bluewave

https://theconversation.com/scientists-looked-at-sea-levels-125-000-years-in-the-past-the-results-are-terrifying-126017 November 6, 2019 2.05pm EST Sea levels rose 10 metres above present levels during Earth’s last warm period 125,000 years ago, according to new research that offers a glimpse of what may happen under our current climate change trajectory. Our paper, published today in Nature Communications, shows that melting ice from Antarctica was the main driver of sea level rise in the last interglacial period, which lasted about 10,000 years. Rising sea levels are one of the biggest challenges to humanity posed by climate change, and sound predictions are crucial if we are to adapt. This research shows that Antarctica, long thought to be the “sleeping giant” of sea level rise, is actually a key player. Its ice sheets can change quickly, and in ways that could have huge implications for coastal communities and infrastructure in future. Aerial footage showing devastation caused by severe storms at Collaroy on Sydney’s northern beaches in June 2016.UNSW Water Research Laboratory A warning from the past Earth’s cycles consist of both cold glacial periods - or ice ages - when large parts of the world are covered in large ice sheets, and warmer interglacial periods when the ice thaws and sea levels rise. The Earth is presently in an interglacial period which began about 10,000 years ago. But greenhouse gas emissions over the past 200 years have caused climate changes that are faster and more extreme than experienced during the last interglacial. This means past rates of sea level rise provide only low-end predictions of what might happen in future. We examined data from the last interglacial, which occurred 125,000 to 118,000 years ago. Temperatures were up to 1℃ higher than today - similar to those projected for the near future. Read more: 11,000 scientists warn: climate change isn't just about temperature Our research reveals that ice melt in the last interglacial period caused global seas to rise about 10 metres above the present level. The ice melted first in Antarctica, then a few thousand years later in Greenland. Sea levels rose at up to 3 metres per century, far exceeding the roughly 0.3-metre rise observed over the past 150 years. The early ice loss in Antarctica occurred when the Southern Ocean warmed at the start of the interglacial. This meltwater changed the way Earth’s oceans circulated, which caused warming in the northern polar region and triggered ice melt in Greenland. Dogs hauling a sled through meltwater on coastal sea ice during an expedition in northwest Greenland,June 2019.STEFFEN M. OLSEN/DANISH METEOROLOGICAL INSTITUTE Understanding the data Global average sea level is currently estimated to be rising at more than 3 millimetres a year. This rate is projected to increase and total sea-level rise by 2100 (relative to 2000) is projected to reach 70-100 centimetres, depending on which greenhouse gas emissions pathway we follow. Such projections usually rely on records gathered this century from tide gauges, and since the 1990s from satellite data. Most of these projections do not account for a key natural process - ice-cliff instability - which is not observed in the short instrumental record. This is why geological observations are vital. Read more: Our shameful legacy: just 15 years' worth of emissions will raise sea level in 2300 When ice reaches the ocean, it becomes a floating ice-shelf which ends in an ice-cliff. When these cliffs get very large, they become unstable and can rapidly collapse. This collapse increases the discharge of land ice into the ocean. The end result is global sea-level rise. A few models have attempted to include ice-cliff instability, but the results are contentious. Outputs from these models do, however, predict rates of sea-level rise that are intriguingly similar to our newly observed last interglacial data. Antactica was long thought to be the sleeping giant of sea level rise, but is now considered a key driver. Australian Antarctic Division Our work examines records of total sea-level change, which by definition includes all relevant natural processes. We examined chemical changes in fossil plankton shells in marine sediments from the Red Sea, which reliably relate to changes in sea level. Together with evidence of meltwater input around Antarctica and Greenland, this record reveals how rapidly sea level rose, and distinguishes between different ice sheet contributions. Looking to the future What is striking about the last interglacial record is how high and quickly sea level rose above present levels. Temperatures during the last interglacial were similar to those projected for the near future, which means melting polar ice sheets will likely affect future sea levels far more dramatically than anticipated to date. Read more: Australia's only active volcanoes and a very expensive fish: the secrets of the Kerguelen Plateau The last interglacial is not a perfect scenario for the future. Incoming solar radiation was higher than today because of differences in Earth’s position relative to the Sun. Carbon dioxide levels were only 280 parts per million, compared with more than 410 parts per million today. Crucially, warming between the two poles in the last interglacial did not happen simultaneously. But under today’s greenhouse-gas-driven climate change, warming and ice loss are happening in both regions at the same time. This means that if climate change continues unabated, Earth’s past dramatic sea level rise could be a small taste of what’s to come.

My guess is that it’s a combination of factors. We saw the historic and rapid warming of the entire Pacific basin in 2013. At the same time, the Arctic has continued to warm with large areas of open water lingering into the cold season. So the lower sea ice can work in tandem with the tropical forcing to produce repeating 500 mb patterns that get stuck for extended periods of time.

The cold November followed by a mild December has been a very persistent pattern this decade. So the snow extent charts are just reflecting this.

Tied with last year for 2nd highest North America snow extent by November 5th. https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_plots.html

Even a T of snow would be impressive for November 12th.

Every month since April has featured top 3 warmth in the Arctic. This is a first for April through October. https://www.esrl.noaa.gov/psd/data/timeseries/

December 2017 came really close. The late month Arctic outbreak began about a week too late. So the historic 950 mb benchmark blizzard occurred on January 4th. Another case of the 2010’s warm up around the solstice. Data for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Avg Temperature Avg Temperature Departure Snowfall 2017-12-18 47 32 39.5 4.7 0.0 2017-12-19 55 40 47.5 13.0 0.0 2017-12-20 51 32 41.5 7.3 0.0 2017-12-21 39 24 31.5 -2.5 0.0 2017-12-22 48 30 39.0 5.3 0.0 2017-12-23 53 35 44.0 10.5 0.0 2017-12-24 43 35 39.0 5.8 T 2017-12-25 40 28 34.0 1.0 T 2017-12-26 29 20 24.5 -8.3 0.0 2017-12-27 25 18 21.5 -11.1 0.0 2017-12-28 18 11 14.5 -17.8 0.0 2017-12-29 22 11 16.5 -15.7 0.0 2017-12-30 22 12 17.0 -15.0 1.3 2017-12-31 19 9 14.0 -17.8 0.0 2018-01-01 17 6 11.5 -20.1 0.0 2018-01-02 25 10 17.5 -14.0 0.0 2018-01-03 28 10 19.0 -12.3 0.0 2018-01-04 30 21 25.5 -5.7 16.0 2018-01-05 21 10 15.5 -15.6 0.0 2018-01-06 12 6 9.0 -22.0 0.0 2018-01-07 19 2 10.5 -20.3 0.0 2018-01-08 35 18 26.5 -4.3 T

December has featured a temperature departure rebound from November during the 2010s. There have been only 2 colder than normal Decembers since 2010. Both 2010 and 2017 were La Ninas. The only year with a cold November and December was 2017. Numerous stations out West had their coldest October on record this year. This type of early cold pattern is a change for this decade. The cold is now spreading east for November. So it will be interesting to see if this can disrupt the default milder December pattern of this decade. 2010’s December temperature departures .............EWR....NYC....LGA 2018....+2.9....+2.6....+2.3 2017....-1.9......-2.5.....-2.0 2016....+1.2....+0.8....+2.1 2015...+13.3..+13.3...+12.6 2014....+3.6....+3.0....+2.4 2013...+0.4....+1.0......0.0 2012...+4.6....+4.0....+4.5 2011...+6.0....+5.8.....+5.1 2010...-3.6......-4.7......-3.2

Difficult to go against the 2010s warm October followed by cold November pattern.

The research points to an interaction between the reduced Arctic sea ice around the Chukchi and lower latitude forcing. This has been a common November pattern this decade. https://www.nature.com/articles/s41598-019-41682-4 Conclusion We showed that a warm hole over the Pacific sector was responsible for the cold 2017–18 winter in the mid-latitudes, in addition to the effect of the semi-permanent ice retreat in the Barents Sea. The warm hole symbolizes the historically largest ice-free ocean in the Bering and Chukchi Seas because the shape of the ice-free ocean appears as a hole with overlying warm air. Analyses focusing on the area of the Pacific sector also showed that there was a positive feedback mechanism between the warm hole, underlying ocean, and overlying atmosphere. This feedback process made the Arctic upper air warm, which caused the jet stream to push northward. Furthermore, we showed that the coincidence of the two events – pre-existing warm holes in late autumn and the occurrence of the sporadic strong and moist northward wind events that are strong enough to move thin ice, such as an atmospheric river, – could initiate and develop the positive feedback system. In addition, the poleward penetration of atmospheric rivers can induce sea ice melt or prevent its formation through enhanced downwelling longwave radiation. The positive feedback between the large ice-free ocean, the atmospheric rivers, and the ocean current actively pushed the jet northward. In reaction to this northward meander, large southward jet stream pathways formed over Asia and America, allowing cold air to spread into Asia and the southern areas of North America. We therefore conclude that the warm hole apparing in the Pacific side of the Arctic is responsible for the anomalous jet meander. The positive feedback system does not operate in isolation within the Arctic. Rather there are contributions from external lower-latitude forcings, such as atmospheric rivers16. Deepening the knowledge of the extra-Arctic processes that control long-term variations of atmospheric rivers is beneficial for long-range winter weather forecasts. Examining the reasons why the warm hole appeared is also beneficial because the sea-ice hole serves as a predictor. The positive feedback could provide Eastern Eurasia and North America with cold winters in the new era of the warm hole. Whether the positive feedback is strong or not must be tested by examining detailed data analyses, together with high-resolution numerical simulations of both the atmosphere and ocean. This study showed an upscale effect, i.e., influence of narrow-width atmospheric rivers upon global-scale jet streams, suggesting that a fine-mesh numerical model that resolves atmospheric rivers is needed to predict the global-scale climate change associated with future global warming.

I am guessing that it’s related to the link between the declining Arctic sea ice and warming Pacific. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL077325

Yeah, the last below normal October and above normal November was back in 2009. The new 2010’s couplet a warm October followed by a cold November. The pattern really stands out when you plot the last 20 years.

Thanks for the link. I wonder if that is the result of the ECMWF relaxing the restrictions on sharing its products?

Pretty wild for ALB and NYC to have their first freeze less than a week apart. This is an extreme version of the warm October followed by a cold November.

This is following our warm October to cold November pattern that has been so persistent since 2013. Even with all the record warmth in the East during October, the CONUS had its 6th coldest October since 1949. Several stations out West had their coldest October on record. The cold and -EPO blocking is finally shifting east for November like we have seen in recent years.

Yeah, we’ll probably have to wait until under 120 hrs for a reliable storm track forecast. But the cold looks impressive either way. The Euro and GFS have early season 20’s for NYC behind the low. It would be another case of repeating weather patterns. This happened 2 years ago around the same dates. NYC record lows 11/9 24 in 1976 28 in 1971 29 in 2003+ 11/10 25 in 2017 27 in 1914 29 in 2004+ 11/11 24 in 2017 28 in 1933 28 in 1926+

Similar to the findings in this recent paper. https://advances.sciencemag.org/content/4/8/eaat6773 DISCUSSION Implications and outlook The doubling of BG halocline heat content over the past three decades appears attributable to a warming of the source waters that ventilate the layer, where this warming is due to sea ice losses in the Chukchi Sea that leave the surface ocean more exposed to incoming solar radiation in summer. The effects of an efficient local ice-albedo feedback are thus not confined to the surface ocean/sea ice heat budget but, in addition, lead to increased heat accumulation in the ocean interior that has consequences far beyond the summer season. Strong stratification and weak mechanical mixing in the BG halocline ensure that significant summertime heat remains in the halocline through the winter. With continued sea ice losses in the Chukchi Sea, additional heat may continue to be archived in the warm halocline. This underscores the far-reaching implications of changes to the dynamical ice-ocean system in the Chukchi Sea region. However, there is a limit to this: Once the source waters for the halocline become warm enough that their buoyancy is affected, ventilation can be shut off. Efficient summertime subduction relies on the lateral surface front in the NCS region between warm, salty water that is denser to the south and cooler, fresher water that is less dense to the north. For longer-duration solar warming (that is, longer-duration ice-free conditions in the region), SSTs on the south side of the front may become warm enough (around 13°C, under the assumption of a 1.5-month ice-free period dominated by solar absorption) that the lateral density gradient is eliminated [see (24)]. It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics of the Arctic halocline. In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

It would be something if portions of the region see another early season snow event next week. We probably need to get this under 120 hrs to know for sure. But the air mass behind the low will be the coldest of the season so far.

Those are gorgeous parts of the country. The Corral Bluff fossil finds highlighted on Nova this week was pretty amazing. https://www.pbs.org/video/rise-of-the-mammals-zuzg8t/

You have to really enjoy heat and humidity to live year round in Florida. But it’s nice for vacations during the cooler parts of the year.

I personally like the new hardier crape myrtles that have really taken off around here. While the palms are ok, they tend to stand out a bit when they are around our native plants. But I draw the line a bamboo. Some people plant that all over their property in Long Beach. It grows sideways underground and runs right into the side of your house. It was the most difficult plant removal that I ever encountered. https://hicksnurseries.com/uncategorized/can-i-grow-crape-myrtle-on-long-island/

They probably didn’t bother to wrap them like this company does.

Updated for the 9th warmest October at EWR and 7th warmest at ISP.

October finished with 10 out of 10 above normal temperature departure months for the 2010s. Oct.......EWR...NYC...LGA 2019..+3.8...+3.0 ...+2.8 2018...+0.8...+0.8...+1.7 2017...+7.2...+7.2...+7.4 2016...+2.3...+1.9....+3.1 2015...+0.6...+1.1....+0.3 2014...+2.7...+2.7....+2.2 2013...+3.0....+3.3...+2.8 2012...+2.2....+1.1....+1.9 2011...+1.5...+0.2.....+0.2 2010...+1.7...+1.2....+2.1

According to the NSIDC data, October 2019 beat 2012 for the lowest monthly average extent. This makes the 3rd new lowest monthly extent record for 2019. It’s also the 10th new lowest monthly extent since 2016. ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Monthly_Data_with_Statistics_G02135_v3.0.xlsx 1 2019 5.66 2 2012 5.89 NSIDC lowest average monthly extents Jan...2018 Feb...2018 Mar...2017 Apr....2019 May...2016 Jun....2016 Jul.....2019 Aug...2012 Sep...2012 Oct...2019 Nov...2016 Dec...2016