I am angry that some people want to use 1965 as a starting point for the Anthropocene, as that date is clearly a political choice.
A less political choice is to simply ask, when did the extinction rate, for all animals, rise above the long term trend? And that is about 12,000 years ago, give or take a few thousand.
If we want to talk about a geological era defined by human influence on the environment, it isn't _political_ to use environmental radioactivity signals. They'll be easy to notice in 100M years. Extinction rate change will be harder to notice with the level of accuracy you want.
In 20 million years it's going to be hard to get something dated to within 100,000 years. So, the fact the die-offs started slightly before this layer of radioactive elements is probably not going to be noticeable.
Similarly the dinosaurs did not die of exactly 65,000,000 years ago it was 65,170,000 plus or minus ~640,000 years.
On top of that humans have probably killed of more species after 1965 than before 1965.
This is exactly why choosing a specific year, such as 1965, is political. It would be intellectually honest if they posted a range, with a large error margin.
Well, consider that one way or another, we've written ourselves into the geological record, as much as we've written our own history about ourselves. History, often airbrushed, is a sociological exercise, and so, it's always been a soft science.
Geological and cosmological history is filled with hypothesized events and broad revisions in the face of emergent (if subtle) proof against common views and norms. Lots of hypothetical place holders aren't apolitical at all. The big bang is pretty political, despite the background radiation that serves as "reasonable evidence" that something like the big bang might have occurred. The truth being that we don't honestly know why a universe would be created through a big-bang-like process, even though it's the best interpretation of the evidence we have access to, lately.
Large error margins are artifacts of incomplete information, and that doesn't mean incomplete information is truly preferable. We have pretty good information about 20th century events, even if the particulars of the social landscape are hotly debated.
"We have pretty good information about 20th century events"
We don't have specific dates for when the vast majority of extinctions have happened. We have a rough idea of what the base line extinction rate was for the last million years, and we have good data suggesting that the trend has been up for maybe 10-20,000 years, give or take several thousand years. Picking a specific year, such 9,874 BC, or 434 AD, or 1965 AD, is arbitrary, and a political act.
Is presence of species and biological diversity more relevant than transient geological evidence, asteroid impacts and tectonic activity? Without geological evidence (fossils) we would have no benchmark for non-living species.
Arguably, all geological timescales and frames of reference (as named by humans, and thus innately political) are based, not on biological taxonomy and known degrees of species diversity, but rather, on geological records, for which radioactive markers from weapons testing carried out by humans, remains a relevant and valid point of reference that may outlast us.
Not really, they are simply using the date related to a specific event which has error bars measured in months and expecting people to relate that event to the extinction. If WWIII happens and we have a full scale nuclear exchange then that's likely to be used as the peak.
Really, it's not a political statement just an interesting observation.
I still don't understand what geological record this would set. Wouldn't the tree eventually die and have its remains scattered around the globe? How would this preserve the radioactive elements in that spot?
Am I understanding geology and radioactivity wrong?
Lets assume you are a geologist 100000 years from now. When you look at a drilling core you most certainly will be able to identify a strata, that is enriched with radionuclides (or fission products of radionuclides), that cannot be found deeper (earlier) in the core.
>> Wouldn't the tree eventually die and have its remains scattered around the globe?
Yes, thats exactly the thing, a lot of trees (and other biomatter) will die, and all of them will scatter their slightly more radioactive remains around the globe to create a layer as an imprint of the history of our planet.
It's just one source of mapping radioactivity and time; I'm sure you'd be able to find a similar trace pretty much everywhere. As the article points out, they saw a similar spike in research done in the northern hemisphere.
I still feel like our mass burning/cutting down of forests for use in agriculture is the real start of the Anthropocene, which arguably began on a global scale thousands of years ago. It certainly made a large impact on the environment and climate, undoubtedly more than any other single species during that time.
What you write seems so obvious. We definitely cut & burnt a lot of wood, but we were not that many earthlings... So have you any source for what you say ? I'm genuinely interested.
Can anybody explain why this tree hasn't reproduced in the last hundred years? The tree does appear to reproduce asexually. Even with a very thin soil level, I would have expected at least one seed to take root in that time frame.
If I had to peg a date on it I'd use the date of the first atomic detonation at Trinity testing ground. That would leave a radioactive trace band around the world and definitely marks the emergence of hominids as a geological force.
I agree. It seems strange to mark the beginning of the age as a peak of some activity that had been going on for a bit. If it's defined by a change in the earth's composition, the ramp up to the peak is absolutely a change.
I’d think coal fueled central heating changed the planet much much more than cars did in the first half of the 20th. Id think a relatively small percentage of the world drove cars before 1965.
Indeed. And not just heating - by the end of the 19th century, billions of tons of coal had already been burned in industrialised nations just to power steam engines. Very few motor cars existed at that time and it was many decades until transport emissions started to catch up with coal.
Those last two sentences are pretty depressing:
> Should we define the Anthropocene by when humanity invented the technology to make themselves extinct? If so, then the nuclear bomb spike recorded in the loneliest tree on the planet suggests it began in 1965.
I hope we do better than being remembered for this.
The steam engine should mark the beginning of the antropocene. Nuclear generators still use steam power to produce electricity. Car pistons are not different than pistons for trains.
I think the antropocene is meant as a permanent change to the composition of the earth such as through changing the naturally occurring rate of carbon isotopes through fission.
So who planted a spruce tree on Campbell Island? These are only native to the northern hemisphere. "Wild" pines and spruces are considered an invasive species elsewhere in New Zealand.
A less political choice is to simply ask, when did the extinction rate, for all animals, rise above the long term trend? And that is about 12,000 years ago, give or take a few thousand.