Emissions of greenhouse gases are caused by economic activity, but the bigger your population, the more activity. So the faster your population is growing the faster your emissions grow.Let's assume that economic activity does spur emissions, as Gittens says. He claims that because immigrants move to better their economic circumstances, they will be emitting more.
Our immigration program is so big it now accounts for more than half the rate of growth in our population.
It's obvious that one of the quickest and easiest ways to reduce the growth in our emissions - and make our efforts to cut emissions more effective overall - would be to reduce immigration.
Of course, you could argue that, were we to leave more of our immigrants where they were, they'd still be contributing to the emissions of their home country. True. But because people migrate to better their economic circumstances, it's a safe bet they'd be emitting more in prosperous Australia than they were before.
However, let's take this idea to the extreme so we can apply reductio ad absurdum. If every morning you travel to the city via car or train, you are an immigrant. You are an immigrant because you move to perform economic activity outside some imaginary line. This imaginary line can be political borders or it can be your household. It doesn't matter where we draw this imaginary line. Suppose you could not leave your house because you were allergic to outside air. Then you cannot move and all trade must be done inside your home. Your economic opportunities would be diminished greatly. However, because you are not trapped in your house, because you can search for opportunities outside your house, you are more prosperous. The same idea applies to immigrations from other countries as it does for those from other households. If Gittens wants to stop immigration among people from different countries then using the exact same logic we must therefore ban movement of all people from their houses since movement of people from their houses to go to work is done to better their economic circumstances, which leads to emissions. So if Government banned trade among households then you will become unemployed, you won't travel to work, and then emissions will drop. That must be what Gittens wants if we are to apply his logic consistently.