My last post argued that Antarctic Ice Cores are poor proxies for world climate. They do not show short term changes. Changes take centuries to develop in ice cores. Sudden changes that last for a few years or even hundreds of years can be completely missed by ice cores. Things like…say…a sudden spike in carbon dioxide levels following a volcanic eruption.
Ice cores provide general information about the world of the past…but it is just that…general information. This post will use one single event, the Toba super volcano eruption to accentuate the point.
Lake Toba is a large lake in Indonesia. The lake is 100 kilometers long and 30 kilometers wide. About 74,000 years ago it was the center of a super volcano eruption. The caldera of this much studied volcanic event encompassed the entire lake and surrounding territory…
This eruption was a really big deal. It almost wiped out mankind. This eruption was such an extraordinary event, it is difficult for me to comprehend exactly how big it was.
Scientists measure volcanic eruptions using the Volcanic Explosivity Index or VEI. The total volume of material expectorated by the volcano is estimated. Small volcanic eruptions are VEI1, super volcanoes are VEI8. The following chart helps me get a sense of the size of the various events. I like this chart because it includes the 3 most recent events I like to use to get perspective, Mt. St. Helens, Pinatubo and Tambora. The St. Helens explosive eruption of 1980 was a relatively small event. Yep a small event. Pinatubo was about 10 times larger and it was big enough to change temperatures worldwide for 2 years. Tambora is the most recent VEI7 event and was some 10 times larger than Pinatubo. Tambora began erupting on April 5, 1815. The eruption could be heard over a 1000 miles away. 1816 was nicknamed the year without a summer.
Tambora was a big deal. The biggest in recent history. Toba was a VEI8 event some 28 times bigger than Tambora.
Imagine if you can what that must have been like. It was so cold and so dark that that man almost didn’t survive the event. NOW let’s take a peek at the Vostok Antarctic Ice Core. I have selected a graph that blows up the period from 50,000 years ago to 100,000 years ago. I see a very small dip some 74,000 years ago. A dip of perhaps half a degree C with virtually no change in carbon dioxide levels. Carbon dioxide levels spiked during the eruption, particulate matter would have stayed in the atmosphere for centuries. Temperatures all over the world would have dropped dramatically. Temperatures are supposed to have dropped 3 to 5 degrees C and the event is supposed to have changed global climate for 1000 years.
The chart is full of bigger moves. Bigger than a VEI8 event? What natural event could that be? About 4000 years before the event there is a sudden fall of about 3 degrees C in a very short period of time. I wonder what caused that?
When I look at ice cores and think about super volcanic events I feel better about the world. If the world can survive a Toba event and recover…maybe the gloom and doom being spouted at UN climate meetings is a bit overdone?