Tonga Eruption Won’t Cool Planet Or Reduce Solar Output

Tonga eruption impacts on cooling and solar power

After I heard about the Tongan volcanic eruption, the first thing I did was determine if the Tongans I knew were all right.  While conditions there are serious, they aren’t as bad as they could have been, so they’re probably okay.  Australia and New Zealand are sending relief, which is a relief. 

The second thing I did was try to determine if the massive eruption would result in global cooling like the Mt. Pinatubo eruption in the Philippines back in 1991. 

The answer to that is, despite being a massive eruption, insufficient material was blown high enough into the stratosphere to cause global cooling. 

I see some people celebrating this fact and saying the world dodged a bullet because there won’t be a repeat of the 1816 “year without a summer” after the eruption of Mt. Tambora.  

On the — literal — bright side, the Tonga eruption won’t contribute to global dimming and reduce the amount of sunlight reaching the ground.  This means — unless volcanic ash lands on them– the eruption won’t reduce the output of solar power systems.

Because a South Seas volcano won’t be giving us any temporary respite from the global roasting we’re subjecting ourselves to, the reasons for rapidly reducing fossil fuel use remain as strong as ever.  At least there will be no minor dip in solar energy generation getting in the way of that.

Big Eruptions Can Cool The World

Massive volcanic eruptions can temporarily cool the world by releasing sulphur dioxide into the atmosphere.  This forms tiny solid sulphate particles and tiny droplets of sulfuric acid.  While their exact effects are complex, they function as anti-greenhouse gases and reflect the sun’s heat into space before it reaches the ground.  

Normally, they don’t hang around for long.  They settle to the ground because they’re heavier than air or are washed out by rain.  In the troposphere, which is the part of the atmosphere we’re most familiar with and extends from the ground to a bit past the top of Mount Everest1, sulphur compounds have a half-life of around ten days.  This means, no matter how much sulphur a volcanic eruption spews into this atmospheric layer, there will only be about 1% left after two months, so no prolonged cooling is possible. 

To cause significant global cooling, enough sulphur has to be blown past the troposphere into the next layer, which is the stratosphere.  Down around Hobart, the stratosphere is about 10 km up, but in the tropics, it starts at around 17 km and at times, its boundary can be up to 20 km high.  While this layer is too high and dry for rain, sulphur compounds still normally only last weeks or months here because they continue to drift downwards due to gravity. 

To cause significant global cooling, enough sulphur compounds have to reach the part of the stratosphere where Brewer-Dobson Circulation occurs.  This is where the stratosphere rises in the topics and circulates to the poles, where it falls again.  This uplift can potentially keep sulphur compounds in the upper atmosphere for years. 

Tonga Eruption Wasn’t Big Enough

The Tonga eruption was massive.  While calculations are crude, one estimate puts the explosion at a little under 50 megatons.  That makes it almost equal to the largest nuclear explosion ever created by human beings. 

The massive Krakatoa eruption in Indonesia in 1883 was estimated to be 200 megatons.  So, in the Australian vernacular, this would make Tonga a quarter-Kraka.

The Mount Pinatubo eruption in the Philippines in 1991 was estimated to be 70 megatons.  This eruption blew roughly 17 million tonnes of sulphur into the atmosphere and resulted in significant global cooling of around 0.5 degrees in the northern hemisphere for two years. 

Under the right circumstances, the Tonga eruption may have resulted in global cooling, but it simply hasn’t thrown sufficient material high enough into the atmosphere for that to occur.  Cooling effects will only be local — a very big local, but still local as far as the world is concerned — and temporary.  The world will also miss out on spectacular sunrises and sunsets caused by stratospheric sulphur aerosols, but Queensland may see some impressive ones.

Previous Volcanic Cooling Events

In the past 200 years, there have been four eruptions resulting in significant global cooling.  These eruptions and the estimated amount of cooling they caused in the northern hemisphere were:

The 1815 Tambora eruption resulted in disaster, as half a degree of global cooling caused crop failures followed by widespread famine across Asia and Europe.  In 1991 the Mt. Pinatubo eruption caused a similar amount of cooling but, overall, was basically a wash as far as agricultural production was concerned:

World grain production

One reason the 1991 eruption did not really hurt world grain production is production had increased in warmer regions, such as Australia.  But a second reason is that the world has become a significantly hotter place than it was in 1815:

This graph starts in 1880 rather than 1815, but temperatures in the early 19th century weren’t much different from the late 19th century.

As the above graph2 from this paper shows, the earth now averages over 1 degree hotter than it did during the 19th century. 

No Help From Volcanic Cooling

I’ve seen people on the internet saying we’re lucky the Tonga eruption won’t cause global cooling, and they give the “year without a summer” of 1816 as the reason why.  But if the Tonga eruption had caused the same half a degree of global cooling as the 1815 Mt. Tambora and 1991 Mt. Pinatubo eruptions, because the earth is warming so rapidly, it would only lower global temperatures to what they were not long before the 1991 eruption. 

I’m not an agronomist, but I strongly suspect half a degree of cooling would only improve agricultural yields overall.  It would also result in a temporary but helpful decline in icecap melting, sea-level rise, killer heatwaves, and other negative effects of global warming.  I don’t think we dodged a bullet thanks to the Tonga eruption not causing global cooling.  It’s more like we dodged something protective, like a vaccination. 

Intentionally Adding Sulphur To The Stratosphere

It s been suggested sulphur could be intentionally added to the stratosphere using planes, drones, balloons, huge artillery shells, or by adding sulphur to a volcano before it makes a big bada-boom.  

This has some major drawbacks.  Three of them are…

  1.  It will be very expensive.
  2. Sulphur in the atmosphere is a nasty pollutant with many negative effects.  We want to breathe in as little of that stuff as possible.  A lot of it is, literally, sulfuric acid.  No matter how carefully we add it to the stratosphere, it will all eventually drift down to our level.
  3. It will cause global dimming and reduce the amount of plant photosynthesis and solar electricity generation.

It’s also pointless unless we also rapidly reduce greenhouse gas emissions.  A transfusion can save someone’s life but will do no good in the long run unless their wounds are treated. 

Right now, rather than artificially adding sulphur to the upper atmosphere, the most sensible course of action is to cut greenhouse gas emissions as hard and fast as possible.

No Respite, No Retreat, No Surrender

The Tonga eruption wasn’t large enough to cause any significant global cooling and will provide no respite from the global warming we’ve created.  Rather than relying on spontaneous, large-scale relocations of geography to lend a hand, we’ll have to work on ending this problem ourselves.  This means…

  • Investing in more renewable generation.  For example, putting solar panels on your roof
  • Making your next private transport purchase an electric car or fuel-efficient hybrid — or better yet, an e-bike or bicycle. 
  • Purchasing energy-efficient appliances, whether a heat pump hot water system or LED lights.

It also means voting out politicians who deny global warming is a serious problem.  When volcanic global cooling that caused one of history’s greatest disasters in 1816 would help the planet if it happened today; it means we have a serious problem that requires immediate, effective action. 


  1. Mt. Everest’s name in Tibetan, Chomolungma, is way cooler.
  2. Update 11:00 am 18th Jan 2022: Geoff suggested I use a more up to date graph in the comments, so I replaced the one I had with one from a recent paper.
About Ronald Brakels

Joining SolarQuotes in 2015, Ronald has a knack for reading those tediously long documents put out by solar manufacturers and translating their contents into something consumers might find interesting. Master of heavily researched deep-dive blog posts, his relentless consumer advocacy has ruffled more than a few manufacturer's feathers over the years. Read Ronald's full bio.


  1. Cuidado com previsões antecipadas. As pessoas dizem como se já soubessem de algo ainda indefinido.

    • Ronald Brakels says

      “Beware of advance predictions. People say as if they already know something that is still undefined.”

      While the eruption may continue for a long time, a second blast equal to or greater than what occurred Friday is not expected. Of course, if an unexpected event like that did occur, it would change things.

  2. Geoff Miell says

    As the above graph from NASA shows, the earth now averages over 1 degree hotter than it did during the 19th century.

    Ronald, couldn’t you find a more up-to-date temperature anomaly graph that includes year 2021?

    On Jan 13, James Hansen, Makiko Sato and Reto Ruedy published their Temperature Update: Global Temperature in 2021. It begins with Figure 1 showing the global mean surface temperature relative to the 1880-1920 average, from 1880 through to 2021, followed by (bold text my emphasis):

    Global surface temperature in 2021 (Fig. 1) was +1.12°C (~2°F) relative to the 1880-1920 average in the GISS (Goddard Institute for Space Studies) analysis.[1,2,3] 2021 and 2018 are tied for 6th warmest year in the instrumental record. The eight warmest years in the record occurred in the past eight years. The warming rate over land is about 2.5 times faster than over the ocean (Fig. 2). The irregular El Nino/La Nina cycle dominates interannual temperature variability, which suggests that 2022 will not be much warmer than 2021, but 2023 could set a new record. Moreover, three factors: (1) accelerating greenhouse gas (GHG) emissions, (2) decreasing aerosols, (3) the solar irradiance cycle will add to an already record-high planetary energy imbalance and drive global temperature beyond the 1.5°C limit – likely during the 2020s. Because of inertia and response lags in the climate and energy systems, the 2°C limit also will likely be exceeded by midcentury, barring intervention to reduce anthropogenic interference with the planet’s energy balance.

    It also means voting out politicians who deny global warming is a serious problem.

    IMO, a vote for ‘climate denier’ politicians, and politicians who support & encourage more fossil fuel developments is a vote for your (and your family’s/friends’) future suffering.

  3. George Kaplan says

    While the 13th through mid 19th centuries may have been a Little Ice Age (mostly regional and mostly less than 1°C), the Late Antique Little Ice Age which ran from ~535 AD to the 7th century AD was far more significant with some estimates suggesting cooling of at least 2 °C.

    How does the LALIA differ to the recent eruption? The Tongan volcano is underwater – expelled materials need to escape the sea before reaching the atmosphere, and was a lone explosion. The LALIA probably entailed multiple volcanos erupting, including 3 large ones over a short span of years, and an “exceptional” minimum of solar activity in the 6th century. The winter of 536 saw widespread crop failures, famine, and millions of deaths in a global population of probably no more than 200 million. Should something similar happen today the result would be tens of millions if not hundreds of millions dead.

    Saying the world dodged a bullet is likely a tad excessive, but certainly the potential for something unpleasant to occur has historical precedent.

  4. Graeme Marshall says

    The excellent Neal Stephenson (‘Snow Crash’ etc.) has recently written ‘Termination Shock’, with eccentric Musk-type billionaires sending elemental sulphur into the high atmosphere – and China/India etc. getting very upset about it. Good technical details on how it would work.

  5. Ross McInnes says

    Given your business it’s no surprise that you push the fallacious AGW thesis.

    In the interests of ‘getting to the truth’, open your mind to the now published, incontrovertible truth available via this site:

    It’s not possible to stop the truth getting out no matter how frenetic the left is in enforcing the current truth suppression campaign.

    Good luck with your irrational scare campaign. Its days are numbered.

    • Ronald Brakels says

      If you believe burning one atom of carbon in a surplus of oxygen results in the formation of one molecule of carbon dioxide, then the burning of fossil fuels is more than sufficient to account for all the increase in CO2 in the atmosphere over the past 200 years. For the emission of CO2 that results from burning fossil fuels to not have been mostly responsible for the increase in CO2 that has occurred you would need:

      1. A mechanism for removing CO2 emitted from burning fossil fuels from the atmosphere.
      2. A mechanism for adding CO2 to the atmosphere from some other source that — perhaps by chance — adds CO2 to the atmosphere in proportion to amount emitted from burning fossil fuels.

      If you believe you can explain how these mechanisms work succinctly and in simple English, please feel free to make the attempt.

    • Geoff Miell says

      Ross McInnes,
      You state: “In the interests of ‘getting to the truth’, open your mind to the now published, incontrovertible truth…

      Astrophysicist Neil deGrasse Tyson said in the YouTube video published on 18 Sep 2017, titled Neil deGrasse Tyson scolds cherry picking climate science:

      0:00:38: “You can find a scientific paper that says practically anything.

      0:00:55: “An emergent scientific truth, for it to become an objective truth – a truth that is true, whether or not you believe in it – it requires more than one scientific paper. It requires a whole system of people’s research, all leaning in the same direction – all pointing to the same consequences. That’s what we have with climate change, as induced by human conduct. This is a known correspondence. If you want to find the three per cent of the papers, or the one per cent of the papers that conflicted with this, and build policy on that; that is simply irresponsible!

    • John Mitchell says

      I think if you’re implying Ronald is in the solar business (which by association he is, although primarily he’s a writer), I’d like to point out that you don’t need to be a greenie to embrace solar and wind generation. Solar panels and wind turbines are actually cheaper than any form of fossil fuel. And a lot cheaper than nuclear. So if you truly love market economics you’ll love solar panels. I’m also not sure what being on the left side of politics has to do with it. The last time I looked physics and politics were different disciplines and the earth’s atmosphere is ambivalent.

      • George Kaplan says

        As a definite non-Greenie (anti-Greenie?) I agree that arguments for solar need not be environmentally based – indeed if you want to convince non-Leftists you likely need to use such arguments. Whether the case can be made successfully depends on capital expenditure, FiT, charges, perhaps even battery costs. I bought into solar based on the performance\RoI I saw at the time. Sadly currently offered FiTs have me rethinking the argument.

        Physics and politics were different disciplines – more generally STEM was free of politics\ideology, but sadly this is increasingly not the case e.g. protests demanding medicine embrace approved racism.

  6. That chart displaying increased production of grain needs to include milestones in technology. We are currently browsing seed supplier websites to identify which broadacre crops to plant over the next couple of years. The options available are substantially greater than those in the 1950’s and as a result the impacts of disease, low rainfall and bugs is less which means an increase in production. There are a number of factors not just the data that supports your point of view or belief system.

    • Ronald Brakels says

      No, the chart doesn’t need to show milestones in technology. It’s there to show there was no significant downturn in world grain production after the 1991 Mt. Pinatubo eruption, despite a similar amount of global cooling resulting in widespread famine in 1816. I did consider adding some pink to it to show where the two years following the eruption were, but I wanted to go to bed.

  7. Des Scahill says

    Reply to Ross McInnes

    Hi Ross,

    I did look at the link you gave to the website and also other pages within the site.

    Published material on his website spans quite a number of years. Dr Edward Berry’s views on some matters may have changed over time, however since at least 2011 his major focus still seems to be mostly that of

    (a) claiming that those who disagree with him have nothing but theoretical models to support their views.

    (b) that there is little or no real world proof for such things as:

    “global warming-induced increases in the worldwide number and severity of floods? No. In the global number and severity of droughts? No. In the number and severity of hurricanes and other storms? No.

    Do they provide any real-world evidence of Earth’s seas inundating coastal lowlands around the globe? No. Increased human mortality? No. Plant and animal extinctions? No. Declining vegetative productivity? No. More frequent and deadly coral bleaching? No. Marine life dissolving away in acidified oceans? No.”

    The above claims at (b) above are made on his webpage here:

    Having (to his own satisfaction) ‘proved’ that such events simply aren’t happening at all, and its ‘alarmist’ to suggest otherwise, he produces an alternative explanation that the REAL truth is along the lines that ‘lefties’ want to alarm everybody as an initial step on a political path that ultimately enables them to achieve world domination.

    The word ‘lefties’ is a rather vague term, but his more recent usages of the terms seem to imply that anyone in the USA who doesn’t vote Republican is definitely one.of them.

    One fact that is relevant (although it may not seem so at first) is that
    Dr Ed Berry is a long term resident of Montana.

    Montana is a USA state that these days has major pollution problems.which have grown steadily worse since at least 1969.

    I’ll quote from a letter written by Montana Senator Mike Mansfield in Feb 1969 to the then POTUS,

    “Yesterday I picked up the newest issue of Life Magazine and read their
    feature on pollution, a problem which has plagued this country for many
    years, the problem we have ignored and quietly hoped would disappear.

    Unfortunately polluted air and water are becoming far more serious and yet very little is being done to stop it.” see:”

    That was some 52 years ago, Little of net significance seems to have changed since.

    Fast forward to today, and the consequences of failing to act in the recent past are now adding to the unaddressed problems from the more distant past. see:

    I’ll quote from the article: “The Berkeley Pit is a former open-pit copper mine in Butte, Montana and now one of the only places in the world where you can pay to see toxic waste. The sheer scale of the site is something to behold”:

    The Berkely Pit mine began operations in 1955, some 26 years after the 1969 warnings given by Senator Mike Mansfield.

    Montana is the 4th largest state by area in the USA, is home to Yellowstone National Park, and has a relatively small population of around 1.08 million according to the 2020 census. It is considered a ‘swing’ state
    politically, with voters fluctuating between Republican and Democrat parties.

    There are some parallels with Australia. Both places had (past tense) a similar human intellectual ‘conflict’ between destroying pristine natural environments by mining or polluting them in order to maintain a revenue flow OR replacing that revenue flow with other income sources that have far less adverse impacts on the environment.

    Ross, I use the past tense, because that intellectual conflict you perhaps misguidedly still seek to foster for human political reasons, seems well on the way to becoming completely irrelevant.

    Various politicians in Australia still attempt to convince many that there is no such thing as added ‘human induced’ climate change impacts, as is the also case in Dr Ed Berry’s home state of Montana.

    But less and less notice is being taken them by more and more Australians.

    Nothing wrong with having a differing viewpoints on various matters, but it is quite another thing to deliberately and knowingly mislead people with false information that could eventually cause loss of life in some cases. . .

    That loss of life occurs because people who have been mislead tend make bad decisions at a time of crisis. That crisis hasn’t fully arrived yet,

  8. Randy WESTER says

    The chart does have some flatter spots in the long general trend upward that might indicate lower demand, or an effect of volcanic activity, or a change in sunspot activity, or a temporary change in weather patterns.

    I would syspect that much of the change is driven by market forces on the demand side that drive farm planting decisions.

    There’s a lot of fear that we’ll suddenly run out of food for some reason, but we can so easily shut down grain biofuel ethanol or liquor production to free up and redistribute grain for the human food market if necessary (but it never has been).

    The biggest impact of Mount St Helens on farming was the damage it caused to engines, machinery, and grain handling equipment. And people’s lungs, of course.

    • Geoff Miell says

      Randy WESTER,
      There’s a lot of fear that we’ll suddenly run out of food for some reason…

      I’d suggest the escalating threat to global food security is based on “a whole system of people’s research” that Neil deGrasse Tyson refers to (see the YouTube video in my comment above). For example:

      Rising temperatures will mean there will be more times of year when temperatures exceed what crops can stand…

      Challenges to our food production systems will be just one of the impacts, the report found: changing rainfall patterns will leave many areas vulnerable to drought, while extreme weather will make agriculture harder and damage crops.


      Risks of simultaneous crop failure, however, do increase disproportionately between 1.5 and 2 °C, so surpassing the 1.5 °C threshold will represent a threat to global food security. For maize, risks of multiple breadbasket failures increase the most, from 6% to 40% at 1.5 to 54% at 2 °C warming. In relative terms, the highest simultaneous climate risk increase between the two warming scenarios was found for wheat (40%), followed by maize (35%) and soybean (23%). Looking at the impacts on agricultural production, we show that limiting global warming to 1.5 °C would avoid production losses of up to 2753 million (161,000, 265,000) tonnes maize (wheat, soybean) in the global breadbaskets and would reduce the risk of simultaneous crop failure by 26%, 28% and 19% respectively.

      Then there’s the increasing threat of sea level rise on low-lying major food growing regions, including the Mekong Delta and Bangladesh.

      The Mount St Helens eruption event was relatively short-lived, as the Tonga eruption event will likely be. The detrimental consequences for humanity and civilisation from human-induced climate change will likely extend for centuries if not for millennia.

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