Who here is claiming that there are moral facts? Of course morals are constructs of human culture, but that doesn’t make them less important. Morals are essentially what we have learned to be important rules for good, healthy societies. Humans who abide by the idea that it is “wrong” to kill another human are far more compatible in a community than ones who do not. These concepts have developed over a very long time, which is why we tend to “know” when things are wrong (eg feel bad, guilty conscious, etc). One of these “rules” is that needlessly inflicting pain on intelligent animals is wrong. Similarly, causing unnecessary damage to the environment is wrong. The context of climate change is quite new, but the principle is the same.