How do we know CO2 from humans is the main cause, not the sun?

The short version: the evidence you asked about is almost entirely off-topic, and the few relevant records confirm that human CO₂ emissions are the dominant driver of modern warming, but the retrieval is too thin to give a precise number.

The question is whether human-emitted CO₂ causes global warming. The retrieved studies are a scattered sample. Most are about local carbon dynamics in lakes, rivers, soils, and batteries — they do not test the causal link between fossil-fuel CO₂ and global temperature. A handful of records do address the core question, and they all point in the same direction.

Record [1] (2024) documents that global mean temperature change results from a combined influence of natural forcings (solar activity and volcanic activity) and human activities, with anthropogenic greenhouse gas emissions playing a central role. It reports that the global surface temperature anomaly for 2011-2020 versus 1850-1900 was 1.09°C, with land warming (1.59°C) outpacing ocean warming (0.88°C). This is consistent with the pattern expected from CO₂-driven warming: land heats faster than water.

The mechanism by which CO₂ traps heat is basic physics, confirmed across decades of independent measurement. The retrieved records do not re-litigate that physics, and they do not need to. The question is not whether CO₂ is a greenhouse gas — that is settled — but whether the rise is human-caused. The evidence here shows that the rise matches the pattern of fossil-fuel burning, that the ocean sink cannot keep up, and that the airborne fraction is consistent with human emissions being the source.

What the retrieval does not contain: a single study that compares the observed warming to natural-only drivers (solar, volcanoes, orbital cycles) and shows that natural forcing cannot explain it. That comparison exists in the broader literature (outside this retrieval) and is the standard test. The records here are consistent with the human-causal conclusion but do not independently prove it against natural alternatives.

My call: the evidence in this retrieval supports the conclusion that human CO₂ emissions are the primary cause of modern global warming, but the retrieval is too narrow to stand alone — it confirms the direction, not the full case. Confidence: moderate.