I've always said there is ways to co-op environmentalism to piss off the left.
There are actual facts to it too.
More people = More people using gas to get around in cars. Even with public transport, more buses will be required. You'll even use more energy and electricity from coal plants or nuclear plants to build those buses. More pollution.
More people = More crumbling infrastructure. You have to use big gas guzzling machines to repair roads. Even worse, with traffic jams happening due to construction and with more people around, causing a bigger jam, you'll have a ton of idle vehicles wasting gas, producing greenhouse gasses and pollution.
More people = More waste. More trash to pick up, our land fills will go through the roof.
More people = More water use. There is not much drinking water left in the world. More people means more water, and a state can run dry, like California.
More people = More farming. Farming causes environmental damage. Check out what happened to the amazon rain forests when McDonalds had to meet demand for their food. Sure they CLAIM to be stopping it, but with so much demand, they can't stop it unless there is less demand, which means more people.
theguardian.com/sustainable-business/2015/apr/21/mcdonalds-deforestation-global-supply-chain
More people = More energy demand. A lot of power comes from coal, nuclear, or hydro. More people for regions with coal plants = More coal to be mined (and mining causes environmental damage) along with the pollution coal mines cause. Nuclear power can be unsafe due to nuclear disasters we have seen in the past. Hydro plants, you have to build big damns, which can ruin the local environment. Fishes get caught in the turbines as well, killing them off.
You simply cannot be an environmentalist and be pro immigration.