Two hundred and thirty-six years ago, when General George Washington returned to New York City when British troops were leaving, a volcano erupted in Iceland.
During eight months of 1783, the Laki volcano threw lava and released noxious fumes into the atmosphere. A quarter of the residents of Iceland died, and the sulfur-rich gases that spread throughout the world reflected the sun's rays, making many places on Earth colder.
Researchers believe that the Laki eruption was a catastrophe for residents of northwest Alaska, who had no idea why their July became November of that year.
Rosanne D'Arrigo of the tree-ring laboratory at the Lamont-Doherty Earth Observatory in New York recently told the story of Alaska's year without a summer. She attended the fall meeting of the American Geophysical Union last month in Washington, D.C.
On a poster in a cavernous meeting room there, she showed a photo of tree rings from an Alaskan white spruce tree. In the middle of a series of dark lines is a weak one that lines up with the year 1783.
Tree rings are thick-walled cells that form in conifers at the end of the growing season. The tree ring difficult to see in D'Arrigo's example shows a very unusual year, 1783, in the middle of centuries of normal spruce growth.
D & # 39; Arrigo, Alaska archaeologist Karen Workman and the late Gordon Jacoby once wrote about a "disaster for the Inuit of northwest Alaska" caused by the Laki eruption and the low temperatures that followed. Scientists based their conclusion largely on wood cores extracted from white spruce trees in the northern tree line.
James Louis Giddings gathered many of those plugs.
In June 1940, Giddings, an archaeologist and mining engineer educated at the UAF, flew from Fairbanks to Allakaket. Once in that small village, he aimed his compbad at a mountain pbad across the Koyukuk River that would take him to the headwaters of the Kobuk River.
Giddings then started walking. He carried a 40-pound package and a .22 rifle, along with "a change of heavy underwear that one should use as protection against mosquitoes."
He hit a log raft when he reached the Kobuk River. It floated along, traversing cores of trees along the road and stopping at known and possible archaeological sites.
At the mouth of the Kobuk, he turned right and traveled down the Noatak River. When Giddings ended there, he went to the Seward Peninsula, without finishing his scientific journey until he entered the town of Haybad, not far from the village of Koyuk.
In the fall of 1940, Giddings wrote his master's thesis, in which he details his remarkable season of fieldwork and the hundreds of tree cores he acquired.
Half a century later, scientists from Lamont-Doherty used some samples from Giddings. With recordings of tree rings from Giddings and others in Alaska and real data from the weather station gathered at the University of Alaska and elsewhere, the researchers reconstructed Alaska's summer temperatures from the late 1600s to the present.
They calculated that Alaska's average temperature from May to August was approximately 53 degrees Fahrenheit for most of that time. In 1783, the average temperature from May to August was around 44 degrees.
"You have this anomaly that is off the charts," said D'Arrigo.
To further show the rarity of 1783, the Lamont-Doherty scientists also cited a book of oral traditions of the Northwest Alaska Natives, written by William Oquilluk.
In the book, Oquilluk describes four ancient legends, each related to the near extinction of everyone living in northwest Alaska. The first two events were too far behind for the researchers to imagine what they might have been. The fourth and most recent disaster was the 1918 influenza epidemic that hit Alaska and the rest of the world with such force.
The researchers argued that the third calamity in northwest Alaska was related to the eruption of Iceland. Oquilluk wrote about this as "Summer time did not arrive".
That year (perhaps 1783), in the spring, the migratory birds had returned to Alaska and all seemed normal, until after last June. Then, "it suddenly became a cold climate … and people" could not go hunting and fishing, "Oquilluk wrote.
"In a few days, the lakes and rivers, recently thawed, froze. "The warm weather did not return until the spring (beginning of April) next year," the Lamont-Doherty scientists wrote in their 1999 article.
Since the late 1970s, the Fairbanks Geophysical Institute of the University of Alaska has provided this column for free in cooperation with the UAF research community. Ned Rozell is a scientific writer at the Geophysics Institute.