March 18, 2025

Grant Statham and the Evolution of the Avalanche Terrain Exposure Scale v.2

A significant milestone in avalanche risk assessment has been reached with the release of the Avalanche Terrain Exposure Scale (ATES) v.2, a groundbreaking update to a system that has shaped backcountry safety for over two decades. Developed by Grant Statham in collaboration with Cam Campbell, the newly published research refines how avalanche terrain is classified and mapped, furthering its role as a critical tool in backcountry travel and avalanche safety planning.

From Concept to Reality
Statham first introduced the idea of a terrain rating system in 2003 while working with Parks Canada, which led to the launch of ATES in 2004. Originally designed to classify backcountry touring routes, the system was soon expanded when legendary climber Barry Blanchard suggested applying it to waterfall ice climbing. By 2005, the rating scale became an essential part of Parks Canada’s avalanche terrain classification efforts, helping both professionals and recreational users better assess the risks associated with their objectives.

In 2009, Cam Campbell extended ATES beyond specific routes, developing the ATES Zoning Model, which enabled GIS mapping of entire avalanche-prone areas. This breakthrough, later adopted by Avalanche Canada, allowed for the systematic assessment of avalanche terrain across British Columbia, making risk assessment more accessible to the public.

As ATES continued to evolve, it was tested and adopted internationally, influencing avalanche safety protocols worldwide and becoming an essential component of Avalanche Safety Plans in Canada. Researchers also used the ATES framework to analyze backcountry user behavior and terrain preferences, demonstrating its value in guiding decision-making.

Designated hiking, snowshoeing, and track set cross-country ski trails in the Lake Louise area of Canada’s Banff National Park, with the white trails showing Class 0 – Non-avalanche terrain – in the area.

ATES v.2: A New Era in Avalanche Terrain Classification
Recognizing the need to refine and merge their methodologies, Statham and Campbell began working on an updated ATES v.2 in 2019. Their collaborative efforts culminated in a presentation at the International Snow Science Workshop in 2023, and last week, their definitive research paper was officially published in the journal Natural Hazards and Earth System Sciences.

ATES v.2 is not just an update—it represents a major advancement in avalanche terrain classification. The new framework delves deeper into key avalanche risk factors, including:

• Slope angle and its role in avalanche formation
• Forest density and its influence on snowpack stability
• Terrain traps that increase the consequences of an avalanche
• Slope shape and orientation, affecting avalanche frequency
• Historical avalanche activity, helping to predict future risks

The Kindergarten Couloir, a popular 1100 m free-riding route in Canada’s Kootenay National Park rated ATES Class 4 – Extreme terrain due to its sustained exposure (ascent and descent), high slope angle, very high avalanche frequency (> 1 : 1), and lack of options for reducing exposure. This is a place where even small avalanches can be fatal.

By integrating new research and modern mapping techniques, ATES v.2 enhances decision-making for backcountry users, guides, and land managers. The update also bridges the gap between the original ATES route-based classification and broader terrain zoning methods, creating a more comprehensive, user-friendly model for evaluating avalanche terrain.

A Lasting Impact on Backcountry Safety
Statham hopes that this latest work will improve understanding of avalanche terrain and help backcountry travelers make better-informed decisions. With climate change affecting snowpack stability, tools like ATES v.2 will become increasingly important in mitigating risk and adapting to changing mountain conditions.

For those interested in a deeper dive into ATES v.2 and the science behind avalanche terrain assessment, the full research paper is available here:
Research article by Grant Statham & Cam Campbell

Looking Ahead
As ATES v.2 gains traction, its influence will continue to shape avalanche safety standards worldwide. Whether you’re a backcountry skier, snowboarder, or ice climber, understanding ATES and incorporating it into trip planning and terrain assessment can mean the difference between a successful adventure and a life-threatening situation.

With ATES v.2 now published, the legacy of Statham and Campbell’s work is solidified, offering a more precise, data-driven approach to navigating avalanche terrain.

Stay informed, plan wisely, and always check avalanche forecasts before heading into the mountains.

Source: www.egu.eu