At Crissy Field, San Francisco’s giant park on the north side of the Bay, one of the old airport hangars that line the beach has been converted into a cavernous rock climbing gym. When you reach the top of the man-made peaks, dotted with colorful plastic formations, you are rewarded with gusts of cool, salty ocean air and magnificent views of the Golden Gate Bridge, as dozens of dogs and their owners play catch in the sand below. I only recently started rock climbing, and I’m a novice at best, still training my body to climb with my legs, not my arms; to trust my ­belayer when rappelling down; to not get tangled in other climbers’ ropes (that was an awkward moment early on … ). But I love it, nevertheless. I feel strong and toned and energized after a couple hours of climbing.

Yet when I was asked by a group of regulars at the gym if I was interested in joining an outdoor climbing group, I took a rain check. Don’t get me wrong: I love to be outdoors, to camp and hike and fish—and I have a rather ambitious goal of lead climbing in the Painted Desert. But I wasn’t ready to risk my own 127 Hours moment. Part of climbing is knowing your limits, understanding what you can and can’t do, and building confidence in your scaling skills as you move to increasingly more difficult climbs.

Right now, the apartment industry is also being asked to test its limits. All signs point to a 2011 revenue forecast devoid of any humps. In fact, experts paint quite the rosy picture, pointing to the trifecta of growing demand, inadequate supply, and significant rent increases—around 5 percent on average, and up to 15 percent in some metros. (For more on the rental outlook for 2011, see senior editor Chris Wood’s article “Outta Sight,” on page 36.) The optimism is unbridled, exuberant, and, in my opinion, slightly flawed.

When it comes to real estate cycles, we have a tendency to repeat our mistakes. And this period of resurgence will be no different. The supply–demand equation is out of balance? Let’s start building again—maybe even throwing up condos! People are willing to pay higher rents? Then let’s kick out solid residents, target the wealthiest renters, and ignore the shortage of workforce and affordable housing we leave in our wake. The core markets are where it’s at? Then let’s overpay for land and properties and lay the foundation for yet another bubble in asset valuations.

Sure, many companies are still struggling to stabilize their portfolios in markets severely weakened by the Great Recession. And while banks and life companies have loosened the purse strings, it is still quite challenging to get your capital mix in order for a new execution, even through the GSEs. (Oh, and then there’s that pesky thing called unemployment, which is still hovering at more than 9 percent nationwide. But who’s counting?)

The reality is that the gates of growth have been cracked open, and rather than taking our time to ease through, we have shoved our way in, hoping that the door doesn’t swing back to slam us in the face. Why? Because we don’t know our limits. No one in the industry knows just how long this period of expansion will last. And since real estate professionals are, by nature of their business, aggressive, a full-steam-ahead attitude is currently prevailing among most owners, managers, and developers. To date, I have yet to hear of anyone in the industry who has been skeptical of—or even cautioned against—the optimistic projections of 2011 and 2012.

Unfortunately, we have a long climb ahead of us before the rosy projections are sustainable and executable. The Obama administration has to address the continuing problems of unemployment, housing finance, and general economic uncertainty. We need sustainable job growth. Greater consumer confidence. More liquidity. And until these seismic shifts occur, no amount of rent growth, real or forecast, will make the climb to the top any smoother.