Thanos

Yesterday, the Italian island of Sicily registered the highest temperature, 119.84°F (48.8°C), ever recorded in Europe.  Meanwhile, fires fueled by the record-breaking heat wave ravaged the Greek island of Evia. 

The NY Times is reporting that hundreds more people died during the recent Pacific Northwest heat wave than the official figures reported.  

Extreme weather has damaged crops in Brazil, and soon your cost for a cup of coffee at Starbucks will be higher.  Prices at smaller distributors will increase even more rapidly.

Fred has been downgraded to a Tropical Depression, but is expected to again become a Tropical Storm, if not a full-blown Hurricane, as it crosses the Straits of Florida this weekend, and seems likely to pass over the City of Atlanta.

The current interval in Earth's geologic history, the Quaternary Period, began about two million years ago.  The Quaternary is divided into two epochs, the Pleistocene, which ended approximately 100,000 years ago, and the Recent, or Holocene.  Some people have suggested naming the Recent, or at least the time dating from the start of significant human impact on Earth's geology and ecosystems, the "Anthropocene." I prefer the term "Thanoscene," from the Greek thánatos, meaning "personification of death," as these are surely end times.

The Quaternary is famous for the Ice Ages that occurred throughout the Pleistocene.  The advances of continental glaciers during the Ice Ages were interrupted by warmer, interglacial intervals, during which the ice retreated.  The Holocene is the current interglacial period, but on a geological time scale, there's no reason not to expect another continental glaciation, another Ice Age, unless something dramatic happens to break the cycle of periodic global glaciations and interglacial periods.

During most of my life, people were convinced that a seemingly inevitable nuclear war would lead to a nuclear winter, which in turn would commence the next Ice Age.  These fears resurfaced in the 1980s, when a hole in the ozone layer raised awareness of the level of aerosols in the atmosphere which, along with particulates, were reflecting the Sun's warmth away from the Earth.

What we didn't think much about back then was the carbon dioxide we were also pumping into the atmosphere. However, I do remember one geology professor way back in the '70s noting that the warmest interval in Earth's history was the Eocene Epoch of the early Tertiary Period.  We know this was the warmest interval, he explained, due to plant fossils, a lack of any evidence of glaciation during that time, and, based on the geochemistry of Eocene sediments, the high level of carbon dioxide in the atmosphere.  The carbon dioxide concentrations during the Early Eocene are inferred to be between 1,000 and 2,000 parts per million due to volcanic activity.  

Anyway, as the professor was telling us this, he off-handedly noted that perhaps we should think twice about all of the carbon dioxide we're putting in the atmosphere now, because you never know what might happen.  He wasn't alarmist about this, he was just casually mentioning it - it might even have been the first time he put the Eocene climate and current pollution levels together in his head.

That was 1978.  That was the first time I heard of the concept of anthropogenic climate change.

There were plenty of other catastrophes to worry about at that time - not only nuclear war, but the eruption of Mt. St. Helens (1980), the Bhopal disaster (1984), the hole in the ozone layer (1985), the Chernobyl disaster (1986), etc.  The potential threat from carbon dioxide levels seemed to be way down on the list of things we needed to worry about.  But here we are now in 2021 with Fred, the fourth or fifth major tropical storm in the last 10 months, heading our way.

But if we can learn anything from history, perhaps we can learn from Earth's geologic history as well.  Being the most recent, the Quaternary deposits are generally at the surface, and the Quaternary is probably the most understood interval in Earth's history.  Based on multiple lines of geologic research, including sediment analysis, examination of fossils, ice cores, and analyses of lake-bottom sediments, the warmest multi-century period during the Holocene occurred around 6,500 years ago. The last interglacial period,  back during the Quaternary, was around 125,000 years ago.  These warm periods were caused by slow (multi-millennial) variations in the Earth's orbit.  

According to this week's Intergovernmental Panel on Climate Change Sixth Assessment Report, the scale of recent changes across the climate as a whole and the present state of many aspects of the climate system are unprecedented over many centuries to many thousands of years. In 2019, atmospheric carbon dioxide concentrations were higher than at any time in at least two million years (i.e., before the Quaternary).  We have to go all the way back to the previous Pliocene Epoch or even earlier to find similar levels.  Concentrations of methane were higher than at any time in at least 800,000 years (i.e., before the Holocene).  Since 1750, increases in carbon dioxide (47%) and methane (156%) concentrations far exceed the natural multi-millennial changes between glacial and interglacial periods over at least the past 800,000 years.

Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2,000 years. Temperatures during the most recent decade (2011–2020) exceed those of the warmest period in all of the Holocene around 6,500 years ago. Prior to that, the next most recent warm period was about 125,000 years ago.

In 2011–2020, annual average Arctic sea ice area reached its lowest level since at least 1850. Late summer Arctic sea ice area was smaller than at any time in at least the past 1,000 years. The global nature of glacier retreat since the 1950s, with almost all of the world’s glaciers retreating synchronously, is unprecedented in at least the last 2,000 years.

Global mean sea level has risen faster since 1900 than over any preceding century in at least the last 3,000 years. The global ocean has warmed faster over the past century than since the end of the last glaciation  (around 11,000 years ago). A long-term increase in open-ocean pH occurred over the past 50 million years, and open-ocean pH as low as recent decades is unusual in the last two million years.

This is particularly significant when you consider that although the first human ancestors appeared between five and seven million years ago when some apelike creatures in Africa began to walk on two legs, primitive Homo sapiens with brains as large or larger than ours first appeared in Africa only about 300,000 years ago. They were followed by anatomically modern Homo sapiens at least 200,000 years ago, and brain shape became essentially modern by about 100,000 years ago.

Our species, Homo sapiens, has never lived on a planet with carbon dioxide and methane levels as high as they are now.  Our species has not lived on a planet with average temperatures as high as now since the last Pleistocene interglacial. We're clever apes - we managed to survive the Pleistocene interglacial and we'll likely live through this one as well. The late Holocene appears to be the great Sixth Extinction (which is why I favor the term "Thanoscene" for the post-Holocene interval), and while many species are dying now and will die in the very near future, this probably isn't an extinction event for us humans.  We'll figure out a way to live through this, but the "this" we live through might very literally be hell on Earth.