In comparison ...

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We all know it's getting warmer, the question to ask is, how fast is the earth heating up? Researchers are now finding out the answer and it's disquieting to say the least.

University of Arizona-led effort to reconstruct Earth's climate since the last ice age, about 24,000 years ago, highlights the main drivers of climate change and how far out of bounds human activity has pushed the climate system.

The study, published this week in Nature, had three main findings:

• It verified that the main drivers of climate change since the last ice age are rising greenhouse gas concentrations and the retreat of the ice sheets.
• It suggests a general warming trend over the last 10,000 years, settling a decade-long debate about whether this period trended warmer or cooler in the paleoclimatology community.
• The magnitude and rate warming over the last 150 years far surpasses the magnitude and rate of changes over 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 Jessica Tierney, a UArizona geosciences associate professor and co-author of the study.

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When looking at the temps of the last ice age, compared to today, the difference is most revealing.

A University of Arizona-led team has nailed down the temperature of the last ice age—the Last Glacial Maximum of 20,000 years ago—to about 46 degrees Fahrenheit (7.8 C).

In context ...

Tierney is lead author of a paper published today in Nature that found that the average global temperature of the ice age was 6 degrees Celsius (11 F) cooler than today. For context, the average global temperature of the 20th century was 14 C (57 F).

"In your own personal experience that might not sound like a big difference, but, in fact, it's a huge change," Tierney said.

The temperature differential in the Arctic is most telling.

"In North America and Europe, the most northern parts were covered in ice and were extremely cold. Even here in Arizona, there was big cooling," Tierney said. "But the biggest cooling was in high latitudes, such as the Arctic, where it was about 14 C (25 F) colder then today."

The loss of albedo in the Arctic, due to global warming, is key to why this is so. 

Any questions?