I have an outdoor fire pit in my backyard. The fire pit is about 3 feet in diameter and is similar to ones you might find at a camp site. My family and I enjoy using it purely for recreation. I’ve been trying to limit my carbon footprint, and in doing so, wondered how much a fire in the fire pit contributes to it. We usually have about 2 to 3 logs, and a handful of sticks. So what’s an estimate for how many pounds of CO2 are released every hour of from an average sized camp fire? Are there other gases released other than CO2 that are harmful to the environment?
The Short Answer
Burning 1 kg of wood releases 1.6 kg of CO2. (source: EPA)
I'm not sure how big your 2-3 logs are, so I'll just say that 5 kg wood is probably enough to make a reasonable outdoor fire for one evening of entertainment. That would emit 8 kg CO2, or 17.6 lbs in one evening.
For comparison, the global average of CO2 emissions per capita (per-person) is 26 lbs/day (4.8 metric tons/year), but that varies a lot from one country to another!
... but it's complicated
Trees have been growing, decomposing, burning, and growing again as a natural part of the carbon cycle for millions of years without causing rapid global warming like we're seeing now. As long as global forest cover remains constant, burning wood doesn't make much difference to carbon in the atmosphere.
Anthropogenic global warming (and climate change) is caused by extraction and combustion of underground carbon (oil, gas, etc.) that was removed from the atmosphere over millions of years, and also by deforestation that results in burned wood and loss of soil carbon.
Where does the wood come from?
If you have waste wood lying around that would have eventually decomposed, it would release the same amount of CO2, but over a different timespan. By burning it now, you do create a temporary flux of CO2 into the atmosphere that makes a small contribution to global warming for many years until the carbon is reabsorbed by new plants or trees.
In the end, understanding the impact of burning wood is really a question about understanding forest management, which I can't fully explain in this short answer.
Other air pollution
Other than CO2, burning wood also releases soot and fine particulate matter that can be harmful to human health.