Carbon Dioxide Levels in the Atmosphere Hit Highest Level in 3 Million Years
According to a recent National Oceanic and Atmospheric Administration (NOAA) report, the last time carbon dioxide levels were this high was 3 million years ago "when temperature was 2°–3°C (3.6°–5.4°F) higher than during the pre-industrial era, and sea level was 15–25 meters (50–80 feet) higher than today."
That period, the Pilocene Era, is unrecognizable from today. Giant camels walked around on the ice-free land above the Arctic Circle, as NBC News reported.
Earth first passed the 400 million parts per million of CO2 in the atmosphere in 2013. Rather than take it as a dire warning, we have become inured to that level of concentration and have seen it rise slightly in subsequent years. In 2018, the concentration was 407.4 parts per million (ppm), according to NOAA. This year, CO2 concentrations are predicted to peak at 417 ppm, according to NBC News.
That level will put humans in new, unfamiliar territory. "For millions of years, we haven't had an atmosphere with a chemical composition as it is right now," said Martin Siegert, co-director of the Grantham Institute at Imperial College London, to NBC News.
In fact, just two weeks ago, on Feb. 10, NOAA's Mauna Loa Observatory, an atmospheric baseline station in Hawaii, recorded the daily average of CO2 levels on as 416.08 parts per million, according to Common Dreams.
Carbon Dioxide concentrations are an effective measure of how many fossil fuels we are burning. Coal and crude oil contain carbon that plants have pulled out of the atmosphere through photosynthesis over millions of years. However, in short order, human activity has returned that trapped carbon back into the atmosphere, as NOAA reported.
"We've done in a little more than 50 years what the earth naturally took 10,000 years to do," said Siegert to NBC News.
University of Exeter geography professor Richard Betts, head of the climate impacts division at the UK's national weather service, expects this year's CO2 concentrations to be 10 percent higher than normal, with one or two percent of that carbon rise attributed to the Australia wildfires, as NBC News reported. The fires, which raged for nearly five months, released about 900 million tons of carbon dioxide into the atmosphere.
The Pliocene Era from 5 to 2.6 million years ago provides a window of what a world with such high carbon dioxide concentrations can look like. It was a period well before humans evolved. Temperatures at the poles then were likely about 15 degrees Fahrenheit higher than they are now, according to Siegert, who spoke to NBC News.
"There would have been a lot less ice on the planet — there probably wasn't a Greenland Ice Sheet, the West Antarctic Ice Sheet had probably melted, and big chunks of the East Antarctic Ice Sheet had probably de-glaciated, as well," he said to NBC News.
Carbon dioxide in the atmosphere is also notable for its contribution to ocean acidification. According to NOAA, when CO2 reacts with water molecules, it produces carbonic acid and lowers the ocean's pH. Already, the ocean's surface pH has dropped from 8.21 in pre-industrial times to 8.10."The rate of rise in the last decade has been faster than previous decades," said Betts, as NBC News reported. "We're just tracking ever onwards, and 400 ppm is now a distant memory."
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By Katherine Kornei
Clear-cutting a forest is relatively easy—just pick a tree and start chopping. But there are benefits to more sophisticated forest management. One technique—which involves repeatedly harvesting smaller trees every 30 or so years but leaving an upper story of larger trees for longer periods (60, 90, or 120 years)—ensures a steady supply of both firewood and construction timber.
A Pattern in the Rings<p>The <a href="https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/coppice-standards-0" target="_blank">coppice-with-standards</a> management practice produces a two-story forest, said <a href="https://www.researchgate.net/profile/Bernhard_Muigg" target="_blank">Bernhard Muigg</a>, a dendrochronologist at the University of Freiburg in Germany. "You have an upper story of single trees that are allowed to grow for several understory generations."</p><p>That arrangement imprints a characteristic tree ring pattern in a forest's upper story trees (the "standards"): thick rings indicative of heavy growth, which show up at regular intervals as the surrounding smaller trees are cut down. "The trees are growing faster," said Muigg. "You can really see it with your naked eye."</p><p>Muigg and his collaborators characterized that <a href="https://ltrr.arizona.edu/about/treerings" target="_blank">dendrochronological pattern</a> in 161 oak trees growing in central Germany, one of the few remaining sites in Europe with actively managed coppice-with-standards forests. They found up to nine cycles of heavy growth in the trees, the oldest of which was planted in 1761. The researchers then turned to a historical data set — more than 2,000 oak <a href="https://eos.org/articles/podcast-discovering-europes-history-through-its-timbers" target="_blank" rel="noopener noreferrer">timbers from buildings and archaeological sites</a> in Germany and France dating from between 300 and 2015 — to look for a similar pattern.</p>
A Gap of 500 Years<p>The team found wood with the characteristic coppice-with-standards tree ring pattern dating to as early as the 6th century. That was a surprise, Muigg and his colleagues concluded, because the first mention of this forest management practice in historical documents occurred only roughly 500 years later, in the 13th century.</p><p>It's probable that forest management practices were not well documented prior to the High Middle Ages (1000–1250), the researchers suggested. "Forests are mainly mentioned in the context of royal hunting interests or donations," said Muigg. Dendrochronological studies are particularly important because they can reveal information not captured by a sparse historical record, he added.</p><p>These results were <a href="https://www.nature.com/articles/s41598-020-78933-8" target="_blank">published in December in <em>Scientific Reports</em></a>.</p><p>"It's nice to see the longevity and the history of coppice-with-standards," said <a href="https://www.teagasc.ie/contact/staff-directory/s/ian-short/" target="_blank">Ian Short</a>, a forestry researcher at Teagasc, the Agriculture and Food Development Authority in Ireland, not involved in the research. This technique is valuable because it promotes conservation and habitat biodiversity, Short said. "In the next 10 or 20 years, I think we'll see more coppice-with-standards coming back into production."</p><p>In the future, Muigg and his collaborators hope to analyze a larger sample of historic timbers to trace how the coppice-with-standards practice spread throughout Europe. It will be interesting to understand where this technique originated and how it propagated, said Muigg, and there are plenty of old pieces of wood waiting to be analyzed. "There [are] tons of dendrochronological data."</p><p><em><a href="mailto:email@example.com" target="_blank" rel="noopener noreferrer">Katherine Kornei</a> is a freelance science journalist covering Earth and space science. Her bylines frequently appear in Eos, Science, and The New York Times. Katherine holds a Ph.D. in astronomy from the University of California, Los Angeles.</em></p><p><em>This story originally appeared in <a href="https://eos.org/articles/tree-rings-reveal-how-ancient-forests-were-managed" target="_blank">Eos</a></em> <em>and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.</em></p>
Earth's ice is melting 57 percent faster than in the 1990s and the world has lost more than 28 trillion tons of ice since 1994, research published Monday in The Cryosphere shows.
By Jewel Fraser
Noreen Nunez lives in a middle-class neighborhood that rises up a hillside in Trinidad's Tunapuna-Piarco region.