Bears ears to be cut by 80%

These leaders first come to power through democratic elections and subsequently harness widespread discontent to gradually undermine institutional constraints on their rule, marginalize the opposition, and erode civil society.

Basically this is largely being done because some on the far right didn't like anything that Obama did, and now want to undo it.

No President has ever abolished or revoked a national monument proclamation, so the existence or scope of any such authority has
not been tested in courts. However, some legal analyses since at least the 1930s have concluded that the Antiquities Act, by its terms, does not authorize the President to repeal proclamations, and that the President also lacks implied authority to do so. Under this view, once a President has applied the Antiquities Act to protect objects of historic or scientific interest, only Congress can undo that protection. On the other hand, Presidents have deleted acres from national monuments, proclaiming that the deleted acres do not meet the Antiquities Act’s standard that the protected area be the “smallest area compatible with the proper care and management of the objects to be protected.”

After their establishment by a President, national monuments often have been expanded or reduced over time by subsequent Presidents, or within the same administration. For example, Bandelier National Monument in New Mexico was established by President Woodrow Wilson in 1916 and was later expanded by Presidents Herbert Hoover and Dwight Eisenhower. President John F. Kennedy later issued a proclamation adding 2,882 acres and removing 3,925 other acres from the monument. President Kennedy cited the Antiquities Act as authority, declaring that “it appears that it would be in the public interest to add [the 2,882-acres] to the Bandelier National Monument because they possess unusual scenic character together with geologic and topographic features, the preservation of which would implement the purposes of such monument,” and that “it appears that it would be in the public interest to exclude from the detached Otowi section of the monument approximately 3,925 acres of land containing limited archeological values which have been fully researched and are not needed to complete the interpretive story of the Bandelier National Monument....” As another example, the former Mount Olympus National Monument was diminished in acreage three times after its establishment—including once by nearly half—before it was ultimately redesignated by Congress as a national park in 1938.

Antiquities Act authority to add new acres to national monuments appears analogous to the authority to create monuments in the first place; however, diminishment of national monuments potentially may raise distinct issues. While the Antiquities Act does not expressly address changes in the size of national monuments, it does contain a provision governing monument size: reservations of land for monuments “shall be confined to the smallest area compatible with the proper care and management of the objects to be protected.” At least one analyst has contended that the same logic cited above against presidential abolishment of national monuments should also prohibit presidential modification of national monuments to diminish their size. However, the 1938 Attorney General opinion discussed above contemplates reduction of monuments in size pursuant to the “smallest area” language:

While the President from time to time has diminished the area of national monuments established under the Antiquities Act by removing or excluding lands therefrom, under that part of the act which provides that the limits of the monuments “in all cases shall be confined to the smallest area compatible with the proper care and management of the objects to be protected,” it does not follow from his power so to confine that area that he has the power to abolish a monument entirely.

Thus, despite some potential ambiguity in the phrasing of the Antiquities Act, there is precedent for Presidents to reduce the size of national monuments by proclamation. Such actions are presumably based on the determination that the areas to be excluded represent the President’s judgment as to “the smallest area compatible with the proper care and management of the objects to be protected.” It remains undetermined whether removal of a high enough proportion of a monument’s acreage could be viewed as effectively amounting to an abolishment of the monument.

Obama setting aside millions of acres as he did adversely affected far more people than Trump cutting the acreage down a bit will.