气候变化与海平面上升威胁美国历史遗址詹姆斯敦

S ITS 250TH ANNIVERSARY, A GROWING THREAT IS PUTTING SOME OF AMERICA'S MOST HISTORIC PLACES AT RISK. RISING SEAS AND COASTAL EROSION ARE RESHAPING THE LANDSCAPE WHERE OUR HISTORY UNFOLDED. SPECIAL CORRESPONDENT BEN TRACY WITH CLIMATE CENTRAL TAKES US TO JAMESTOWN, VIRGINIA, WHERE ACHAEOLOGISTS ARE RACING TO UNCOVER AMERICA'S PAST, BEFORE IT'S WASHED AWAY. IT'S PART OF OUR ONGOING SERIES, "TIPPING POINT."

WE KNOW THAT IT IS SHALLOW. BEN: IF YOU SPEND YOUR DAYS DIGGING THROUGH THE PAST, SEAN SAID THIS IS THE PLACE TO DO IT.

YOU CANNOT PUT A SHOVEL IN THE GROUND WITHOUT FINDING SOMETHING. BEN: HE IS DIRECTOR OF ARCHAEOLOGY FOR JAMESTOWN REDISCOVERY. AT THE SIDE OF AMERICA'S FIRST PERMANENT ENGLISH SETTLEMENT FOUNDED IN 1607. WHAT TOOK PLACE HERE AND WHY DOES IT MATTER?

FOR AMERICAN HISTORY IT IS HARD TO HAVE MORE IMPACT THAN JAMESTOWN. IT IS THE FIRST PLACE WHEN ENGLISH COLONISTS COME OVER HERE, THEY END UP STAYING. WITH NO JAMESTOWN THERE IS NO MODERN U.S. BEN: THIS IS WHERE AMERICA'S FIRST REPRESENTATIVE ASSEMBLY MET, WHERE POCAHONTAS MARRIED JOHN, AND WHERE THE FIRST ENSLAVED AFRICANS WERE FORCED ONTO THE SHORES.

THEY WERE CAMPED ENSLAVED BY THE ENGLISH COLONISTS. IN JAMESTOWN WE HAVE OUR IDEALS OF AMERICAN DEMOCRACY AND OUR BIGGEST MISTAKE, SLAVERY. MANY DIFFERENT CULTURES INTERACTED. THE HISTORY IS PRETTY COMPLICATED. BEN: THE RUINS OF THE ORIGINAL FORT WERE DISCOVERED IN 1994. ARCHAEOLOGISTS HAVE UNEARTHED 5 MILLION ARTIFACTS OF THE TELL THE STORIES OF THE PEOPLE WHO LIVED HERE.

THIS IS A CHAIN. IT WAS FOUND AT THE BOTTOM OF ONE OF JAMESTOWN'S EARLY -- YOU CAN HOLD IT IF YOU LIKE BEN: THIS IS FROM HOW LONG AGO?

THE BEGINNING OF THE 17TH CENTURY. BEN: NOW THEY ARE USING RADAR TO MAP OUT WHAT STILL LIES BURIED.

IF IT SHOWS UP THAT WILL BE REALLY COOL. BEN: THIS HAS BECOME TRIAGE. A RACE TO SAVE AS MUCH HISTORY AS POSSIBLE BEFORE IT IS LOST.

WHEN I THINK OF ARCHAEOLOGY I THINK OF A SLOW, PAINSTAKING PROCESS. YOU, HOWEVER, DO NOT HAVE TIME ON YOUR SIDE.

NO. WE HAVE TO BE METICULOUS BUT WE HAVE TO PICK THE PACE UP. WE ARE UNDER SEVERE THREAT FROM CLIMATE CHANGE. BEN: JAMESTOWN IS UNDER SIEGE FROM RISING WATERS. SEA LEVELS HAVE RISEN 1.6 FEET OVER THE PAST CENTURY AND COULD RISE ANOTHER THREE FEET BY 2075. THE JAMES RIVER IS BATTERING THE SHORELINE ON ONE SIDE. THAT SWAMP IS REALLY CLOSE.

IT DID NOT USED TO BE. BEN:BEN: AN EXPANDING SWAMP ON THE OTHER REGULARLY FLOODS THE EXCAVATION SITES. WHAT HAPPENS ON A DAY WITH A LOT OF RAIN?

WE ARE IN THE WATER. BEN: WHEN YOU TALK ABOUT HISTORY BEING WASHED AWAY, IT IS A LITERAL THING.

THAT IS NOT HYPERBOLE. IT IS ACTUALLY HAPPENING. BEN: IT IS NOT JUST HERE. OUR BURNING OF FOSSIL FUELS IS RAPIDLY BURNING THE PLANETS, CAUSING ICE SHEETS TO MELT AND OCEAN WATER TO EXPAND. 2.5 MILLION AMERICANS AND MANY HISTORIC SITES COULD BE AT RISK OF SEVERE COASTAL FLOODING BY 2050.

IF YOU WANT TO ARGUE ABOUT WHY, OR WHAT IS CAUSING IT, GREAT. KNOCK YOURSELF OUT. BUT THE SEA LEVEL IS RI