4We May Grow More Food
If you're a farmer in America or Europe, or a multinational conglomerate that owns all the farms, global warming is your friend. As temperatures rise, areas formerly barren, like tundra, will begin to produce vegetation. In addition, increased temps will create longer growing seasons and yields will also benefit from fewer crop-killing freezes. Canada and parts of Europe could start growing more food right away.
Also, remember that plants eat CO2. The additional CO2 global warming brings will increase photosynthesis in plants, making the process more efficient, requiring less water. With new, water-sipping plants, not only can we expect more food, trees and agriculture with fewer resources, but a cheaper, easier way to create biofuels, which up to this point have created more ecological damage than good.
It could be a no-win situation.
Hell, what are we even worried about?
On the Other Hand...
Climate change also messes with rainfall patterns, and could turn a lot of the current farmland we depend on into the Dust Bowl. We just don't know. Maybe we'll be knee-deep in corn cobs. Maybe we'll all starve. It'll be a surprise! That's the thing, when you're talking about your food supply, uncertainty is automatically a bad thing. Most people would rather eat at a restaurant where they know they'll get a mediocre steak every time, than one where you may get either Kobe beef or a cow turd depending on the mood of the chef.
3Cheaper Imported Goods
Ever since man realized that there was money to be made by piling valuable things on a boat and selling them to faraway lands where they're even more valuable, we've had one huge problem: To get back and forth between two of the biggest markets--Asia and Europe--your boats have to sail this massive pain-in-the-ass route...
...during which basically everybody on board would be dead of scurvy or eaten by a kraken. Because of this and other reasons, explorers were continually sailing around Canada trying to find a way to do this instead:
We literally spent centuries trying to sail through the frozen Northwest Passage over Canada, even though expedition after expedition found themselves wedged in 20 feet of ice every time. Even after we built the Panama and Suez canals to make it less of a pain in the ass to get from one ocean to the other, it would still be hugely beneficial to have the Northwest Passage opened up.
Global warming is about to give it to us, because all of that ice is finally melting up there (for part of the year, anyway). If so, it'll shorten some shipping Europe-to-Asia shipping routes by half. Goods will get there faster, and cheaper.
On the Other Hand...
There are also massive offshore oil reserves ready to be exploited under that ice, and they will exploit them.
That sounds like great news until you realize it's oil that got us into this situation in the first place. Also, you know that horrific oil spill currently turning America's gulf coast black and brown? Drilling up there will be done with platforms just like the one that blew up, only with the added benefit that nobody is quite sure how to clean up a similar spill if it should happen in the Arctic.
Eh, we'll figure it out when it happens.