Calendar has an option to create copies of your personal calendar on a local computer that can be used in the even that the internet connection is lost.
To activate Offline Access:
Click on the Offline menu item at the top right of the Calendar screen.
Allow Google to install Gears, the special software it needs to perform this service.
You can continue to use email while your older emails are synced with the local computer.
This service is Web Browser specfic. So if you set it up in Firefox it will only work in Firefox.
Create a special icon on the desktop to access Calendar if the internet is not available:
Click on the Offline menu item and select ... more to follow
If internet access is not available, click on the special offline Calendar icon oin the desktop.
You can now use all the Calendar functions.
Any events you create will be stored in the local calendar and will be synced when the internet connection is reestablished, and Calendar is opened again.