Tim Kohler.There is perhaps no one in the Inland Northwest who understands the dire consequences laid out in the United Nations’ Intergovernmental Panel on Climate Change’s (IPCC) report better than Tim Kohler, a WSU emeritus professor of archaeology and evolutionary anthropology.

He holds the distinction of being the first archaeologist to contribute to an IPCC report as a lead author.  He is also the only lead author from Washington state on the recently released 157-page section of the IPCC’s report on North America.

“One of the things archaeologists see that most other IPCC authors do not is that the changes are going to come more rapidly than we have ever seen in the past,” Kohler said. “Contributing to the report is really a small breakthrough for archaeology and shows that the IPCC is starting to take longer sweeps of history into account when assessing the significance of the coming climate changes.”

The latest IPCC report forecasts bad news for a host of issues from rising food insecurity to increasing social inequality in North America unless steps are taken now to reduce global carbon emissions.

In the Pacific Northwest, increased summer temperatures and reduced precipitation are expected to pose a major risk to semi-arid landscapes such as Eastern Washington, according to the report. Forest disturbances, including wildfire, drought, insects, and pathogens are also expected to increase with warming, potentially altering or threatening local ecosystems.

Warming-induced reductions in mountain snowpack and earlier seasonal snowmelt are expected to affect everything from local stream ecology and water supplies to winter tourism. For example, the report predicts with high confidence an 80-100% reduction in the length of the cross-country skiing and snowmobiling seasons in North America by mid-century, depending on future greenhouse-gas emissions.

Reduced snowpack coupled with more frequent droughts will increase water scarcity during the summer season especially in regions like Central Washington that have extensive irrigated agriculture. This could, in turn, lead to economic losses and increased pressure on groundwater as a substitute for diminished surface water supplies.

In Seattle, the report predicts sea level rise will threaten low lying areas, near shore habitats, stormwater drains, roads, homes, and businesses. Communities of people that are socially or economically vulnerable are expected to bear the brunt of the impact.

On the Pacific Coast, an increase in the intensity and frequency of marine heat waves is expected to threaten aquatic ocean life, and projected river warming of 1-3 C (1.8–5.4 F) is expected to reduce habitat for salmon and trout species by as much as 31%.

Overall, the report predicts major losses to North American biodiversity, hundreds of billions of dollars in economic losses in the U.S., and spikes in heat-related human mortality and crime during the hot summer months.

“All organisms on the surface of the Earth—plants, animals, and people—are adapted to specific climate conditions,” Kohler said. “Increasing temperatures will ultimately result in movement (or possibly disappearance in some cases) of the locations on Earth’s surface that these plants and animals are adapted to, with dire consequences for organisms that cannot move.”

Sand dunes stretching across the Sahara Desert (stock image).

The IPCC released the climate assessment last week which included contributions by 195 UN member countries on how global warming is influencing nature, agriculture, and human health. It leaves little room for debate the planet is at its tipping point, and some of the damage is already irreversible. For example, the planet is already, on average, 1.1 C warmer (2 F] than 1850-1900 levels and is on pace to reach 2 C (3.6 F) degrees or more, according to Kohler. The IPCC report explains how these patterns will worsen over time, in some places affecting how long humans can be outside for work or recreation because the heat would be intolerable.

As far as what can be done to mitigate the fallout of climate change, the IPCC authors provide a detailed roadmap for policy makers that lists many of the strategies and innovations that could be used to help humans adapt. For example, advances in weather forecasting are expected to provide vulnerable communities ample warning time before the occurrence of many extreme weather events, and major water agencies throughout North America are using climate scenarios to identify vulnerabilities and evaluate adaptation options. Other adaptation responses include modifying structures and the urban landscape of major cities through the planting of trees and other green infrastructure, which increases climate resilience and quality of life by reducing urban heat effects while improving air quality.

Much of Kohler’s research focuses on how humans have adapted to a changing climate in North America throughout history. He explained that people were able to flourish across the continent at the end of the last ice age almost 12,000 years ago because the world entered a period of climatic conditions conducive for agriculture called the Holocene.

“The Holocene helped us to become agriculturalists,” Kohler said. “It helped us grow cities and have really productive agriculture systems that would allow for the development of writing and all the various sorts of superstructures we’ve had in our societies. And we are in danger of kicking ourselves out of this precious Holocene climate envelope.”

Top image: Tim Kohler

By Will Ferguson, WSU Insider