Holocene Atmospheric Circulation in the Central North Pacific
From ScienceDirect: “The North Pacific is a zone of cyclogenesis [the development of an area of low pressure in the atmosphere, resulting in the formation of a cyclone] that modulates synoptic-scale atmospheric circulation. We present the first Holocene oxygen isotope record (δ18Odiatom) from the Aleutian Islands supported by diatom assemblage analysis. Our results demonstrate distinct shifts in the prevailing trajectory of storm systems that drove spatially heterogeneous patterns of moisture delivery and climate across the region.”
Read more about the new Holocene oxygen isotope record from the Aleutian Islands here.
The Enigma of Survival Strategies in Glacial Stream Environments
From Freshwater Biology: “Glacier retreat is a key component of environmental change in alpine environments, leading to significant changes in glacier-fed rivers. The species compositions of Diamesinae and Orthocladiinae (of the non-biting midges family) are diverse and strongly affected by the changing habitat conditions upon glacier retreat. Here, we show that Diamesinae have extremely flexible feeding strategies that explain their abundance, high body-mass and predominance in glacier-fed streams.”
Discover more about the insects that live within the glacier-fed streams here.
Phylogenetic Diversity of Prokaryotes on Lewis Glacier in Mount Kenya
From African Journal of Microbiology Research: “The seasonal snowpack of the temperate glaciers are sources of diverse microbial inoculi. However, the microbial ecology of the tropical glacial surfaces is endangered, hence posing an extinction threat to some populations of some microbes due to rapid loss of the glacier mass. The aim of this study was to isolate and phylogenetically characterise the prokaryotes from the seasonal snow of Lewis glacier in Mt. Kenya. Analyzing snow samples, the results confirm that the seasonal tropical snowpack of Lewis glacier is dominated by the general terrestrial prokaryotes (e.g. Bacillus with 53%) and a few glacier and snow specialist species (e.g. Cryobacterium with 5.9%).”
Find out more about these cellular organisms living on the surface of a Mount Kenya glacier here.
From 2001 to 2014, climate scientists observed a “hiatus” or pause in global warming. It is an issue that has led to much discussion in the scientific community and among climate skeptics who see the trend as an indication that global warming does not exist. According to a paper published by Fyfe et al., the word “hiatus” is not fully accurate. Instead, instrument data shows a slowdown or deceleration (as opposed to a full halt) of global warming at the beginning of the 21st century. Glaciers are key in helping us understanding the global warming slowdown.
In a recent article, Wenling An et al. describe how the glaciers of the Tibetan Plateau show evidence of the recent warming slowdown. Known as the “Roof of the World,” the Tibetan Plateau spans 1,565,000 square kilometers and is the origin of the Indus, Mekong, and Yangtze Rivers. Due to its large size and location near the tropics, the plateau is one of the most ecologically diverse alpine regions in the world. Therefore, the Tibetan Plateau’s response to climate change has been studied extensively, with researchers relying on both meteorological and paleoclimate data.
Most studies to date have taken place in the more accessible eastern and central parts of the Tibetan Plateau, where there are a greater number of meteorological stations. Meanwhile, the northwestern part of the plateau remains remote and formidable. Thus, data gathered in the northwestern plateau continues to be sparse and collected during shorter timeframes. But the northwestern area has an important connection to the Asian monsoon season and mid-latitudes, recently prompting scientists to focus increased attention on gathering higher resolution data from the area. For one, the Tibetan Plateau plays an important role in the Asian monsoon season by acting as a heat source in the summer and a heat sink in the winter, according to an article by Hongxu Zhao and G.W.K. Moore.
Interestingly, the new data collected by An et al. revealed that the eastern and northwestern parts of the plateau have experienced entirely different temperature trends since the beginning of the 21st century. The eastern part shows increased warming during that period, while the northwestern part shows no warming.
In their research, An et al. describe the usefulness of using ice cores (drilled samples of ice from a glacier) to detect this phenomena in climate data. For example, ratios of stable isotopes (forms of the same element with a different number of neutrons) found in ice cores provide information that informs us about past climate conditions.
Studies were done on ice cores taken from the Tibetan Plateau examining the relationship of a particular variation of the amount of an oxygen isotope (δ18O) with precipitation and air temperature. The precipitation on the plateau was captured within the ice core as snow, which then converted to ice. The data demonstrated a positive correlation. This means the higher the concentration of δ18O, the higher the temperature of the air when the water evaporated.
In situations of higher δ18O, the research indicates that the air temperature was higher at the time the snow formed. Aside from temperature, the effect of seasonality and the precipitation amount were also examined to understand the relationship of the δ18O concentrations. Through statistical t-tests, An et al. concluded that seasonality and the precipitation amount did not have an effect on the concentration as temperature does. The results indicate that the temperature is the factor influencing the concentration of δ18O, rather than other factors.
The authors of the study drilled ice cores at Chongce Glacier on the northwestern part of the Tibetan Plateau. They looked at samples approximately 60m long and 6000m above sea level, focusing on the δ18O in the ice cores. The team’s conclusions were consistent with other studies of the area, showing that the levels of the isotope increased significantly in the 1990s, and remained high until 2008, when the δ18O levels started to show a steep decline in concentration from 2009 to 2012. This demonstrates that temperature increased significantly until 2008, when the increases in temperature slowed. This research matches two other ice cores taken from the area, as well as instrument data, demonstrating that the Chongce ice cores provide accurate information about past climate. This data further matches global trends.
Temperature has the largest effect on regulating the state of the Tibetan Plateau. As temperatures increase, melting of the glaciers on the plateau increases. The state of the glaciers on the northwestern part of the plateau has been largely stable since the beginning of the 21st century, likely due to slowed warming in the area. Tibetan Plateau glaciers tell us a lot about the pace of global warming and will continue to be a key tool in understanding how the Earth responds to changes in temperature.
Climate change is making the work of glaciologists complicated. Scientists that study paleoclimatology of the Earth have come to the realization that melting ice and receding glaciers are getting in the way of their fieldwork.
“Time no longer starts at the surface,” said Lonnie Thompson, a paleoclimatologist at the Byrd Polar Research Center at the Ohio State University in Columbus, in an interview with Nature.
His ice-core research career started since the mid-1970s. When he drilled an ice core from the Quelccaya ice cap in the Peruvian Andes in 1983, melting had not occurred at altitudes above 5,000 meters. However, 20 years later when he returned for another ice core, things changed completely—melting disrupted the pattern of atmospheric isotopes in the top 40 meters of ice.
To address challenges like those faced by Thompson, the community of ice-core researchers is developing a better approach to saving ice for the next generation of scientists. Patrick Ginot, a paleoclimatologist at the Institute of Research for Development (IRD) in Marseilles, France, advocated that the United Nations Educational, Scientific and Cultural Organization (UNESCO) support a program that would sustainably collect ice cores and store extra samples at the Concordia Research Station in central Antarctica, in order to meet the research demands for both current and future scientists.
The layers in an ice core are a reliable indicator of its age. Scientists and researchers count the layers that record seasonal changes and date ice cores. Ideally, an intact ice core shows the most recent year on the top layer, which scientists use to link to their knowledge about recent climate conditions—temperature, precipitation, etc.
For example, the nuclear tests in 1950s and 1960s, as well as the 1986 Chernobyl disaster, left datable signatures in glaciers all over the world, which mark specific years for scientists. Stable isotopes of oxygen that remain in partially melted ice could enable scientists to obtain average measurements from 5- to 10-year periods, though not year-to year data. Unfortunately, ice core samples with insufficient radioactive signature make it difficult for researchers to identify specific years.
To acquire a pure sample of ice core, glaciologists have no choice but climb higher where melting has not yet begun, though it can be dangerous.
“In most cases, we can’t go higher. We can’t get to a colder environment,” said Douglas Hardy, a geoscientist at the University of Massachusetts Amherst, in an article in Nature. He once placed weather instruments on glaciers to measure temperature, humidity, precipitation rates and the amount of sunlight that shed on the surface of glaciers. These meteorological conditions can help scientists examine the impacts of these factors on layers of ice.
Now, Hardy explained, scientists have to do the work before the ice is gone permanently, otherwise glacier history will remain unknown forever. The pathway to higher altitudes is worthwhile, but risky at the same time. Therefore, collecting and storing ice core samples before they all melt away seems a good solution to the problem.
The major challenge of storing ice cores lies in funding, as most science funding agencies tend to pay for research that is expected to generate quickly published results.
To persuade donors, the International Partnerships in Ice Core Sciences prepared a report on the importance of preserving records of climate history. The co-chair of the organization, Ed Brook, expects to present the report on a major geosciences meeting in 2016.
Younger scientists also expressed their uncertainty of future ice-core research. Aron Buffen, a paleoclimatology doctoral student at Brown University says that scientists will easily lose comparisons for future measurement techniques if all the ice melts quickly.
On the other hand, Buffen also points out that the melting may bring about more research questions, such as distinguishing between melting caused by warming and sublimation caused by lower humidity. If scientists can shed light on how glacier retreat impacts local ecosystems, the research can be used to help communities better adapt to climate change. Additionally, organizations like the Association of Polar Early Career Scientists (APECS), are helping young glacier researchers develop their career paths and networks in an innovative, international and interdisciplinary approach.
While grieving over the disappearing glaciers, scientists can also see the silver lining as intriguing opportunities arise from the perspective of careers and science.