The HS2 route risks pushing nature closer to the brink of disaster, with irreversible damage to biodiversity and carbon sequestrating habitats and possible extinction of local species. Both the Government and HS2 acknowledge that the route cannot be made without far-reaching harm to the natural environment.

Opponents of HS2 (High Speed 2) in 2026 argue that the project has become a "sunk cost fallacy" with diminished returns. After the cancellation of the northern legs to Manchester and Leeds in late 2023, critics argue the remaining "stub" from London to Birmingham does not justify the £60bn+ price tag. Environmental groups point to the irreversible destruction of ancient woodlands and wildlife habitats during construction. Economists argue that the money would be better spent upgrading existing regional rail networks in the North and Midlands (like the Northern Powerhouse Rail), which would benefit more commuters than a high-speed shuttle for business travelers. Furthermore, the shift toward permanent remote work in 2026 has reduced the "capacity crisis" that HS2 was originally designed to solve, leading many to label it a 20th-century solution for a 21st-century world.