How Earth’s Orbit Affected Ice Sheets Millions of Years Ago
https://eos.org/research-spotlights/how-earths-orbit-affected-ice-sheets-millions-of-years-ago
Source: By Emily Underwood, Eos/AGU
Excerpt: When Earth’s atmosphere warms, the vast sheets of ice over Antarctica and Greenland melt. This melting, in addition to the thermal expansion of water, leads to rising sea levels. Although it’s clear that seas are rising at an increasing rate, scientists can’t yet precisely predict how fast or how much they will rise in the future. Now, scientists are using climate and fossil data from one of the warmest periods in Earth’s history to help improve our understanding of ice sheet and sea level behavior in a warmer-than-modern world. When scientists look for hints of how Earth’s warming climate will affect ice sheets, they often refer to the late Pliocene era, between 3.264 and 3.025 million years ago. During this period, the concentration of carbon dioxide in the atmosphere ranged between 300 and 450 parts per million (ppm)—as a reference point, the concentration of atmospheric carbon dioxide in October 2017 was 404.3 ppm. On average, the late Pliocene was warmer than today’s climate by about 2°C–3°C. Although the late Pliocene was relatively stable climatically, there were cool periods when ice sheets expanded and warm “interglacial” periods in which they retreated, according to climate models. However, marine fossil evidence indicates that sea levels did not always rise and fall in sync with global temperatures. In a new study, de Boer et al. explore a likely culprit for the mismatch: wobbles in Earth’s orbit that affect how solar energy is distributed around the planet....
Source: By Emily Underwood, Eos/AGU
Excerpt: When Earth’s atmosphere warms, the vast sheets of ice over Antarctica and Greenland melt. This melting, in addition to the thermal expansion of water, leads to rising sea levels. Although it’s clear that seas are rising at an increasing rate, scientists can’t yet precisely predict how fast or how much they will rise in the future. Now, scientists are using climate and fossil data from one of the warmest periods in Earth’s history to help improve our understanding of ice sheet and sea level behavior in a warmer-than-modern world. When scientists look for hints of how Earth’s warming climate will affect ice sheets, they often refer to the late Pliocene era, between 3.264 and 3.025 million years ago. During this period, the concentration of carbon dioxide in the atmosphere ranged between 300 and 450 parts per million (ppm)—as a reference point, the concentration of atmospheric carbon dioxide in October 2017 was 404.3 ppm. On average, the late Pliocene was warmer than today’s climate by about 2°C–3°C. Although the late Pliocene was relatively stable climatically, there were cool periods when ice sheets expanded and warm “interglacial” periods in which they retreated, according to climate models. However, marine fossil evidence indicates that sea levels did not always rise and fall in sync with global temperatures. In a new study, de Boer et al. explore a likely culprit for the mismatch: wobbles in Earth’s orbit that affect how solar energy is distributed around the planet....