Nepal, May 21 -- As a record number of climbers head up Mt Everest this week, there have been calls in some quarters for Nepal to change strict cutoff date of 31 May for the spring climbing season.

The rules were made when long march-ins from the foothills were inconvenient when the monsoon set in. But with climate breakdown making monsoons more erratic, and better access to the base of mountains, it is not as compelling to set a date for the end of the spring climbing season.

The industry would also generate more revenue if mountaineering was open all year around instead of seemingly arbitrary closure dates in the spring and sometimes in the fall. There is proof that off-season summits are possible, if not on Everest right away, then a...