Past_climate_data.md

Past Climate Data

WorldClim paleo climate

WorldClim offers past climate data from two different time periods: the Mid-Holocene (6000 years ago) and the Last Glacial Maximum (22,000 years ago). This data comes from GCMs (just like the future climate data!), but for this data, the GCMs have been projected back in time.

During both of these time periods, our sloth species had all evolved and were living in South America (B. torquatus split from B. tridactylus and B. variegatus around 12 million years ago, and B. tridactylus and B. variegatus split 5-6 million years ago).

Last Glacial Maximum

As you can probably guess, the Last Glacial Maximum was the most recent time in Earth's history when global ice sheets were at their highest volume, which occurred around 22,000 years ago. Global climate was overall cooler and drier than it is today.

Some things going on during the Last Glacial Maximum:

• There was a land bridge between North and South America
• The Amazon was split into two main parts by savanna
• Megafauna, like mammoths and giant ground sloths, roamed the Americas

Further reading:

• The Global Last Glacial Maximum - Antarctic Glaciers
• The Last Glacial Maximum - Science

Mid-Holocene

The Mid-Holocene Warm Period was a period of high global temperatures that occurred from about 7,000 years ago to 5,000 years ago. The "warm" part of this period does not mean that the whole planet was warmer then compared to today. The difference in temperature in the mid-Holocene was caused by changes in Earth's orbit: during this time, the Northern Hemisphere was warmer than today in the summer and colder in the winter.

Some things going on in the Mid-Holocene Warm Period:

• Sea ice was at its minimum
• Stone Age settlements in Denmark ate many warm-climate animals, like swordfish and sturgeon
• The Nile River had 3 times its present volume
• Civilizations were developing in Mesopotamia

Further reading:

• Mid-Holocene Warm Period - NOAA
• OK, But we do know it was warmer than present 6000 years ago, don’t we? - Real Climate