Climate Change: Past climate change
This chapter summarises some of the major episodes between the Earth's formation and the beginning of the current, Quaternary, ice age.
Abstract
Post-industrial global warming is not the Earth's first major climate-change event. If we are to appreciate the significance and relevance to biology of current climate change, it is important to be aware of past climate events, at least the significant ones. This chapter summarises some of the major episodes between the Earth's formation and the beginning of the current, Quaternary, ice age. Early biology and climate of the Hadean and Archeaen eons (4.6–2.5 billion years ago, bya) The pre-biotic Earth (4.6–3.8 bya) The Earth and the solar system formed some 4.6 bya, give or take a few hundred million years. It formed with the solar (Sol) system accreting out of a dust and gas cloud. The dust, ice (composed of various volatiles compounds and not just water) and rocks were not all small and particulate but themselves had accreted into small and large asteroid-sized bodies that ranged in size up to, and including, small planets. One of these, a Mars-sized planetoid (Thea) is thought to have had a glancing blow with the proto-Earth, exchanged material, and formed the Moon (Luna). This is not irrelevant to the nature of the Earth's climate. The lunar/Earth ratio of mass of 1:18.3 is much greater than any satellite/planet mass ratio for any other planet in Sol's system. Taking the Copernican principle, that there is nothing cosmologically special about the Earth as a life-bearing planet, this begs the question as to whether our large moon is a necessary factor facilitating a biosphere, or at least a biosphere with longevity.