Today’s #MakeAPlanet quiz: This essential element was a toxic product of early life that first caused extinction, but later allowed life to establish on land. Its production formed distinct rock layers. 50-80% comes from the oceans today.
A) Carbon
B) Oxygen
C) Iron
D) Nitrogen
Adding a little buffer so folks can guess without seeing the comments.
I tried to mislead you with some sneaky references (the reddish rocks and the ocean), so this was a fun one.
Remember coloring in the parts of a cell in school? Cyanobacteria are bacteria that contain chloroplasts (an organelle used in photosynthesis). Like other organelles, it’s thought these were once a separate single-called organism that formed a symbiosis and got assimilated!
Around 3.5 billion years ago, those early cyanobacteria started forming mats called stromatolites, which are some of the oldest evidence of life we have. And guess what? There are still active stromatolites today! These are in Shark Bay, Australia.
Stromatolites were turning ☀️ into sugar—photosynthesizing, like plants. What’s the byproduct of photosynthesis? Oxygen, which is essential to almost every organism today. But! There was no oxygen Earth’s early atmosphere, so the first life evolved without it. Oxygen was toxic.
For tens of millions of years most of that dissolved oxygen reacted with iron-rich waters, forming red, rust-like layers in what eventually became sedimentary rocks. These “banded iron formations” are some of the oldest rocks on Earth, and hold up to 60% of global iron reserves.
Eventually, the iron levels in the oceans dropped, and oxygen started building up in the atmosphere, where some of it formed our ozone layer (ozone= 3 oxygen molecules). Ozone protects life from harmful UV radiation from the sun; without it, life was largely restricted to the 🌊.
And while we often credit 🌳 for producing our life-sustaining oxygen, more than half of it actually comes from phytoplankton and seaweed in the ocean (both of which are algae, and not technically even plants).
But back to that early life and toxic oxygen—did the Great Oxygenation Event really trigger a mass extinction? You’ll just have to back @MakeAPlanetPod to find out.
Correction: I misremembered how cyanobacteria do photosynthesis—they don’t have chloroplasts (they do photosynthesis via special pigments, including chlorophyll). Cyanobacteria are thought to have BECOME organelles like chloroplasts! They were the assimilated, not assimilators!
Over a month after the vote, the think pieces on the "rejected" Anthropocene are still coming strong, so I wanted to take a moment to (finally!) offer some background and thoughts about the vote, the process, and what it all means.
Geologists define different intervals in Earth's past so we can share a common language. Earth's 4.5 billion year history is divided into a series of eons (longest), eras, periods, epochs, and ages (shortest), based on visible changes in rock layers and fossil ecosystems.
For example, the Cenozoic Era began 66 million years ago with the impact that killed the dinosaurs. Within that, the Paleocene (66 to 56 mya) was the first epoch within the Paleogene Period (66 to 23 mya). Each is defined by rock layers that record extinctions and climate events.
Last December, a @DukeU Magazine article explored the "uncertain future" of the Duke Herbarium.
The scientific community is now learning that Duke has decided that this facility will be closed. This is bad, and here's why.dukemag.duke.edu/stories/nowher…
A herbarium is basically a collection of plant specimens that are preserved for research and teaching. They're a vital resource to help scientists identify species, understand changes in biodiversity patterns, or even changes in flowering time or other climate change impacts.
Herbaria require resources and space, as well as staff, who use the collections for research and outreach, and who assist visiting scientists to conduct research. Many collections are digitized, but the actual specimens have tons of value. Internet photos aren't enough.
If you say humanity is doomed to extinction and that nothing we can do can prevent total climate breakdown and ecosystem collapse, I need you to know's just as unscientific as saying there's no climate crisis.
I don't platform disinformation. I don't care what kind it is.
Sadly, I've learned that just as there's no convincing the dismissives the climate crisis is real, there's no convicing defeatists that this isn't pass-fail, and that our work will always matter. I only have so much time and energy. It needs to go where it can be of the most use.
Most defeatists seem to come from demographics that haven't historically faced the loss of their bodily autonomy, rights, homelands, or cultures. I empathize with those experiencing their first-ever existential threats, but I really wish their first instinct wasn't to give up.
I woke up this morning full of pain at so much violence, to each other and to the planet. I wrote a short message to my lab, and it helped me see a clearer path. I'm sharing it here in case it helps you, too.
Witnessing trauma is its own kind of trauma, especially in a society that wants us to suppress that trauma so we can continue to function as well-oiled cogs. We don't have a lot of good tools for how to bear witness without becoming numb. And we cannot become numb.
I wish I had the answers, but I'm fumbling through this, myself. What I can say is that when things are difficult, anything we can do to show up for each other and our communities makes a difference. The fabric of society is threadbare and torn; we must patch and weave.
Since 2009, the Anthropocene Working Group has been trying to decide whether geologists should revise the geologic timeline to include a new epoch defined by human impacts, and if so, when. 🧵
If you're not familiar with this project or the debates about when the Anthropocene would start, here's a thread I did on exactly that:
Now that you're all caught up on golden spikes, here's an update:
Today, the Anthropocene Working Group (AWG) announced their recommendation, which is that we should have a new geologic epoch, and it started in 1950, as recorded in lake sediments from Crawford Lake, Ontario.
Milloy’s opinion gets an F in accuracy, but is a master-class in denialist propaganda. It employs the classic tactic of discrediting experts with what seem to be reasonable, obvious statements. They’re superficial and easy to discredit, but the point is to hijack the narrative.
He first tries to lay blame with the media's use of Climate Reanalyzer, a tool developed by my colleagues here at UMaine, claiming it exaggerates temperature anomalies (aka, warmer or colder than average) relative to a different website, temperature [dot] global.
Temperature [dot] global has little info about data sources or methods, and the "About" lists no names or orgs. They say their averages are calculated from a "30-year mean," but provide it. The only time interval mentioned is on in the one graph provided: Jan 2015-Jun 2023.