If you type or handwrite a letter, that carries even more weight than a petition or postcard.
You may not agree with everything they say BUT they are your avenue to putting pressure on their parties. Ask them to put pressure on world decision makers. Write a letter. Below are some contact details AND links to sample letters.
Australian Parliament - for the big national & global issues
Currently being updated.
A letter to a Tasmanian Member of Parliament. - you can personalise it by adding or taking parts of this letter.