If an unforeseen event occurs after a contract has been made that makes one of the party's performance under the contract prohibitively more expensive than was contemplated when the contract was made: 

• the party whose performance is now more expensive still has to perform their obligations under the contract.
• that party's obligation to perform under the contract can be cancelled under the doctrine of commercial impracticability.
• the parties to the contract will have to renegotiate the terms of the contract.
• the contract is automatically breached.