With Brexit now threatening to isolate the UK from the European Union, the researchers think politicians should take this as a cautionary tale. “By joining England, Scotland became more resilient,” said lead author Rosanne D’Arrigo, a tree-ring scientist at Columbia University’s Lamont-Doherty Earth Observatory. “The bigger message for today is arguably that as the climate changes, nations will be stronger if they stick together and not try to go it alone.” The study appears in the early online edition of the Journal of Volcanology and Geothermal Research.

The “Scottish Ills” have long been noted in history books. In some years, snow from the winter persisted on the ground well into summer, and frosts struck every summer night for weeks. The planting season was cut short, and crops were struck down before they could be harvested. Livestock had nothing to eat. The study quotes Mary Caithness, Countess of Breadalbane, describing “cold misty weather such as the oldest person alive hath not seen.” Other regions including France, England and the Netherlands also suffered unusually cold weather, but generally with less drastic results. In Scandinavia, however, tens of thousands died. It was “likely the worst era of crop failure, food shortage and mortality ever documented in Scottish history,” the researchers write.

Based on the width and density of tree rings the researchers collected, they showed that 1695-1704 was Scotland’s coldest decade in 750 years. This, on top of the fact that much of the northern hemisphere was already in the grip of the so-called Little Ice Age, when cold temperatures were the norm for centuries, until the 1800s. “Before this, we knew it was cold. Now we have an understanding of exactly how cold,” said coauthor Rob Wilson of Scotland’s University of St. Andrews, and an adjunct researcher at Lamont-Doherty. “The whole 17th century must have been a horrible time to live in Scotland, but this was the worst part.”

The researchers say that the Ills coincided closely with multiple large volcanic eruptions. Previous researchers have identified particles in ice cores that traveled long distances from eruptions that probably took place somewhere in the tropics in 1693 and 1695. And Iceland’s Mount Hekla darkened the skies for seven months in 1693. Scientists already know that large-scale volcanism throws sulfate particles into the atmosphere; these deflect sunlight and can lower temperatures far from the eruption itself for years. Thus, the researchers believe the eruptions would explain the chilly weather that hit Scotland and other northern hemisphere nations all at the same time. (Unsurprisingly, the tree rings also show that the warmest century of the record was 1911-2010, almost certainly due to human greenhouse-gas emissions.)

The findings are an outgrowth of the Scottish Pine Project, in which Wilson and his colleagues have been gathering tree-ring samples for the past 10 years in northern Scotland. In the desolate Highlands region of Cairngorms, they have drilled out cores from living trees going back to the 1400s. To extend the record back further, they have snorkeled along the nearshore bottoms of icy lochs, searching for long-dead trees that have fallen in and been preserved over the centuries in cold, oxygen-poor mud. Once they find specimens, they winch them out by hand and take out cross sections with chain saws. The team has also studied buildings whose timbers went back to the 1100s, though these were not included in the climate reconstruction. Their initial chronology was published in 2017. In the course of their work, the team has found trees in the lochs as old as 8,000 years. They are still collecting samples and working to construct a continuous climate record predating the Middle Ages.

In the new study, the researchers say that climate was not the only factor in the Scottish Ills. “The connection seems simple — volcanic cooling triggered famine — but the drivers toward famine are far more complex,” they write. They cite Scotland’s economic circumstances and political isolation from England as major factors. England had more good farmland and, at the time, better agricultural technology and organization for delivering relief to the poor. While also hit with cool weather, England did not suffer a famine, and probably would have come to the aid of Scotland had the nations been united. Scotland also unwisely encouraged the export of crops at a time when they were needed at home.

At the height of the Ills, the Scots developed an intricate venture to send colonists to the Darien region of Panama. Driven in part by the desperation of the famine, the idea caught on as a national mania, and people of all social and economic classes invested much of their assets — in all, as much as half the nation’s entire liquid capital. Starting in 1698, a total of 2,500 colonists began sailing to this malarial jungle coast. They were quickly cut down by disease, malnutrition (Scotland could ill afford to resupply the colony) and conflicts with Spanish forces, which already controlled much of South and Central America. The colony was abandoned after just 16 months; only a few hundred colonists survived; and Scotland was financially ruined. The inhospitable Darien region remains barely inhabited even today.

“At the time, the Scots saw the colony as a kind of Exodus, where they would start over somewhere new,” said D’Arrigo. “In the end, they couldn’t escape.”

Repeated proposals to unite England and Scotland had come up during the 1600s, but the Scots had resisted. As the famine came to a close, they finally gave in; apparently, many of the gentry making the decision figured that hitching themselves to a greater power would buffer them from further misfortunes. The Acts of Union, passed by the parliaments of Scotland and England, took effect in 1707. Scotland suffered other climate extremes in succeeding centuries, but never again collapsed in this way.

In 2014, more than 300 years after the union, the Scots took a referendum on whether to once again become an independent state; 55 percent voted to stay with the UK. Then came the 2016 UK-wide referendum that set Brexit in motion — deeply unpopular in Scotland, where 62 percent voted to remain in the EU. In last week’s UK parliamentary elections, pro-Brexit forces won overall, but lost resoundingly in Scotland. Many Scots now seem to be reconsidering independence — not because they want to stand alone again, but because independence might allow them to rejoin the larger community of the EU, and leave the isolationist English to fend for themselves. Calls for another independence referendum are already circulating.

“Scotland became more resilient when it became part of a union,” said Wilson. “It’s a cautionary tale from history.”

The study’s other authors are historians Patrick Klinger of the University of Kansas and Timothy Newfield of Georgetown University, and climate scientist Milos Rydval of the Czech University of Life Sciences.

The UC archaeologists announced the discovery Tuesday in Greece.

Jack Davis and Sharon Stocker, archaeologists in UC’s classics department, found the two beehive-shaped tombs in Pylos, Greece, last year while investigating the area around the grave of an individual they have called the “Griffin Warrior,” a Greek man whose final resting place they discovered nearby in 2015.

Like the Griffin Warrior’s tomb, the princely tombs overlooking the Mediterranean Sea also contained a wealth of cultural artifacts and delicate jewelry that could help historians fill in gaps in our knowledge of early Greek civilization.

UC’s team spent more than 18 months excavating and documenting the find. The tombs were littered with flakes of gold leaf that once papered the walls.

“Like with the Griffin Warrior grave, by the end of the first week we knew we had something that was really important,” said Stocker, who supervised the excavation.

“It soon became clear to us that lightning had struck again,” said Davis, head of UC’s classics department.

The Griffin Warrior is named for the mythological creature — part eagle, part lion — engraved on an ivory plaque in his tomb, which also contained armor, weaponry and gold jewelry. Among the priceless objects of art was an agate sealstone depicting mortal combat with such fine detail that Archaeology magazine hailed it as a “Bronze Age masterpiece.”

Artifacts found in the princely tombs tell similar stories about life along the Mediterranean 3,500 years ago, Davis said. A gold ring depicted two bulls flanked by sheaves of grain, identified as barley by a paleobotanist who consulted on the project.

“It’s an interesting scene of animal husbandry — cattle mixed with grain production. It’s the foundation of agriculture,” Davis said. “As far as we know, it’s the only representation of grain in the art of Crete or Minoan civilization.”

Like the grave of the Griffin Warrior, the two family tombs contained artwork emblazoned with mythological creatures. An agate sealstone featured two lion-like creatures called genii standing upright on clawed feet. They carry a serving vase and an incense burner, a tribute for the altar before them featuring a sprouting sapling between horns of consecration, Stocker said.

Above the genii is a 16-pointed star. The same 16-pointed star also appears on a bronze and gold artifact in the grave, she said.

“It’s rare. There aren’t many 16-pointed stars in Mycenaean iconography. The fact that we have two objects with 16 points in two different media (agate and gold) is noteworthy,” Stocker said.

The genius motif appears elsewhere in the East during this period, she said.

“One problem is we don’t have any writing from the Minoan or Mycenaean time that talks of their religion or explains the importance of their symbols,” Stocker said.

UC’s team also found a gold pendant featuring the likeness of the Egyptian goddess Hathor.

“Its discovery is particularly interesting in light of the role she played in Egypt as protectress of the dead,” Davis said.

The identity of the Griffin Warrior is a matter for speculation. Stocker said the combination of armor, weapons and jewelry found in his tomb strongly indicate he had military and religious authority, likely as the king known in later Mycenaean times as a wanax.

Likewise, the princely tombs paint a picture of accumulated wealth and status, she said. They contained amber from the Baltic, amethyst from Egypt, imported carnelian and lots of gold. The tombs sit on a scenic vista overlooking the Mediterranean Sea on the spot where the Palace of Nestor would later rise and fall to ruins.

“I think these are probably people who were very sophisticated for their time,” she said. “They have come out of a place in history where there were few luxury items and imported goods. And all of a sudden at the time of the first tholos tombs, luxury items appear in Greece.

“You have this explosion of wealth. People are vying for power,” she said. “It’s the formative years that will give rise to the Classic Age of Greece.”

The antiquities provide evidence that coastal Pylos was once an important destination for commerce and trade.

“If you look at a map, Pylos is a remote area now. You have to cross mountains to get here. Until recently, it hasn’t even been on the tourist path,” Stocker said. “But if you’re coming by sea, the location makes more sense. It’s on the way to Italy. What we’re learning is that it’s a much more central and important place on the Bronze Age trade route.”

The princely tombs sit close to the palace of Nestor, a ruler mentioned in Homer’s famous works “The Iliad” and “The Odyssey.” The palace was discovered in 1939 by the late UC Classics professor Carl Blegen. Blegen had wanted to excavate in the 1950s in the field where Davis and Stocker found the new tombs but could not get permission from the property owner to expand his investigation. The tombs would have to wait years for another UC team to make the startling discovery hidden beneath its grape vines.

Excavating the site was particularly arduous. With the excavation season looming, delays in procuring the site forced researchers to postpone plans to study the site first with ground-penetrating radar. Instead, Stocker and Davis relied on their experience and intuition to focus on one disturbed area.

“There were noticeable concentrations of rocks on the surface once we got rid of the vegetation,” she said.

Those turned out to be the exposed covers of deep tombs, one plunging nearly 15 feet. The tombs were protected from the elements and potential thieves by an estimated 40,000 stones the size of watermelons.

The boulders had sat undisturbed for millennia where they had fallen when the domes of the tombs collapsed. And now 3,500 years later, UC’s team had to remove each stone individually.

“It was like going back to the Mycenaean Period. They had placed them by hand in the walls of the tombs and we were taking them out by hand,” Stocker said. “It was a lot of work.”

At every step of the excavation, the researchers used photogrammetry and digital mapping to document the location and orientation of objects in the tomb. This is especially valuable because of the great number of artifacts that were recovered, Davis said.

“We can see all levels as we excavated them and relate them one to the other in three dimensions,” he said. UC’s team will continue working at Pylos for at least the next two years while they and other researchers around the world unravel mysteries contained in the artifacts.

“It has been 50 years since any substantial tombs of this sort have been found at any Bronze Age palatial site. That makes this extraordinary,” Davis said.