This is the problem with people like you. You are so far up your own ass in identity politics, that anything that "leftists" latch onto, like climate change and other scientific issues, you immediately discredit simply because a majority of leftists understand that it's occurring.
Maybe, just maybe not every single idea supported by liberals is bad, just like maybe, just maybe not every single idea supported by conservatives is bad. I'm anti-immigration, anti-importing refugees, and anti-globalism in many respects, yet at the same time I'm a scientist and I understand and agree with the evidence for climate change, because it's not a political issue, it's a scientific one.
The mistake is that the majority of liberals, or as you say "leftists" that "understand" climate change, really don't understand it. They have about the same grasp of the issue as any other normal person with no formal education in the matter, and parrot things they read in the media, instead of looking at the scientific literature. That said, much reporting in the media on climate change is fair, depending on the source.
Climate science is as its core, a scientific, not a political issue. Of course there are many divisions within the field; you have economists for example that do nothing but study the economic impacts of climate change, or physicists who study the greenhouse effect, or chemists who study radiative forcings and climate sensitivity. The evidence stands for itself, however it's an issue with political and economic ramifications, which is why it has become so politicized by both sides of the field. Climate scientists in general don't like to politicize their research, but the media and politicians love to.
Overall though, the solution to climate change replies on policy changes, as well as economic responses, which is why the issue is so damn contentious. Conservatives do not want more taxation, or regulation, even if future benefits of taxes will pay themselves.