As Cyclone Gabrielle leaves its mark on New Zealand, there are still limits on what the scientific research can say definitively about how climate change will affect future cyclonic activity in the South Pacific. For the past decade or more, the research language has been couched in terms of medium to high probabilities. Paradoxically, fewer cyclones are being expected, but these are likely to be more intense in nature, and characterised by higher rainfall, greater wind speed and bigger storm surges.

In the past, researchers have been wary about how much the causes of these changes can be attributed to natural atmospheric cycles, and how much to human-induced climate change. A decade ago, the limited availability of quality historical data on the frequency and intensity on tropical cyclones created uncertainty as to “whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes.”

Since that paper was published in 2010, the analysis of the historical evidence has improved. The good news is that the world is experiencing significantly fewer tropical cyclones than it did in pre-industrial times, but the bad news is that they seem to be increasing in intensity.

The findings show a 13% decrease in tropical cyclones around the world between 1850-1900 and 1900-2000. More specifically, they find a drop from more than 100 tropical cyclones a year in pre-industrial times to around 80 in 2012. The study does not look at changes in the intensity – or damage – of cyclones over this period.

But here’s the bad news on that likely increase in cyclone intensity. Again, the language is one of likelihoods and probabilities, rather than absolutes:

Warming of the surface ocean from anthropogenic (human-induced) climate change is likely fuelling more powerful tropical cyclones (TCs.) The destructive power of individual TCs through flooding is amplified by rising sea level, which very likely has a substantial contribution at the global scale from anthropogenic climate change.

And here comes the rain:

In addition, TC precipitation rates are projected to increase due to enhanced atmospheric moisture associated with anthropogenic global warming. The proportion of severe TCs (category 3 & 5) has increased, possibly due to anthropogenic climate change. This proportion of very intense TCs (category 4 & 5) is projected to increase, yet most climate model studies project the total number of TCs each year to decrease or remain approximately the same.

Again, there is still an as yet unknown mix between the human induced (anthropogenic) causes and the natural causes, but both have been contributing to recent outcomes:

Additional changes such as increasing rates of rapid intensification, the poleward migration of the latitude of maximum intensity, and a slowing of the forward motion of TCs have been observed in places, and these may be climate change signals emerging from natural variability. While there are challenges in attributing these past observed changes to anthropogenic forcing, models project that with global warming in coming decades some regions will experience increases in rapid intensification, a poleward migration of the latitude of maximum intensity or a slowing of the forward motion of TCs.

Given the likelihood of more intense cyclones occurring, this will have an inevitable impact on coastal communities, thanks to the expected rise in sea levels and the cyclone-induced storm surges. These looming changes have implications for the issuing of local body building permits in areas at risk. To repeat:

Consensus projections of future TC behaviour continue to indicate decreases in TC numbers, increases in their maximum intensities and increases in TC-related rainfall. Future sea level rise will exacerbate the impact of storm surge on coastal regions, assuming all other factors equal.

Some of the building permit changes required may have to be driven by directives from central government to local councils. After all, central government does pick up a sizeable share of the tab for rescue and remediation efforts. Changes beyond the mere conditions for future building permits will be required.

Once the initial clean-up is over, some locations and the transport links to them may no longer be feasible, given the likelihood that intense storms will no longer be just once-in-a-century events. Hard calls may have to be made by central and local government, working in unison. Hopefully such decisions can be taken without political opportunists playing on the politics of grievance.

The changes required also cannot be achieved overnight. Obviously, the building permits to many of the people now in harm’s way were issued long ago. As with the building code responses to the threat posed by earthquake activity, it may take a disaster to lend a sense of urgency to the precautionary work that’s deemed to be legally required. Similar timelines – 10 or 15 years say – may have to be given to the people, firms and communities whose lives will need to change to meet the climatic conditions they’re now likely to face. There’s no pain free option.

While the exact mix of human-induced climate change and natural cycle causation remains an unknown, the outlook from their combined impacts make a “let's get back to business as usual ASAP” response no longer tenable. On that point, here’s a useful summary of the scientific consensus on the likely patterns or tropical cyclone incidence, and the likely severity of these events. Tropical cyclone research may still be a work in progress, but the social implications of the direction in which that research is headed seem unavoidable.

Footnote One: Much of the modelling for the findings cited above are based on a 2 degree increase in global warming over the course of the 21st century.

Footnote Two: This region of the South Pacific (including New Zealand) is on the cusp of moving from successive years of the La Nina weather pattern to an El Nino weather pattern. Research published last year with respect to the Bay of Bengal (B ofB) region known to be prone to cyclonic activity found that “El Niño events suppress the formation of cyclones…while La Niña enhances TC genesis with changes in large-scale environmental conditions. “

Again, while that El Nino pattern we are about to enter next summer may suppress the number of tropical cyclones that form in this part of the globe, it is still worth repeating : the intensity of the ones that we do experience is likely to increase, in tandem with planetary warming.

The Nuclear Option

As concerns rise about the combo of climate change, fossil fuels and global emissions, nuclear energy is being seen as a more palatable option in some quarters. Last year for instance, the European Union declared natural gas and nuclear energy to be “green” technologies, provided (in small print) that nuclear waste from the world’s current crop of reactors can be disposed of cleanly and safely. It can’t, of course.

Many developed economies heavily depend on nuclear power. France for instance, gets 72% of its energy needs from nuclear reactors, and is planning to build more. The fact that nuclear accidents are relatively rare does not detract from their immense social, environmental and economic impacts when they do happen eg. Chernobyl, whose global costs have been estimated at $200 billion, not counting the health costs. The problem of waste disposal has recently been highlighted by Japan’s threat to dispose of its Fukushima nuclear waste by treating it and dumping it into the Pacific. With good reason, Pacific nations do not trust Japan’s assurances.

Here's another scary thing: A lot of the world’s current reactors are already old, and their projected lifetimes are now being extended well beyond their original intended time frames. The US has 92 nuclear reactors, with an average age of 42 years. Reportedly, six of them have received extensions for up to 80 years, and operators of 25 more have applied for or announced they will seek the same renewal.

By the end of the decade, two-thirds of the world’s currently operating nuclear reactors will be running on borrowed time, splitting uranium atoms longer than they were ever designed or licensed to, in a risky experiment with planetary consequences.

“They never were expected to run as long as they have,” said Chris Gadomski, head nuclear analyst for Bloomberg NEF. “I’m not sure I’d want to live next to a reactor that’s 100 years old.”

The struggle to repair brittle concrete buildings housing the even trickier-to-repair internal componentry is a big part of the concern with these ageing reactors. Regardless, the drive to reduce greenhouse gas emissions is pushing the world to embrace the nuclear option, risks and all. Germany, for example, is having to weigh the widespread public opposition to nuclear power against its residual level of dependency on Russian-supplied natural gas, in the wake of the Ukraine war.

Also, there’s the chronic problem of nuclear waste disposal, which will pose a danger to humanity and the natural environment for thousands of years. Bloomberg News has outlined how the world is caught between a rock and a hard place:

Meanwhile, reliance on wind, solar and hydro power has proved unwieldy -- as seen with California’s seemingly constant threat of summer blackouts and the surge for European energy prices last year. Part of nuclear’s appeal is that unlike renewables, reactors deliver around-the-clock power, on cloudy days or during the still of night.

Many experts also argue that it would be all but impossible to reach the world’s net-zero goals by 2050 without increasing nuclear power. Low-carbon sources provided about 40% of the world’s electricity supply in 2021 — only about 4 percentage points more than 20 years earlier. That’s because while renewable energy scaled up, nuclear generation scaled down — these sites were sometimes replaced by gas plants, driving up carbon emissions.

Given the regional and global consequences of nuclear accidents (and of nuclear waste disposal) there is a glaring gap in the global order to do with legal enforceability. As this Deutsche Welle news report indicates, there is no international protocol governing the siting, building, operation, maintenance and dismantling of nuclear power plants, let alone any enforceable compensation mechanisms in the event of accidents.

All the key decisions are being left to the individual nations themselves, despite the potential for regional (and international) catastrophic consequences.

It is striking how little has been done with respect to international rules to do with responsibility for nuclear reactor outcomes. Especially say, when compared to the proliferation of international trade agreements and the rules to do with their legal enforceability. As usual, there are more rules to do with safeguarding profits than with protecting human life and planetary wellbeing.

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