Juneau is getting 20 inches more rain annually than a century ago, snowfall could decrease by nearly 60% during the end of this century and the Mendenhall Glacier will likely mostly vanish from view of the visitor center by 2050, according to a new Juneau-specific climate report published Monday.
The changes are also significant threats to local food sources, such as salmon and crab species, to whales and tour operators profiting from sighting cruises and infrastructure ranging from a large percentage of Juneau’s downtown buildings to the Mendenhall Wastewater Treatment Plant.
However, the report published by the Alaska Coastal Rainforest Center at the University of Alaska Southeast goes beyond merely listing all of the past and future changes and their mostly adverse impacts, detailing remedies already being attempted and possibly mitigating future actions.
“Long before western observations of climate change, Indigenous people of Southeast Alaska observed and responded adaptively to changes in this dynamic environment, including rapid glacial advances and retreats, sea-level rise and fall, and a host of extreme events that are well-documented in oral histories,” Thomas Thorton, one of the study’s 22 co-authors, wrote in an introductory message.
“Now, a new era of climate change unprecedented in human history is upon us, and Juneau, as a modern capital city and regional hub, must respond and adapt accordingly. Juneau’s citizens have launched an innovative carbon offset program, its scientists engage in impactful marine, temperate forest, and glacial research, and its downtown port holds the world’s first plug-in shore power for cruise ships to reduce harmful greenhouse gas emissions.”
A webinar about the study hosted by some of its authors is scheduled for 9 a.m. Thursday.
For skeptics who argue changes in climate have occurred historically during periods measured in decades to millennia, the new Juneau-focused report agrees that is true — from a certain point of view.
For instance, the increase in average annual rainfall from roughly 160 inches in 1920 to 180 inches in 2020 didn’t occur in a straight line.
“The mid-1930s to mid-1940s were wet, then the 1950s to 1970s were comparatively dry, and since the mid-1990s wetter conditions have returned,” the study notes. “And within these decade or two intervals, there are individual years that are unusually wet or dry.”
However the key finding, as with most modern climate change impacts, is the historic amounts of the overall changes are likely to continue and often at increasing rates in the future.
“This year-to-year and decade-to-decade variability will continue in the future even as the long-term trend of precipitation continues to increase,” the study notes.
The changes will be harmful for local animal life ranging from tiny seabed organisms imperiled by increasingly acidic waters to mountain goats who may find only the peaks of mountains cool enough for them to exist during warmer months, according to the studies.
Harm to humans will range from Alaska Natives increasingly unable to survive on traditional food sources, to the potential loss of homes due to landslides and floods, to struggles for all involving everything from transportation to mental health.
In a similar way, while the overall increase in annual temperature of about 1 degree Fahrenheit since 1925 is not huge, the changes are significant during the winter and summer months.
“Taken as a whole, the retreat of glaciers, increased flooding, and greater avalanche threat are all related to these larger-scale changes in the environment,” the study notes. “Other observed changes that have cascading impacts, such as the duration of low- elevation snow cover, are directly traceable to seasonal changes in temperature and total precipitation. These changes will continue in the future, possibly at a much greater scale.”
There’s also some quirks contrary to global trends, such as rising sea levels, which has some major coastal cities worrying about significant portions being eventually submerged. But Juneau is experiencing a relative decrease in sea level that’s been occurring for centuries due to the area’s land surface uplift rates.
That finding gets stranger looking to the future, predicting sea level may drop up 2.9 feet or rise by as much as 4.3 feet by 2100 depending on the amount of global greenhouse gas emissions.
The report details nine primary findings, including seven impacts and two related to responses:
■ More precipitation: Juneau is experiencing a long-term upward trend, with average annual precipitation increasing about 20 inches during the past 96 years
■ Rising temperature: A general overall increase is marked by significant rises during in winter and summer, but much less during spring and autumn.
■ Less snowfall: Average winter accumulation at Juneau declined between 1940 and 2020, and continuing warming is expected to decrease snowfall near sea level.
■ Surface uplift and sea level rise: Sea level rise is currently outpaced by land surface uplift caused by receding glaciers, but sea level rise may overtake land surface uplift later this century.
■ Ocean warming: Warming sea temperatures are anticipated to greatly stress many parts of the ocean’s ecosystems — such as marine mammals, fish, and seabirds — and may enhance algal blooms.
■ Increasing ocean acidification: Declining marine pH will likely cause broad negative social and ecological impacts to marine ecosystems.
■ More landslides: Landslides are expected to increase as the climate becomes warmer, wetter and characterized by more extreme precipitation events.
■ Response – lowering greenhouse gasses: The City and Borough of Juneau has developed a climate policy and proposed implementing strategic climate actions to lower greenhouse gasses by obtaining 80% of Juneau’s energy from renewable sources by the year 2045.
■ Response – residents taking action: Juneau’s nonprofits and Tribal and local governments are taking action to mitigate and adapt to climate change.
“The fact that traditional wild food sources are now being ranked so that Indigenous people can better manage harvests under the limits imposed by climate change is a testament to the resilience of the Tlingit and Haida people,” the report notes on the second response item. “Faced with the bitter facts of change, the authors of the Climate Adaption Plan opted to tackle the situation head-on and find ways to adapt. The broader community can learn from this, as everyone in the CBJ can expect to have to adjust to changes in their food supply brought on by climate-related factors.”
• Contact reporter Mark Sabbatini at mark.sabbatini@juneauempire.com.
