[Noozhawk’s note: Second in a series. Click here for the first article.]
There’s an aphorism that helps distinguish the difference in understanding weather versus climate. Climate is what you expect, weather is what you get.
The World Meteorological Organization, an agency of the United Nations, defines a climate normal as an average over a 30-year period. But in our fast-paced digital world, even when we might not know the questions, we want answers faster (so too often some reverse this aphorism order).
Let’s walk through a time capsule of climate science through the view of a telescope, and not a microscope view. It starts with a deeper dive into the many parts in the climate box, the mechanics of operations, and outcomes scientifically explained, recorded and/or observed.
At the turn of the 20th century, Serbian astrophysicist Milutin began studying the ice ages of the Pleistocene.
The Pleistocene is the epoch (a period of time noted by particular characteristics) that began 1.8 million years ago and ended about 11,500 years ago. It was characterized by long ice ages, with glaciers covering large regions of most continents, interrupted by short interglacial periods with more temperate climate.
The Earth’s orbital mechanics had already been studied for centuries through astronomical observations with widely different conclusions. Milanković more fully understood the various factors of Earth’s orbits, particularly the tilts during the last 600,000 years of this epoch period.
Through 30 years of research, using longhand math, Milanković was able to divide these into three distinct orbital variations, with consistent time scales, acting differently but consistently over time:
» Eccentricity — Earth’s planetary orbit ~1 million years called Ice Age Climate cycle with ~100,000 year intervals:
~85,000 years is more elliptical (oval) producing a Glacial Phase
~15K years is more circular (overall nearer to sun) producing a Warming Phase
Changes occur with interrelationships of magnetic fields/orbits of other terrestrial bodies (planets/moons), primarily Jupiter and Saturn
» Tilt — ~41,000-year cycle in the tilt (obliquity) of the Earth’s axis
Earth always has tilt on its axis, creating our seasons, however adjusts in degree
Varies between 22.1 and 24.5 degrees (currently tilted at 23.5 degrees or half cycle)
Less tilt produces more glaciers as summers in the northern hemisphere are cooler, more tilt produces more warmth in the North …
This cycle (even today) is less precise in causation, but the moon is a stabilizing factor
» Wobble — ~23,000 years Earth’s axis wobbles (presession)
Earth does not always spin on an axis running through its poles and because of weight distribution (land mass versus ice sheets) in the northern hemisphere
Wobble causes Earth to be closer to the sun in summer, intensifying summer heat
Milanković wasn’t able to discern all of the effects of climate variability when these cycles appeared simultaneously, but he attempted through mathematical computations to forecast.
Current analysis, modern technology and computer modeling has improved on the Milanković Theory, but his calculations and charts are still used today.
“The Milanković Theory has become part of the toolbox of ocean historians in the last several decades,” said the late W.H. Berger, an oceanographer, geologist, micropaleontologist and emeritus professor at Scripps Institution of Oceanography at UC San Diego.
“In fact, the theory has achieved textbook status after many decades of discussion, and is now a tool without peer when applied to problems of dating ice-age sediments from the deep-sea floor, when determining sedimentation rates of such sediments even well before the northern ice ages.”
But before we get specifically to greenhouse gases, there are other tangibles that are influencers (or effects of such) that are important for both weather patterns and climate.
Most notable are the major tectonic plates and their constant gravitational shifts and effects.
Let’s just explore the Pacific Oceans plates, also known as the Ring of Fire. The Pacific Plate is by far the largest of the 60-plus plates in the world, 30 times the size of the continental United States.
Here’s the deal: With so many plates, which do not align horizontally nor vertically, collide with another, we get spectacular seismic events (earthquakes, volcano eruptions and tsunamis) that constantly change Earth’s crust, all life forms, weather and climate.
This Ring of Fire is ~25,000 miles in circumference along the Pacific northern hemisphere (between seven large and small plates). First and foremost, there are more than 400 active volcanos, including some of the major fault lines in existence, most notably the San Andreas Fault.
It’s only been since the 1970s that the Ring of Fire has been more fully explored, most notably by the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. In addition to beginning to map the ocean floor, scientists found hundreds of hydrothermal vents around volcanos and fissures in the Earth’s crust constantly hemorrhaging.
“Hydrothermal vents act as natural plumbing systems that transport heat and chemicals from the interior of the Earth,” according to Woods Hole.
What science has not better understood (yet) is what effects these activities have on long-term climate change. But what we do know, the temperature of a hydrothermal “smokers” can reach 750 degrees on the ocean floor (and, amazingly, sea life exist under these conditions without sunlight).
The Pacific Decadal Oscillation (PDO) is often described as a long-lived El Niño-like pattern of Pacific climate variability (Zhang et al. 1997). Like the better-known El Niño/Southern Oscillation (ENSO), extremes in the PDO pattern are marked by widespread variations in the Pacific Basin and North American weather and climate.
In parallel with the ENSO phenomenon, the extreme phases of the PDO have been classified as being either warm or cool, as defined by ocean temperature anomalies in the northeast and tropical Pacific Ocean. But what triggers El Niños, or its sister, La Niña, still baffles scientists even today.
Now, let’s dive into the Earth’s climate by opening up the aperture of history for the past 500 million years.
The data are based on an accumulated knowledge of Earth’s temperature that’s been aggregated for a 1960-1990 baseline in Celsius degrees. The temperatures tabulated are reconstructed temperatures using proxy data (tree rings, coring into ice sheets) mostly from the northern hemisphere.
The scale, starting from the left, is blocked in the epoch periods with a 10X factor reduction through the present. (Notice the Milanković (mathematical) Theory for the Pleistocene period’s 100,000-year Ice Age cycles in the last 500,000 years is very noticeable in the data charted.)
Now let’s look at our current warming period, over the last 15,000 years, with temperature (in Celsius) collected in the Ice Core of Greenland. As recorded, the temperatures show that our present-day measurements are at or below the last 8,000 years of history.
The Little Ice Age introduces a significant factor in natural climate variability. Scientists believe the four major volcanic eruptions in the tropics around 1250 A.D. may have triggered this climatic reversal.
Earth was knee deep into its most recent historical warming period (called the Medieval Period) when these volcanic eruptions produced multiple blasts of aerosol sulphate particles into the atmosphere, thereby cooling the Earth by reflecting solar energy back into space.
This period ended some 450-500 years later in the mid 1700s when there was a gradual spike in temperatures (shown in the nearby chart above).
Even today “cloud-aerosol interactions are on the bleeding edge of our comprehension of how the climate system works and it’s a challenge to what we don’t understand … Current modelers are pushing the boundaries of human understanding …” (Steven Koonin, Unsettled)
Let me share two historical observations. The Pacific Coast Archaeological Society Quarterly published a research paper on the depth of sea-level change in the Santa Barbara Channel since the Holocene era (last 12,000 years).
This happens to correlate with the first indigenous tribes (our Chumash Indians) that lived both on the Channel Islands and our Santa Barbara coastline at the same time.
Today, the distance by boat between the Santa Barbara Harbor and Santa Cruz Island is 26.6 miles; back then, it was 9.1 miles! And the surface depth of the sea in our channel was 201 feet lower than our depth today! (“Early Holocene Coastline of the California Blight: The Channel Islands as first visited by Humans,” a 1999 article by Paul Porcasi, Judith Porcasi and Collin O’Neill)
A quick sidenote, the NOAA website records sea-level trends measured by tide gauges for local relative sea-level (RSL) trends for both the West and East coasts. Tide gauge measurements are made with respect to a local fixed reference on land and are a combination of sea-level rise and any local vertical land motion.
The buoy for the Santa Barbara Channel is identified as 9411340.
“The relative sea-level trend in 1.08 mm/year with a 95% confidence interval of +/- 0.96 mm/year based on monthly mean sea-level data from 1973 to 2020 which is equivalent to a change of 0.35 feet in 100 years,” according to NOAA.
So, in the last 38 years, the Santa Barbara Channel relative sea-level rise has been 1.3 inches.
NOAA also has calculated the same for buoy’s worldwide:
The forecast in the bottom box (Relative Sea Level Trends) interestingly shows the “green arrows,” which are the lion’s share of the globe’s oceans, as also only having a 0-1 foot rise over 100 years based on recent historical data.
Finally, Glacier Bay National Park and Preserve in southeast Alaska is one of the most spectacular sights to visit and view several glaciers.
In a recent visit, my wife and I took a cruise from Point Gustavus to the Grand Pacific Glacier, some 65 miles. The guides pointed out that, because of man-made global warming over the last 150 years, all the glaciers are receding at a rapid pace without putting into any historical context.
So I researched the National Parks Service website and found that all glaciers in this bay were in fact at their maximum distance, a little beyond Point Gustavus, at the end of the Little Ice Age (~1750).
Here’s the interesting fact: Of those 65 miles, all but the last four were melted and eroded by 1907. That’s 94%.
Part III will do a deep dive into all greenhouse gases and their impacts.
— Michael Rattray is a longtime Santa Barbara resident, retired after 34 years in the defense industry. Today, active in both the preservation of Goleta Beach Park and the restoration of the Goleta Bay macrocystis (sand-dwelling kelp) forest lost during the 1982-1983 El Niño. Click here to read previous columns. The opinions expressed are his own.