A tribute to Arthur H. Lachenbruch (1925-2021)
and reflections on his contributions to permafrost science and engineering
The IPA has learned with sadness of the death of Arthur H. Lachenbruch at Corvallis, Oregon, on 20 September 2021. He was 95.
Art was a giant of North American permafrost science. From the late 1950s until the 1990s, he produced consistently stimulating and innovative research papers, with techniques of analysis that were quickly adopted and applied in the United States and Canada. His career was spent with the United States Geological Survey, which he joined after high school in 1943. His contributions to permafrost science sprang from extensive fieldwork on the Alaskan North Slope, starting as camp cook and field assistant, an innate interest in terrestrial heat flow, and a remarkable facility with quantitative analysis. His first two articles, concerning the thermal disturbance to permafrost from heated buildings and from the ocean at the coastline, were published in 1957, a year before he received his Harvard Ph.D. They were immediately seized on by J. Ross Mackay, who used Art’s methods to model the development of taliks beneath lakes in the Canadian western Arctic
Art’s field time in Alaska during the 1950s stimulated a series of papers and reports on thermal contraction cracking, culminating in his Geological Society of America Special Paper (1962) on the Mechanics of Thermal Contraction Cracks and Ice-wedge Polygons in Permafrost. He received the Kirk Bryan award of the GSA for the monograph and insights on contraction cracking in other environments, such as in the formation of basalt columns (1961). The monograph remains the primary source of theoretical analysis on the development of ice-wedge polygons. He pointed out the importance of the rate of temperature change in permafrost for ice-wedge cracking. It was his principal contribution to the geomorphology of permafrost environments, for by the time of the Special Paper and the first ICOP (1963), his work was oriented to geothermal problems including measurements of temperature and heat flow at great depths.
Art’s geothermal research was largely focused on the western states of the lower 48, but exploration for oil in the 1960s and 70s in Alaska led to wells that penetrated deep permafrost and provided access to its entire temperature profile. These profiles, published in the JGR (1982) and Science (1986), showed warming of the upper permafrost that Art was able to reconcile with post-Neoglacial climate amelioration. The work led to great interest in the response of permafrost to climate change, which Art directed towards the near surface in his lecture at the fifth ICOP in Trondheim (1988). This paper presented a rational structure for permafrost-climate relations that was subsequently an impetus for Vladimir Romanovsky and Tom Osterkamp’s 1995 characterization of the thermal offset. A few years later Tom established the trans-Alaska monitoring transect, a series of ground temperature installations that continues to yield the premier baseline record of permafrost response to climate change for the permafrost regions of North America.
The monitoring transect is spread out along the Trans-Alaska pipeline, infrastructure that was originally designed to be buried throughout its entire length, even in the ice-rich permafrost north of Fairbanks and on the North Slope. Art knew this design was untenable and prepared a short USGS Circular, innocently titled Some estimates of the thermal effects of a heated pipeline in permafrost. It was a devastating critique that averted environmental disaster. It led to redesign of the pipeline as an elevated structure above ice-rich permafrost and an order-of-magnitude increase in the project’s cost. In terms of societal consequences, it can be considered the single most important report on permafrost published in North America. Today, no one would venture to bury facilities operating above 0°C in permafrost.
We know Art best for the work summarized here, but for 25 years from the early-1960s he led work on heat flow in the western US with his principal collaborators John Sass and Vaughn Marshall. The research yielded insights into the structure and active processes in several geologic provinces, such as the distribution with depth of radiogenic heat producing elements and tectonic effects on heat flow. Along with his earlier contributions, including to permafrost environments, these activities led to his election in 1975 as a Fellow of the National Academy of Sciences. His work was further recognised in 1989 with the Bucher Medal of the AGU indicating for us the breadth of his interests and capacity. His final paper was published in 2019, at age 93. It reported data collected over 50 years ago that could not be fully analysed at the time due to pressures induced by the pipeline work.
Art was a gentle and gracious man, devoted to his family and sadly predeceased by his dear wife Edie and second son, Charlie. He leaves his elder son, Roger, and daughter, Barbara. We will remain astonished by his contributions and will remember him with our utmost respect.
Christopher R. Burn
I thank Barbara Lachenbruch, Jerry Brown, and Fritz Nelson for helpful comments and Colin Williams for notes on Art’s work beyond the permafrost environment.
Lachenbruch, A.H. (1957). Three-dimensional heat conduction in permafrost beneath heated buildings. U.S. Geological Survey, Bulletin 1052-B, 51-69.
Lachenbruch, A.H. (1957). Thermal effects of the ocean on permafrost. Geological Society of America Bulletin, 68(11): 1515-1530.
Lachenbruch, A.H. (1961) Depth and spacing of tension cracks. Journal of Geophysical Research, 66(12): 4273-4292.
Lachenbruch, A.H (1962). Mechanics of thermal contraction cracks and ice-wedge polygons in permafrost. Geological Society of America, Special Paper 70. 69 p.
Lachenbruch, A.H. (1966). Contraction theory of ice-wedge polygons—a qualitative discussion. Permafrost—International Conference, Lafayette, Indiana, Nov. 1963. National Academy of Sciences – National Research Council Publication 1287, 63-71.
Lachenbruch, A. H. (1970). Some estimates of the thermal effects of a heated pipeline in permafrost. U.S. Geological Survey, Circular 632, 23 p.
Lachenbruch, A.H., J.H. Sass, B.V. Marshall, T.H. Moses, Jr. (1982). Permafrost, heat-flow, and the geothermal regime at Prudhoe Bay, Alaska. Journal of Geophysical Research, 87(B11): 9301-9316.
Lachenbruch, A.H., B.V. Marshall (1986). Changing climate–geothermal evidence from permafrost in the Alaskan Arctic. Science, 234(4777): 689-696.
Lachenbruch, A.H., T.T. Cladouhos, R. Saltus (1988). Permafrost temperature and the changing climate. Proceedings of the Fifth International Conference on Permafrost, Trondheim, Norway, August 1988, Tapir, Trondheim. v. 3: 9-17.
Ruppel, C.D., A.H. Lachenbruch, D.R. Hutchinson, R.J. Munroe, D.C. Mosher (2019). Heat flow in the western Arctic Ocean (Amerasian Basin). Journal of Geophysical Research – Solid Earth, 124(8): 7562-7587.