Samples of air trapped over the centuries in the glacial ice of Greenland show no change in CO 2 content until 300 years ago. In recent decades, large areas of the Amazon rain forest have been cleared for agriculture and cattle grazing. Curiously, the increase in atmospheric CO 2 is only about one-half of what would have been expected from the amount of fossil fuel consumption and forest burning. Research has shown that increased CO 2 levels lead to increased net production by photoautotrophs. There is some evidence that the missing CO 2 has been incorporated by increased growth of forests, esp.
Carbon dioxide is transparent to light but rather opaque to heat rays.
At this point, the answer depends on limited data and what assumptions you plug into your computer models. The very activities that deposit CO 2 in the air also deposit dust particles that impede the passage of light through the atmosphere so more is reflected back into space. Air pollution thus appears to reduce the arrival of energy as well as its departure. Whether these opposing effects cancel each other out is not yet known. Average temperatures do seem to have increased slightly in recent decades.