2018 (Version 4, Tschudi et al., 2019). Data is available here. In addition, an interim QuickLook product that will provide preliminary updates every month is in development. Changing ice and sediment transport Figure 5a. This map shows the main sea ice drift patterns. Figure 5b. This illustration shows how sediments can be ingrained into the newly forming sea ice. Figure 5c. This graph shows the probability that newly formed ice in the winter will survive the summer. Credit: T. Krumpen High-resolution image Figure 5d. This image shows sediment-rich sea ice in the Transpolar Drift Stream. A crane lowers two researchers from the decks of the icebreaker RV Polarstern to the surface of the ice to collect samples. Photo Credit: R. Stein, Alfred Wegener Institut High-resolution image Scientists from the Alfred Wegener Institut (AWI) monitored and analyzed sea ice motion using satellite data from 1998 to 2017 and concluded that only 20 percent of the sea ice that forms in the shallow Russian seas of the Arctic Ocean now reaches the central Arctic Ocean to join the Transpolar Drift Stream(Figures 5a and b). The Russian seas, including the Kara, Laptev, and East Siberian Seas, are considered the ice nursery of the Arctic. The remaining 80 percent of this first-year ice melts before it has a chance to leave this nursery. Prior to the year 2000, that number was about 50 percent (Figure 5c). These conclusions find support from sea ice thickness observations in Fram Strait, which is fed by the Transpolar Drift Stream. AWI scientists regularly gather ice thickness data in Fram Strait as part of their IceBird program. The ice now leaving the Arctic Ocean through the Fram Strait is, on average, 30 percent thinner than it was 15 years ago. There are two reasons for this. First, winters are warmer and the melt season now begins much earlier than it used to. Second, much of this ice no longer forms in the shallow seas, but much farther north. As a result, it has less time to thicken from winter growth and/or ridging as it drifts across the Arctic Ocean. These changes in transport and melt affect biogeochemical fluxes and ecological processes in the central Arctic Ocean. For example, in the past, the sea ice that formed along the shallow Russian seas transported mineral material, including dust from the tundra and steppe, to the Fram Strait (Figure 5d). Today, the melting floes release this material en route to the central Arctic Ocean. Far less material now reaches the Fram Strait and it is different in composition. This finding is based on two decades of data sourced from sediment traps maintained in the Fram Strait by AWI biologists. Instead of Siberian minerals, sediment traps now contain remains of dead algae and microorganisms that grew within the ice as it drifted. Putting current changes into longer-term perspective Figure 6. This map shows Arctic regions used in the Walsh et al. study and how much each area’s September extent contributes to the total September sea ice extent. The top number gives the percentage (as squares of correlations, or R2) when the raw 1953 to 2013 ice extent time series is used. The bottom number (bold) gives what the percentage drops to after the time series data have been detrended. For example, about 70 percent of the September Arctic-wide extent number is explained by the September extent in the seas north of Alaska, but that drops to about 20 percent once the trends have been removed. Credit: Walsh et al., 2019, The Cryosphere High-resolution image While changes in sea ice extent over the past several decades are usually shown as linear trends, they can mask important variations and changes. A recent study led by John Walsh at University Alaska Fairbanks compared various trend-line fits to sea ice extent time series back to 1953, for the Arctic as a whole and various sub-regions. This data set extends the satellite record by using operational ice charts and other historical sources (Walsh et al., 2016). They found that a two-piece linear fit with a break point in the 1990s provides a more meaningful basis for calculations of sea ice departures from average conditions and their persistence, rather than a single trend line computed over the period 1953 to the present. Persistence of sea ice departures from average conditions represents the memory of the system, which can be used to forecast sea ice conditions a few months in advance. September Arctic-wide ice extent can also be predicted with some limited skill when the data include the trend. However, this apparent skill largely vanishes when the trend is removed from the data using the two-piece linear fit. This finding is consistent with the notion of a springtime predictability barrier, such that springtime sea ice conditions are usually not a strong predictor of the summer ice cover because atmospheric circulation patterns in summer erode this memory in the system. For example, despite the extensive coverage of fairly young—and hence thin—ice this spring, cool summer weather conditions may limit melt, leading to a higher September ice extent than might otherwise be expected. April snow melt in Greenland—notable but not unusual Temperatures were well above average over Greenland for much of April but were still below freezing except near the coast. Satellite data indicate that there was a small area surface melt on the southeastern coastal part of the ice sheet early in the month. In the last week of April, melt became more extensive, spreading further north on the east coast and starting on the west coast. While interesting, this is not especially unusual. Most years of the past decade have some surface melt in April. In 2012 and 2016, strong melt events occurred in April that covered a much larger area than in 2019. NSIDC is now trackingGreenland surface melt for 2019 on a daily basis.