everal GEITP’ers expressed further questions about this unusual volcano. First, what is a “greenhouse gas” (GHG)…?? Most of Earth’s energy comes from the sun. Absorption of sunlight causes molecules of objects or surfaces on Earth to vibrate faster, increasing their temperature; this energy is then re-radiated by land and oceans as longwave, infrared radiation (heat). A GHG is anything that absorbs negligible incoming sunlight, but captures a substantial fraction of thermal radiation as it is re-radiated (from Earth’s surface and atmospheric GHGs) back into space.
The major gases of nitrogen, oxygen and argon — comprising 78%, 21%, and 0.93%, respectively, of the atmosphere — show negligible absorption of thermal radiation and therefore are not GHGs. Important GHGs include water vapor (average of 2%, with a range of 1% to 5%), carbon dioxide (CO2; 0.042%, or 420 parts per million (ppm) by volume), methane (CH4; 0.00017%) and nitrous oxide (N2O; 0.0000334%, or 334 parts per billion). Even more miniscule effects of GHGs include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3). Water vapor (clouds) has at least five times greater warming effect on Earth’s temperature than all other GHGs combined.
The huge amount of Tonga volcano water vapor hurled into the atmosphere, as detected by NASA’s Microwave Limb Sounder (MLS), represents the GHG that has been warming Earth’s surface now, for more than 18 months — with no end in sight (so far)… The underwater eruption in the South Pacific Ocean blasted an enormous plume of water vapor into Earth’s stratosphere [the layer of the atmosphere between ~8 and 33 miles (12 and 53 kilometers) above Earth’s surface] — enough to fill more than 58,000 Olympic-size swimming pools. The sheer amount of water vapor apparently is (temporarily?) affecting Earth’s global average temperature. When will this effect dissipate? Nobody knows. ☹
In a study published in Geophysical Research Letters, Millán and colleagues estimated that the Tonga eruption sent about 146 teragrams (1 teragram = a trillion grams) of water vapor into Earth’s stratosphere — equal to 10% of the water already present in that atmospheric layer. That’s nearly four times the amount of water vapor that scientists estimate the 1991 Mount Pinatubo eruption in the Philippines lofted into the stratosphere.
Volcanic eruptions rarely inject much water into the stratosphere. In the 18 years that NASA has been taking measurements, only two other eruptions — the 2008 Kasatochi event in Alaska and the 2015 Calbuco eruption in Chile — sent appreciable amounts of water vapor to such high altitudes. But those were mere blips compared to the Tonga event, and the water vapor from both previous eruptions dissipated quickly. The excess water vapor injected by the Tonga volcano, on the other hand, could remain in the stratosphere for several years.
This extra water vapor appears to be increasing surface temperatures. Massive volcanic eruptions like Krakatoa and Mount Pinatubo typically cool Earth’s surface by ejecting gases, dust, and ash that reflect sunlight back into space. In contrast, the Tonga volcano did not inject large amounts of aerosols into the stratosphere, and the huge amounts of water vapor from the eruption may have a temporary warming effect, since water vapor traps heat. The effect would dissipate when the extra water vapor cycles out of the stratosphere and would not be enough to noticeably exacerbate climate change effects.
The sheer amount of water injected into the stratosphere was likely only possible because the underwater volcano’s caldera — a basin-shaped depression usually formed after magma erupts or drains from a shallow chamber beneath the volcano — was at just the right depth in the ocean: ~490 feet (150 meters) down. Any shallower, and there wouldn’t have been enough seawater superheated by the erupting magma to account for the stratospheric water vapor values Millán and his colleagues saw. Any deeper, and the immense pressures in the ocean’s depths could have muted the eruption.
The MLS instrument was well situated to detect this water vapor plume because it observes natural microwave signals emitted from Earth’s atmosphere. Measuring these signals enables MLS to “see” through obstacles such as ash clouds that can blind other instruments measuring water vapor in the stratosphere. “MLS was the only instrument with dense enough coverage to capture the water vapor plume as it happened, and the only one that wasn’t affected by the ash that the volcano released,” said Millán.
DwN ☹
From: Nebert, Daniel (nebertdw)
Sent: Tuesday, July 30, 2024 6:15 PM
For any of you who have read anything about “a sudden burst of increased temperatures recently” (at least in the Northern Hemisphere), this article is the best I’ve read (a fair, balanced report of what might be going on). In numerous cities and States in the Northern Hemisphere, many records of “average monthly temperatures” (very frequent satellite measurements, day-and-night, throughout each month) — have only reported “above normal.” Where we are located — there has not been even one month, since January 2023, in which the monthly average temperature was reported as just “normal average” or “below normal.”
This phenomenon (never seen before in any meteorological records — going back several centuries) has puzzled virtually all meteorologists and climatologists. What might be the cause of this mystery? This article by Javier Vinós [see below] is very carefully written, calm, no hysteria, yet straightforward. Also, this article is an excellent example of critical thinking. Vinos methodically applies logical thinking, and, one-by-one, considers all possible “suspects” he can think of.
He then focuses on the most likely culprit (in his opinion), but he concludes that we currently don’t know enough to solve the mystery. As of yet, there are no quantitative calculations of the forcings responsible for affecting Earth’s global temperatures. To summarize his article:
—Wow. The year 2023 broke the global temperature record for a 1-year increase in global warming by the largest margin in satellite records (which began in Dec 1978), 0.17°C warming… WHY?
—”We are in uncharted territory”…!!
—El Niño southern oscillation (ENSO) is ruled out.
—Sulfate aerosols cannot be responsible.
—Increasing levels of global CO₂ also didn’t do it.
—The Hunga Tonga volcano (Jan 2022) is the prime suspect — which suddenly resulted in a rise in total global water vapor levels from 100% to ~110%. [Water vapor is in a steady-state equilibrium between land and oceans; after Jan 2022, Earth’s atmosphere “inherited” an extra 10% of water, and climatologists don’t know how long it takes before that “extra 10%” returns to “normal.”]
—But why did it take almost one year for this water vapor increase to apparently affect global temperatures? This is not without precedent (i.e., in previous meteorological records, one previous volcano that pushed excessive water into the atmosphere — also exhibited a “delayed effect” of about one year).
—Javier Vinós states, “Of course, we cannot conclude yet that the 2023 warming was caused by the volcano, but it is clear that it is by far the most likely suspect.” Calm, cool, collected. No hysteria. No wild predictions or unfounded claims.
DwN