WunderBlog Archive » Category 6™
Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Common Thread at 2015 AGU Conference: The Big Melt
The weather story of this month is the record warmth swaddling much of eastern North America and Europe. We’ll have much more to say about that next week, but keeping with the warm theme for today, I’ll share a couple of melt-related tidbits that drew my attention at this year’s Fall Meeting of the American Geophysical Union, which Jeff Masters and I attended this week. This is the world’s largest gathering of Earth-related scientists, with more than 20,000 researchers, journalists, and others in attendance. Thousands of posters and talks cover the whole spectrum of Earth sciences--at any one moment, there can be 50 or more presentations going on. Various science journalists and WunderBlog commentors have done a great job of capturing the broad array of science presented this week. You can browse the enormous number of abstracts at the meeting website. Many of the presentations were recorded and are now available through AGU On Demand (free registration is required). Here's a full list of those recorded sessions. (Thanks for WU member spbloom for the tip.] If the drip-drip-drip of climate change news starts getting to you, there’s a handy remedy: Jeff’s AGU post from Wednesday, “The Top Ten Reasons to be Hopeful on Climate Change”.
Lots of red on the Arctic Report Card
NOAA introduced its 2015 Arctic Report Card with a press conference on Tuesday, viewable in archive form (as are all of the press conferences). The Arctic’s grades were not good. Our northern polar regions are failing--that is, failing to shield themselves from the relentless build-up of greenhouse gases. The polar year running from October 2014 to September 2015 was the warmest in more than a century of recordkeeping, with the region now 3°C (5.4°F) warmer than it was at the start of the 20th century. The minimum summer extent of Arctic sea ice, which occurred on September 11, was not a record--it ranked fourth lowest in the satellite era (starting in 1979). However, the maximum winter extent did set a record low, and that occurred on February 25, two weeks ahead of average and the second earliest max in the satellite era.
One of the lesser-known but still profound changes to the Arctic is the decline in June snow cover, which is decreasing at around 18% per decade. Because the northern sun is at its strongest in June, this decline means that a good deal less sunlight is being reflected from polar regions, thus allowing more absorption of heat at the surface.
Figure 1. Top: Average temperature for October 2014-September 2015 compared to the 1981-2010 average. All around the Arctic, temperatures were much warmer than average, with only Greenland and a small part of northeastern Canada near or below average. Bottom: Annual temperatures for the Arctic (blue line, representing 60°N - 90°N) and the globe (black line) since 1900. Arctic temperatures are more variable from year to year than global temperatures (bigger swings above and below average). But despite the variability, a trend is clear: the Arctic has warmed more than the globe as a whole. Image credit: climate.gov.
Figure 2. Permafrost is thawing across the Arctic, causing northern lands to sink or change shape. In Gates of the Arctic National Park, a bank of this lake thawed in the summer of 2014, allowing the Okokmilaga River to cut through and drain it to sea. Researchers from the University of Alaska Fairbanks and the University of Colorado presented new work at the AGU Fall Meeting on the speeded-up pace of permafrost melt across northern Alaska. Image credit:Howcheng/US National Park Service/Wikimedia Commons.
More than polar bears at risk
Polar bears are the poster creatures of climate change, which makes it easy to overlook how warming temperatures might affect other Arctic creatures. These impacts can be difficult to pin down, because there are complicated intersections between human-driven warming and other anthropogenic factors, such as variations in hunting rates over time and the build-up of oil and gas infrastructure. An increase in rain-on-snow events over the Arctic is already having noteworthy impacts on reindeer, which forage for vegetation beneath snow cover during winter. A record number of reindeer (about 20% of a herd of 300,000) died in the winter of 2013-14 on the Yamal Peninsula of Western Siberia. A team led by Bruce Forbes (University of Lapland) described its post-event research in an AGU poster. “More than a year later, participatory fieldwork with nomadic herders during spring-summer 2015 revealed that the ecological and socio-economic impacts from this extreme event will unfold for years to come,” the group reported. They’re now investigating whether the loss of sea ice in the Barents and Kara Sea is playing a role in the growing prevalence of rain-on-snow events. “There is an urgent need to understand whether and how ongoing Barents and Kara Sea ice retreat may affect the region’s ancient and unique social-ecological systems.”
The state of Arctic walrus is analyzed in detail in this year’s Arctic Report Card. Sea ice is an integral part of walrus life: adults hang out and mate along the edges of pack ice in the winter, and mothers bear their young on ice in the spring. As sea ice retreats further from the shore of Chukchi Sea in late summer, walruses have been making dramatic “haulouts” over land, where young walrus are especially vulnerable to being trampled in the rush. An estimated 35,000 walruses clambered onto the coast at Point Lay, Alaska, in September 2014, and thousands more did the same in 2015. At the same time, some of the Arctic’s regional walrus populations have had a chance to rebuild their numbers in recent decades after years of largely unrestricted hunting. Walrus are at no immediate risk of extinction: there are at least 25,000 walruses in the high-latitude Atlantic, with many tens of thousands more in the Pacific. As sea ice continues to suffer, though, the concern is that the negative effects will put an increasing dent in walrus recovery. The Chuckchi Sea is now free of sea ice for about a month each year, but that may rise to several months later in this century.
Figure 3. A female walrus rests beside a yearling during a land-based “haulout” on September 19, 2013. The coastal walrus haulouts that form during periods of sea ice scarcity in the Chukchi Sea are composed primarily of adult female walruses and young, as well as some adult male walruses. Image credit: Ryan Kingsbery, USGS.
The big shift from snow to rain in Western mountains
Several posters examined the ongoing trend across the US West toward more winter rain and mixed-precipitation events and fewer all-snow events. Temperatures during winter and spring have warmed by roughly 2°C over the West since the 1950s. Michael Dettinger (USGS) extended prior work by others showing that most stations across the West are experiencing a larger fraction of their precipitation on days when no snow is reported. One of the best-instrumented locations in the West provides a closer look at this transition. More than three dozen precipitation stations with 55 years of data are scattered across the Reynolds Creek watershed of southwestern Idaho, which covers 93 square kilometers (about three times the size of Manhattan). Elevations vary from about 3000 to 6700 feet, so it’s easy for a winter storm to bring rain to lower elevations and snow to the higher terrain. Looking at the trends over the last three decades (1984 to 2014), Danny Marks (USDA) and colleagues found a doubling of the area in which most winter precipitation events arrived primarily as rain, and a halving of the area in which most of the events were primarily snow.
There will be far more rain than snow next week over the United States east of the Rockies, but one famously snowy city is on the verge of its first accumulation of the winter, which would fall atop green grass (see photo below). Buffalo, NY, received several hours of light snow on Friday afternoon, with a measurable amount possible before the evening is done. Update: Just before 7:00 pm EST Friday, Buffalo finally reported its first measurable snow of the season (0.1", the minimum amount that qualifies as measurable]. Prior to this year, the latest that Buffalo has seen its first 0.1” of snow for the winter was on December 3, 1899.
Steve Gregory has an update today on the long-range outlook beyond the impending holiday warmth. We’ll be back on Monday with a new post. In the meantime, have a great weekend, everyone!
Bob Henson
Lots of red on the Arctic Report Card
NOAA introduced its 2015 Arctic Report Card with a press conference on Tuesday, viewable in archive form (as are all of the press conferences). The Arctic’s grades were not good. Our northern polar regions are failing--that is, failing to shield themselves from the relentless build-up of greenhouse gases. The polar year running from October 2014 to September 2015 was the warmest in more than a century of recordkeeping, with the region now 3°C (5.4°F) warmer than it was at the start of the 20th century. The minimum summer extent of Arctic sea ice, which occurred on September 11, was not a record--it ranked fourth lowest in the satellite era (starting in 1979). However, the maximum winter extent did set a record low, and that occurred on February 25, two weeks ahead of average and the second earliest max in the satellite era.
One of the lesser-known but still profound changes to the Arctic is the decline in June snow cover, which is decreasing at around 18% per decade. Because the northern sun is at its strongest in June, this decline means that a good deal less sunlight is being reflected from polar regions, thus allowing more absorption of heat at the surface.
Figure 1. Top: Average temperature for October 2014-September 2015 compared to the 1981-2010 average. All around the Arctic, temperatures were much warmer than average, with only Greenland and a small part of northeastern Canada near or below average. Bottom: Annual temperatures for the Arctic (blue line, representing 60°N - 90°N) and the globe (black line) since 1900. Arctic temperatures are more variable from year to year than global temperatures (bigger swings above and below average). But despite the variability, a trend is clear: the Arctic has warmed more than the globe as a whole. Image credit: climate.gov.
Figure 2. Permafrost is thawing across the Arctic, causing northern lands to sink or change shape. In Gates of the Arctic National Park, a bank of this lake thawed in the summer of 2014, allowing the Okokmilaga River to cut through and drain it to sea. Researchers from the University of Alaska Fairbanks and the University of Colorado presented new work at the AGU Fall Meeting on the speeded-up pace of permafrost melt across northern Alaska. Image credit:
More than polar bears at risk
Polar bears are the poster creatures of climate change, which makes it easy to overlook how warming temperatures might affect other Arctic creatures. These impacts can be difficult to pin down, because there are complicated intersections between human-driven warming and other anthropogenic factors, such as variations in hunting rates over time and the build-up of oil and gas infrastructure. An increase in rain-on-snow events over the Arctic is already having noteworthy impacts on reindeer, which forage for vegetation beneath snow cover during winter. A record number of reindeer (about 20% of a herd of 300,000) died in the winter of 2013-14 on the Yamal Peninsula of Western Siberia. A team led by Bruce Forbes (University of Lapland) described its post-event research in an AGU poster. “More than a year later, participatory fieldwork with nomadic herders during spring-summer 2015 revealed that the ecological and socio-economic impacts from this extreme event will unfold for years to come,” the group reported. They’re now investigating whether the loss of sea ice in the Barents and Kara Sea is playing a role in the growing prevalence of rain-on-snow events. “There is an urgent need to understand whether and how ongoing Barents and Kara Sea ice retreat may affect the region’s ancient and unique social-ecological systems.”
The state of Arctic walrus is analyzed in detail in this year’s Arctic Report Card. Sea ice is an integral part of walrus life: adults hang out and mate along the edges of pack ice in the winter, and mothers bear their young on ice in the spring. As sea ice retreats further from the shore of Chukchi Sea in late summer, walruses have been making dramatic “haulouts” over land, where young walrus are especially vulnerable to being trampled in the rush. An estimated 35,000 walruses clambered onto the coast at Point Lay, Alaska, in September 2014, and thousands more did the same in 2015. At the same time, some of the Arctic’s regional walrus populations have had a chance to rebuild their numbers in recent decades after years of largely unrestricted hunting. Walrus are at no immediate risk of extinction: there are at least 25,000 walruses in the high-latitude Atlantic, with many tens of thousands more in the Pacific. As sea ice continues to suffer, though, the concern is that the negative effects will put an increasing dent in walrus recovery. The Chuckchi Sea is now free of sea ice for about a month each year, but that may rise to several months later in this century.
Figure 3. A female walrus rests beside a yearling during a land-based “haulout” on September 19, 2013. The coastal walrus haulouts that form during periods of sea ice scarcity in the Chukchi Sea are composed primarily of adult female walruses and young, as well as some adult male walruses. Image credit: Ryan Kingsbery, USGS.
The big shift from snow to rain in Western mountains
Several posters examined the ongoing trend across the US West toward more winter rain and mixed-precipitation events and fewer all-snow events. Temperatures during winter and spring have warmed by roughly 2°C over the West since the 1950s. Michael Dettinger (USGS) extended prior work by others showing that most stations across the West are experiencing a larger fraction of their precipitation on days when no snow is reported. One of the best-instrumented locations in the West provides a closer look at this transition. More than three dozen precipitation stations with 55 years of data are scattered across the Reynolds Creek watershed of southwestern Idaho, which covers 93 square kilometers (about three times the size of Manhattan). Elevations vary from about 3000 to 6700 feet, so it’s easy for a winter storm to bring rain to lower elevations and snow to the higher terrain. Looking at the trends over the last three decades (1984 to 2014), Danny Marks (USDA) and colleagues found a doubling of the area in which most winter precipitation events arrived primarily as rain, and a halving of the area in which most of the events were primarily snow.
There will be far more rain than snow next week over the United States east of the Rockies, but one famously snowy city is on the verge of its first accumulation of the winter, which would fall atop green grass (see photo below). Buffalo, NY, received several hours of light snow on Friday afternoon, with a measurable amount possible before the evening is done. Update: Just before 7:00 pm EST Friday, Buffalo finally reported its first measurable snow of the season (0.1", the minimum amount that qualifies as measurable]. Prior to this year, the latest that Buffalo has seen its first 0.1” of snow for the winter was on December 3, 1899.
Steve Gregory has an update today on the long-range outlook beyond the impending holiday warmth. We’ll be back on Monday with a new post. In the meantime, have a great weekend, everyone!
Bob Henson
Snowboard at @NWSBuffalo at #Buffalo airport waiting for first 0.1" #snow of the season. Light #snow falling now! pic.twitter.com/hoNC9GnTa8
— NWS BUFFALO (@NWSBUFFALO) December 18, 2015Climate Change Arctic Winter Weather
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.