It just prodded them into evolving into birds. Polar bears, after all, don't have any real value. The world once got along without them, it will survive fine when they're gone. Personally, I'm not sentimental about cute fuzzy wuzzies. I think polar bears are magnificent creatures, but so are cockroaches. When the cockroaches suddenly start going extinct, I think I'll be concerned for other reasons.

The polar bear is the apex land predator in a very sensitive ecosystem. Its elimination in a short period of time all by itself will alter the landscape in ways that can't be forecast. Not to mention, it is also a canary in a coal mine, it is only the tip of the iceberg of arctic change, if you'll pardon the metaphor.

Even if you cavalierly dismiss the potentially disastrous effects of sudden climate change on the entire world order; industry, agriculture, economics, politics, in a generation (the change has taken several centuries but it has been concentrated and accelerating in the the last few decades), you might ponder its changes in the arctic alone. Already, the world is gearing up for resource development, settlement, competition, trade and military conflict there, local populations (and not just aboriginal ones) will have their lives and economies dramatically altered.

These effects will cascade through geography and history, there will be "opportunities" but there will be catastrophes, too . It is impossible to predict the ultimate consequences of even those changes we have already seen, but we can expect they will be disruptive. Its probably already too late to do anything to stop AGW, but until we at least recognize and admit it is happening we can't begin to respond to it. There is also still time to mitigate its worst effects, and to prepare for those we can't. And maybe we can prevent it from happening any sooner, or any faster, or any worse. Change is inevitable, but ignoring its effects when it so global, sudden and unpredictable is negligent, if not irresponsible. Doing so for short-term economic benefit or political expediency is downright criminal.

Then again, you could just ignore it. I guess you could use the same laissez faire logic to describe how the human economic and political system should respond to any easily anticipated future shock that might be too inconvenient or troublesome to deal with now (budget deficits, for example):

Humanity has been around for millions of years. I suspect we’ve survived worse than this. My theory is that when the world suddenly changes, we'll basically go back to a hunter-gatherer mode.