What are the effects of extreme, prolonged UV exposure on carbon fiber frames? I live in AK where we get much more than our share of UV exposure.

So you want us to put sunscreen on our bikes...?

Welcome to 2008 !

SPF 50 I think works best.

I ride Ti

The CF itself doesn't particularly care, but the binder used might care a little.
If you look at yachting stuff even the really good clearcoats have a tendency to turn a little yellow over time.
If it was me I wouldn't worry about the time the bike is being ridden in the sun at all, but I'd try to avoid storing it in direct sunlight.

Ya, thats the problem with carbon fiber, it gets sun burns whereas steel and Ti bikes don't. Don't worry though if it happens, just rub some Aloe on and your bike will feel better in no time.
In the future, be sure to use carbon sunscreen . . .

The clearcoat should protect the carbon resins from breaking down. For extra protection you can use some of the frame polishes offered by FinishLine, Pedros etc.

This basically acts in a similar way to waxing a car. It adds an extras layer of protection and also helps keep the bike a bit cleaner (dirt doesn't stick as well).

Bike frame tubing has no shear panels for the sun to strike like a car surface thus since there is only a very small amount of the tube getting intense sunlight at any given time danger due to UV exposure would probably take at least 100 years for any accumulated effect to ruin the fibre. The paint may fade, the decals may fade, but the CF will not rot away.

Your biggest concern with Carbon fiber is not UV exposure but what happens to the carbon fiber if you have a accident and nick the fibers...now that will destroy the CF frame whereas with steel or titanium it's just a scratch.

I have an unpainted carbon frame. The framebuilder says the epoxy can turn yellow over time with UV exposure so suggests using 303 Protectant. The yellowing does not affect the strength of the tubes.

Yeah, epoxy turns yellow but it retains its integrity.

Off beat as this may sound,this is a question you might want to pose on Paddling.Net.
There are a ton of Carbon Fibre kayak and canoe owners and I know this topic has been bantered about before on the sites message board.