As the Climate Emergency requires radical change immediately, what then are major crises where gradual change remains the norm regardless of any such urgency?

How about starting with the following?

The resulting loss of prosperity and destabilization, and even more so the loss of the ability to provide protection and security would benefit no one. Therefore, an immediate and complete opening of borders as well as an immediate shift away from the concept of citizenship towards new models of citizenship cannot be a panacea, because such drastic measures at this present time appear to be utterly utopian, given the numerous purposes that borders and the concept of citizenship undeniably serve and the disadvantages that could result from their abolition.

Yet the previously developed critique of the border and the concept of citizenship shall not be in vain. Rather, this critique is meant to highlight the need for gradual change.

https://www.cambridge.org/core/journals/german-law-journal/article/borders-citizenship-and-global-inequality-what-barriers-pushbacks-and-passport-controls-reveal-about-our-understanding-of-the-equality-of-humankind/55C2EA985F7E5BD97222CCC638CF7E1B

The author argues in particular that “the increasing number of problems of global scope—especially environmental problems such as the ozone hole in the past or climate change now—underlined the need to transcend existing borders,” adding that this and other globalization also “raised expectations of a gradual transcendence of borders.” Again, that highlighting of “gradual,” even in the climate domain.