donsutherland1

Utqiagvik (formerly Barrow) has seen a dramatic increase in the number of days each year where the temperature stays above freezing. Much of the increase has come recently, as summer Arctic sea ice has declined markedly from prior levels. The change in the 30-year moving averages (to remove the noise of interannual variability) for the number of such days provides further illustration of the dramatic warming that is underway in the Arctic region. For the 1961-90 base period, the 30-year moving average was 43.9 days. For the latest 30-year period (1989-2018), the moving average has increased to 63.4 days. That's a nearly 20-day increase over a remarkably short period of time. Through September 3, Utqiagvik has had 76 days with temperatures above freezing. The last time Utqiagvik had fewer than 50 days above freezing was 2003. In 2007, the minimum Arctic sea ice extent fell below 5 million square kilometers for the first time (JAXA data set). Since then, only 2009 has had a minimum extent of 5 million square kilometers (5.054 million square kilometers). As of September 3, Arctic sea ice extent was 4.175 million square kilometers. During the "low ice" era that commenced in 2007, Utquiavik has averaged 76.8 days per year (2007-18) with above freezing temperatures. Through September 3, Utqiagvik had a record 70 consecutive days where the temperature has stayed above freezing. The old record was 68 consecutive days from July 1-September 6, 2009. Prior to 2009, there were no cases with 60 or more consecutive days above freezing.

I included a chart for AO-/EPO- summers (averages are based on all days that met both criteria). That historically warm pattern has also grown warmer.

Let me rephrase things a little. The pattern was not forecast to be especially unfavorable to ice reduction. The forecast showed fluctuations in the NAM, not a persistent anomaly. One would have needed a fairly extraordinary development to lead to an unprecedented early end to melt season. The MAN had been forecast to slide back toward neutral during the first week of September. All other things being equal, that suggested reductions in Arctic sea ice would continue probably for another week and perhaps two.

As you noted correctly, had there been an August minimum, it would have been unprecedented. Since 8/31, Arctic sea ice extent has continued to decline. That a piece of guidance would suggest an unprecedented situation, moreso when the upper air pattern had been forecast to grow more favorable for continued reductions in sea ice, raises some questions about the model itself. I'm not sure what the track record of the model in question is, but this is a high profile miss. Overall, forecasting of sea ice minimums remains a fairly low skill endeavor at present.

With Hurricane Dorian's historic intensification, it is a good time to point to an article in the American Meteorological Society's Journal of Climate from last fall. The article noted that one can expect more intense storms on account of climate change. Abstract: As one of the first global coupled climate models to simulate and predict category 4 and 5 (Saffir–Simpson scale) tropical cyclones (TCs) and their interannual variations, the High-Resolution Forecast-Oriented Low Ocean Resolution (HiFLOR) model at the Geophysical Fluid Dynamics Laboratory (GFDL) represents a novel source of insight on how the entire TC intensification distribution could be transformed because of climate change. In this study, three 70-yr HiFLOR experiments are performed to identify the effects of climate change on TC intensity and intensification. For each of the experiments, sea surface temperature (SST) is nudged to different climatological targets and atmospheric radiative forcing is specified, allowing us to explore the sensitivity of TCs to these conditions. First, a control experiment, which uses prescribed climatological ocean and radiative forcing based on observations during the years 1986–2005, is compared to two observational records and evaluated for its ability to capture the mean TC behavior during these years. The simulated intensification distributions as well as the percentage of TCs that become major hurricanes show similarities with observations. The control experiment is then compared to two twenty-first-century experiments, in which the climatological SSTs from the control experiment are perturbed by multimodel projected SST anomalies and atmospheric radiative forcing from either 2016–35 or 2081–2100 (RCP4.5 scenario). The frequency, intensity, and intensification distribution of TCs all shift to higher values as the twenty-first century progresses. HiFLOR’s unique response to climate change and fidelity in simulating the present climate lays the groundwork for future studies involving models of this type. The article also covers the likely increase in the most extreme tropical cyclones: The increased probability of higher-intensity TCs becomes more tangible when focusing on the number of TCs that exceed 165 kt in each simulation, which is the fastest wind speed ever recorded during a TC landfall (Typhoon Haiyan; Takagi and Esteban 2016). In the 70-yr HiFLOR CTL experiment, nine TCs achieve awind speed of greater than 165 kt. The number of TCs that exceed this threshold grows to 32 for the 2016–35 simulation and 72 for the 2081–2100 simulation. https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0898.1

On August 31, Arctic sea ice extent was 4,259,262 square kilometers on JAXA. Based on sensitivity analysis, the following are implied probabilities for various minimum extent figures: 4.25 million square kilometers or below: 99% 4.00 million square kilometers or below: 59% 3.75 million square kilometers or below: 0.6% 75th percentile: 4.041 million square kilometers 25th percentile: 3.916 million square kilometers Minimum extent figures based on historic 2010-2018 data: Mean decline: 3.979 million square kilometers Median decline: 4.016 million square kilometers Minimum decline: 4.078 million square kilometers Maximum decline: 3.757 million square kilometers Summary: After a pause likely due to storminess over the Polar region, Arctic sea ice extent has again begun to decline. Arctic sea ice extent will likely decline with some momentary increases over the next 1-2 weeks. A minimum extent figure below 4.000 million square kilometers still remains possible, but the probability of that outcome has declined markedly over the past week.

Notes: This post was prepared in scientific style to provide links to key points in the section on climate change. All temperature data is from the National Climatic Data Center. The EPO data is through August 29. OVERVIEW Prior to 2019, July 2016 was Anchorage, Alaska's warmest month on record. Summer 2019 was even warmer than July 2016. A warm synoptic pattern that occurred within the context of increased anthropogenic greenhouse gas forcing resulted in exceptional and persistent record-breaking warmth this summer. During June-August 2019, Anchorage experienced its warmest summer on record by 2.0°F (1.1°C). Its summer mean temperature (62.815°F/17.119°C) exceeded that of its warmest month on record prior to 2019 (62.694°F/17.052°C in July 2016). Summer 2019 saw Anchorage record its warmest-ever June, July, and August. Anchorage tied its all-time record high minimum temperature on two consecutive days. Anchorage reached 90°F (32.2°C) for the first time on record. The duration of the excessive warmth and extreme temperatures recorded during the summer would have been very unlikely, if not improbable, without human-induced climate change. PREDOMINANT SYNOPTIC PATTERN Summer 2019 featured a remarkable coupling of atmosphere and ocean. A persistent upper air ridge that promoted warm and dry conditions was anchored over the waters with the highest sea surface temperature anomalies. These conditions promoted a synoptic pattern where the East Pacific Oscillation (EPO) was negative. The negative EPO combined with a negative Arctic Oscillation (AO) to form a negative Arctic Oscillation-negative EPO pattern (AO-/EPO-) that predominated during the summer. During summer 2019, the AO was negative on 81/92 (88%) days. The EPO was negative on 64% of days. An AO-/EPO- pattern is typically a warm one in Anchorage. For the current climate reference period (1981-2010), the average summer temperature in Anchorage was 56.9°F (13.8°C). During AO-/EPO- patterns, the average was 57.6°F (14.2°C). Climate change has led to summers becoming warmer and also warm synoptic patterns (AO-/EPO-) becoming warmer. ROLE OF CLIMATE CHANGE The observed global warming since the 1950s is unequivocal with anthropogenic greenhouse gas emissions being the dominant driver of that warming (IPCC Climate Change Synthesis Report 2014). The warming is a global phenomenon with 98% of the world having experienced its warmest 51 years during the current 2,000 years (Neukom, et al. 2019). Since 1880, Arctic temperatures have been increasing at more than twice the rate of global temperatures (GISTEMP Data Set). In recent decades, the rate at which the Arctic has been warming relative to worldwide temperatures has increased. From 1980 through 2018, the Arctic has warmed at a decadal rate of 1.51°F (0.84°C), which is just over 3.5 times the global rate (GISTEMP Data Set). Multiple lines of evidence corroborate the rapid warming that is taking place in the Arctic. Increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage; warming of near-surface permafrost; and, decreases in sea ice thickness and extent, and spring snow cover extent and duration are consistent with rising temperatures (Box, et al. 2019). Consistent with the Arctic warming, Alaska has recently experienced temperatures that are warmer than they have been at any time in the past century (Thoman et al., 2019). As Alaska has warmed, Anchorage has also experienced rising temperatures. A disproportionate share of Anchorage's warmest months has occurred in 2000 or later. During the 1961-1990 base period, Anchorage had a summer (June 1-August 31) mean temperature of 56.4°F (13.6°C). During the current climate reference period (1981-2010), Anchorage's average summer temperature had risen to 56.9°F (13.8°C). For the most recent 30-year period (1989-2018), Anchorage's average summer temperature had increased further to 57.6°F (14.2°C). The last time Anchorage had a cooler than normal summer (mean temperature below the 1981-2010 reference period) was 2012 when the average summer temperature was 56.0°F (13.3°C). Without climate change, the extreme summer 2019 warmth would have been improbable. However, the combination of a rising average summer temperature and increasing variability (1961-1990: mean temperature 56.4°F/13.6°C; standard deviation: 1.4°F/0.8°C vs. 1989-2018: mean temperature: 57.6°F/14.2°C; standard deviation: 1.6°F/0.9°C) has made summers like 2019 approximately 190 times more likely than they had been. The long duration of the AO-/EPO- synoptic pattern led to the relentless persistence of above to much above normal temperatures in Anchorage that allowed monthly warm temperature records to be set in June, July, and August. Rapid Arctic warming has contributed to an increasing frequency of long-duration upper air patterns (Francis, et al. 2018). Should the world warm 3.6°F (2.0°C) above its pre-industrial temperatures, the persistence of boreal summer weather will likely increase further (Pfleiderer, et al. 2019). Based on the above evidence, human-driven climate change played a key role in bringing about Anchorage's historic summer warmth. Without anthropogenic warming, the combination of the exceptional heat and remarkable duration of the warmth in Anchorage would have been very unlikely, if not improbable. DATA AND RECORDS Summer 2019 Temperature Thresholds: Lows 60°F (15.6°C) or above: 9 days (previous summer and annual record: 4, 2016) Highs 70°F (21.1°C) or above: 49 days (previous summer record: 40, 2004; previous annual record: 42, 2013) Highs: 80°F (26.7°C) or above: 8 days (previous summer and annual record: 4 days, 2015) Highs: 90°F (32.2°C) or above: 1 day (none prior to 2019) Daily Record High Minimum Temperatures: June 8: 54°F (12.2°C) (old record: 53°F/11.7°C, 1978) June 24: 58°F (14.4°C) (tied record set in 1984) June 28: 57°F (13.9°C) (old record: 56°F/13.3°C, 2015 and 2016) June 29: 60°F (15.6°C (old record: 58°F/14.4°C, 1984 and 1990) June: 3 new records and 1 tied record July 2: 57°F (13.9°C) (tied record set in 1970) July 3: 58°F (14.4°C (tied record set in 1979 and tied in 1999 and 2014) July 5: 61°F (16.1°C) (old record: 60°F/15.6°C, 1984) July 6: 59°F (15.0°C) (tied record set in 2015) July 8: 61°F (16.1°C) (old record: 59°F/15.0°C, 1968, 2003, and 2004) July 9: 62°F (16.7°C) (old record: 59°F/15.0°C, 2003) July 12: 60°F (15.6°C) (old record: 59°F/15.0°C, 1977) July 13: 59°F (15.0°C) (tied record set in 1972 and tied in 2013) July 20: 59°F (15.0°C) (old record: 58°F/14.4°C, 1973, 1983, 2003, 2004, and 2016) July 22: 58°F (14.4°C) (tied record set in 1984 and tied in 1996, 2013, and 2016) July 24: 59°F (15.0°C) (tied record set in 1984) July: 5 new records and 6 tied records August 7: 61°F (16.1°C) (old record: 58°F/14.4°C, 1979 and 1983) August 13: 63°F (17.2°C) (old record: 57°F/13.9°C, 2003) ***tied all-time record*** August 14: 63°F (17.2°C) (old record: 58°F/14.4°C), 2001) ***tied all-time record*** August 16: 58°F (14.4°C) (tied record set in 1967) August 17: 57°F (13.9°C) (old record: 56°F/13.3°C, 1984) August: 4 new records and 1 tied record Summer: 12 new records and 8 tied records Daily Record High Maximum Temperatures: June 23: 78°F (25.6°C) (old record: 75°F/23.9°C, 1974) June 24: 75°F (23.9°C (old record: 74°F/23.3°C, 2015) June 27: 79°F (26.1°C) (old record: 78°F/25.6°C, 1997) June 28: 81°F (27.2°C) (old record: 80°F/26.7°C, 1997) June 29: 82°F (27.8°C) (old record: 77°F/25.0°C 1968, 1989, and 1990) June: 5 new records July 3: 80°F (26.7°C) (tied record set in 2018) July 4: 90°F (32.2°C) (old record: 77°F/25.0°C), 1999) ***all-time record*** July 5: 81°F (27.2°C) (old record: 77°F/25.0°C, 1999) July 6: 81°F (27.2°C) (tied record set in 2015) July 7: 85°F (29.4°C) (old record: 79°F/26.1°C, 2009) July 8: 85°F (29.4°C) (old record: 84°/28.9°C, 2003) July: 4 new records and 2 tied records August 7: 77°F (25.0°C) (tied record set in 2015) August 10: 77°F (25.0°C) (old record: 75°F/23.9°C, 1960, 1972, and 2004) August 12: 77°F (25.0°C) (tied record set in 2005) August 13: 77°F (25.0°C) (old record: 75°F/23.9°C, 1963, 1977, 2007) August 14: 75°F (23.9°C) (old record: 74°F/23.3°C, 1990) August 15: 77°F (25.0°C) (old record: 76°F/24.4°C, 1984) August: 4 new records and 2 tied records Summer: 13 new records and 4 tied records CONCLUSION Anchorage experienced a historically warm summer. The all-time record high temperature was established, the all-time record warm minimum temperature was tied on two consecutive days, and numerous daily record high maximum and minimum temperatures were set or tied. June 2019 was the warmest June on record. July 2019 was the warmest July and month on record. August 2019 was the warmest August on record. Ocean-atmosphere coupling produced a persistent pattern associated with warmer than normal temperatures. Anthropogenic climate change, that has driven global and Arctic warming and led to increasing temperature variability in the Arctic region, has dramatically increased the probability of persistent warmth and extreme high temperatures. Absent the contribution of climate change, the kind of warmth seen during summer 2019 was extremely unlikely, if not improbable. Going forward, the ongoing warming is likely to continue on account of a continuing rise in the atmospheric concentration of greenhouse gases. Although summer warmth equivalent to 2019 will likely remain rare over the next decade or two, the probability of such occurrences will very likely increase.

Early this morning, Joe Bastardi retweeted a twitter post noting that Moscow had an unusually cold summer and wrote, "yet not a peep from the warming weather media." The reason the warmth, not Moscow's cold, received widespread news coverage is or should be largely self-evident: 1. This summer, warmth, not cold, was the big global story 2. Cold areas were relatively localized, but areas of warmth were widespread 3. Historic heat waves affected Europe (two of which shattered widespread all-time high temperature records, including national high temperature records) 4. Alaska experienced its warmest month on record and Anchorage's summer will likely match its warmest month on record prior to 2019 On August 1, the World Meteorological Organization (WMO) reported: Exceptional heat has been observed across the globe in recent week, with a string of European countries logging record highs temperatures that have caused disruption to transport and infrastructure and stress on people's health and the environment. As the heat dome spread northwards through Scandinavia and towards Greenland, it accelerated the already above average rate of ice melt. "July has re-written climate history, with dozens of new temperature records at local, national and global level," said WMO Secretary-General Petteri Taalas. "The extraordinary heat was accompanied by dramatic ice melt in Greenland, in the Arctic and on European glaciers. Unprecedented wildfires raged in the Arctic for the second consecutive month, devastating once pristine forests which used to absorb carbon dioxide and instead turning them into fiery sources of greenhouse gases. This is not science fiction. It is the reality of climate change. It is happening now and it will worsen in the future without urgent climate action," Mr Taalas said. "WMO expects that 2019 will be in the five top warmest years on record, and that 2015-2019 will be the warmest of any equivalent five-year period on record. . https://public.wmo.int/en/media/news/july-matched-and-maybe-broke-record-hottest-month-analysis-began Below are the global Temperature Anomalies (June 1-August 27, 2019): Below are the GISS temperature anomalies and rank: June: +0.92°C (1st warmest June) July: +0.93°C (1st warmest July and also 1st warmest month) August: To be available by mid-September　 In sum, in the big picture, excessive and persistent warmth was the major story of summer 2019. Widespread monthly and all-time high temperature records were set. Localized areas of cold existed, but they were the exception this summer. Only few monthly record low temperature records were set. The coverage properly focused on the major weather story of this summer, the widespread and, in places, historic warmth.

The ugly side of the climate change denial movement... Excerpts from Scientific American: The verbal and written attacks derive mostly from men. That’s probably not a coincidence. Studies show that climate skepticism is a male-dominated perspective. Men are less likely than women to accept scientific conclusions about people being responsible for rising temperatures. And they’re more likely to overestimate their knowledge of the issue... “I do see a shift toward a lack of substance sharing,” Cobb said. “So much of the flak from the climate-denial community, I think, was in the form of trying to share graphs to show their point, trying to question you on the validity of the science. And a lot of that was very misguided, of course, but it was still pretending to be substantive, on the data, on the issues themselves. But it seems much of it today has turned completely to ad hominem attacks, these stream of emotionally laden insults with no substance whatsoever behind them, just trying to land one below the belt.” ...“I can tell you that there is a very large overlap between those who harbor conspiracy theories about climate science and those who express unenlightened views when it comes to matters of ethnicity and gender,” Mann said. “In short, yeah—a surprisingly large number of climate deniers are misogynists. And so our female colleagues are at the receiving end of a particularly toxic brew of denialism, conspiratorial ideation and misogyny. It is most unfortunate and most disturbing.” https://www.scientificamerican.com/article/as-climate-scientists-speak-out-sexist-attacks-are-on-the-rise/

The JAXA data suggests otherwise. 1990-2007: Mean Melt: 8.897 million square kilometers (59.4% of mean maximum) 2008-2018: Mean Melt: 9.916 million square kilometers (69.2% of mean maximum)

The science doesn't suggest that in 12 years we will "die." That's a caricature of what the science is actually suggesting: time is somewhat limited if the world is to achieve its 1.5°C goal.

If one is referring to the AOC plan, I strongly oppose it. It contains substantial extraneous provisions that have nothing to do with climate/clean energy. Instead, those provisions would dramatically shift the U.S. away from a market-oriented economy. There are far better ways to approach the issue.

The points the guide is making are: 1. Carbon dioxide has a long residency in the atmosphere. 2. Anthropogenic greenhouse gas emissions have been the dominant influence for recent warming. The IPCC explained: Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century. As the guide is intended for young audiences, it greatly simplifies the conclusions. Concepts such as probability and atmospheric residency are for older students. This is introductory material aimed at providing the big picture. It was vetted by climate scientists and the IPCC.

On August 23, Arctic sea ice extent was 4,412,266 square kilometers on JAXA. Based on sensitivity analysis, the following are implied probabilities for various minimum extent figures: 4.25 million square kilometers or below: 99% 4.00 million square kilometers or below: 86% 3.75 million square kilometers or below: 45% 3.50 million square kilometers or below: 9% 75th percentile: 3.918 million square kilometers 25th percentile: 3.635 million square kilometers Minimum extent figures based on historic 2010-2018 data: Mean decline: 3.776 million square kilometers Median decline: 3.788 million square kilometers Minimum decline: 3.941 million square kilometers Maximum decline: 3.618 million square kilometers Summary: Through August 23, Arctic sea ice extent remains firmly on a path that will very likely result in the second lowest minimum extent figure on record and the second such figure below 4.0 million square kilometers.

Earlier this year, France's Office for Climate Education prepared a guide for teachers on climate science. The guide was written in multiple languages and it was also publicized by the World Meteorological Organization. It would make a useful addition to any early STEM class that covers earth science. Among other things, the guide explains the ongoing warming, climate change impacts at 1.5°C and 2.0°C, potential approaches for achieving the Paris Agreement's target of limiting warming to 1.5°C above the pre-industrial temperature average, and addressing climate change within the context of sustainable development. The guide introduces educators and students to credible resources. For example, one task involves looking up the definition of "climate" on the World Meteorological Organization's website. It also provides a link by which users can visit the relevant portion of the IPCC's 2013 assessment. The report is consistent with the climate science consensus. Among other things, its summary explains: Human activities have caused a 1.0°C rise in the global temperature over the past 150 years. Global warming is likely to reach 1.5°C between 2030 and 2052, if warming continues at the current rate. Our CO2 emissions will remain in the atmosphere for centuries to millennia, maintaining the warmer temperatures long after these emissions were released. The English version of that guide can be found at: http://www.oce.global/sites/default/files/2019-04/ST1.5_final_040419.pdf Under a creative commons license, it can be freely shared, used, and adapted for non-commercial use.

Redundancy doesn't have to cover the whole system. Only a sufficient share of excess power capacity from alternative approaches needs to be available during the transition to cover issues that may arise. Complete failure of the entire system is not a likely scenario. Partial failure is. China is aggressively pursuing solar power and making rapid progress in terms of production cost effectiveness. Nuclear power is another alternative.

I agree. I suspect that such technology isn’t too far in the future (probably a decade or less away).

Multiple steps are required. Bringing about cost parity and later cost superiority (lower costs) is one part of the larger problem. Expansion of the application, including but not limited to issues related to storage is another. Redundancy will still be needed for the foreseeable future, even if solar power ultimately becomes the primary source of electricity.

On August 20, Arctic sea ice extent was 4,507,767 square kilometers on JAXA. Only 2007 (4,877,731 square kilometers), 2012 (4,143,648 square kilometers) and 2016 (4,922,931 square kilometers) had figures below 5 million square kilometers by August 20. Based on sensitivity analysis, the following are implied probabilities for various minimum extent figures: 4.50 million square kilometers or below: 99.9% 4.25 million square kilometers or below: 98% 4.00 million square kilometers or below: 86% 3.75 million square kilometers or below: 55% 3.50 million square kilometers or below: 20% 75th percentile: 3.895 million square kilometers 25th percentile: 3.543 million square kilometers Minimum extent figures based on historic 2010-2018 data: Mean decline: 3.719 million square kilometers Median decline: 3.711 million square kilometers Minimum decline: 3.922 million square kilometers Maximum decline: 3.542 million square kilometers Summary: Through August 21, Arctic sea ice extent remains firmly on a path that will very likely result in the second lowest minimum extent figure on record and the second such figure below 4.0 million square kilometers.

New research has revealed that solar power has reached grid parity in China’s cities. Such an outcome in which new technologies become cost effective with scale and experience has been the norm with major technologies that move from the introductory to the growth phase. The abstract is below: We reveal that all of these cities can achieve—without subsidies—solar PV electricity prices lower than grid-supplied prices, and around 22% of the cities’ solar generation electricity prices can compete with desulfurized coal benchmark electricity prices. https://www.nature.com/articles/s41560-019-0441-z

It's not an "attack" on person. It's an attack on deeply flawed article that has little to do with science. Noting that Watts does not have a background in climate science and is not an expert in the area of glaciers are both facts. Indeed, if one wants further details, there's question as to whether he, in fact, completed his college studies. http://sourcewatch.org/images/4/4d/Anthony_Watts.pdf That wasn't the point. Thus, the issue about his not possessing expertise in climate science and glaciers was noted. Nothing was mentioned about the above controversy. The major focus was on the flawed article he had written. Iceland is a volcanically active region, but not every volcano is active. The OK Volcano last erupted during the Pleistocene Epoch and may well be extinct. If it is extinct, there's no heat. Watts also posted the NSIDC quote. Nowhere does the quote issue any ranking concerning temperature, much less the claim of "temperature coming in last" as factors related to the retreat of glaciers. Were the Watts framework accepted, OK's retreat would be a relatively rare case due to unique circumstances (location atop a volcano, setting aside that the volcano is dormant and possibly extinct). Instead, as the paper to which I provided a hyperlink (which is one from among numerous studies related to global glacier trends), OK's retreat is part of a broader global trend where glaciers across the world are generally in retreat, even as many of those glaciers are not located atop volcanoes. Why is this the case? If not volcanoes, what factor do they have in common? The global data make the common factor unmistakably clear: temperatures are rising. Multiple high-quality datasets (HadCrut, GISS, NCDC, Berkeley, Copernicus) all show this trend. Further, 98% of the globe has experienced the warmest 50 years on record (Common Era). https://www.nature.com/articles/s41586-019-1401-2.epdf Instead, Watts discounted the importance of temperature (something NSIDC had not done). At the same time, he omitted any mention of the Arctic temperature record. That's a material omission. Further, Iceland is expected to continue its ongoing robust warming trend, which has contributed to OK's retreat. https://en.vedur.is/media/vedurstofan-utgafa-2017/VI_2017_009.pdf

The Greenland Ice Sheet holds 7.2 m of sea level equivalent and in recent decades, rising temperatures have led to accelerated mass loss. Current ice margin recession is led by the retreat of outlet glaciers, large rivers of ice ending in narrow fjords that drain the interior. We pair an outlet glacier–resolving ice sheet model with a comprehensive uncertainty quantification to estimate Greenland’s contribution to sea level over the next millennium. We find that Greenland could contribute 5 to 33 cm to sea level by 2100, with discharge from outlet glaciers contributing 8 to 45% of total mass loss. Our analysis shows that uncertainties in projecting mass loss are dominated by uncertainties in climate scenarios and surface processes, whereas uncertainties in calving and frontal melt play a minor role. We project that Greenland will very likely become ice free within a millennium without substantial reductions in greenhouse gas emissions. https://advances.sciencemag.org/content/5/6/eaav9396

The following is an example of the kind of scientific illiteracy and efforts at disinformation that climate scientists must combat in order to ensure that the public has accurate information concerning climate change. Excerpts from an article by Anthony Watts: The media are abuzz over the first icy “casualty” of climate change: a small glacier in Iceland named Okjökull, also known as “OK.” The claim, made in a press release from Rice University, is that OK became the first glacier in Iceland to lose its glacial status because of global warming... As the U.S. Geological Survey noted, OK is actually an icecap on top of a volcano — located on a volcanically active Iceland. Yes, OK is slowly disappearing, but it is completely disingenuous to say climate change is without any doubt the main reason for OK’s demise. Even if we assume there’s no heat from the volcano, what else could be causing OK’s ice loss? To answer that question, you need to understand how glaciers work. According to the National Snow and Ice Data Center (NSIDC): "A glacier forms when snow accumulates over time, turns to ice, and begins to flow outwards and downwards under the pressure of its own weight[.] … Glacier retreat, melt, and ablation result from increasing temperature, evaporation, and wind scouring. Ablation is a natural and seasonal part of glacier life. As long as snow accumulation equals or is greater than melt and ablation, a glacier will remain in balance or even grow. Once winter snowfall decreases, or summer melt increases, the glacier will begin to retreat." If snow is not added, glaciers don’t grow, and they naturally lose ice due to sublimation, ablation, and melt. I don’t think these people pushing OK’s death fully understand glaciers. The process of ice loss in a high-latitude glacier is mainly due to three things, with temperature coming in last. http://blog.heartland.org/2019/08/the-reports-of-icelands-glacial-death-have-been-greatly-exaggerated/ Now the facts: First, there is no credible evidence to implicate the volcano. Indeed, Mr. Watts claims the volcano may or may not be responsible. The volcano is, in fact, dormant and perhaps extinct. The OK volcano isn't even listed in the modern eruption record, as no known eruptions have occurred for millennia or longer. https://volcano.si.edu/database/search_volcano_results.cfm Second, the NSIDC language Watts quotes notes the role of temperature (underlined), "Glacier retreat, melt, and ablation result from increasing temperature, evaporation, and wind scouring..." Notice the NSIDC language never ranks the role of temperature, even as temperature is the first factor cited. Mr. Watts subjectively injects personal opinion into his piece. Temperature has played a large role. The Arctic has experienced unprecedented warmth during the instrument record and rapid warming over the past 50 years. The data can be found at: https://data.giss.nasa.gov/gistemp/tabledata_v4/ZonAnn.Ts+dSST.txt (64N-90N) Third, the dramatic retreat of the OK glacier is not an isolated event. Worldwide, glaciers have largely been retreating. That broad retreat has been documented in numerous scientific papers. One such paper: https://www.nature.com/articles/ngeo2863 Further, most of those glaciers don't sit atop volcanoes. In sum, Mr. Watts ranked the role of temperature based on a read of the NSIDC's language on glaciers that is inconsistent with the intellectual integrity of that language. He engaged in speculation about a volcano's possible role without looking into the facts about that volcano. In the end, Mr. Watts, who has no background in climate science, much less the study of glaciers, reached an unsupported conclusion that has no foundation in the scientific literature. It is pure opinion spiced with baseless speculation. Its purpose is not to inform, but to mislead.

On August 17, Arctic sea ice extent was 4.635 million square kilometers (JAXA). Arctic sea ice extent remains on track of the second lowest figure on record. If Arctic sea ice extent declines at the 2010-18 mean rate, it would achieve a minimum figure of 3.695 million square kilometers. The median rate would produce a minimum extent of 3.672 square kilometers. Implied probabilities based on sensitivity analysis: 4.000 million square kilometers or below: 84% 3.750 million square kilometers or below: 57% 3.500 million square kilometers or below: 26% Highest 25th percentile: 3.905 million square kilometers Lowest 25th percentile: 3.486 million square kilometers In sum, Arctic sea ice extent will very likely fall below 4.0 million square kilometers for only the second time on record.

Back in late July, both the average statistical decline (2010-18 period) and sensitivity analysis indicated that it was likely that Arctic sea ice extent would fall below 4.000 million square kilometers at its minimum for only the second time on record. Since then, things have remained on track for such an outcome.