Re: [cornishe] UNESCO / NPS
The fact that Yosemite is on the UNESCO World Heritage List doesn't mean it's been given away to the UN

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It just means that it's been internationally recognised as a site of "outstanding value to humanity". Having a site on the World Heritage List brings tourism, expert help in conservation, and a strong incentive not to put a shopping mall on top of the thing.
It's a pretty cool program

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edit: As for lobbying UNESCO for access, dunno. They don't have any direct control over the park, but if denying BASE jumpers access was against the principles of the WHL, it might be a good way to put pressure on the NPS. The WHL is very high profile. Whether that'd be counterproductive by just pissing off the NPS is another matter...