Getting to the Core of Climate Change

Getting to the Core of SCOPE ON THE SKIES Climate Change BY BOB RIDDLE hat image may come to and permafrost. As such, the cryo- that study the climate history of mind when the word sphere is part of the hydrosphere the cryosphere (paleoclimatol- Wglacier is heard? Before and could be thought of as the ogy) study global ice in a variety answering that question, here is “frozen water” part of the Earth. of ways, including data and ob- another one: glaciers are part of The cryosphere plays a signifi- servations from Earth’s orbit, fly- the Earth’s “cryosphere”—so what cant role in our planet’s climate, overs with instrument-equipped is the cryosphere? The cryosphere and an understanding of how cli- airplanes, and a ground-based includes any place on our planet’s mate has changed in the past may collection of observations and surface covered with water in the provide information about what data (see Hunting for Ice on Hud- form of snow, ice on land or sea, to expect in the future. Scientists son Bay in Resources). NASA’s Operation IceBridge is an airborne flyover of the ice at | FIGURE 1: Ice core sample. both the North and South Pole. (Source: climate.nasa.gov/system/news_items/main_images/2616_ A variety of instruments docu- p1000526-1280px-90.jpg) mented changes in the gain or loss in the thickness and mass of ice on land and sea as well as glaciers. Data collected by IceBridge is added to data from previous and current NASA satellite missions, ICESat, ICESat-2, and the ESA’s satellite missions Cryo-Sat and CryoSat-2 (see Resources). All the airborne and satellite missions make some of the measurements using either radar or laser altime- try. As a side note, this is the tech- nology that allowed us to map the surface of Venus, for example (see Resources). Using either a radar or laser signal, the travel time to and from the surface is timed as the satellite or airplane passes over an 96 area. The differences in times are gen by its inclusion in the famil- what one has seen or read about converted into elevation or alti- iar chemical formula of H2O. This glaciers—perhaps an image of tude data. With this, the height is a water molecule where there sheets of ice, like those cover- of sea ice above the level of wa- are eight protons and eight neu- ing the Arctic and Antarctic, or ter or the altitude of ice sheets trons in the nucleus of the oxygen maybe a video showing calv- and glaciers may be measured atom (oxygen 16). Sometimes the ing of glaciers falling into the and used for determining the ice oxygen atom can have more than ocean. Many glaciers slowly thickness. Satellite and airplane eight neutrons in the nucleus— make their way to lower eleva- flyovers provide important data; oxygen 18 for example (8 protons tions as shown in the picture however, ground-based obser- and 10 neutrons), the heavy oxy- taken with the Earthkam camera vations and data collection is an gen. The ratio measured in an ice of snow, ice fields, and some gla- important component to piecing core sample is compared with a ciers in the Andes Mountains of together the connection between standardized ratio between the the southern Patagonia region of global ice and climate. two oxygens, and the difference Chile and Argentina (see Figure Instrumental to ground-based is used to determine trends in 2). Glaciers come in a variety of data collecting is the work of how atmospheric temperatures sizes based on location, and gla- glaciologists and the use of core have changed. For example, a ciers may be defined according to samples extracted from ice and high ratio of light oxygen would their respective location. Using snow fields. Like core samples suggest cooler temperatures. location, there are several catego- taken by geologists, ice core sam- ries of glaciers that could be di- ples and the materials they con- Glaciers vided into two somewhat broad tain—in addition to the ice and Remember that first question: groups—those in mountains and snow—contain clues to the cli- What image may come to mind those not in mountains. mate at the time the ice or snow when the word glacier is heard? Glaciers are large-scale objects was deposited. Once extracted, The answer may depend on that are incredible at weather- a core sample is only handled by glove-wearing scientists and technicians to avoid contaminat- ing the sample as it is carefully | FIGURE 2: Glacier Perito Moreno, Southern Patagonia. wrapped and packed for ship- (Source: Author using Earthkam) ment to a laboratory for analysis. In the laboratory, the core samples are often allowed to melt in a sealed container, making it possible for scientists to capture any trapped gases. The water itself is examined for particulate mate- rial like seeds and volcanic ash— anything collected from the melt- ing ice is analyzed (see Figure 1). When the core sample gases are analyzed, scientists look for the ratio between oxygen atoms and an oxygen isotope, known as light oxygen and heavy oxygen, respectively. Students know oxy- January/February 2021 97 ing and eroding the surface of ocean or driving through moun- on some of the seven Ecuadoran the Earth. Over time, continents tain glacier areas like the Tetons of mountains capped by snow and are changed and mountains wear Wyoming, the glaciers in Glacier glaciers. away. Ice, in terms of glaciers and National Park in Montana, or the Sadly, many of the glaciers in ice sheets, covers approximately glaciers of the Andes Mountains Ecuador and worldwide are re- 10% of the Earth’s surface. Ice in South America. However, how ceding, and some are disappear- sheets are now only located in often is it possible to know these ing—all at alarming rates as a Antarctica and Greenland; how- bodies of ice up close and person- result of changes in our climate. ever, in the past, ice sheets covered al? Glaciers, especially the high- Mountain glaciers, under most much of North America, forming altitude mountain glaciers of the climatic conditions, do not really the Great Lakes and creating the Andes in Ecuador, have a special disappear but typically recede fertile soils of the Midwest and the and personal place in my heart and then often regenerate them- cliffs of glacial till, loess, along the (also in my feet, my lungs, my selves. However, many of the cur- Missouri River near Mound City, knees!). Over the years I have had rently receding glaciers are not Missouri. several opportunities to spend recovering or regenerating at a In many locations glaciers are time on many of the mountains rate that balances or exceeds the typically viewed from a distance— in Ecuador, hiking, climbing, and rate of receding. The receding of maybe aboard a cruise ship when scrambling on their rocky surfac- a glacier or an ice sheet is a pro- watching glaciers calve into the es as well as traversing glaciers cess known as deglaciation, and Visible planets Mercury moves into the evening skies and passes by Jupiter during the first week of January. The in- nermost planet moves through inferior conjunction by the end of January and again passes by Jupiter and Saturn during the last week of February as a morning planet. Venus is visible but low over the eastern horizon at sunrise but will soon be lost in the Sun’s glare as Venus moves into superior conjunction, on the opposite side of the Sun. Watch for Venus to show up as an evening planet during March. Mars is visible over the southwestern horizon after sunset. Follow Mars as it moves eastward along its orbit. With binoculars, watch as it passes by the outer planet Uranus during January and slowly but steadily catches up with the open star cluster the Pleiades by the end of February. Dwarf planet Ceres is over the southwestern horizon at sunset; however, it has an apparent magnitude that is too dim to seen without some optical assistance. Jupiter starts the new year close to Saturn and very low over the western horizon at sunset, and by the middle of the month the Sun has caught up with Jupiter as Jupiter moves into conjunction with the Sun. Watch for Jupiter to reappear in the morning skies by the end of February. Saturn is close to Jupiter and like Jupiter will move through conjunction with the Sun and will become visible as a morning planet by the end of February. 98 SCOPE ON THE SKIES this represents the loss of a part the lifestyles and environment ies of Riobamba and Guaranda, a of the cryosphere. On the basis of of people and animals living in long-time source of income came elevation, a glacier has a line of their shadows? As glaciers recede, from blocks of ice carved from the equilibirum, an elevation at which what impact does this have on the glaciers on Chimborazo and was the amount of snow and ice accu- environment and the people and sold locally (see “The Story of the mulation is approximately equal animals living in those areas? One Last Ice Merchant” in Resources). to the amount of ablation, or loss, may not often think of glaciers in Volcan Chimborazo is the tall- of glacial ice. This elevation varies those terms, but to many people est of the mountains in Ecuador based on local geographical cir- and animals the nearby glaciers at 20,500 feet (6100 m).

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