The Arctic and sub-Arctic are warming almost twice as fast as the rest of the world. As a result, people traveling across Interior Alaska are encountering climate-related changes in the environment that are challenging their traditional access to important local resources. There are almost no roads in this region, so travel is mostly by boat and four-wheelers in summer, and by snowmachines or dogsleds in winter.
Between 2016 and 2017, 26 observers from nine communities in Interior Alaska documented climate-related environmental conditions that were affecting their travel to areas used for hunting, fishing, trapping, and gathering. These conditions included ice, snow, erosion, sedimentation, water levels, vegetation composition, and weather.
Rivers and lakes have always been efficient “highways” for snowmachine and dogsled travel. Thick, stable, and predictable ice meant safe and reliable winter travel. Increasingly, this is not what is being experienced by people.
Observers reported rivers and lakes freezing later and thawing earlier than what they experienced in the past. Also, thin ice and open water are becoming more common in midwinter and restricting access to otherwise well used travel routes. Open holes and thin ice throughout winter make for extremely dangerous conditions that have claimed lives. More frequent overflow on river ice slows or reroutes travel. More frequent occurrences of shelf ice forming along riverbanks can pose obstacles to snowmachine routes all winter long.
Unusual freeze-up and ice shelf caused by a 3 day wind storm as it cooled and froze. The lake ice was very rough with large chunks and a very thick buildup of solid ice near the shore and on grasses. This is a large (10 ft approx.) ice shelf that is so slippery and uneven to walk on it required crampons of the extreme toothed kind and is dangerous where it drops off to lake ice for machines and man trying to go from land to lake for travel. The snowmachines require snow. This needed to be crossed for main winter wood gathering.
This change affects trapping. I first started noticing this change in 2016, and have not observed it before. It has a strong effect on safety.
Thin ice on river. Can't travel the river yet and there is not enough snow to go overland on snowmachines—have to use 4×4s for setting trapline. Rivers that are not frozen this time of year are a hazard to traveling.
This change affects trapping. I first started noticing this change in 2005 and now observe it seasonally. It has a strong effect on safety.
Open water in January. Froze to the bottom, then flooded over because of lack of snow (no insulation). This can be dangerous and hard for snowmachine travel. It's hard on machines and I had to find a route around.
This change affects trapping. I first started noticing this change in 2011, but do not observe it seasonally. It has a strong effect on safety.
Open water in snowmachine trail on way to check beaver sets going toward Kaiyuh. Open all the way across, makes snowmachine access dangerous.
This change affects trapping, happens seasonally, is observed often, and has a moderate effect on safety.
Mushing from shore onto the spring ice, then out on the ice of the lake. Travel on the lake is still good by dog team, although the dogs need to go through water flooding the edge of the ice getting on/off the pack ice. Usually at this point the surface is hard and free of snow and slush, but this year found a layer of thin ice overlying watery slush sitting on the pack ice, making it slow and a little unpleasant for the dogs. Can be challenging and occasionally dangerous.
This change affects travel, and is observed seasonally. It has a moderate effect on safety.
Blue dots show where ice condition observations were recorded. Observers reported open holes on rivers during winter, thin ice, late freeze-up, early-thaw, overflow, and shelf ice.
Other data support observations of changing ice conditions. This map shows average winter (Dec, Jan, Feb) air temperatures from 1970–1979. Shades of blue indicate temperatures below 0°F. Red shades indicate temperatures above 0°F.
As you slowly scroll to the next map, notice how the red areas expand across interior Alaska.
This map shows winter temperatures in the 2010s. While average winter temperatures are still below freezing (32°F), consistently long periods of very cold (below 0°F) conditions are decreasing, resulting in significant changes to the onset, quality, and duration of ice.
Observers describe that in the past temperatures would drop in September. By October, snow would begin to accumulate and remain all winter. Consistent drops in temperature and dependable snow accumulation provide optimal winter travel conditions by snowmachine and dogsled.
Recently, delayed and more variable seasonal snow accumulation, as well as precipitation in the form of rain during winter, are making winter travel harder and unpredictable. Rain-on-snow (icing) events are more common, and leave the snowpack crusty, thinner, and hard. Trails are much rougher, can be difficult to traverse, and are hard on sled suspensions and dog feet. It’s much easier to get stuck on brush and overheat snowmachines that need a deep, soft snowpack to cool engines. With these changing conditions there is more use of four-wheelers during what had been the winter travel season in the past.
ATV on frozen trails through swamp with no snow yet. These are good conditions for travel. Mud holes are frozen so ATV doesn't get stuck and no snow to plow through.
This change affects hunting and fishing. I first started noticing this change in 2006, and now I observe it yearly. It has no effect on safety.
The trapline trail with not enough snow to snowmachine on. I had to use 4x4s to set the trapline - too little snow for snow-gos, areas were limited as 4x4s can't go some places (ATVs).
This change affects trapping. I first started noticing this change in 2005 and now observe it seasonally. It has a strong effect on safety.
No snow, driving on a snowmachine from Kaltag to Unalakleet. Creeks running open with open water. Low snow and warm temps meant the snowmachine kept overheating, and I had to make many stops.
This change affects hunting and village travel. I first started noticing this change in 2013. I observe this change seasonally. It has a strong effect on safety.
Dog team hauling gas during spring melt. Gravel exposed on Holek Spit grinds on sled runners, a problem especially when hauling heavy loads.
This change affects traveling and hauling supplies. This change happens seasonally, but is happening earlier now. It has a strong effect on safety.
Blue dots show where snow condition observations were recorded. Reports include later snow, rain-on-snow events, no snow in midwinter, significant snow accumulation during a single weather event, and early snowmelt.
This map shows the average of the proportion (fraction) of wet days in November that received snow during the 1970s. Darker colors indicate more precipitation falling as snow; lighter shades indicate less.
As you slowly scroll to the next map, notice how the map becomes dominated by lighter shades.
The greater amount of lighter shades across Interior Alaska indicates that more November precipitation is falling as rain. This is being directly observed by those living and traveling on the landscape.
Rivers in Interior Alaska have always provided critical travel corridors for residents in this mostly-roadless region. For Interior Alaska residents, the Yukon, Tanana, Kuskokwim, and Chandalar rivers are equivalent to major highways around urban areas.
Once river ice thaws, boats replace snowmachines. Although these rivers always undergo seasonal changes that influence their navigability, those changes have become more erratic. Observers reported rapid bank erosion and unseasonably high or low water. Increased erosion can make boat travel on rivers more dangerous due to the increased amounts of debris in the water, and river channels becoming shallower and wider. Debris can also quickly change otherwise well established river channels. Increased sediment deposition in rivers is increasing the size of sandbars across larger glacier-fed rivers and making some rivers shallower and harder to navigate.
Changing water levels and shallower rivers impact fishing: locations that have been reliable in the past are no longer a sure bet and sometimes force people to find new spots to fish. Fishing nets or fish wheels snag on the river bottom or fill more quickly with debris, often sustaining damage in the process.
Unseasonably high or low water in September—an important time for moose hunting—can help or hinder hunting. High water on main rivers covers riverbanks where moose might otherwise be found, but can also fill small tributaries that improve hunting access. Abnormally low water prevents access to lakes and sloughs near river channels.
Huge chunks of land eroding along the Yukon River, large sections of shoreline falling in, even in areas that are not exposed to current (maybe just sunny). This changes the navigability of river channels, because the rate of change has increased. We need to find new fishing spots. You have to watch out for trees falling on you and rolling waves. It has changed historic fishing area for the first time. In 2016 this change was way worse, with way warmer temperatures. There is riverbank erosion in other areas, but this is one of the most severely affected areas. We are trying new spots all the time now, regulations add another layer of challenges.
This change affects fishing, and I observe it seasonally although it was way worse in 2016. This change has a strong effect on safety.
Erosion and mudslide. It loads debris in water and changes boat travel.
I notice this change every few decades and I have seen it in a few other areas. It has a moderate effect on safety.
High water in mid September, 4 miles up the Innoko. It usually goes way down by this time. It's harder to catch fish, and harder to see moose (but better access, although leaves grown back (from caterpillars) obstructing visibility).
This change affects hunting and fishing. I notice this change every few years. I've seen this change everywhere. It has a moderate effect on safety.
Historial (gray bars) and future projections (colored bars) of precipitation for Nulato, Alaska. Precipitation is projected to increase in every month by mid century, with mid summer and early fall months experiencing the highest increases. Some of these changes are already being observed throughout interior Alaska, as observers have noted.
Trails along riverbanks, through the boreal forest, and across wetlands are used year-round. Although trails are always important corridors for accessing resources, trail access across lakes and wetlands is limited in summer by the increased presence of water.
Trails and roads located close to riverbanks and lakes are increasingly being damaged or completely destroyed by bank erosion. Banks are steeper, making it more difficult to get to portages. On land, unseasonably wet conditions quickly deteriorate trails and sometimes make them impassible.
As they traversed the landscape, observers reported seeing more sinkholes, which are likely related to thawing permafrost. In the summer, these holes fill with water and sometimes cut off trail access. In winter, sinkholes create conditions that are easy to get stuck in and difficult to navigate through. All of these environmental changes have made for slower and more uncertain travel conditions throughout the year.
River bank erosion. River bank was flat across here about 2 years ago. "Hungwinja" is this name of this place. Erosion wiped out the road, you can't drive across it anymore, you have to walk. Pretty soon water might flow into a nearby man-made pond.
This change affects village travel. I first started noticing this change in 2013. I've seen this change in a few other places and it has a strong effect on safety.
Water on the road towards the mountain, restricting access to berry picking (blueberry, cranberry) and fall moose hunting. The water is caused by runoff from the mountain - fire north of here opened ways for water to come down.
This change affects hunting and gathering berries. I first started noticing this change in 2004, but now I see it seasonally. This change has a strong effect on safety.
A huge sinkhole in the trail from cabin to road access. This slows everything and prevents travel when accidents are likely, falling into hole or ruining motor on machine if it sinks into water, due to higher temperatures, excess rain and humidity.
This change affects all travel from our cabin. I first started noticing this change in 2014. This change occurs seasonally and I've seen it in other areas. It has a strong effect on safety.
The intersection of the roads paralleling the main runway on the west with the lake and beach roads going north and then south to access the north beach runway and parking area. The water is too deep to travel through and loose gravel pile up hampered us also. It flooded up along the stop sign, usually on the beach. No road at all usable, blocked by water, banks and brush. This completely prevents the use of this travel area in several directions because of high deep water and new loose gravel preventing good traction. We have to travel by boats only, subject to wind conditions over water, or go up over the hills in the woods over longer, slower route, which is also often not usable.
This change affects travel for all purposes. I’ve never seen this before. This change has a strong effect on safety.
Sand deposited on trail from washouts. Just a photo to show how much material has been moved. Actually makes travel in this location easier now.
This change affects hunting and gathering. I first started noticing this change in 2012, but no see it seasonally. This change has a moderate effect on safety.
Here, participants noted land and water conditions that impact travel in terms of erosion, sedimentation, and changes in water levels. Observer reports include seeing more debris in rivers from bank erosion and greater amounts of water level variability—each of which directly affect navigability of rivers and trails.
These maps show model output for July soil temperature at 2 meters depth as a proxy for permafrost changes. As you scroll to the 2010s, you can see the northern half of the region cross over the 32°F freezing threshold. This is likely the threshold that observers are now experiencing through deteriorating trail conditions across Interior Alaska.
Lakes now contain more vegetation, or are drying up and being replaced by thick shrubs. Thicker brush on trails makes travel more difficult and requires more trail maintenance. Some airstrips are no longer usable because of brush expansion. Excess lake vegetation clogs boat motors or becomes entangled in propellers. In some cases lakes are drying up altogether. This is changing both the travel methods that are possible for people in those areas as well as the distribution of fish, birds, or wildlife harvested in those areas.
Fire rapidly changes the landscape. Forest fires are a part of the natural cycle of the boreal forest and can improve moose and berry harvest opportunities. However, increasing fire frequency and intensity can hinder travel. After a fire, trails can be very obstructed and difficult to find. Accessing a trail for the first time after a fire requires a lot of work to clear slash, often with a chainsaw. Even after the initial clearing of a trail, trees will continue to fall for years after a forest fire and require continual trail maintenance.
Many hunting areas turned into meadows. This lake is drying on the north side of river (sunnyside). We need to find new hunting and trapping areas (requires traveling further, 10 miles in the past, 40 miles today). Areas are ‘shrubbing over’. This condition does provide for easier winter trail access (no ice or water).
I first started noticing this in 1987. This change has increased over time and I've seen it in other areas. This change has a weak effect on safety, and even has increased safety.
Extreme amount of lake grass. It's harder to get around with outboards and I have switched to a go devil style outboard.
I first started noticing this change in 2006. It has become more extreme in the last 10 years, and I've seen this change in a few other areas. It has a moderate effect on safety.
Fire in Nulato during hot, dry summer. Very poor air quality. It shut down all travel during fire. I couldn't go on ATV trails because of fallen trees (lots of trees fell).
This change affects village travel. I see this happen every few years. It has a moderate effect on safety.
Trapping trail through burned forest. The 2015 Carlson Lake Burn had a few places where deadfall seriously impeded travel the first time through, requiring prodigious use of chain saw. This delayed getting the trail opened up during a critical time. It also required a halfway tent camp to be used; normally we don’t have to camp out for this run.
This change affects trapping and occurs every few years. This change has a strong effect on safety.
This plot shows historical and projected total area burned across Alaska. The decades of the 1990s and 2000s have had several high fire years, and a “new normal” of high fire occurrence and total area burned is beginning to emerge when looking at expected projections in the future.
These are areas of vegetation changes that affect travel and access. Observer reports include the presence of more vegetation, falling trees from fires and erosion, and changes to vegetation from fire.
This map indicates that the majority of areas burned has occurred in more recent decades (red shades). More fire on the landscape is resulting in more impacts to communities.
Environmental changes are affecting people in many ways as they traverse the landscape. In many cases, travel is more dangerous as a result of conditions such as open water during winter, or more debris in the rivers during summer. Some changes are harder on equipment, like boat motors clogging more often or having to navigate rougher, eroded terrain. Some travel routes are being damaged or cut off by things like erosion and high water levels. In some cases, access can improve—for example, high water levels in fall have allowed travel up small streams that may have previously been unnavigable.
Some hunting, fishing, trapping, and gathering opportunities are reduced or even missed, with increased variability in seasonal weather and physical events such as the timing of fall freeze-up and spring break-up. River ice in spring deteriorates faster, increasing the amount of time when river travel by snowmachine is unsafe yet still impossible by boat. Higher water levels and warm temperatures during a time a year that was previously noted for having less precipitation and cool temperatures affects fall hunting opportunities.
With these changes, people are having to find ways to adjust when or how they travel, and adapt to different conditions that often make it harder to access important harvest resources.
This project would not have been possible without the contributions of individuals across Interior Alaska. We would like to thank all of those who submitted photos and observations to this project as well as those who wished to remain anonymous.