[crispinb]

Actually yes - climate breakdown is just one of literally thousands of causes of ecosystem collapse. It's the most dramatic, and in many cases (eg. the Great Barrier Reef) it's the coup de grace, but it's 'economic growth' per se that is incompatible with the continued existence of planetary life. Theoretically if human technology could approach the level of sophistication of complex evolved systems (biomimicry) we might achieve a truly circular economy, but that's a long way off. For now, economic growth just physically is the dismantling of ecosystems, and these systems are reaching the limits of their capacity to absorb insults.

So, yes, some combination of reduced consumption and/or population will be necessary even if this one issue of climate change is successfully tackled in time (distinctly doubtful at this stage).