Recently I've been working on a debate for climate change and I'm working on a rebuttal statement but then I came across many different sites that claimed that there were higher CO2 levels before there was even industrialization or a substantial amount of CO2 being made from humans. I just need an explanation on how this happened.


1 Answer 1


The explanation is that human activities are not the only processes that affect atmospheric composition.

Last time CO2 levels were higher than today was 10-15 million years, during the Miocene epoch. During the Miocene, sea level estimated to be 100 feet higher and the global average surface temperature estimated to be 10°F warmer than today.

Sea Level Change over time

Temperature over time


Miocene Sea level graph.

Temperature over time graph.


Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years

  • $\begingroup$ What other things affected climate change during that time? I read that position changes of the continents and warmer climates were the reasons for changes in global circulation patterns but what caused such warm climates? Was it also related to plate tectonics? References: ucmp.berkeley.edu/tertiary/miocene.php $\endgroup$
    – Math4life
    Commented Mar 7, 2017 at 6:48
  • $\begingroup$ Wow, a log scale would have made more sense. $\endgroup$
    – Spencer
    Commented Jul 21, 2022 at 23:24

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