If some of the Australian "aid to Africa" budget were applied to the camel situation, they could create a synergy that would be a win-win instead of a waste. Whoever justified the slaughter on the basis of green house gases isn't looking at the whole picture.
Climate change has multiple components including;
1) need to reduce green house gases
2) strategies to deal with flooding due to climate change
3) strategies to deal with drought due to climate change
4) dislocation of populations
Australia may need to address feral camels, but it strikes me as counter productive to spend 19 million dollars to slaughter an animal suited to drought conditions, when there are people who need to adapt, and camels could substitute for cattle. Drought doesn't care who is left without food.
Using tranquillizer darts instead of bullets, they could separate male from females and young camels, farm the females, and do whatever is necessary with excess bulls. Farming the females will control births in the feral herds, and the resulting resource can be used to support populations which already having to deal with droughts caused by climate change.
Instead, 19 million is being spent to kill animals that are worth approximately $1000 each at current prices in Ethiopia. If only half are females, $500 X 500,000 camels represents a huge lost asset. Wholesale slaughter is just a waste, there has to be a better way than simply shooting them.