Jack D. Ives (October 15, 1931 – September 15, 2024) was a British-born Canadian montologist, an honorary adjunct research professor of geography and environmental studies at Carleton University in Ottawa, Ontario, Canada, an author, and a prominent advocate of mountain issues at the global level.

[4] He studied geography at the University of Nottingham, and organized that institution's first undergraduate glaciological expeditions to Iceland, leading groups of students to Skaftafell and Vatnajökull in 1952, 1953, and 1954.

[4][3] On 11 September 1954, immediately after witnessing a jökulhlaup (also known as a glacial lake outburst flood, or GLOF) at Skeiðará, Ives married Pauline Angela H. Cordingley.

[7] Along with his wife Pauline, he explored the Labrador-Ungava Peninsula, with the result that he was able to overturn the current hypothesis about the repeated growth and disappearance of ice sheets in northeastern North America during the Quaternary period.

Based on geomorphological evidence, as well as on his perception that the so-called Torngat Mountain Range is actually an escarpment on the edge of a tilted peneplain with almost no western slopes, Ives refuted the previous model, proposing instead that inception of glaciation occurred across wide areas of the plateau as climate change permitted year-round snow cover to accumulate, a process he refers to as instantaneous glacierization.

[4][7] In 1968 Carl Troll founded the Commission on High Altitude Geoecology under the auspices of the International Geographical Union, and invited Ives to join the organizing committee.

From 1978 to 2000, Ives served as Research Coordinator for the United Nations University's project on Highland-Lowland Interactive Systems, later to be renamed Mountain Geoecology and Sustainable Development, which entailed fieldwork in the Himalayas, northern Thailand, Yunnan (China), Tajikistan, and Ecuador.

[5] One result of the conferences was the publication of The Himalayan Dilemma (Ives and Messerli, 1989), which challenged the popular theory according to which highland population growth and poor land management by uneducated farmers was leading to catastrophic deforestation of the Himalayas.

[22] Ives with Bruno Messerli and colleges organized the inclusion of "Chapter 13 — Managing Fragile Ecosystems — Sustainable Mountain Development" in its final publication, Agenda 21.

[27] After retiring from UC Davis, Ives returned to Ottawa, Canada, where he was appointed honorary research professor of geography and environmental studies by Carleton University.