How can I consistently set an environment variable for a single program?

I'm using LC_TIME="en_AU.UTF-8" in general, and I'm happy with that. However, when I use Thunderbird, I'd like it to use a 12-hour clock. I've created a custom locale, and it works fine if I launch Thunderbird with

LC_TIME=en_AU_12h.utf8 /usr/bin/thunderbird

However, can I make Thunderbird launch like this by default? It seems to me that I'd have to make several modifications.

• I sometimes launch Thunderbird from my Desktop Environment, so I'd have to modify thunderbird.desktop.


• I sometimes launch Thunderbird from the command line, so I'd have to put the altered command in my $PATH, perhaps /usr/local/bin/thunderbird.


• I have a custom script to launch several programs at once, so that would also have to be modified.

Is there a way to change Thunderbird's default environment variables, so I don't have to change so many files?