It has become increasingly difficult for climate change deniers to rationalize their position. They’ve gone from claiming that the globe isn’t warming to saying this is just part of a normal cycle. That position is just as wrong, according to climate scientists. A trio of new studies adds weight to that assessment, showing that the current rate of warming is “unparalleled” in the last 2,000 years.
Modern climate change opponents often point to anomalies — like the Roman Warm Period that ran from 250 to 400 CE and the Little Ice Age that occurred in the 17th through 19th centuries — as evidence than our current situation is normal. To finally and entirely debunk this claim, scientists had to reconstruct past climate data in unprecedented detail and compare that with the most accurate modern readings.
Of course, there were no thermometers around 2,000 years ago, and any written records are suspect. However, scientists can make measurements of temperature changes over time using tree rings, corals, lake sediments, ice cores, and so on. Climate scientists who have examined the data have been impressed with its scope and accuracy. After gathering more than 700 of these “proxy records” of the ancient climate, the teams concluded that past climate events were not active on a global scale.
Current temperature trends are far outside the norm for Earth’s natural variation.
The Little Ice Age? The researchers concluded it was only strongly felt around the Pacific Ocean in the 15th century and in Europe during the 17th century. Before that, the “Medieval Warm Period” from 950 to 1,250 CE featured increased temperatures across just 40 percent of Earth. Volcanic activity appeared to have the most powerful impact on climate prior to the modern era, and solar cycles didn’t appear to have any effect.
By comparison, the scientists say that today’s climate is the hottest of the past two millennia for 98 percent of the planet. The rate and degree of warming in global temperatures exceeds natural variation by a wide margin, according to the studies. These papers do not aim to identify the cause of the current warming trend, but there’s plenty of research that points the finger squarely at humans. Some people will continue disputing this claim, but the new research should at least put this “natural cycle” argument to rest.
Top image credit: Luca Galuzzi/CC BY-SA 2.5
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