Why is 2023 so hot? A rare Pacific volcano is among the suspects.

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Context

Scientists recently hypothesized that an underwater volcanic explosion off the coast of Tonga in the South Pacific in January 2022 could be the primary cause of 2023 being such a hot year.
The period from June to August 2023 was the warmest on record globally, with heat waves occurring all across the planet.

Details

What is the cause of 2023's hot weather?

According to climate scientists at Maynooth University in Ireland, an underwater volcanic eruption in the South Pacific Ocean was largely responsible for the world's record temperatures in 2023.
The Hunga Tonga-Hunga Ha'apai erupted in January 2022, releasing the equivalent of 60,000 Olympic swimming pools of water into the stratosphere.
This amounted to more than 150 million tonnes of water vapor or over 10% of the 1.4 billion tonnes found in the stratosphere on average.
The erupting water in the form of water vapor trapped heat in the atmosphere, causing the temperature to rise.
The water plume could remain in the sky for up to eight years.
The eruption also released around 500,000 tonnes of sulfur dioxide into the stratosphere.
Although sulfur dioxide tends to cool the planet, the mix of water and sulfur released by the eruption complicated the situation.
The eruption altered atmospheric pressure and briefly helped clear out the fog in Seattle, U.S.A.
According to a study by the Nature Journal, global temperatures were at risk of breaching 1.5°C in at least one of the next five years.
Experts claimed that Hunga Tonga-Hunga Ha'apai is the first observed volcano that may warm rather than cool the surface.

Role of water vapor in global warming

Water vapor is a natural greenhouse gas and the most abundant greenhouse gas in the atmosphere, which acts as a blanket over the earth.
It is an effective greenhouse gas because it is capable of absorbing longwave radiation and radiating it back to the surface, thereby contributing to warming as well as the greenhouse effect.

Volcanoes' Contribution to Global Warming

According to scientists, more research about the effect of volcanic eruptions on long-term global warming trends.

Cooling effect

Typically, the dispersal of ash from land-based volcanoes causes a temporary darkening of sunlight until it falls back onto the earth.
As a result, volcanic eruptions frequently result in a cooling effect.
For example, Pinatubo in the Philippines (1991) reduced global average temperatures by around 0.5°C (0.9°F) for more than a year.
According to the United Nations' Intergovernmental Panel on Climate Change (IPCC), sun-dimming eruptions have happened twice per century over the last 2,500 years.
Tambora in Indonesia (1815) caused a "year without a summer" and harmed crops around the world.
The Samalas (1257) in Indonesia caused famines and are thought to be one of the key causes of the Little Ice Age, a period of extremely chilly weather that lasted until the nineteenth century.
There is a lack of knowledge on the number of volcanoes in shallow water and previous eruptions similar to the 2022 eruption.
Shallow-water volcanoes can deposit erupted material in the atmosphere.
For example, before its eruption, the Hunga Tonga-Hunga Ha'apai was around 150 meters below sea level.
According to the IPCC, at least one Pinatubo-style eruption is likely this century.
Volcanoes, on the other hand, have had a minor impact on the general trend of global warming, which has been driven by human emissions of greenhouse gases since the Industrial Revolution.

Impact

As a result of climate change, eruptions are projected to become more common in frigid locations.
Previously, thick glaciers kept a lid on the volcanoes, which might melt due to climate change-induced thaw, resulting in eruptions.
The eruption rate in Iceland was roughly 100 times higher at the end of the last Ice Age (12,000 years ago) than it is now.
Climate change-induced increases in rainfall may trigger erosion on the flanks of volcanoes.
For example, extremely heavy rain driven by climate change undermined the flanks of Hawaii's Kilauea volcano in 2018.
Volcanic eruptions help to generate new rock on the Earth's surface.
Atmospheric circulation patterns assist tropic eruptions in affecting the climate in both hemispheres by distributing the dust and pollutants emitted by the volcanoes.

Volcano-based climate change mitigation activities

More research on the effects of volcanoes is required because volcanic activity is irregular, unpredictable, and uncontrollable.
If numerous Pinatubo-style eruptions occurred in addition to the existing hazard posed by climate change, it would be a significant challenge.

Volcano-inspired geoengineering

Volcanic eruptions have spurred geoengineers to propose methods to cool the globe.
This involves the deliberate reduction of sunlight as a shortcut, as well as the creation of a Pinatubo-like haze that can be maintained all year by the use of a fleet of special planes pouring sulfur into the stratosphere.
Make Sunsets, a U.S. start-up, began flying balloons carrying sulfur dioxide into the stratosphere in 2022.
It also sells "cooling credits" for $10 per gram of sulfur, which negates the warming effect of one tonne of CO2 for one year.
However, CO2 can remain in the atmosphere for hundreds of years.
The possibility of geoengineering to disturb weather patterns has been challenged.
This could also allow countries to avoid making the necessary severe emissions reduction.

About Tonga

Tonga is an island nation in the South Pacific Ocean.
It is an archipelago comprising 171 islands, 45 of which are inhabited.
To the northwest, it is bounded by Fiji Wallis and Futuna (France).
Samoa is to the northeast, New Caledonia (France) is to the west, and Vanuatu is to the west.
To the east is Niue, and to the southwest is Kermadec (New Zealand).
The climate of Tonga is tropical rainforest.
It is a Commonwealth member and a constitutional monarchy since 2010.
It was visited by Captain James Cook in 1773 and became known as the "friendly islands" because of the warm welcome they received from the natives.

Since the establishment of diplomatic relations in 1970, India and Tonga have had a close connection.

PRACTICE QUESTION

Examine the role of volcano activities in cooling effect and global warming.