Finding honest signals in the midst of the noise

Apologies to professional biologists if I muck this up, but there are things known to biologists as 'honest signals' - cues that the receiver understands to reliably correlate with some aspect of the sender. Large male elephant seals can bellow louder than small ones, for example, so in their competitions for females, the bellow is an honest signal of the size and therefore fighting ability of the male. In this way, potential disputes between males can be avoided if one recognizes that the other is the superior fighter through its bellowing. (And then the larger one gets all the females, even though he's probably a jerk and the smaller one is probably a really nice guy with a good sense of humor).

Dudes...talk it out first.

So I set out this morning to think of some honest signals - not from huge males, which as a 5'9" guy myself I am inclined to think are overrated. No, I set out to try to think of information that just might be sending a direct, unmistakable message about the status of our current social and environmental conditions. And so, without having exerted myself too much because I'm kind of jet-lagged, here are some that struck me (note - the term 'signal' may technically not be the correct word to use here, but I'm using the term anyway).


Fisheries:
The signal: Declining mean trophic level of fisheries landings
The message: "Most of the big fish are gone."
Modern commercial fisheries have progressively fished 'down' the food web, starting with the largest fish and, when they are reduced in number, move on to smaller ones...and so on, on down the marine food web. The honest signal here is that while we may improve some aspects of fisheries, the bottom line is that the ones that happened to be both tasty and big are pretty much gone. And they aren't going to be coming back anytime soon - not with 6.9 billion (and counting) hungry humans running around.

Climate:
The signal: Northwest Passage ship traffic is increasing.
The message: "The Arctic is warming" (despite the best efforts of the denial industry).
Three consecutive years of commercial transits seems like a pretty honest signal about the warming of the Arctic.  People have been trying to find way to transit the Northwest Passage for centuries, but they've been turned back by ice. There have been isolated successes in the past few decades, but it was only in 2008 that the first commercial vessel transited the Passage. In 2009, seven vessels made the trip - and in 2010, at least 18 have done so.

Energy: 
The signal: We're producing energy from the Alberta tar sands.
The message:  "The good stuff is gone, but we're junkies who can't quit."
Remember the scene in There Will Be Blood where they're scooping oil up in buckets? That was yesterday, and that kind of energy return on energy invested was awesome for building economies. Today, we have the Alberta tar sands, where we get oil only after expending huge amounts of energy and resources. The fact that such an energy-intensive source of oil is so  profitable seems like an honest signal about the state of both our energy dependence and our reserves of fossil fuels - the easy stuff is gone, but the demand is so great that the hard-to-get stuff is profitable.

So these are just a few potential candidates. Whaddya think? Are they truly 'honest signals'? Are they likely offering clear evidence regarding the larger state of our affairs? Or are they just random and potentially easily-reversed occurrences that don't speak to anything larger than themselves? And what other 'honest signals' are out there?