Climate Change Landmark of 400 PPM of CO2: More Evidence From 3 Million Years Ago
In these days of continually streaming propaganda over nearly any politically sensitive issue, the subject of climate change has become so entangled with local and national political interests that it is good to step back and look at what the science is really saying, again.
Today Science magazine published a paper that presented analyses of lake sediments from a north-east Russian lake:
Understanding the evolution of Arctic polar climate from the protracted warmth of the middle Pliocene into the earliest glacial cycles in the Northern Hemisphere has been hindered by the lack of continuous, highly resolved Arctic time series. Evidence from Lake El’gygytgyn, NE Arctic Russia, shows that 3.6-3.4 million years ago, summer temperatures were ~8°C warmer than today when pCO2 was ~400 ppm. Multiproxy evidence suggests extreme warmth and polar amplification during the middle Pliocene, sudden stepped cooling events during the Pliocene-Pleistocene transition, and warmer than present Arctic summers until ~2.2 Ma, after the onset of Northern Hemispheric glaciation. Our data are consistent with sea-level records and other proxies indicating that Arctic cooling was insufficient to support large-scale ice sheets until the early Pleistocene.
From the press release:
The Arctic was very warm during a period roughly 3.5 to 2 million years ago—a time when research suggests that the level of carbon dioxide in the atmosphere was roughly comparable to today’s—leading to the conclusion that relatively small fluctuations in carbon dioxide levels can have a major influence on Arctic climate, according to a new analysis of the longest terrestrial sediment core ever collected in the Arctic.
“One of our major findings is that the Arctic was very warm in the middle Pliocene and Early Pleistocene—roughly 3.6 to 2.2 million years ago—when others have suggested atmospheric carbon dioxide was not much higher than levels we see today,” said Julie Brigham-Grette, of the University of Massachusetts Amherst.
She added that “this could tell us where we are going in the near future. In other words, the Earth system response to small changes in carbon dioxide is bigger than suggested by earlier climate models.”
The lake being examined is north of the Arctic Circle.
It is important to remember the phrase Polar Amplification. This lake evidence is just one more in a long list that indicates that the climate will change more significantly towards the poles of the planet. This is why an island in the Pacific, say Hawaii, will experience much less temperature change than the north side of Greenland.
As noted in today’s article in Scientific American, 400 PPM: Carbon Dioxide in the Atmosphere Reaches Prehistoric Levels:
The last time CO2 levels at Mauna Loa were this high [400 ppm], Homo sapiens did not live there. In fact, the last time CO2 levels are thought to have been this high was more than 2.5 million years ago, an era known as the Pliocene, when the Canadian Arctic boasted forests instead of icy wastes. The land bridge connecting North America and South America had recently formed. The globe’s temperature averaged about 3 degrees C warmer, and sea level lapped coasts 5 meters or more higher.
While the Science paper is behind a pay-wall, the supplemental material is not. Among the information that impressed me was the graph of vegetation changes (from pollen):
In that diagram we can see how the transition from the warmer Pliocene (on the right of the diagram) to the Pleistocene (the “Ice Age”, on the left of the diagram) was accompanied by a change in vegetation. There is no doubt that climate change does indeed change the biome.
Whether we are discussing changes in ecosystems or sea level, it is important to remember that we humans have such a short life and even shorter attention span that large changes are often just overlooked if we rely upon casual glances at the world around us. As common in all areas of science, only careful and systematic observations and analyses can take us out of our biases and “common sense” to gain a greater knowledge of the world around us.
That appears, though, by looking at our popular press and current political environment, to be quite a challenge for us today. There has been no substantive change in the production of CO2 in our modern industrialized world. Growth in CO2 output continues with only modest slowing during the deepest of economic recessions.
What will it take to change our way?