At present, when most of us think about weird weather, we think about global warming and carbon dioxide emissions. And so we should. But we make a mistake if we think only of global warming as a source of weird weather. Few think about the broader – and nastier – effects such weather may have.

In April 1815, just over 200 years ago, Indonesia’s Mount Tambora exploded in the biggest volcanic eruption in 74,000 years. 160 cubic kilometres of volcanic “stuff” was blasted into the sky. The heavy stuff fell within a few weeks, killing and suffocating hundreds of thousands across Java, and sending “islands” of pumice 4.8km long out across the Pacific. The rest of the stuff – mostly tiny particles – stayed in the stratosphere for about four years. Global temperatures fell by 3 degrees Celsius, creating a “volcanic winter” that wrought havoc across the world. Crops failed for three successive years in China, India, North America and Europe. Tens of millions are thought to have starved in Yunnan, and similar numbers in India. Millions starved in Ireland.

Everywhere, people reported “weird weather”. Glaciers fingered out from alpine Europe, destroying Swiss villages that had flourished since records existed. In Geneva, the wild and drug-addled art group around Lord Byron complained of horrid weather and astonishing sunsets. Mary Shelley wrote Frankenstein there, weighed down by the gloomy influence of those awful non-summers between 1815 and 1819.

But there were other awful, and less obvious impacts. For some still-unexplained reason, the then relatively benign cholera virus in India morphed into a new and much more virulent strain, killing millions – including British soldiers set on “pacifying” unruly Indian states. That more virulent strain has haunted the poor world ever since, accounting for countless millions of cholera deaths since 1815. Give a thought to the weird new zika virus, carried by same type of mosquitoes that carry dengue fever.

Tambora teaches us many things. First, that alongside the chronic and accelerating dangers linked with global warming, there are other threats that can muddle longer-term trends, and wreak as much damage creating “volcanic winters” as global warming incubates “CO₂ summers”. Since Tambora, we have had many volcanic eruptions that have impacted global weather – Krakatoa, Mount St Helens, Pinatubo and the unpronounceable Eyjafjallajokull to name but four. And what about solar storms triggered by sunspots, or El Nino-type shifts in ocean currents?

Second, such dangers can, and normally do, hit us from unexpected directions. However meticulously clever people plan to protect us against the “known knowns” and the “known unknowns”, there will always be “unknown unknowns” to confound best-laid plans. Do you think anyone suffering that four-year winter from 1815 to 1819 had the slightest idea of its volcanic source on the opposite side of the world?

Third, and perhaps most sobering, is the reality that the earth has been around for very much longer than us. Whether human beings are around or not matters little in the big sweep of history. Dinosaurs were around for several million years, and for whatever awful set of reasons, were exterminated. Life on earth moved on. And it will continue to move on with or without us. These “weird” occurrences are weird and threatening to us humans, but in the big picture, they are not weird at all.

Here in 2016, it is easy to be flippant and dismissive about once-in-a-blue-moon events. They possibly signify nothing, and may just be fun opportunities to don warm clothes, and make dawn sorties up Tai Mo Shan in search of icicles. But since it is in the interests of we humans to ensure that the earth remains as hospitable to us for as long as possible, then it is important not to be so dismissive or flippant.

For a tiny place like Hong Kong, it is easy to believe that nothing we do amounts to much, but that need not be so. In the coming decades, more-volatile weather seems inevitable, and our government has a responsibility to mitigate that volatility:

●If sea levels are going to be higher, and storms more violent, then a coastal city like Hong Kong needs to invest in defences that provide safety against “black swan” events.

●If viruses can “morph” like cholera did – and like zika appears to be doing – then early warning arrangements against pandemic threats make great sense.

●If food supplies can be put in jeopardy not just for a few weeks or months, but for a few years, then plans to ensure food security across the globe need to be rethought. Almost no economy in the world – including Hong Kong – has food stocks sufficient to avert catastrophic food supply disruption for more than two or three months.

●And finally, there is of course the obvious: as a matter of urgency we need to reduce CO₂ emissions.

I am among many sceptics on whether the fine commitments made in Paris last December will ever be honoured. The price we will pay for dishonouring those commitments may be huge. It will be higher than just “weird weather”.

David Dodwell is executive director of the Hong Kong-Apec Trading Policy Group