Answer:
Below
Explanation:
While your classmate is correct in that respiration does cause the release of CO2, it's inaccurate to say that it has contributed to climate change, and it's especially inaccurate to say it has contributed to the same extend as the use of fossil fuels.
Let's break it down shall we:
When a human breathes, they release 35,000 to 50,000 ppm (parts per million) of CO2 with every exhale. On average, we breathe out 20,000 times a day. Multiply that by the amount of people on Earth, about 7.8 billion, you get 1.716x10^14 breaths a day. Therefore, you have that times 50,000 ppm of CO2 released. That sure is a lot, however, let's look at how much carbon dioxide is released from coal alone in a day. In general, the world consumes over 8.5 million tons of coal a year, and in the US alone 14,000 tons are burnt in one day. When you burn one pound of coal, around 2 pounds of CO2 is released, as the carbon of the coal mixes with the oxygen requiring it to burn. Therefore, 28,000 tons of CO2 is put into the environment from coal alone (not even including all of the other fossil fuels like natural gas and oil), showing how extensive the CO2 burning of fossil fuels is.
Additionally, I want to address the point of increased human population leading to more CO2 from respiration. Consider this, with more people, there is more need for agriculture. Aka, we need to grow more plants in order to sustain our growing population. Plants grow using photosynthesis which needs Carbon Dioxide to begin. Therefore, as our population grows, the amount of CO2 taken from our atmosphere in order to sustain our population actually shows that growing population doesn't necessarily relate to more CO2 from exhalation overall.
