High CO2 Levels in the Air were Responsible for High Temperatures on Young Earth Written by AZoCleantechJun 1 2021 The temperature on the young Earth was warm despite that radiation of the sun was comparatively low. An international group of geoscientists has discovered essential clues that high levels of carbon dioxide (CO 2) in the air led to such high temperatures. Image Credit: 2 was slowly captured and stored on the newly forming continents. Three to four billion years ago, very high atmospheric CO 2 levels caused the high temperatures on the still-young Earth. During that time, the Sun shone with only 70%–80% of its current intensity. However, the climate on the young Earth was quite warm since there was barely any glacial ice.