Contrary to most of the opinions in this thread, I think this (and the van gogh incident) is a great and appropriate protest.

It causes a knee-jerk reaction to be mad that they are harming a precious piece of history and culture, which is a perfect juxtaposition to how the climate change harms our precious natural resources and will harm ourselves, and

It achieves this without actually causing permanent damage to the subject artifact, and

It is incendiary enough to remain in our public consciousness long enough for it to affect the discourse.

I only wish there was a more direct way to protest the people most responsible for the worst effects (oil executives, politicians, etc.), but the truth is that the "average middle-class Westerner" (most of the people who have access to enjoy these particular cultural relics) is globally "one of the worst offenders". While I firmly believe that individuals have less power to enact change than corporations and policymakers, this protest does achieve the goal of causing reflection within people who have the power to make changes.