Jacquelyn Gill on rapid climate change 13,000 years ago

Jacquelyn Gill: Understanding the past is often the key to understanding the future.

Jacquelyn Gill is a PhD candidate at the University of Wisconsin-Madison. She’s been researching a period of rapid cooling that occurred about 13,000 years ago. Gill said that global temperatures took an extreme and sudden dip, just as the world was coming out of an ice age. She spoke with EarthSky at a science meeting in late 2009.

Jacquelyn Gill: It’s important because it’s one of our best-dated and most studied examples of rapid climate change.

Gill has been studying animals that lived around that time, using fungal spores preserved in sediment as an indicator of wildlife presence. She’s found that extinctions of big ice age animals – creatures like mastodons – happened about 1,000 years before this brief cooling period.

Jacquelyn Gill: Immediately following the decline in these animal populations, the first wildfires pop up on the landscape. We also see widespread vegetation change. It really seems like the landscape is noticing the loss of these herbivores.

She said that scientists still aren’t sure why animals of the ice age died off, or why the world’s climate might suddenly warm and cool. But, she added, mining the past for clues about rapid climate change could help us better understand how the environment stands to be affected by today’s global warming. Gill said that this short period of rapid cooling that happened after the last ice age is called the Younger Dryas.

Jacquelyn Gill: It’s important because it’s one of our best dated and most studied examples of rapid climate change. We can see this cold period that lasts several centuries but it really only takes a few years for this return to glacial conditions. We are not talking about 0.1 degrees Celsius in 100 years; we’re talking about a really rapid event here. It’s really interesting to understand the Earth’s climate system from that perspective if, for example, we are interested in rapid climate change events in the future.

Gill told EarthSky that this is also the period when the first evidence of human life appears in North America. She explained that there is growing evidence suggesting that during this period humans were setting fires, using the land, and hunting animals, all pressures that could have significantly affected animal populations and extinctions.

Jacquelyn Gill: Because we don’t have time machines, paleoecologists and paleoclimatologists have had to become ecological detectives to try to determine what happened. We do know that temperatures got colder but we don’t necessarily know what caused this global climate change.

Jacquelyn Gill: We like to think of the end of the last ice age as this really fascinating natural experiment. It’s the last time that we really saw the earth undergo rapid climatic warming and vegetation and plants had to respond to that climate change. Understanding the processes surrounding these events, extinctions, the relationships between humans and their natural world, climate change during this period, help us understand the extinction and global warming events that we are currently experiencing.

March 1, 2010

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