Global warming over the last 150 years is unprecedented

New research from the University of Arizona reconstructed the Earth’s climate for the last 24,000 years – since the last ice age. The goal of the research was to look more closely at global warming to see how far “out of bounds” human activity has pushed the climate. 

The researchers found that main drivers of climate change are greenhouse gases and the feedback loop of melting ice sheets. They determined that the last 10,000 years has been a warming period for Earth. 

Furthermore, the experts report that warming for the last 150 years has been much faster than for the last 24,000 years. 

“This reconstruction suggests that current temperatures are unprecedented in 24,000 years, and also suggests that the speed of human-caused global warming is faster than anything we’ve seen in that same time,” said study co-author Professor Jessica Tierney.

Study lead author Matthew Osman, a postdoctoral researcher in Geosciences, created global maps showing the change in climate every 200 years going back to 24,000 years ago. 

“The fact that we’re today so far out of bounds of what we might consider normal is cause for alarm and should be surprising to everybody,” said Osman.

“These maps are really powerful. With them, it’s possible for anyone to explore how temperatures have changed across Earth, on a very personal level. For me, being able to visualize the 24,000-year evolution of temperatures at the exact location I’m sitting today, or where I grew up, really helped ingrain a sense of just how severe climate change is today.”

To create the maps, the scientists combined two datasets – temperature from marine sediments and computer simulated climate models. The experts used a method called data assimilation. Professor Tierney explained that this method is commonly used in weather forecasting,

“To forecast the weather, meteorologists start with a model that reflects current weather, then add in observations such as temperature, pressure, humidity, wind direction, and so on to create an updated forecast.”

The research provides a glimpse into a future with rising greenhouse gases, as well as a window into the past, and will hopefully serve as a useful tool for planning. 

The research is published in the journal Nature.

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By Zach Fitzner, Earth.com Staff Writer