HISTORICAL ACCOUNTS AND TWO DECADES OF TEMPERATURE DATA SHOW SUBSTANTIAL WARMING AT TWO APPALACHIAN COLD-AIR TRAPS

Historical accounts from Central Appalachian cold-air traps, such as algific talus deposits and enclosed caves, indicate seasonal ice accumulations persisted much later in the 19^th and 20^th centuries than in recent years. Semi-hourly temperature measurements and field observations at two study sites in eastern West Virginia record distinct signatures of short-term weather events, but also show a 21^st Century warming trend. Up to 20 m deep, bouldery talus at Ice Mountain drains cold air via >150 vents that sustain a refugium for regionally rare boreal flora and fauna at the bottom of the slope. Although only 230 m above sea level, the mean temperature at the longest monitored vent was 8.5 C° colder than nearby weather stations between 2004 and 2022. Over 200 air-flow observations and 2.1 million temperature measurements support the “cold-air-sinks” temperature-driven, density-stratification model that C.B. Hayden (1841; 1843) used to explain natural refrigeration at Ice Mountain. Several 19^th Century publications state that ice commonly persisted until very late summer, occasionally lasting winter to winter, but ice lasted no later than June during this study, when annual mean and maximum temperature trends rose 1.5 C° while annual minimum temperature trend remained unchanged.

A blocky boulder talus near Beartown Rock City exceeds 4 m deep locally but only a few weak cold-air vents occur below a series of depressions aligned along an avenue of large sandstone blocks 1030 m above sea level. Mean temperatures at the main ice hole were 7.5 C° colder than nearby weather stations between 2010 and 2022. Over 1 million temperature measurements suggest Hayden’s “cold-air-sinks” model applies to the Beartown ice holes, albeit moderated by a denser forest canopy and significantly greater snowfall than exist at Ice Mountain. Former Park Superintendent Mike Smith’s nearly continuous journal of July 4^th ice conditions notes that ice was present every year from 1985 to 1999, but missing at least three years between 2000 and 2009, and totally absent nine of the last 15 years. Smith’s journal is consistent with a 2.5 C° increase in the trend of July 4^th noon ice hole temperatures from 2009 to 2023. This study and historical accounts collectively raise concerns about the impact of escalating climate change on rare Appalachian ecosystems.