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TheMcMurdo Sound is asound inAntarctica, known as the southernmost passable body of water in the world, located approximately 1,300 kilometres (810 mi) from theSouth Pole.[1]
CaptainJames Clark Ross discovered the sound in February 1841 and named it after LieutenantArchibald McMurdo ofHMSTerror.[2] The sound serves as a resupply route forcargo ships andairplanes that land on floating iceairstrips nearMcMurdo Station. The McMurdo seasonalIce Runway was operated from October to December from the 1950s to the 2010s, then in December the ice breaks up and McMurdo port is opened by an Icebreaker ship and ships can resupply the Antarctic bases.
The sound extends approximately 55 kilometers (34 mi) in length and width, and opens into the largerRoss Sea to the north. To the south, the sound is bounded by theRoss Ice Shelf cavity, to the west lies theRoyal Society Range, and to the east isRoss Island. McMurdo Sound is separated from theMcMurdo Ice Shelf (part of the Ross Ice Shelf) by theHaskell Strait.Winter Quarters Bay lies at the south end of the Sound and is the southernmost port onEarth.
While the sound is navigable, it contains a significant amount ofdrift ice, especially along the shoreline ofWinter Quarters Bay. The pack ice that girdles the shoreline at Winter Quarters Bay and elsewhere in the sound presents a considerable obstacle to surface ships. Vessels require ice-strengthenedhulls and often have to rely upon escort byicebreakers. Less than 10 percent of McMurdo Sound's shoreline is free of ice.[3]
During austral winter, McMurdo Sound presents a large expanse of surface ice. In summer, ships approaching the sound are often blocked by various amounts of first-year ice,fast ice (connected to the shoreline), and hard multi-year ice. Subsequently, icebreakers are required for maritime resupply missions to McMurdo Station.
Ross Island is the southernmost piece of land in Antarctica that is accessible by ship. In addition, the harbour at McMurdo's Winter Quarters Bay is the world's southernmostseaport (Department of Geography,Texas A&M University). The access by ships depends upon favorable ice conditions.
Tourism is increasingly popular in other parts of Antarctica but remains limited in McMurdo Sound due to the extreme sea conditions.
Cold circumpolar currents of theSouthern Ocean shrink the flow of warm South Pacific or South Atlantic waters reaching McMurdo Sound and other Antarctic coastal waters. McMurdo Sound experienceskatabatic winds from theAntarctic polar plateau. McMurdo Sound freezes over with sea ice about 3 metres (9.8 ft) thick during the winter. During the austral summer when the pack ice breaks up, wind and currents may push the ice northward into the Ross Sea, stirring up cold bottom currents that spill into the ocean basins. Temperatures during the winter months at McMurdo Station have dropped as low as −28 °C (−18 °F). December and January are the warmest months, with average highs at −4 °C (25 °F).[4]
Polar winds are a driving force behind weather systems arising from three surface zones that converge at McMurdo Sound: the polar plateau and theTransantarctic Mountains, the Ross Ice Shelf, and theRoss Sea. These surface zones create a range of dynamic weather systems. Cold, heavy air descending rapidly from the polar plateau at elevations of 3,000 metres (9,800 ft) or more spawns fierce katabatic winds. These dry winds can reach hurricane force when they reach the Antarctic coast. Wind instruments recorded Antarctica's highest wind velocity at the coastal stationDumont d'Urville in July 1972 at 320 kilometres per hour (200 mph) (Australian Government Antarctic Division).
Prevailing winds into McMurdo Sound shoot between mountain passes and other land formations, producing blizzards known locally as "Herbies". Such blizzards can occur any time of year. Residents of McMurdo Station andScott Base have dubbed the nearbyWhite Island andBlack Island "Herbie Alley" due to winds that funnel blizzards between the islands (Field Manual for the U.S. Antarctic Program).
Overall the continent's extremely cold air does not hold enough moisture for significant snowfall. The annual snowfall on Ross Island averages only 17.6 centimetres (6.9 in). Snowfall in Antarctica's interior is far less at 5 centimetres (2.0 in). Snow seldom accumulates on theMcMurdo Dry Valleys on the western shores of McMurdo Sound.
McMurdo Sound provides an important component in Antarctica's global effects uponclimate. A key factor is thepolar winds that can drive the sound'spack ice into the Ross Sea summer or winter. Frigidkatabatic winds rake subsequently exposed water, causing sea ice to form. Freezing surface water excludes salt from the water below; leaving behind heavy, cold water that sinks to the ocean floor. This process repeats along Antarctica's coastal areas, spreading cold sea water into Earth's ocean basins.[5]
According to an interview with climatologist Gerd Wendler, published in the National Science Foundation's Antarctic Sun, one could dive to the ocean floor anywhere in the world and encounter water from the coast of Antarctica. "Seventy-five percent of all the bottom water, wherever you are, comes from Antarctica."
A rich sea life thrives under the barren expanse of McMurdo Sound's ice pack. Frigid waters that would kill many other fish in the world sustain the Antarcticnotothenioid, a bony "ice fish" related towalleyes andperch. Cactus sponges, globe sponges,starfish,sea urchins, andsea anemones are also present. Largesea spiders inhabit the depths of the sound and feed on sea anemones.Antarctic krill flourish in the upper depths of the waters[6]
Antarctic penguins,emperor penguins, andAdélie penguins live in and around the sound.[6] TheWeddell seal,leopard seal, andcrabeater seal have been spotted, as well asorcas.
McMurdo Sound's role as a strategic waterway dates back to early 20th-century Antarctic exploration. British explorersErnest Shackleton andRobert Scott built bases on the Sound's shoreline for their overland expeditions to theSouth Pole.
McMurdo Sound's logistic importance continues today. Aircraft transporting cargo and passengers land on frozen runways atWilliams Field on theMcMurdo Ice Shelf. Moreover, the annualsealift of a cargo ship and fuel tanker rely upon the sound as a supply route to the continent's largest base, the United StatesMcMurdo Station. Both the U.S. base and New Zealand's nearbyScott Base are on the southern tip of Ross Island.
In March 2000, the 282-kilometre (175 mi) longIceberg B-15, the largest ever seen at the time, broke off from theRoss Ice Shelf (Antarctic Climate & Ecosystems: Cooperative Research Center) and then suddenly broke up on 27 October 2005.
Research based upon measurements retrieved from aseismometer previously placed on B-15 indicated that ocean swells caused by an earthquake 13,000 kilometres (8,100 mi) away in theGulf of Alaska caused the breakup, according to a report by the U.S. National Public Radio.[7] Wind and sea currents shifted the smaller, but still massive Iceberg B-15A towards McMurdo Sound. B-15A's girth temporarily blocked the outflow of pack ice from McMurdo Sound.
Iceberg B-15A's grounding at the mouth of McMurdo Sound also blocked the path for thousands of penguins to reach their food source in open water. Moreover, pack ice built up behind the iceberg in the Ross Sea creating a nearly 150-kilometre (81 nmi) frozen barrier that blocked two cargo ships en route to supply McMurdo Station, according to theNational Science Foundation.
TheicebreakersUSCGCPolar Star and the RussianKrasin were required to open a ship channel through ice up to 3 metres (9.8 ft) thick. The last leg of the channel followed a route along the eastern shoreline of McMurdo Sound adjacent toRoss Island. The icebreakers escorted the tanker USNSPaul Buck to McMurdo Station's ice pier in late January. The freighterMVAmerican Tern followed on 3 February.
Similar pack ice blocked a National Geographic expedition aboard the 34-metre (112 ft)Braveheart from reaching B-15A. However, expedition divers were able to explore the underwater world of another grounded tabular iceberg. They encountered a surprising environment of fish and other sea life secreted within a deep icebergcrevasse. Discoveries includedstarfish,crabs, and ice fish. The latter were found to have burrowed thumb-sized holes into the ice.
The expedition reported witnessing an iceberg exploding. Shards of ice erupted into the air as if a bomb went off only hours after divers surfaced and after theBraveheart moved away from the iceberg (National Geographic).[8]
More than 50 years of continuous operation of the United States and New Zealand bases on Ross Island have left pockets of severe pollution in McMurdo Sound. Until 1981,McMurdo Station residents simply towed their garbage out to the sea ice and let nature take its course. The garbage sank to the sea floor when the ice broke up in the spring, according to news reports.[9]
A 2001 survey of the seabed near McMurdo revealed 15 vehicles, 26 shipping containers, and 603 fuel drums, as well as some 1,000 miscellaneous items dumped on an area of some 20 hectares (49 acres). Findings by scuba divers were reported in the State of the Environment Report, a New Zealand-sponsored study.[10][11]
The study by the government agencyAntarctica New Zealand revealed that decades of pumping thousands of gallons of raw sewage from 1,200 summer residents into the sound had fouled Winter Quarters Bay. The pollution ended in 2003 when a $5 millionwaste treatment plant went online.[12] Other documented bay water contaminants include leakage from anopen dump at the station. The dump introducedheavy metals,petroleum compounds, and chemicals into the water.[11]
A study by the Australian Institute of Marine Science found thatanti-fouling paints on the hulls of icebreakers are polluting McMurdo Sound.[13] Such paints killalgae,barnacles, and other marine life that adhere to ship hulls. Scientists found that samples taken from the ocean floor contained high levels oftributyltin (TBT), a component of the anti-fouling paints. "The levels are close to the maximum you will find anywhere, apart from ship grounding sites", said Andrew Negri of the institute.
Ships, aircraft, and land-based operations in McMurdo Sound all present hazards of oil spills or fuel leaks. For instance, in 2003, the build-up of two years of difficult ice conditions blocked the U.S. tanker MV Richard G. Matthiesen from reaching the harbour at McMurdo Station, despite the assistance of icebreakers. Instead, shore workers rigged a temporary 5.6-kilometre (3.5 mi) fuel line over the ice pack to discharge the ship's cargo. The ship pumped more than 23 million litres (6.1 million US gallons) of fuel to storage facilities at McMurdo.[14]
Officials balance the potential for fuel spills inherent in such operations against the critical need to keepMcMurdo Station supplied with oil. A fuel tank spill in an unrelated onshore incident in 2003 spilt roughly 25,000 litres (6,600 US gallons) ofDiesel fuel at ahelicopter pad at McMurdo Station.[15] The 1989 grounding of theArgentinean shipBahía Paraíso and subsequent spillage of 640,000 litres (170,000 US gallons) of oil into the sea near the Antarctic Peninsula showed the environmental hazards inherent in supply missions to Antarctica.[9]
Zoologist Clive Evans from Auckland University described McMurdo's harbor as "one of the most polluted harbors in the world in terms of oil", according to a 2004 article by the New Zealand Herald.
Modern operations in McMurdo Sound have sparked surface cleanup efforts,recycling, and exporting trash and other contaminants by ship. The U.S. National Science Foundation began a 5-year, $30-million cleanup program in 1989, according toReuters News Agency.[16] The concentrated effort targeted the open dump at McMurdo. By 2003, the U.S. Antarctic Program reported recycling approximately 70% of its wastes, according to Australia'sHerald Sun.
The 1989 cleanup included workers testing hundreds of barrels at the dump site, mostly full of fuels and human waste, for identification before they were loaded onto a freighter for exportation. The precedent for exporting waste began in 1971. The United States shipped out tons of radiation-contaminated soil after officials shut down a small nuclear power plant.[17]
Antarctica's extreme remoteness and hazardous travel conditions limit Antarcticatourism to an expensive niche industry largely centered on theAntarctic Peninsula. The number of seaborne tourists grew more than four times throughout the 1990s, reaching more than 14,000 by 2000, up from 2,500 just a decade earlier.[18] More than 46,000 airborne and seaborne tourists visited Antarctica during the 2007–2008 season, according to theInternational Association of Antarctic Tour Operators (IAATO).[19]
This confederation of tour operators reports that only 5% of Antarctic tourists visit theRoss Sea area, which encompasses McMurdo Sound. Tourists congregate on the ice-free coastal zones during summer near theAntarctic Peninsula. The peninsula's wildlife, soaring mountains, and dramatic seascapes have drawn commercial visitors since the late 1950s, when Argentina and Chile operated cruises to theSouth Shetland Islands.[20]
Tourists flights began in 1957, when a Pan AmericanBoeing 377 Stratocruiser made the first civilian flight to Antarctica. Commercial flights landed at McMurdo Sound and theSouth Pole in the 1960s. Routine overflights from Australia and New Zealand took place between 1977 and 1980, transporting more than 11,000 passengers, according toAntarctica New Zealand, which managesScott Base. One such flight,Air New Zealand Flight 901, crashed intoMount Erebus on the eastern shores of McMurdo Sound. The impact, occurring in sector whiteout into the lower slopes of the active volcano, took the lives of all 257 people aboard the aircraft.
In 1969 theMSExplorer brought seagoing tourists to Antarctica (British Antarctic Survey). The cruise's founder,Lars-Eric Lindblad, coupled expeditionary cruising with education. He is quoted as saying, "You can't protect what you don't know" (IAATO). In the decades since then, ships engaged in Antarctic sightseeing cruises have grown in size and number.
Infrequent Antarctic cruises have included passenger vessels carrying up to 960 tourists (IAATO). Such vessels may conduct so-called "drive-by" cruises, with no landings made ashore.
The Russian icebreakerKapitan Khlebnikov (picture to the right) has conducted voyages to theWeddell Sea andRoss Sea regions since 1992. High-latitude cruises in dense pack ice are only achievable during the austral summer season, November into March. In 1997, the vesselKapitan Khlebnikov claimed the distinction of being the first ship to circumnavigate Antarctica with passengers (Quark Expeditions). Passengers aboard the icebreaker make landings aboardZodiac inflatable boats to explore remote beaches. Their itinerary may also include stops at Ross Island's historic explorer huts atDiscovery Point near McMurdo Station orCape Royds (Antarctica New Zealand). Additionally, the Russian icebreaker extends the reach of tourism by launching helicopter trips from its decks, including visits to sites such as theMcMurdo Dry Valleys and areas noted for wildlife viewing.
The 'Spirit of Enderby has been conducting cruises to theRoss Sea region for many years, including McMurdo Sound. Although theEnderby has an ice-strengthened hull, the ship is not an icebreaker. TheEnderby sports Zodiac inflatable boats, ahovercraft for Antarctica voyages, andall-terrain vehicles for over ice or overland travel. Land-based tourism in Antarctica, however, continues to be rare. Antarctica lacks a permanent land-based tourism facility, despite the annual surge in the number of visitors.
The International Association of Tour Operators (IAATO) has established voluntary standards to discourage tourists from disrupting wildlife. Nonetheless, large ships, carrying more than 400 passengers, may spend up to 12 hours transporting tourists to and from breeding sites. Such large-ship operations expose wildlife to humans far longer than smaller vessels.[18]
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