Marine Isotope Stage 11

Marine Isotope Stage 11, or MIS 11, was a warm time in Earth's past. It happened between 424,000 and 374,000 years ago and is part of the geologic temperature record. This warm time is called an interglacial period.

Scientists study times like MIS 11 to learn about Earth's climate. By looking at the past, they can understand what might happen in the future. MIS 11 is special because it can be compared to the warm time we live in now, called the Holocene. This helps scientists predict future climate changes.

Characteristics

MIS 11 was a very warm and long time without ice ages. It lasted longer than other similar periods in the past. During this time, the oceans were warmer, especially in colder areas, and the sea level was higher than it is today. Coral reefs grew more than usual. Scientists think MIS 11 was the warmest time without ice ages in the last half a million years.

Concentration of CO₂

Carbon dioxide levels during MIS 11 were similar to levels before the industrial period. They were not very high compared to other warm times. One special thing about MIS 11 is that carbon dioxide did not rise early, unlike usual warm periods. This happened because the oceans were very active early in MIS 11.

The long warm time during MIS 11 was affected by changes in carbon dioxide levels and sunlight. When certain patterns in Earth’s orbit were at their lowest, even small changes in sunlight could let carbon dioxide affect the climate a lot.

Carbonate productivity

In shallow waters, big reefs like the Great Barrier Reef grew because more calcium carbonate was made. This happened in both colder and warmer oceans far from the equator. Tiny sea creatures changed kinds when the water got warmer. This extra carbonate made in some places might be why we find less of it in other parts of the ocean, like the Indian and Pacific oceans. Sea levels rose and covered land near the coasts, which could be another reason for lots of reefs in warm areas during this time.

Sea level & marine transgression

Beach deposits in Alaska, Bermuda and the Bahamas, as well as uplifted reef terraces in Indonesia, show that global sea level was once twenty metres higher than it is today. Records of δ¹⁸
O show changes that match this, but we don’t know if it was because of temperature or melting ice.

The higher sea level means that big ice sheets, like those in West Antarctica and Greenland, were smaller or even gone during this time. Deposits from Greenland suggest that much of south Greenland had no ice, causing sea level to rise by about 4.5 to 6 metres around 410,000 to 400,000 years ago.

Astronomical features

MIS 11 was a special warm time between ice ages. It happened about 424,000 to 374,000 years ago. This warm time lasted longer than others because of changes in Earth’s orbit. These changes kept the climate warm for a longer time.

Scientists think MIS 11 can help us learn about our future climate. Some studies say that without humans, our warm time today might have lasted longer, like MIS 11.