During its worst climatic episodes, about 2300 million years ago and about 700 million years ago, the Earth was in deep freeze. Even tropical coastlines would have looked like this scene from Antarctica today, to judge from evidence of stones dropped by icebergs near the equator. The explanation is that our planet suff ered from the eff ects of close encounters between other galaxies and the Milky Way, which provoked enhanced star formation rates and intense cosmic radiation.
|Title of host publication||Engineering Challenges : energy, climate change & health|
|Editors||Carsten Broder Hansen|
|Place of Publication||Kgs.Lyngby|
|Publisher||Technical University of Denmark|
|Publication status||Published - 2009|
|Series||DTU research series|