Two quick points:
1) When you call the embassy you may be asked with whom you'd like to speak. Explain that you'd like to speak to someone about the Adani mega coal mine in Queensland, Australia so you can express your disappointment in the Australian government for supporting a scheme so clearly harmful to our climate.
2) It is likely that you will be told that this isn't possible. Be persistent and ask to speak to someone who can pass on your thoughts directly to the Australian government.
If you are able to speak to someone you can say the following:
1) If the Adani mine proceeds, it will become one of the largest coal mines on the planet, covering an area of 200 square kilometres. The proposed Adani mine sits on one of the world’s largest untapped coal reserves, where a further eight new coal mines have been proposed. If they go ahead, the coal from these projects would unleash 705 million tonnes of co2 into the atmosphere each year.
2) The latest IPCC special report into keeping global warming under 1.5°C makes clear that if we want to avoid devastating climate impacts on humanity’s health and welfare, we have to leave fossil fuels in the ground. To ignore the warnings of the UN’s top climate scientists and allow the mine to be built poses an unacceptable risk to Australians, the country’s low-lying Pacific neighbours, and the world at large.
3) The Australian government should listen to the majority of Australians who oppose the Adani mega mine; the voices of the Traditional Owners of the land, the Wangan and Jagalingou people who also oppose the Adani mine; and the Pacific climate activists have been fighting to raise awareness of the threat that the Adani coal mine poses to lives, livelihoods and ecosystems in the Pacific.