International climate change and rainforest experts warned that without drastic and immediate cuts to greenhouse gas emissions and new forest protections, the world’s most expansive stretch of temperate rainforests from Alaska to the coast redwoods will experience irreparable losses.
Using global climate models, researchers assessed changes in temperature and precipitation from recent to future climatic conditions projected toward the end of the century if emissions from burning fossil fuels and deforestation continue to rise.
According to the lead researcher, Dr. Dominick A. DellaSala, Chief Scientist of Geos Institute, “In the Pacific Northwest, the glass is half empty as the climate may no longer support rainforest communities like coast redwood, while on the Tongass National Forest in southeast Alaska the glass is half full as cooler, moister conditions may prevail as a refuge for rainforest communities that can migrate in time.”
Applied climate models predicted the future distribution of eight rainforest conifers of commercial value and broad rainforest communities across a 2,200-mile stretch of coastal rainforests in the Pacific Northwest, British Columbia, and Alaska. Published by Science Direct in the online global reference “Earth Systems and Environmental Sciences,” key findings include:
- Coast redwood could lose up to 23% of its current distribution as the climate changes more drastically in the southern rainforest region.
- Alaska yellow-cedar could lose up to 21% of its current distribution and already is experiencing extensive dieback from warming and reduced snow pack.
- Entire rainforest communities in southern Oregon and northern California may contract, while in southeast Alaska and British Columbia rainforests may expand upward in elevation as glaciers recede.
- Most of the region’s parks and wilderness areas do not include localized pockets of relatively stable vegetation and climate suitable for rainforest species to find refuge from a warming climate.
Dr. Marni Koopman, Climate Change Scientist, Geos Institute, stated, “Our results provide the first comprehensive assessment of climate change shifts likely to affect commercially valuable conifers and rainforest communities across two countries (US and Canada) and four states (Alaska, Washington, Oregon, California).”
The study concluded that there is still time to act by reducing greenhouse gas emissions and protecting rainforest vegetation. Priority areas include north-facing slopes with older forests in the Pacific Northwest, which are likely to maintain cooler conditions in a warmer and drier climate, and extensive old-growth rainforests on the Tongass National Forest where rainforest communities could find refuge despite declines in some species (e.g., yellow-cedar).
DellaSala added, “The Tongass is our best hope for holding onto the verdant rainforest web-of-life that has sustained native peoples for millennia and supported the subsistence economy of southeast Alaska but only if the old-growth forests are protected for their climate and wildlife benefits.”
Dr. Patric Brandt of the Research Program on Climate Change Agriculture and Food Security (CCAFS), which specializes in global warming research, participated in the study, adding, “We know from studies around the world that if rainforests are stressed by the combined impacts of climate change and land-disturbances, there is little hope in maintaining their ecosystem benefits for people or wildlife over the long term.”
North Pacific coastal rainforests represent 35% of the world’s total temperate rainforests. Globally, most of Europe’s temperate rainforests and the coast redwoods are already gone due to logging and development, while temperate rainforests on the Tongass and Great Bear (British Columbia), Tasmania, Russia, and Chile remain relatively intact.
The impacts of human-caused climate change are scientifically indisputable and Alaska is already experiencing some of the most rapid and severe changes in the world. During the past thirty years, Alaska has experienced sharp reductions in snow-cover, shorter river- and lake-ice seasons, melting glaciers, sea-ice and permafrost retreat, increased depth of summer thaw, and displacement of aboriginal villages from traditional lands. Actions taken now should explicitly address such issues to avoid exacerbating consequences for Alaska’s natural resource-based economies as temperatures are projected to increase by another 4 to 8 degrees Fahrenheit by mid-century.
For a copy of the study abstract:
For additional information on temperate rainforests: