Well, UP, I'm not an economist, but I am smart enough to get banned for posting on DU.
Here is what would have happened if the world capital system froze up. Everything would quickly drop to only the value it has right now, at this very moment. Farmers in Southern Hemisphere would miss their window to put in crops, because they need capital to buy seed, fertilizer, herbicide, pesticide, equipment, and gas to plant their crop. Of course, the value of their crop won't be realized for months. Since they didn't plant their crops, food prices will begin to shoot up beyond your imagining. The world food supply, currently about 45 days, would drift into the 7 to 15 day margins by next April. Starvation would be widespread in the third world, and very likely we would see a few wars over it. We were dangerously close to this scenario.
If the problem persists into the northern hemisphere planting season in March and April (or if a crop failure hits the northern hemisphere), you get global starvation.
Everything I am typing is truth. It is verifiable. It is also the second most direct example that UP might understand.