#petm

[greenfue]

الأرض قبل 56 مليون سنة.. ارتفاع حرارة مفاجئ أثر على قدرة النباتات على امتصاص الكربون

الأرض قبل 56 مليون سنة.. ارتفاع حرارة مفاجئ أثر على قدرة النباتات على امتصاص الكربون

[lemonthepotato]

The “natural cycles” crowd confuses me because. How the fuck does this look natural to you

The Paleocene–Eocene thermal maximum is the closest analogue to what is happening today. It was a temperature rise of 5–8 °C… over 5,000 years. 0.01∘C a decade. We’re ‘officially’ warming at like, 0.2 a decade. It was caused by a massive carbon injection into the atmosphere, the equivalent of 11k to 26k gigatons. (though the source is debated)

This was a slow process.

We, on the other hand, have released 2,650 Gt in the span of 175 years. 0.00000385% of Earth’s history and 0.058% of our history. 3.5% of our recorded history.

We have risen global temperatures 1.5 degrees in that timespan. Most of that since the 1970’s (after we exploded our numbers.)

Since about 1979, the Arctic has warmed nearly 4× (four times) faster than the global average.

Over half of all CO2 emissions since 1751 occurred after 1988 or the last 30 years.

But yeah, natural cycles and all that.

Yeah, it’s “natural” in the sense that we are a part of the Earth and caused it. Not natural, otherwise.

We have been in a sixth mass extinction event for the past 50 years. Global wildlife populations have plummeted by an average of 73% in just 50 years, from 1970 to 2020. Why does this matter? Because we are also a part of nature and wildlife, and we rely on biodiversity. Estimates suggest that between 150 to 200 species disappear daily, a rate thousands of times higher than the natural background extinction rate. The way we’re going, it’s only a matter of time before we join the party from our own hubris and stupidity.

[greenfue]

المحيطات تغيّرت قبل الاحتباس الحراري العظيم بـ200 ألف عام

المحيطات تحمل ذاكرة طويلة لمناخ الأرض. مع كل دفقة كربون وكل ارتفاع في الحرارة، تسجل المياه القصة. واليوم، تواصل امتصاص كميات هائلة من الانبعاثات البشرية، مما يسبب تحمّض المياه السطحية ويهدد العوالق، قاعدة الشبكة الغذائية. للتنبؤ بما قد يحدث لاحقًا، يعود العلماء إلى الماضي. ومن أبرز الأمثلة الحدث الحراري الباليوسين–الإيوسيني (PETM)، وهو فترة احترار سريع وقعت قبل نحو 56 مليون عام. خلال هذه الحقبة…

المحيطات تغيّرت قبل الاحتباس الحراري العظيم بـ200 ألف عام

[harpagornis]

What if Mesozoic mammals were tiny because of the heat?

Recently a study for no evidence for Bergman’s rule (animals growing larger with colder climates) in Mesozoic dinosaurs and synapsids. Then another study came to mind, finding that mammals shrunk during the Paleocene-Eocene Thermal Maxium.

This lead to a question: what if Mesozoic mammals were strongly impacted by higher global temperatures, and couldn’t grow much larger?

Animals like Patagomaia, Repenomamus and Oxlestes among others show that relatively large sizes could be attained by Mesozoic mammals. The presence of absence of dinosaurs doesn’t seem to impact how large mammals grow (for instance both Maastrichtian Patagonia and early Cretaceous Liaoning have highly diverse small to large dinosaur faunas), so maybe global temperatures being higher made it harder for mammals to grow larger due to their high metabolisms.

Then again some Mesozoic synapsids didn’t have as high metabolisms and modern mammals, so who knows?

[a-dinosaur-a-day]

https://vxtwitter.com/albertonykus/status/1757175498378219573?s=20

Curious as to your thoughts on the legitimacy of this study? Cause it doesn't seem to line up with what we know of previous studies and the fossil record

I study how birds adapted to the PETM and I am extremely skeptical about their claim that this water bird clade they recovered emerged right after - one of the best bird fossil records from the Paleocene we have is stem-penguins. So clearly, they were around before then. And they don't even acknowledge that in the paper!

The phylogeny is interesting but as always I am a major skeptic about molecular clocks and this is no exception, given, again, the fossils that directly contradict the damn conclusion.

Other than that I haven't had time to go in depth enough, but those are my initial thoughts

Side note, when will a stable Neoavian phylogeny return from the war

The paper, for those curious:

Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative

[a-dinosaur-a-day]

@seimsisk great question!

During the Paleocene-Eocene Thermal Maximum, the entire world rapidly warmed due to the activity of the North Atlantic Igneous Province, which caused rapid release of carbon and, well, we know the rest from today

That warming lead to the entire planet - the whole world - having one climate: tropical. Above the usual tropical realms, it's called "paratropical".

So we call the regions of the world during the PETM by their current names - the polar region, the temperate region, etc. - but the climate of each of these was still Tropical

[a-dinosaur-a-day]

What sorta animals would show up in a PHP season set within the Ypresian?

So. Many. Things.

the Ypresian was the time when most modern groups of animals got their start! But there was still a lot of weird things - weird early experiments in mammalian gigantism, groups of animals that don't exist anymore, all sorts of stuff

yeah it would mostly be small things, but there'd be plenty of big stuff too

Gastornis would definitely be a huge hit

[twiglet192]

FRINGE ASTRONOMY, EP. 4: WHAT IS THE SILURIAN HYPOTHESIS?

Fig. 1: Two dinosaurs in a hypothetical past civilization. Figure made by the author with VUE Creator 2022. The Silurians are fictional creatures that appeared in an episode of the cult science fiction TV show Dr. Who. According to the plot, these lizard-like creatures achieved industrial expertise about 450 million years ago, long before humans evolved on Earth. In recent years, the idea of…

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