Bridging Traditional Knowledge and Satellite Images in Bolivia
From Regional Environmental Change: “In the Andes, indigenous pastoral communities are confronting new challenges in managing mountain peatland pastures, locally called bofedales. Assessing land cover change using satellite images, vegetation survey, and local knowledge (i.e., traditional ecological knowledge) reveals the multi-faceted socio-ecological dimensions of bofedal change in Sajama National Park (PNS), Bolivia. Here, we present results from focus groups held in 2016 and 2017 to learn about the local knowledge of bofedales in five Aymara communities in PNS. Land cover maps, created from Landsat satellite imagery, provided a baseline reference of the decadal change of bofedales (1986, 1996, 2006, and 2016) and were field verified with vegetation sampling. At the park level, the land cover maps show a reduction of healthy bofedales (i.e., Juncaceae dominated peatland) cover from 33.8 km2 in 1986 to 21.7 km2 in 2016, and an increase in dry mixed grasses (e.g., Poaceae dominated land cover) from 5.1 km2 (1986) to 20.3 km2 (2016). Locals identify climate change, lack of irrigation, difficulty in water access, and loss of communal water management practices as key bofedal management challenges. Local improvement of bofedales was found in one community due to community-based irrigation efforts. Bridging knowledge of mountain land cover change helps to articulate the socio-ecological dimensions that influence local decision-making regarding bofedal management, and consideration of local actions that may be strengthened to support the sustainability of bofedales for local livelihoods in the context of climate change in the Andes.”
Pleistocene and Holocene Cirque Glaciation in the Western United States
From Nature: “Our [glacier chronology] demonstrates that each of the moraines originally interpreted as Neoglacial was deposited during the latest Pleistocene to earliest Holocene (between ~15 and 9 ka), indicating that, with the exception of some isolated locations, cirque glaciers in the western U.S. did not extend beyond their LIA limits during much, if not all, of the Holocene.”
These Svalbard Glaciers Survived Early Holocene Warming
From Science Direct: “About 60 percent of Svalbard is covered by glaciers today, but many of these glaciers were much reduced in size or gone in the Early Holocene. High resolution modeling of the glacial isostatic rebound reveals that the largest glaciers in Nordaustlandet and eastern Spitsbergen survived the Early Holocene warming, while the smaller, more peripheral glaciers, especially in the northwest, started to form about 5,500 years ago, and reached 3/4 of their current size about 600 years ago.”
From the Oxford University Press: “Vast, majestic, and often stunningly beautiful, glaciers lock up some 10 percent of the world’s freshwater. These great bodies of ice play an important part in the Earth system, carving landscapes and influencing climate on regional and hemispheric scales, as well as having a significant impact on global sea level… This Very Short Introduction offers an overview of glaciers and ice sheets as systems, considering the role of geomorphology and sedimentology in studying them, and their impacts on our planet in terms of erosional and depositional processes.”
Read more about the author, David J. A. Evans, and get a copy here.
Dissolved Organic Carbon in Tibetan Plateau Glaciers
From PLOS One: “Dissolved organic carbon (DOC) released from glaciers has an important role in the biogeochemistry of glacial ecosystems. This study focuses on DOC from glaciers of the southeastern Tibetan Plateau, where glaciers are experiencing rapid shrinkage.”
Park Enlists Citizens to Track Changes in Teton Glaciers
From U.S. News: “The project aligns with one of Grand Teton’s fundamental duties, keeping tabs on its natural resources. Estimates vary, but with global temperatures increasing some studies suggest many glaciers could disappear within the next few decades.”
Fracturing Glacier Revealed by Ambient Seismic Noise
From AGU 100: “Here we installed a seismic network at a series of challenging high‐altitude sites on a glacier in Nepal. Our results show that the diurnal air temperature modulates the glacial seismic noise. The exposed surface of the glacier experiences thermal contraction when the glacier cools, whereas the areas that are insulated with thick debris do not suffer such thermal stress.”
From Science Direct: “Here, we use a multi-proxy approach that combines proglacial lake sediment analysis, cosmogenic nuclide surface-exposure dating (in situ10Be and 14C), and radiocarbon dating of recently ice-entombed moss to generate a centennial-scale record of Holocene GIC fluctuations in southwestern Greenland.”
Read more about holocene mountain glacier history here.
A new study in Nature says the Earth, previously headed for an Ice Age before the Industrial Revolution, is likely to maintain its current warm phase in the glacial cycle for an unprecedented amount of time.
The researchers―Andrey Ganopolski, Ricarda Winkelmann, and Hans Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research―first examined the effect of the Earth’s orbital characteristics on the glacial cycle, but found that increased carbon dioxide (CO2)played a more important role. Additionally, they found a critical relationship between CO2 and solar radiation that could aid in predicting the beginning of the next glacial period.
“This illustrates very clearly that we have long entered a new era, and that in the Anthropocene humanity itself has become a geological force. In fact, an epoch could be ushered in which might be dubbed the Deglacial,”co-author Hans Joachim Schellnhuber said in a press release for the study.
Interglacial periods are the phases in Earth’s history with generally low amounts of global ice, and glacial periods have the most ice. The study uses the commonly accepted theory that glacial periods occur when Northern Hemisphere summer solar radiation (the amount of solar energy reaching the Earth’s surface) is at its lowest.
If summer solar radiation is low in the Northern Hemisphere, where there is more land, snow does not melt as readily. This build up of snow leads to more reflectivity―albedo―at the surface. As global albedo increases, even less snow melts and this process continues enhancing itself; this positive feedback loop could potentially trigger a glacial period.
This concept was used to support the study’s claim that our planet was headed for a glacial period prior to the Industrial Revolution since the solar exposure was, and still is, close to its minimum. The authors argue that the level of CO2 and low amount of solar radiation seen prior to industrialization should have led to a rapid buildup of ice sheets.
The team also considered the effect that the Earth’s orbital shape might have on climate. The eccentricity of the Earth is currently in a low phase―the Earth’s orbit fluctuates over thousands of years between having a more pronounced elliptical shape in its high phase and a more circular one in its low phase. In its current orbital pattern, the Earth does not get far enough from the sun during the Northern Hemisphere summer to achieve the solar radiation minima that typically spur the buildup of ice. They believed that the current near-circular orbital pattern may have countered the effects of the cooling that would be expected from the lower solar radiation.
In other words, the team thought the shape of the Earth’s orbit could explain why we have not entered an ice age.
In order to test this theory, the researchers used paleoclimate data (data derived from studying natural indicators of the conditions found in previous geologic times) from two similar glacial periods to see if there are any important similarities to the period we are in today, known as the Holocene.
The theory that the orbit had caused the delayed ice age was challenged by the fact that similar orbital patterns have led to glacial periods in the past. It was found that neither period matched the Holocene’s characteristics well enough, again showing the unprecedented behavior of the glacial cycle.
Though not a providing a perfect replication of current circumstances, this paleo data provided the closest geological approximation of similar global conditions and was incorporated into their simulations to try to get the most accurate representation of when the next glacial period should begin. The team used a highly sensitive model which had accurately modeled the last eight glacial cycles to examine the effect CO2 and orbit patterns had on this cycle.
Ultimately, they concluded that carbon dioxide, not the Earth’s orbital shape, was the more important factor.
The team surmised that even accounting for the planet’s current near circular orbit “…the Earth system would already be well on the way towards a new glacial state if the pre-industrial CO2 level had been merely 40 ppm [parts per million] lower than it was during the late Holocene…” This clearly shows the importance of the increased CO2 levels.
Using their data, a more accurate threshold of CO2 levels was determined in order to predict the onset of the next glacial period; with this threshold the team was able to find the “glacial inception” point for various levels of solar radiation.
The researchers argue that even without further human influence, the system would still have an exceedingly long time between glacial periods.
“[O]ur study also shows that relatively moderate additional anthropogenic CO2-emissions from burning oil, coal, and gas are already sufficient to postpone the next ice age for another 50.000 years,” the lead author said in a press release for the study.
“The bottom line is that we are basically skipping a whole glacial cycle, which is unprecedented. It is mind-boggling that humankind is able to interfere with a mechanism that shaped the world as we know it.”
Researchers have long used preserved sediment layers in glaciers as time records to understand the climate of the past. But now, researchers, publishing in Quaternary Science Reviews, have used lake sediments in glacier-fed Lake Hajeren in Svalbard to recreate glacier variability during the Holocene period.
The sediments, which were deposited over millennia, have been undisturbed, allowing researchers to develop a continuous and full record of glaciers as early as 11,700 calibrated Before Present (BP). The dates were calculated using radiocarbon calibration, meaning that the dates have been compared to other radiocarbon samples. Atmospheric carbon varies over time, so it does not necessarily correspond to the current Gregorian calendar. By comparing different radiocarbon samples, researchers hope to develop a more accurate dating system.
The researchers’ complete record revealed a number of new findings about the advance and presence of the Svalbard glacier. Sediments in Lake Hajeren indicated that between 3380 and 3230 cal BP there was a glacier advance that lasted more than 100 years. The glacier advance had never before been recorded.
Researchers also noted that during the deglaciation period before 11,300 cal BP, glaciers in Svalbard remained, and that between 7.4 and 6.7 thousand cal BP, glaciers disappeared. It wasn’t until 4250 cal BP that glacier reformation began. The variability in glacier presence and formation can be attributed to pulses from the melting Laurentide Ice Sheet, episodes of cooling in the Atlantic and reduced isolation during summers.
“These findings highlight the climate-sensitivity of the small glaciers studied, which rapidly responded to climate shifts,” the authors wrote.
Their research contributes to a body of work looking to better understand the driving forces behind climate variability in the Arctic, the region most affected by climate change. The Arctic also has a disproportional impact on the global climate compared to other parts of the world.
Arctic response to climate change can also be used to develop climate models that estimate the impacts of global warming.
“The rapid response of the small Hajeren glaciers improves our understanding of climate variability on Svalbard, suggesting that the Holocene was punctuated by major centennial-scale perturbations,” the authors concluded. “As such, this study underlines the value of glacier-fed lake sediments in contextualizing Arctic climate dynamics.”
Ecuador has a series of beautiful cone-shaped volcanoes along the Andes. This week, GlacierHub features three volcanoes from Ecuador: Cayambe, Chimborazo, and Tungurahua. Cayambe, locating in the Cordillera Central, is a Holocene compound volcano. Chimborazo, locating in the Cordillera Occidental, is the highest mountain in Ecuador. These two volcanoes are currently inactive. On the other hand, Tungurahua is an active volcano, located in the Cordillera Oriental.
Photo Friday highlights photo essays and collections from areas with glaciers. If you have photos you’d like to share, let us know in the comments, by Twitter @glacierhub or email us at firstname.lastname@example.org.