Archives par mot-clé : Synthesis

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The extraordinary climate events of 2022-24

by J. Vinos, March 24, 2024 in ClimateEtc

The unlikely volcano, the warmest year, and the collapse of the polar vortex.

The climate events of 2022-24 have been were truly extraordinary. From an unlikely undersea volcanic eruption to the warmest year on record to the collapse of the polar vortex after three sudden stratospheric warming events. This rare convergence presents a unique learning opportunity for climatologists and climate aficionados alike, offering insights into a climate event that may not be repeated for hundreds or even thousands of years.

  1. January 2022, the unlikely volcano

Never before have we witnessed an undersea volcanic eruption with a plume capable of reaching the stratosphere and depositing a large amount of vaporized water. This extraordinary event occurred in January 2022 when the Hunga Tonga volcano erupted. The conditions for such an event are rare: the volcano must be deep enough to propel enough water with the plume, but not too deep to prevent it from reaching the stratosphere. Most undersea volcanoes do not produce plumes at all, which makes Hunga Tonga’s eruption all the more remarkable.

The Hunga Tonga volcano occupied a unique “sweet spot” at a depth of 150 meters the day before the eruption. In addition, the eruption itself must be exceptionally powerful for water vapor to rise into the stratosphere. The January 2022 eruption of Hunga Tonga was the most powerful in 30 years, since the 1991 eruption of Mt. Pinatubo.

Figure 1. The Hunga Tonga eruption from space.

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  1. 2023, the hottest year on record

Beginning in June 2023, the last seven months of the year marked the warmest period on record, significantly exceeding previous records. Such an event is quite remarkable, given the considerable temperature variability observed from month to month. But how unlikely is it?

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  1. January-March 2024, the collapse of the polar vortex

The polar vortex is a circular wind pattern that develops on rotating planets with an atmosphere. It results from the conservation of potential vorticity, a property depending on the Coriolis force and the potential temperature gradient. The potential temperature refers to the portion of the temperature of an air parcel that is not affected by its potential energy, and is often defined as the temperature the parcel would have if it were brought to the surface (1,000 hPa).

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  1. What can we expect in the near future?

The unlikely volcanic eruption is the likely cause of the extraordinary warming, which in turn led to the occurrence of the unprecedented three SSW events. Our understanding of the effects of these events supports this interpretation.

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climate-debate

Studies Show Glaciers Worldwide Were Smaller Than Today

by Die Kalte Sonne & P. Gosselin, February 26, 2020 in ClimateChangeDispatch

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19th century glacier retreat in the Alps preceded the emergence of industrial black carbon deposition on high-alpine glaciers

Light absorbing aerosols in the atmosphere and cryosphere play an important role in the climate system. Their presence in ambient air and snow changes the radiative properties of these systems, thus contributing to increased atmospheric warming and snowmelt. High Spatio-temporal variability of aerosol concentrations and a shortage of long-term observations contribute to large uncertainties in properly assigning the climate effects of aerosols through time.

Starting around AD 1860, many glaciers in the European Alps began to retreat from their maximum mid-19th century terminus positions, thereby visualizing the end of the Little Ice Age in Europe. Radiative forcing by increasing deposition of industrial black carbon to snow has been suggested as the main driver of the abrupt glacier retreats in the Alps. The basis for this hypothesis was model simulations using elemental carbon concentrations at low temporal resolution from two ice cores in the Alps.

Here we present sub-annually resolved concentration records of refractory black carbon (rBC; using soot photometry) as well as distinctive tracers for mineral dust, biomass burning and industrial pollution from the Colle Gnifetti ice core in the Alps from AD 1741 to 2015. These records allow precise assessment of a potential relation between the timing of observed acceleration of glacier melt in the mid-19th century with an increase of rBC deposition on the glacier caused by the industrialization of Western Europe. Our study reveals that in AD 1875, the time when rBC ice-core concentrations started to significantly increase, the majority of Alpine glaciers had already experienced more than 80 % of their total 19th-century length reduction, casting doubt on a leading role for soot in terminating of the Little Ice Age. Attribution of glacial retreat requires expansion of the spatial network and sampling density of high alpine ice cores to balance potential biasing effects arising from transport, deposition, and snow conservation in individual ice-core records.”

Also, a glacier history of the Alps since the end of the last ice age was published in 2009 by Susan Ivy-Ochs and colleagues.

Between 10,500-3300 years before today, glaciers were mostly smaller than today and ended 200 meters above modern levels. The Alpine glaciers expanded during the cold period of migration and the Little Ice Age.

Want to know more about glacier history? Here’s the abstract:

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