Friday, May 8, 2015

Climate Change, Deccan Traps: Still Learning

Scientists found a two-century lag between temperature changes near Earth's poles — and maybe a "bipolar seesaw" temperature cycle.

Other scientists say that shock waves from the Chicxulub impact may have triggered volcanic eruptions in the Deccan Traps and elsewhere.
  1. Ice Cores and a Climate Lag
  2. Deccan Traps and the Chicxulub Impact
We don't, I think, have all the answers about how Earth's climate changes and what we should do about it: but we're discovering what some of the questions are. That's a good start.


Aristotle, Galileo, and All That


We've come a long way since Aristotle said we live in the sublunary sphere where stuff changes: unlike his heavenly bodies that didn't change, had always existed, and always would.

Aristotle's opinion carried considerable clout 16 centuries later, when the Church prohibited folks from claiming that Aristotle's preferences outvote God. Some rulings of 1277 got reversed in subsequent centuries: but not the basic idea — God's God, Aristotle's not. (February 23, 2014; January 29, 2012)

A bit later, observations of a supernova and comet wouldn't fit into Aristotle's cosmology.

Tycho Brahe measured the 1572 supernova's position over several days. Since it didn't move against the background stars, he decided that it was very distant — certainly not a terrestrial phenomenon.

A few months later, he noted that it still hadn't moved: suggesting it was farther away than the planets. Brahe didn't think much of the folks who still insisted that the "nova stella" had to be an earthly phenomenon, because Aristotle said the heavens don't change.

Then in 1577, Brahe observed the Great Comet of 1577 and compared notes with Tadeáš Hájek. Brahe, on Hven, and Hájek, in Prague, had observed the moon and comet. Their measurements made sense only if the comet was a lot further away than the moon.

Galileo was turning 13 at the time. He observed Kepler's Supernova in 1604, and got in trouble for insisting that his (at the time unproven) theories were facts. It didn't help that some theologians of the day didn't realize that poetry isn't science, and that's another topic. (April 18, 2014; October 26, 2009)

Aristotle was right about our part of the world changing, though:
"...The same tracts, therefore, of the earth are not some always sea, and others always continents, but every thing changes in the course of time."
("Meteorics," Aristotle, translated by Charles Lyell, via Wikipedia)
We've discovered that today's continents grew around what geologists call cratons. These cratons haven't changed all that much over the last few billion years, although they've gotten pushed around as Earth's lithosphere moved.

Gothic Cathedrals and the Universe


I've drifted off-topic. Let's see: cosmology, Aristotle, astronomy, more Aristotle, continents. Got it.

Giorgio Vasari blamed the Goths for destroying ancient Roman buildings and inventing a "barbarous German style" — like Sante-Chapelle. I think designing stone buildings whose walls are mostly stained glass is nifty: but I'm a Norwegian-Irish-Scots-American who married a German-Dutch-English-American. I'm pretty "barbaric," myself.

Anyway, European society had been getting puréed by the Renaissance for nearly two centuries when Martin Luther touched off the Protestant Reformation in 1517. I've discussed newfangled ideas, Joshua 10:13, and getting a grip, before. (July 18, 2014)

Around 1650, a Dublin-born Calvinist published a history of the world. He said the first day of creation started at nightfall on Saturday, October 22, 4004 BC. That was a reasonable estimate — in the 17th century.

Meanwhile, Danish scientist Nicolas Steno — a pioneer in anatomy and geology — was questioning assumptions about fossils. Turns out, he was right: Fossils don't grow in the ground.

Somewhere around 1778, Georges-Louis Leclerc, Comte de Buffon decided that Earth was roughly 75,000 years old. Instead of basing his estimate of Bible verses, the Count had measured how fast iron cools. He was wrong, by quite a few powers of ten.

In 1862, William Thomson figured it would take 20,000,000 to 400,000,000 years for Earth to cool to what we have today. His figures didn't take radioactive decay into account: understandably, since we didn't know about it at the time.

We're reasonably sure Earth is 4,540,000,000 years old, plus or minus 50,000,000. Our current estimates are based on analysis of radioactive decay in samples from Earth, our moon, and meteorites.

That number has been tweaked a bit during my lifetime, but I'd be very surprised if scientists are off by more than a fraction of a percent.

Some folks still insist that a 17th-century Calvinist was right about Earth's age: including, oddly enough, some Catholics.

Me? I'm willing to take God's universe "as is."

Pursuing Truth


Nicolas Steno's parents were Lutherans, and so was he: until he studied comparative theology in Florence. He became a Catholic on All Souls day, 1667. Steno's studies turned from science to theology, and he eventually became a bishop.

Nicolas Steno was beatified by Pope St. John Paul II on October 23, 1988. Other renditions of his name in my language are Niels Stensen and Nicolaus Steno.

Folks are beatified for displaying holiness.1 Lacking curiosity is not a requirement, or St. Albertus Magnus would never have become patron Saint of natural sciences. For Catholics, thinking is not a sin. (November 21, 2014; February 23, 2014)

Thinking, being a rational creature, is part of being human. Using our brains is optional, so is how we use them, and that's yet another topic. (Catechism of the Catholic Church, 1730-1742)

This universe, filled with order and beauty, is an invitation to "greater admiration" for God's greatness. I think accepting that invitation makes sense. Bottom line, faith and reason get along: or should. Faith is deciding that I'll trust God, and cooperate with reality. (Catechism, 31-35, 154-155, 283)

There's more to life than studying this astounding universe: but pursuing truth does not threaten an informed faith.
"...I would urge them to continue their efforts without ever abandoning the sapiential horizon within which scientific and technological achievements are wedded to the philosophical and ethical values which are the distinctive and indelible mark of the human person. Scientists are well aware that 'the search for truth, even when it concerns a finite reality of the world or of man, is never-ending, but always points beyond to something higher than the immediate object of study, to the questions which give access to Mystery'...."
("Fides et Ratio," Pope St. John Paul II (September 14, 1998))

"...if methodical investigation within every branch of learning is carried out in a genuinely scientific manner and in accord with moral norms, it never truly conflicts with faith, for earthly matters and the concerns of faith derive from the same God...."
("Gaudium et Spes," Pope St. Paul VI (December 7, 1965))

"...truth cannot contradict truth...."
("Providentissimus Deus," Leo XIII (November 18, 1893))

As I've said before — science and technology, studying this universe and using that knowledge to develop new tools, is part of being human. Ethics apply, of course: whether we're using the latest tech, or nothing but our fingers and teeth. (Catechism, 2293-2295)




1. Ice Cores and a Climate Lag



(From BBC News, used w/o permission.)
("The Antarctic core provides a comparison with records from Greenland"
(BBC News))
"Ice cores show 200-year climate lag"
Stephanie McClellan, BBC News (May 5, 2015)

"Scientists have found a 200-year lag time between past climate events at the poles.

"The most detailed Antarctic ice core provides the first clear comparison with Greenland records, revealing a link between northern and southern hemisphere climate change.

"Scientists found that abrupt and large temperature changes first occurred in Greenland, with the effect delayed about 200 years in the Antarctic...."
Climate change is real: and, as I've said recently, it's not new. Earth's climate has been changing ever since the planet formed, some four-and-a-half billion years back.

What's new is how much we know about Earth's story: including the most recent glacial epoch, that started around the time we arrived. (February 20, 2015)

This BBC News article talks about "very abrupt and large swings in temperature approximately 20,000 to 60,000 years ago."

Let's put that in perspective.


(From Lisiecki and Raymo (2005), via Wikimedia Commons; under GNU Free Documentation License, Version 1.2 or any later; used w/o permission.)

That graph shows average temperatures at Vostok Station in Antarctica — based on analysis of an oxygen isotope in deep-sea ocean sediments. My guess is that it's not spot-on accurate: but not very far from what actually happened.

More about Earth's most recent five million years of climate change:
The "41 kyr cycle" is a Milankovitch cycle: regular variations in how far Earth's rotational axis wanders. The "100 kyr cycle" is another cyclic variation in Earth's axis: and an issue for folks trying to make sense of Milankovitch cycles.

Earth's equator is tilted 23.44 degrees from the ecliptic today. It tilts up to 24.5 degrees, and is on its way to the 22.1 degree minimum at the moment. The cycle takes about 41,000 years: hence the "41 kyr (kiloyear)" name.

Milutin Milanković made the connection between these changes and Earth's climate a little less than a century back. His theory wasn't popular when I was in high school, but data collected since the '60s shows that he was on the right track: or that Earth's climate changed the way he said it did, by some wild coincidence.

Earth is much more than 5,000,000 years old, though: and hasn't been the same since the dinosaurs died.

A Half-Billion Years of Climate Change



(From Robert A. Rohde, from published and publicly available data, incorporated into the Global Warming Art project; via Wikimedia Commons; under GNU Free Documentation License, Version 1.2 or any later; used w/o permission.)

Again, this graph comes from analysis of deep-sea sediments. I'm quite sure it isn't an exact fit with reality: but I'm also confident that it's pretty close to what's happened.

Earth's current ice age started very roughly 3,000,000 years back. That's continental glaciers started spreading on North America and Greenland — and when the Isthmus of Panama closed, stopping circulation between the Pacific and Atlantic Oceans. Scientists think shifting ocean currents helped start the glaciers, but we're not entirely sure. The Tibetan plateau has been getting higher, too.

I suspect we're learning how much we don't know almost as fast as we're solving existing puzzles. The good news is that we're learning: a lot, very fast.

One more graph, and I'll get back to ice cores and this week's science news.


(From Dragons flight, from publicly available data, part of the Global Warming Art project; via Wikimedia Commons; under GNU Free Documentation License, Version 1.2 or any later; used w/o permission.)

Again, this is a pretty good estimate of Earth's average temperature, based on analysis of oxygen isotopes. The Phaerozoic is what scientists call Earth's current geologic eon. It started 541,000,000 years ago, give or take 1,000,000, when critters like Trilobites and reef-building Archaeocyatha appeared.

Looks like Earth in humanity's day is colder than it's been since the Andean-Saharan glaciation, 460,000,000 to 430,000,000 years ago — when Earth's second-largest cluster of extinction events happened. The big one happened about a quarter-billion years later. (April 24, 2015)

We're accustomed to a world where a mile-deep glacier covers most of Greenland. Earth has been colder, but not by much. The last I heard, scientists still aren't sure if we're in an interglacial period: or if the Quaternary glaciation is finally over.

"...We Still Don't Know...."

"...The 3,405 metre-long ice core, taken from the centre of West Antarctica, is the longest high resolution ice core. Researchers documented 18 abrupt climate events.

" 'This record has annual resolution, meaning we can see information about every year going back 30,000 years, and close to that resolution all the way back to 68,000 years ago,' explains Eric Steig, professor of Earth and Space Sciences at the University of Washington, who co-wrote the paper.

" 'Our new results show unambiguously that the Antarctic changes happen after the rapid temperature changes in Greenland. It is a major advance to know that the Earth behaves in this particular way.'

"The new core also supports the 'bipolar seesaw' effect between poles, meaning that when it's warm in Greenland, Antarctica is cooling, and vice versa.

" 'The fact that temperature changes are opposite at the two poles suggests that there is a redistribution of heat going on between the hemispheres,' said Christo Buizert, lead author on the study and a post-doctoral researcher at Oregon State University.

" 'We still don't know what caused these past shifts, but understanding their timing gives us important clues about the underlying mechanisms.'..."
(Stephanie McClellan, BBC News)
Professor Steig said the 200-year lag points to Earth's ocean as the heat transfer medium. Atmospheric heat transfer would take years, maybe decades: not centuries.

As Christo Buizert said, "we still don't know" why these climate shifts happened. But we're learning.

Temperature Swings: There's More to Learn



(From BBC News, used w/o permission.)
("Cores contain a record of past temperature swings"
(BBC News))
"...The team has planned further studies to really unpack the annual resolution seen in the core.

"Prof Steig concluded: 'We've actually been talking about and planning for this ice core for essentially my entire career.

" 'I remember an old colleague of mine telling me how we should go to this spot in Antarctica and drill an ice core in 1989 when I was beginning graduate school. And we've only really just finished the work about 25 years later.' "
(Stephanie McClellan, BBC News)
We've come a long way in the last hundred years.

Oswald Avery identified DNA as the genetic material in chromosomes, Jonas Salk developed polio vaccine, Andrew Wiles proved Fermat's Last Theorem — and Helmut Landsberg applied statistical analysis to climatology, "which led to its evolution into a physical science." (Wikipedia)

Many folks apparently replaced unbridled optimism about science and technology — with equally-unrestrained fear of science and technology. Or, perhaps more likely, the loudest folks in a new generation wore a different set of intellectual blinders.

I don't see science and tech as a panacea, or a bogey man. Whether they help or hurt humanity depends on our decisions: blaming our tools makes no sense. Not to me.

I also don't see a problem with regulating Earth's climate: after we learn how it works. Part of our job is managing Earth's resources: wisely, with respect for the integrity of creation, and with a concern for future generations. (Catechism, 2415-2418)

Geoengineering should wait until we have a few more answers. Today, we're still learning what questions to ask. (February 20, 2015; June 15, 2014)

More:

2. Deccan Traps and the Chicxulub Impact



(From Richards et al, UC Berkeley; via ScienceDaily; used w/o permission.)
("Illustration of a hot mantle plume 'head' pancaked beneath the Indian Plate...." ScienceDaily)
"Did dinosaur-killing asteroid trigger largest lava flows on Earth?"
University of California - Berkeley, ScienceDaily (April 30, 2015)

"The asteroid that slammed into the ocean off Mexico 66 million years ago and killed off the dinosaurs probably rang the Earth like a bell, triggering volcanic eruptions around the globe that may have contributed to the devastation, according to a team of University of California, Berkeley, geophysicists.

"Specifically, the researchers argue that the impact likely triggered most of the immense eruptions of lava in India known as the Deccan Traps, explaining the 'uncomfortably close' coincidence between the Deccan Traps eruptions and the impact, which has always cast doubt on the theory that the asteroid was the sole cause of the end-Cretaceous mass extinction...."
"It's complicated" seems to describe most aspects of Earth's long history.

Volcanic eruptions had been forming the Deccan Traps before the Chicxulub impact: but these scientists say they've found evidence that lava flow increased after the impact.

Shock waves from the impact could have felt like a magnitude 9 earthquake everywhere on Earth — triggering more massive eruptions in the Deccan Traps, and in other volcanically active areas.

As we learn more about the dinosaurs' last days, it looks like they might have survived the Chicxulub impact: if gasses from eruptions in the Deccan Traps hadn't been dropping Earth's temperature as sea level fell.

It was not a good time to be a dinosaur.

Whatever blasted out the Chicxulub crater may not have been alone. There's serious doubt about whether the Shiva formation west of Mumbai/Bombay, India, is an impact crater, but the Boltysh crater in Ukraine is definitely from an impact.

The Boltysh crater is only 24 kilometers, 15 miles, across: but whatever made it hit Earth within a thousand years or so of the Chicxulub event. One of today's unanswered questions is whether these two impacts were a statistical fluke — two of many impacts around that time.

Cosmic debris big enough to trigger an extinction-level event come at (apparently) irregular intervals of much more than ten million years, on average. Smaller bits and pieces, like the one that exploded over Chelyabinsk in 2013, come every century: more or less.

We're not quite ready to move an incoming asteroid into a harmless orbit: but we're nearly there, and that's yet again another topic. (January 16, 2015)


(Image © Don Davis; from PAINTINGS at www.donaldedavis.com)

More about using our brains:

1 "New procedures in the Rite of Beatification," Congregation for the Causes of Saints (September 29, 2005)

2 comments:

Brigid said...

Missing a word or 's' missing? "hadn't been dropping Earth's temperature as sea level fell."

The Friendly Neighborhood Proofreader

Brian Gill said...

Brigid, I cleaned up the sentence - but decided to keep "sea level" singular. Earth only has one ocean: and, other than tidal fluctuations, its sea level is pretty much the same world-wide.

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Marian Apparition: Champion, Wisconsin

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What's That Doing in a Nice Catholic Blog?

From time to time, a service that I use will display links to - odd - services and retailers.

I block a few of the more obvious dubious advertisers.

For example: psychic anything, numerology, mediums, and related practices are on the no-no list for Catholics. It has to do with the Church's stand on divination. I try to block those ads.

Sometime regrettable advertisements get through, anyway.

Bottom line? What that service displays reflects the local culture's norms, - not Catholic teaching.