There's no single most critical issue, as biodiversity loss, habitat loss, and climate change are deeply interconnected crises that worsen each other, forming a vicious cycle; habitat destruction often drives immediate species loss, while climate change acts as a powerful, escalating threat, potentially causing widespread extinctions, especially as its impacts amplify other stressors. Climate change makes ecosystems less resilient, while biodiversity loss reduces nature's ability to buffer climate impacts, creating a feedback loop. These problems will grow to be overwhelming and like previous civilization this we have would not continue.
un.org/en/climatechange/scienc…