Lurkers yea, totally impossible to say who is or isn't a scientist or with science background or has a job that involves weather. And what is a layman, anyway. I'll list impressions here (without nicknames)
Some retired scientists, journalists, people in agriculture, fishing, energy sector, teachers (geography, biology, physics, engineering, even chemistry), few data analysts, other shipping/navy. Weather geeks, meteorologists, even some climate scientists (some are definitely inactive) among other scientists and scientifically oriented people. Some representatives of humanities/social sciences. Few people of transportation/car industry (consequences/solutions). Some architectural discussion i haven't read (energy-saving buildings). Very few economists ( usually they look on shorter gains/losses than what the arctic sea ice presents), though there are probably threads by them (not that interested myself).
A shared interest on climate, weather, and the disappearance of ice off the planet, and the consequences of this, is a common factor here. Excluding trolls.
Won't put out guesses on how many from each occupation is active. Some lurkers activate on some subjects showing considerable knowledge/expertise just to go back to lurking, some may have seen a dubious article somewhere and come to seek assistance in debunking, still some have just said hello.
Hope this clears up things a bit.
