The earth is constantly 'venting' gas to space. This is known as atmospheric escape. https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org

The earth is constantly 'venting' gas to space. This is known as atmospheric escape. https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape The earth is currently losing 3kg/s hydrogen and 50g/s of helium because that's what is in the upper atmosphere where a molecule can gain sufficient velocity to escape the orbit. The issue with CO2 is that it is a heavier gas and so takes more energy to escape and is also more likely to fall. Left on its own over a sufficiently long time period, you'll end up with an atmosphere that is mostly rarefied carbon dioxide (see Mars). Ejecting CO2 from ground level to the upper atmosphere and beyond in the quantities that are talked about when dealing with carbon sequestration (tons - not kilograms or grams) would be very energy intensive and using current technologies (we don't have surplus non-carbon based energy) would mean that we are adding to the total amount of carbon instead of reducing it.