In 1570, construction was going strong on
sod houses in Nunalleq, a village in what’s now southwest Alaska. There were two rivers close by, perfect for
salmon fishing. Near the village, seals and caribou were abundant. And while this all sounds great, things weren’t
quite the same as they’d been in the past. It was colder than usual, there weren’t
as many salmon in the rivers, and the glaciers seemed to be expanding. The village, it turns out, was actually living
through a period now known as the Little Ice Age. Usually, “ice age” refers to glacial-interglacial
cycles - or times when there are major ice sheets and times when there aren’t - that
last for thousands of years. But this Ice Age lasted only a few hundred
years, which is why it’s “little.” During this period, ocean temperatures were
just a few degrees colder. That small change was enough to plunge most
of Europe into cold so extreme that Dutch canals froze solid, something that rarely
happens now. But Nunalleq seems to have thrived during
this period, based on the evidence a team of researchers has found in the remains of
hundreds of animals who lived - and died - near there. So how did this village manage to survive
and prosper during the Little Ice Age, and what caused this period of climate change
in the first place? We don’t have all the answers yet, but the
ones we do have come from some unlikely places: caribou teeth, dead beetles, and maybe even
the Sun itself. The term “Little Ice Age” was first used
in the 1930s to refer to a different 4,000-year-long period, but the definition has changed over
time. Today, climate scientists and geologists use
Little Ice Age to mean a few hundred years of climate change in recent history - but
exactly which few hundred years they mean varies; it’s still an ongoing debate. So, for this episode, we’ll call it 1400
to 1850. Now, in the grand scheme of deep time, the
Little Ice Age was basically just a blink - but for life in the Northern Hemisphere,
it was a game-changer. It’s particularly interesting to climate
scientists because it happened so fast. And while the Little Ice Age has mostly been
studied in Europe, researchers are now starting to look at its effects in other places. Which brings us back to Nunalleq, that village
in Alaska. From oral history passed down by community
elders, people living nearby have known about the site for a long time, but they left it
alone to preserve it. Things changed though, when the permafrost
started to melt, exposing two sod houses and thousands of artifacts to the elements. Since 2009, researchers have been working
with the Quinhagak Village Corporation to excavate the site, and to catalog, stabilize,
and store more than 100,000 artifacts as they emerge from the permafrost. These objects are currently housed in a museum
in Quinhagak, the community closest to the site. It’s the largest museum collection of pre-contact
Yup’ik artifacts in the world. Based on radiocarbon dating, it looks like
the site was primarily occupied from 1570 to 1675 - entirely during the Little Ice Age
- making it incredibly valuable for understanding how people there survived the colder climate. And one way to study this is through their
trash. Refuse piles near the sod houses contain animal
bones, antlers, and teeth that are a treasure trove of environmental and archaeological
data. From these piles, we know that the residents
of Nunalleq ate a combination of different types of wild game, including fish and marine
mammals, as well as land animals and birds. And in 2020, more data emerged to help quantify
the impact of the Little Ice Age on the village. The research team used the remains of beetles
from the site to find that temperatures were at least 1.2 degrees Celsius colder than the
modern average. Which might sound like a small change, but
it’s actually more extreme than other parts of the Northern Hemisphere. -- On average, summers were between 0.5 and
1 degrees Celsius colder during the LIA, compared to the 20th century. And between the archaeological data and the
climate data, it looks like Nunalleq was doing just fine during one of the coldest parts
of the LIA. But the landscape around it was changing throughout
that period. From tree rings, ice cores, and other chemical
records, it’s clear that there was a climate shift in Alaska and Canada that spanned the
Little Ice Age. And this brings us back to the caribou found
in the village’s refuse piles. Throughout the site’s history, caribou were
an extremely important resource. While the people there didn’t actually eat
much of their meat, they did hunt a lot of caribou for their antlers and skins, used
to make tools and clothing. And from teeth found in the refuse piles, the research team was able to study four caribou and reconstruct their lives using
isotopes. These showed that the caribou used different
breeding and calving grounds than the herds that live in the region today. Something made the caribou shift their ranges
between the LIA and today. And whether that was human adaptation to the
climate or the changes to the environment caused by the changing climate itself, we’re
still not sure. What it does tell us, though, is that this
region of Alaska is part of the bigger global story of changes caused by the Little Ice
Age. Decades of research have shown that the Arctic
cooled more than some temperate regions, but there were still impacts around the world. Geoscientists have studied all kinds of natural
archives, from isotopes in bones in western Argentina to flood deposits in Greece, that
recorded change during the LIA. Now, that doesn't mean that the world's climate
cooled everywhere. There's still a lot of debate about how exactly
the LIA affected different parts of the world. But it does look like it was a time of increased
climate variability - one that seems to have had many different causes. One hypothesis with solid evidence is that
several solar minima were partially responsible These are times when there’s just less solar
activity, meaning that the sun doesn’t send as much light to Earth. These are a part of the normal solar cycles
that happen to this day. But it wasn’t enough to cause the Little
Ice Age by itself. Another potential cause was changing land
use in the Northern Hemisphere. Computer models and climate simulations suggest
that as humans disturbed natural land cover, like forests, the new bare surface was more
reflective. Scientists call that reflectivity albedo. High albedo means the surface reflects a lot
of sunlight away from the Earth, and low albedo means that the heat and light are absorbed. The snow covered ground without trees increased
albedo during the Little Ice Age, making it colder, especially in the winter. So far, estimates suggest that the impact
of changes in land-use was about the same as the impact of the solar minimum. And those weren’t the only potential contributors
to the cold - there were also volcanoes. Increased volcanic activity can lead to cooling
because it puts more particles in the atmosphere, shading the surface of the Earth from the
Sun’s energy. One study noted 16 different eruptions linked
to cooling events between 1630 and 1850, based on particle data from ice cores. And two of the eruptions - one in Japan and
one in the Philippines - happened toward the end of the time Nunalleq was occupied. These eruptions, plus reduced solar radiation,
might’ve also caused a major change in an important ocean-atmosphere interaction, called
the North Atlantic Oscillation. See, there’s a delicate balance between
sea surface temperatures and wind, and when that balance is thrown off, it can have wide-ranging
effects. And it can be thrown off by things like volcanic
eruptions triggering colder summers. Man, to be honest, the Little Ice Age sounds like
a really tough time: volcanic eruptions, changing wind and temperature, and even a weaker Sun?! Despite these changes, there’s no indication
that food was scarce at Nunalleq, even though there were famines and struggles in Europe
during the same period. So why the difference? Well, one reason is probably that the people
of coastal Alaska had a diverse diet, eating a mixture of marine and land animals. Life in the Arctic was often relatively extreme
and unpredictable, so they were just more used to change. If Nunalleq had relied on just one source
of food, or on agriculture, they would have been in trouble. But instead, they were able to adapt to the
shifting environment. In fact, the end of the occupation of Nunalleq
doesn’t seem to have been directly caused by an environmental disaster. Instead, it looks like the settlement was
attacked or involved in a war that occurred roughly between 1645 and 1675. However, some researchers have suggested the
negative effects of the changing climate may have triggered this conflict. Eventually the sod houses sank into their
surroundings and the artifacts they held were trapped underground, perfectly preserved. Though centuries have passed, Nunalleq lives
on as a valuable cultural and environmental archive as new data and artifacts emerge. Those artifacts help draw connections between
life in the village and the modern community: Caribou hunting and salmon fishing remain
an important part of life in southwest Alaska today. And perhaps there are lessons we can all learn
from this village about resilience in the face of extreme climate change. A bunch of our PBS friends across YouTube
are celebrating Earth Day — follow me over to Overview on Terra for a look at one of
the world’s largest garbage dumps (and how this trash is being turned into usable energy). Tell them Eons sent you! One more thing — for those of you in the
US, you should check out Greta Thunberg: A Year to Change the World, a new 3-hour Earth
Day broadcast event on your local PBS station. The special is going to premiere on Thursday,
April 22nd at 8/7 central, and will then repeat starting Wednesday, April 28th at 8/7c. A big thank you to the Nunalleq Archaeology
Project for providing us with materials for this episode! If you want to learn more about Nunalleq,
check out their very cool interactive educational resources in the link in the description. Also thanks to this month’s Eontologists
for being so cool: Sean Dennis, Jake Hart, Annie & Eric Higgins, John Davison Ng, and
Patrick Seifert! Becoming an Eonite at patreon.com/eons and
you can get fun perks like submitting a joke for us to read, like this one from Lil: What
does a cow do when she is stressed? She gets a moosage. I need a moosage too And as always thank you for joining me in
the Konstantin Haase studio. Subscribe at youtube.com/eons for more evolutionary
escapades.
