Throughout Earth’s history, mass extinctions of species were closely
related to physical and chemical changes in the atmosphere and the
oceans. These variations were controlled by heat from the sun, the
distribution of oceans and continents, the extent of ice sheets;
volcanic eruptions and asteroid impacts, air-borne particles, the
eruption of methane and greenhouse effects. Greenhouse episodes were amplified by carbon dioxide and methane
feedback effects from warming oceans and drying vegetation, and by
changed reflection effects due to the extent of ice and snow. Current
climate changes, triggered by human-generated emissions, will lead to
shifts in the Earth’s climate zones toward the poles. The instability
of ice sheets melting may lead to significant sea level rises over a
time scale of decades.
