The world's human population has exploded over the past 200 years. Humans expire CO2. Has anyone looked into whether this source of CO2 is of any significance? Just wondering.

The amount we exhale is from what we eat so it's not an issue. However, even with very small CO2 footprints that number of people add up. All the things people need, from heat to roads to writing paper grows and grows, both with population and with modern 'necessities'. Much of the energy expended is from non renwables and even they have a CO2 footprint. So the bulk of the CO2 rise is probably man made. While I'm not anti Salby's work, it's like much of climate science in it lacks hard proof yet so can be filed under pending. Emissions are still in line to increase.

So on the face of it, we are emitting CO2 and we don't seem to be able to stop with the current renewables and proof of catastrophe. The powers that be, either need to improve the evidence for catastrophic warming or resign themselves to more CO2 and whatever ensues.