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Fact check: Was there more CO2 in the atmosphere before current times

Checked on September 19, 2025

1. Summary of the results

The question of whether there was more CO2 in the atmosphere before current times has been analyzed through various sources. Most sources agree that current CO2 levels are higher than pre-industrial levels, with some sources stating that CO2 levels are now more than 50% higher than pre-industrial levels, exceeding 417 parts per million [1]. The current level of 422.8 parts per million is significantly higher than pre-industrial levels, which were around 280 ppm or less [2]. Historical data from ice cores and direct measurements also support the conclusion that current CO2 levels are higher than in the past [3]. However, some sources do not provide direct evidence of higher CO2 levels in the past, instead discussing the variability of CO2 levels over the last 1000 years [4].

2. Missing context/alternative viewpoints

A key point missing from the original statement is the timescale being considered, as CO2 levels have fluctuated throughout Earth's history [2]. Alternative viewpoints include the consideration of natural fluctuations in CO2 levels, such as those that occurred at the end of the last ice age 20,000 years ago [5]. Additionally, the methods used to determine past CO2 levels, such as extracting air bubbles from ice cores, are crucial in understanding the historical context of CO2 levels [6]. The impact of human activities on CO2 levels is also an important consideration, with sources stating that human-induced rise in CO2 is greater than the natural increase observed at the end of the last ice age [5].

3. Potential misinformation/bias in the original statement

The original statement may be misleading or biased as it does not consider the timescale or context of CO2 level fluctuations [2]. The statement may benefit those who argue against the significance of current CO2 levels, by implying that CO2 levels have always been high [2]. However, most sources agree that current CO2 levels are higher than pre-industrial levels, and that human activities have contributed significantly to this increase [1] [5]. Therefore, the original statement may be inaccurate or misleading, and a more nuanced understanding of CO2 level fluctuations is necessary [4] [3].

Want to dive deeper?
What were the CO2 levels during the last ice age?
How has human activity affected CO2 levels since the Industrial Revolution?
What is the current CO2 level in parts per million?
How do CO2 levels affect global temperatures?
What were the CO2 levels during the time of the dinosaurs?