Youcannottrade weather, so the next best thing is to trade something that behaves very like it: gas (as it happens, gas prices, which according to Enron are closely correlated with temperature).
Likewise, ultra-lean supply chains no longer look like such a brilliant idea when you have to find cash to keep afloat a supplier that cannot get even basic trade credit.
The problem is Greece cannot compete or trade or produce its way out of this crisis during the Medium Term Fiscal Strategy: you get structural reform, but at the end a country that cannot borrow or pay its debts, only now its debts are bigger.