Loss of biodiversity is in big part caused by global warming (temperature rising, ocean acidification etc.) Global warming is not caused by loss of biodiversity.

On top of that, many of things that need to be done to reduce global warming will directly positively affect biodiversity, such as reducing deforestation and thus habitat loss.

So no, fixing global warming is more important since its a prerequisite to stopping loss of biodiversity.

The problem is we're making the single world we can live in poisonous unstable and dead through short term unsustainable growth, violence and greed.

Maybe we can spare a few murder machines for the Imperial army until we figure out how to stop choking the planet to our collective toxic, entirely preventable deaths?