This April merely tied April 2016 for the lowest extent on record, but it’s hardly reason to celebrate. The Arctic was missing 394,000 square miles of ice, with each day setting a record low or within 36,000 square miles of setting one…
….One of the biggest issues for sea ice is its increasingly youthful appearance. Young ice is more susceptible to the vagaries of weather, whether it be warm air or water or storms that knock it around and break it up.
Ice older than five years in age now only comprises 5 percent of the Arctic’s ice pack. It accounted for 30 percent of all Arctic sea ice in 1984, but relentless warmth driven by rising carbon dioxide in the atmosphere has slowly squeezed it out of existence….
Arctic sea ice extent has trended in record low territory for months.Credit: Zack Labe
In the past, scientists typically avoided linking individual weather events to climate change, citing the challenges of teasing apart human influence from the natural variability of the weather. But that is changing.
…In a new study, published in this week’s issue of Proceedings of the National Academy of Sciences, Diffenbaugh and a group of current and former Stanford colleagues outline a four-step “framework” for testing whether global warming has contributed to record-setting weather events. The new paper is the latest in a burgeoning field of climate science called “extreme event attribution,” which combines statistical analyses of climate observations with increasingly powerful computer models to study the influence of climate change on individual extreme weather
….”Our results suggest that the world isn’t quite at the point where every record hot event has a detectable human fingerprint, but we are getting close,” Diffenbaugh said. For the driest and wettest events, the authors found that human influence on the atmosphere has increased the odds across approximately half of the area that has reliable observations.
….One high-profile test case was Arctic sea ice, which has declined by around 40 percent during the summer season over the past three decades. When the team members applied their framework to the record-low Arctic sea ice cover observed in September 2012, they found overwhelming statistical evidence that global warming contributed to the severity and probability of the 2012 sea ice measurements. “The trend in the Arctic has been really steep, and our results show that it would have been extremely unlikely to achieve the record-low sea ice extent without global warming,” Diffenbaugh said.
Noah S. Diffenbaugh, Deepti Singh, Justin S. Mankin, Daniel E. Horton, Daniel L. Swain, Danielle Touma, Allison Charland, Yunjie Liu, Matz Haugen, Michael Tsiang, Bala Rajaratnam. Quantifying the influence of global warming on unprecedented extreme climate events. Proceedings of the National Academy of Sciences, 2017; 201618082 DOI: 10.1073/pnas.1618082114
The Arctic sea ice maximum extent and Antarctic minimum extent are both record lows this year. Combined, sea ice numbers are at their lowest point since satellites began to continuously measure sea ice in 1979.…”There’s a lot of year-to-year variability in both Arctic and Antarctic sea ice, but overall, until last year, the trends in the Antarctic for every single month were toward more sea ice,” said Claire Parkinson, a senior sea ice researcher at Goddard. “Last year was stunningly different, with prominent sea ice decreases in the Antarctic. To think that now the Antarctic sea ice extent is actually reaching a record minimum, that’s definitely of interest
Arctic sea ice hit a record low wintertime maximum extent in 2017. At 5.57 million square miles, it is the lowest maximum extent in the satellite record, and 455,600 square miles below the 1981 to 2010 average maximum extent.
Credit: NASA Goddard’s Scientific Visualization Studio/L. Perkins
The year 2016 made history, with a record global temperature, exceptionally low sea ice, and unabated sea level rise and ocean heat, according to the World Meteorological Organization (WMO). Extreme weather and climate conditions have continued into 2017.
WMO issued its annual statement on the State of the Global Climate ahead of World Meteorological Day on 23 March. It is based on multiple international datasets maintained independently by global climate analysis centres and information submitted by dozens of WMO Members National Meteorological and Hydrological Services and Research Institutes and is an authoritative source of reference. Because the social and economic impacts of climate change have become so important, WMO partnered with other United Nations organizations for the first time this year to include information on these impacts. WMO also prepared an interactive story map to highlight some of the main trends and events in 2016.
“This report confirms that the year 2016 was the warmest on record – a remarkable 1.1 °C above the pre-industrial period, which is 0.06 °C above the previous record set in 2015. This increase in global temperature is consistent with other changes occurring in the climate system,” said WMO Secretary-General Petteri Taalas….
Arctic sea ice is one of the grandaddy’s of climate indicators. …. This year’s sea ice extent has bottomed out as the second lowest on record, according to the National Snow and Ice Data Center. It continues a troubling trend as rapidly warming air and water eats away at the briny, frozen mantle on the top of the planet…. This year has been exceptional by many standards. March saw the lowest sea ice maximum ever recorded followed by a string of record low months. The Northwest Passage opened up, allowing a luxury cruise ship to travel from Anchorage to New York. And a freak storm in August turned ice thin and brittle near the North Pole. Satellites show the last seven months of sea ice and reveal its steep decline this year. The late August breakup is particularly notable.
… All 10 of the smallest sea ice extents on record have occurred since 2005. In the nearly four decades of satellite monitoring, sea ice has disappeared at a clip of 13.4 percent per decade. This year’s cracked ice also continues a troubling trend of disappearing old ice. Though some of that ice will refreeze together this winter, some has disappeared for good and new ice will be left to fill in the gaps. That’s like putting a piece of paper over a hole in your wall, though. Young ice tends to be weaker and thinner and thus more susceptible to summer melt. It’s a trend that’s already happening. Ice younger than four years comprised 97 percent of all Arctic sea ice in 2015 compared to 80 percent in 1985….
The Arctic’s ice cover appears to have reached its minimum extent on September 10, 2016, according to scientists. Arctic sea ice extent on that day stood at 4.14 million square kilometers (1.60 million square miles), statistically tied at second lowest in the satellite record with the 2007 minimum.
Posted on 22 August 2016 by dana1981 skepticalscience.com
Walsh, J. E., Fetterer, F., Stewart, J. S. and Chapman, W. L. (2016) A database for depicting Arctic sea ice variations back to 1850. Geographical Review, doi:10.1111/j.1931-0846.2016.12195.x
Scientists have pieced together historical records to reconstruct Arctic sea ice extent over the past 125 years. The results are shown in the figure below. The red line, showing the extent at the end of the summer melt season, is the most critical:
….Most fundamentally of all, the new dataset allows us to answer the three questions we posed at the beginning of this article.
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.