University of Bern archaeologists document artifacts exposed by melting alpine ice sheets. (Courtesy University of Bern)

Retreating Swiss Glaciers
The summer of 2003 was a scorcherin Europe, setting record temperatures across the continent andcontributing to the deaths of more than 30,000 people. High in theSwiss Alps, the heat wave melted glaciers and snow, causing severefloods in the valleys below.

On September 17, a hiker named Ursula Leuenberger was crossing aniced-over pass near the Schnidejoch glacier when something odd caughther eye--a leather quiver that had been left high in the Alps by aNeolithic hunter around 2800 B.C.

The following summer, University of Bern archaeologist Albert Hafnerorganized a team of glaciologists and archaeologists to followLeuenberger back up the mountain. There they found a five-foot-thickice patch 260 feet long and 100 feet wide. In just one sunny week, theedges of the ice patch shrank 20 feet. Over the course of two summers,archaeologists found in it everything from prehistoric leather pantsand shoes to nails from Roman sandals.

The finds revealed that people have climbed high in the Alps formillennia, despite its harsh conditions. (At Schnidejoch's altitude,the ground is covered in snow nine months out of the year.) "This wasjust the quickest way from one valley to another," says Hafner. Hiswork also showed that 1,000-year gaps in the ages of the artifactscorresponded with cold periods when glacial ice would have blocked thepass. The fact that fragile organic materials were preserved nearSchnidejoch for more than 5,000 years means the ice cover hasn't beenthis small since the Stone Age. "I think in the next years if there isa hot summer, the ice will disappear completely," says Hafner. "It'sobviously related to climate change."

For archaeologists, the melting ice is both a crisis and anopportunity: the artifacts at Schnidejoch never would have been foundwithout climate change, but as more and more alpine ice fields thaw andvanish, countless more artifacts may rot away and disappear forever,along with the icy glaciers and snowfields that define the Alps. Hafnersays he has his eye on other sites that are on the verge of thawing."I'm very happy to find the objects because they will give us newinputs, but I am not happy about the climate change," he says. "I'm anarchaeologist, but I'm also an alpinist."

Peru's Rainstorms
The civilizations that rose and fell inthe bone-dry deserts of coastal Peru knew the signs well. When Spanishconquistadors arrived, they noticed its effects around Christmas, andnamed the phenomenon El Nino, or little boy, after the Christ child.Every seven to ten years, currents in the Pacific Ocean shift, changingweather patterns from Australia to California. In Peru, El Nino meanswarmer water, and heavy rainfall along the coast.

The difference between a normal and a bad El Nino year can betremendous. Peru's deserts typically get just over an inch of rain peryear. In 1998, the last severe El Nino season, the region was dousedwith 120 inches, which caused serious flooding. Water takes a heavytoll on exposed archaeological sites, many of which are located alongrivers or on easily eroded slopes.

Ironically, archaeologists have made the problem worse. "If we don'tmess with the sites, water runs off without doing too much damage,"says University of Maine archaeologist Dan Sandweiss. "But if youexcavate, that's the end of them, basically." Holes made by lootersalso channel and trap moisture, doing more damage.

Take Chan Chan, an elaborately planned city eight miles square thatdates back 1,000 years. Made of unfired mud brick, Chan Chan's pyramidsand palaces were put on UNESCO's list of World Heritage Sites in Dangerin 1986 because they were threatened by erosion. Over the past twodecades, the site has deteriorated steadily. Researchers areinvestigating whether global warming could make El Nino occur morefrequently. "There's the potential for greater destruction if the paceof El Nino events increases," says Sandweiss.

So far, climatologists can't say for sure what climate change willdo to the powerful weather phenomenon. "The models are all over theplace," says National Oceanic and Atmospheric Administrationclimatologist David Enfield. "We're up against a huge uncertainty atpresent." As climate experts work to refine their predictions,archaeologists anxiously await the arrival of the next El Nino.

Violent wave action is destroying 2,000-year-old sites once occupied bythe Thule culture, the ancestors of modern Inuits. (Courtesy BjarneGronnow)

Greenland's Melting Sea Ice
In a normal summer, Greenland'snorthern and eastern coasts should be ringed by an ice belt 30 to 40miles wide. The drifting ice acts like a shock absorber, dampening thestrength of the North Atlantic. "It takes a lot of wave energy to movethe ice, and normally water along the coast is very calm," says Danisharchaeologist Bjarne Gronnow, of the National Museum in Copenhagen.

But in the past five years, the sea ice has all but disappeared.Without its floating frozen shield, Greenland's coast is being pummeledby storm surges originating hundreds of miles away. When Gronnowvisited the region last summer, his team was barely able to land theirZodiac rafts on the beaches because of waves almost 10 feet high.

The effect on the island's heritage has been catastrophic. Hardesthit have been sites associated with the Thule culture, people closelyrelated to the Inuit of northern Canada who first migrated to Greenlandaround 2,000 years ago. The Thule were formidable hunters and whalers,and their villages were built close to the shore. Today, Thulehouses--made of stone and turf with whale-bone rafters--aredisappearing quickly, along with buried tools and artifacts. "A meterper season will be tumbled down to the beach and washed away," Gronnowsays. "It's not a slow process."

Older sites along the coast are also in danger. As the Arctic warmsup, archaeologists fear the frozen turf that covers Qeqertasussuk, a4,500-year-old settlement where evidence for the earliest settlement ofGreenland was found, may be melting. Gronnow--who excavated the remotesite for the first time in the 1980s--is headed back this summer, andhe is not optimistic. "I've been working in Greenland for 30 yearsnow," he says. "I can see with my own eyes how it has changed."

Andrew Curry is a contributing editor at ARCHAEOLOGY.

Thawing Scythian Tombs
Three thousand years ago, Scythian nomads ruled the Eurasian steppesfrom the edges of the Black Sea in the west to China in the east. TheGreek historian Herodotus reported their exploits as warriors and theirdrug-fueled religious rituals. The Scythians buried their dead in hugegrave mounds that have been rich resources for archaeologists studyinghow this nomadic culture spread, thrived, and ultimately faded awayaround 200 B.C.

Though the burial mounds--called kurgans--are found everywhere fromUkraine to Kazakhstan, few are as spectacularly preserved as those inthe Altai Mountains on the edge of the vast Siberian permafrost region.Many of these graves have been on ice for millennia, sandwiched betweena frozen layer of earth and the insulating grave mound above.

Beginning with Soviet excavations in the 1940s and '50s,archaeologists have found amazingly well-preserved mummies in thetombs, often with their clothing, burial goods, horses, and evenstomach contents intact. "Instead of archaeology, the material cultureis so well preserved it's almost a kind of ethnography," says HermannParzinger, who discovered the tomb of a mummified Scythian warrior inMongolia in 2006 and now directs the Prussian Cultural HeritageFoundation in Berlin.

But scientists say the Altai Mountains aren't as cold as they usedto be. The glaciers that covered the slopes of the Altai are recedingand even disappearing. And for the first time since their occupantswere buried 3,000 years ago, the Scythian tombs are in danger ofthawing out and rotting away. "These tombs are all in an area where thepermafrost is just at an equilibrium," says Jean Bourgeois, anarchaeologist at Ghent University who works on sites in Russia andKazakhstan. "Just a degree or two can be enough to [destroy] frozencontents."

Mapping and listing all the region's kurgans using old spy satellitephotos and old-fashioned ground surveys is the first phase of aninternational effort to save the frozen tombs. Bourgeois says the firstpriority is identifying kurgans that may still have permafrostunderneath.

Archaeologists are scrambling to figure out the next step: how tokeep the grave mounds cool. Instead of emergency excavations, Bourgeoishopes to work with engineers to find low-cost solutions to preserve thekurgans intact for future researchers. Proposals range from reflectingsunlight away from the kurgans by painting them white to stabilizingthe underground temperature by installing "thermo-pumps." But afterseeing the region's climate change with his own eyes over the pastdecade, Bourgeois has come to realize that even in a best-casescenario, archaeologists cannot preserve all of them. "They will haveto choose."

Rising sea levels damage shell middens and other remains at sites that are more than 10,000 years old. (Blake Edgar)

Channel Islands Erosion

The Channel Islands off the coast of California are a critical linkin the study of how humans settled the Americas. For decades, theconsensus has been simple: America's first immigrants crossed theBering Strait on foot and made their way south, over land through whatis now Canada. Many researchers now believe, however, that the firstpeople came to America by boat, island-hopping from Siberia all the waydown to the California coast.

Some of the best evidence for this comes from the Channel Islands."We have in excess of 10,000 years of human occupation," says ChannelIslands National Park Archaeologist Kelly Minas (see "Going Coastal"May/June 2007). Evidence from shell middens, rock shelters, and othersettlement sites supports the idea that early Americans were goodsailors who reached the islands more than 13,000 years ago, huntingpygmy mammoths, elephant seals, and sea lions. Human bones found onSanta Rosa Island in 1959 have been radiocarbon-dated to 13,000 yearsago, making them the oldest human bones found in the Americas.

Back then, the world was much colder, and the oceans much lower--lowenough that four of the Channel Islands were connected by dry land.Now, rising sea levels are threatening some of the last coastal rockshelters left on the islands. "Erosion is a problem on the islands,"Minas says. Coastal winds, waves, storm surges, and even seals haulingout of the water can damage or destroy coastal sites on the islands.

Rising seas now threaten to wipe out clues to how early humans madetheir way into the Americas just as researchers are beginning to lookinto the possibility of coastal migration. At Daisy Cave, a sea-sidesite on San Miguel Island, University of Oregon archaeologist JonErlandson has spent a decade excavating a 65-foot-wide midden that theisland's prehistoric residents built up over thousands of years.Excavators have found the remains of tools, beads, and even baskets.

But, their work is becoming a race against time. Erlandson says themidden has shrunk by about three feet in the past decade. "If we'velost a meter in 10 years, how much will we lose in 50 or 100?"Erlandson asks. "If this keeps up, we're going to lose an incredibleamount of archaeological sites."

Encroaching desert sands threaten the artwork at the 2,000-year-oldsite of Musawwarat es-Sufra. (Courtesy Seminar of Northeast AfricanArchaeology and Cultural Studies, Humboldt University Berlin)

Sudan Desertification
Local nomads call the ruinsMusawwarat es-Sufra, or "Yellow Pictures." More than 2,000 years ago,the kings of the Meroites--a desert kingdom closely linked to ancientEgypt--built a temple complex 20 miles east of the Nile Valley, in whatis today Sudan. Built of soft yellow sandstone, the walls and columnsof the complex were decorated with hieroglyphs and elaborate reliefs,covered in mortar and colorfully painted. "It was probably the mostimportant pilgrimage site of the Meroitic kingdom," says ClaudiaNaeser, an archaeologist at Humboldt University in Berlin who isexcavating the site's reservoirs and temples.

Musawwarat's centerpiece was the 50-foot-long Temple of the Lion God,carved inside and out with reliefs dedicated to the Meroitic god offertility, Apedemak. The lion god's temple was once in the middle of agrassland. But warming temperatures and overuse have killed off thearea's vegetation, and the Sahara's sands are creeping ever closer. Inthe 1960s, an earlier Humboldt University mission uncovered andreconstructed the temple's collapsed walls--in retrospect, a mistake."The reliefs suffer heavily from wind erosion," Naeser says. "Thesandstone is relatively soft, and it just abrades."

Musawwarat is far from alone. Desertification is an often-overlookedproblem because shifting dunes and blowing sand cover archaeologicalremains--leading to a misperception that the ruins are being shieldedfrom further damage. "There's this belief that sand is protective. It'snot," says Henri-Paul Francfort, a director of research at the FrenchNational Center for Scientific Research. "Sand can quickly destroyremains, both because of the weight of dunes and because of terriblewinds that erase everything."

The scale of the problem is overwhelming, and solutions--fromhardening stone with special chemicals to erecting protective walls orplanting trees as windbreaks--are either prohibitively expensive orimpossible because of a lack of water. UNESCO is now considering anapplication to have Musawwarat listed as a World Heritage Site. Soon,however, there may be no more "yellow pictures" to be seen.