But it brings another questions with it: Do we need to provide Welfare to everyone at any cost?

Yes, why not?

I'm surprising you asking it here if in another comment you wrote "Humans don't have to live"[0].

[0]: https://news.ycombinator.com/item?id=34316128

Can you really separate those, given that humans have to live in the environment?

yes you can. Because it will likely be decades before the environment kills people but you can save a life today. Oh, don't drive that ambulance to go pick someone up and rescue them, it pollutes! Where as other solutions may exist for the environment in the future.

Here's another. Maybe no one should go hiking/camping/mountain climbing because the few that need to be rescued generally require cars/helicopters the burn fossil fuels to come to their aid, not to mention all the fossil fuels used to get them to their camp/hike/climb site and all the materials for their gear, all for "entertainment".

Also, you yourself are likely a net negative on the environment. Do you have an obligation to kill yourself?

Many people are killed by "the environment" every year already. This problem will only continue to get worse unless we make radical changes today.

Over 20,000 died in western Europe’s summer heatwaves [0]

Bangladesh, India floods kill over 100; millions in need of aid [1]

Climate Change Causes 5 Million Extra Deaths Per Year [2]

[0] https://www.theguardian.com/environment/2022/nov/24/over-200...

[1] https://www.aljazeera.com/news/2022/6/21/bangladesh-india-fl...

[2] https://www.webmd.com/a-to-z-guides/news/20210708/climate-ch...

Poverty also causes millions of deaths a year.

Humans don't have to live

That’s a false dichotomy. You can’t separate human life from the environment; hurt the latter and you hurt the former.