What two recurring events in earth’s history have an impact on the carbon cycle?

The carbon cycle is affected by a variety of factors, and happens through different processes. The processes can be divided into two, which are biological processes and geological processes. The biological aspect covers the use and production of carbon by living organisms. The geological aspect covers physical processes such as volcanic eruptions, and weathering of rocks, which may result to release of carbon back to the atmosphere. However, both of these aspects can be affected by recurring events in Earth's history. One is the switching between glacial and interglacial periods, and the other one is the seasonal changes. Glacial periods can lead to lower temperatures and lower carbon levels in the atmosphere. In contrast to this, warmer interglacial periods result to higher carbon levels primarily due to an abundance of life. Seasonal changes have a similar effect that can be observed at a shorter time. Human activities such as burning of fossil fuels and deforestation may also bring changes to the carbon cycle.