I'd honestly saying housing at least here in the US. We have so much open land and yet so few people actually want to live in rural areas. People move to cities where housing is already expensive and "maxed" out because no one wants to build more. In turn we get more suburban sprawl of 3bed 3bath ~1700sq foot homes that new home owners can't afford.

Ultimately I think it is a national issue (have not heard of this occuring in East Asia or Europe, unsure about South or Southeast Asia) and will see a further increase in urbanist/YIMBY circles further developing downtown areas into signuficantly higher density and allowing surbia to keep what they currently have. Might not be as large as global climate change or war but the housing situation of millions of Americans is pretty serious and I don't see much talk about it from national outlets and only slight touches from outlets such as The Economist.