If you have a problem with any of the individual statements they make, they look ready to respond to any questions. Given that this individual post was endorsed by Nature, and that one of the top contributors is a NASA climatologist, I'd like to ask if "left-wing" can be supported by anything other than the topic of defending the concept of global climate change itself.
And yes, scientists have acknowledged as a non-anthropogenic warming phenomenon as a drop in the intensity of sandstorms in the Middle East. The sand in the air lowers the albedo of the Earth's surface, causing it to reflect less light and warm the surrounding area. The opposite effect occurs on Mars, when dust storms cause huge temperature increases, which I would then assume is due to the Martian dirt being darker. However, the most credible study of solar cycles contributing to global warming of which I have heard estimated the effect to be as high as 25%, but this was refuted by other scientists and the study was withdrawn by its authors.
With regard to skepticism concerning computer models, would you accept that if a computer model can accurately model climate changes from 1900 to 2000, and is fed accurate data, then if it is powerful enough, it can predict future climate changes to a limited extent? There is such a project that exists using distributed computing, where you download a "module" that starts in 1900 and finishes in 2000 before going into future decades. The results are sent back to the scientists, and each one helps improve future models.
If one day a model from 1900 to 2000 is perfectly correct, might you be inclined to give it some credence? At first the project did things like use a solid slab ocean, without currents, as a developmental stage, but it has progressed far since then. It's hosted by Berkley and you might care to look into it, since their methods are so transparent.