Climate change and sailing

Is this the tipping point?

The problem with models used to predict future events lies in the fact that “probabilities” are simply the odds that extreme events of a certain size will occur in the future, mostly calculated based on past occurrences. But as climate changes, the models become less accurate and less useful in predicting future probabilities. 

As I watched the explosive cyclogenesis that made Tropical Storm Otis intensify into a Category 5 hurricane in 12 hours as it crossed a warm blob of water off the coast of Acapulco, I came to understand that there is no way to get out of such a storm's path. Acapulco was destroyed -- it looks like it was bombed out of existence. Not one of the models came close to predicting this development. 

I believe that climate change will have a negative impact on distance cruising, and sailing in general. Many of the yacht captains who were told to stay onboard vessels at anchor to guard them have not been heard from since. Authorities have identified 33 vessels at the bottom of Acapulco Bay,  A fleet of 480 public tourist boats was wiped out.

Explosive Cyclogenesis

Rapid Cyclogenesis normally describes the fast and intensive development of an extratropical cyclone (mid-latitude cyclone). The criterion of rapid development is the rate of central sea-level pressure's deepening being greater than or equal to 1 hPa per hour, generally over a period of 12 hours or longer. Explosive cyclogenesis (also referred to as a weather bomb, meteorological bomb, explosive development, bomb cyclone, or bombogenesis) is increasingly being used as the speed with which storms intensify increases. We used to have many days' warning and the path was somewhat predictable enabling most vessels to sail out of harm's way or at least secure themselves against its worst impact. Not anymore. We've had several hurricanes form off the coast of Africa and travel directly north to us in recent years. The term explosive cyclogenesis was applied to tropical cyclone Otis in the Pacific.

And now, the third extra-tropical cyclonic system of the season, Storm Ciarán, has thrashed Britain, Brittany and beyond and it's only November 1. We in Ireland were expecting hurricane-force winds and torrential rain, but got only modest rainfall and wind. The southern and eastern coasts were most affected as they were in the previous storms, whereas we used to get the brunt of all the storms coming across in prior years. The patterns have noticeably changed. 

The Transat Jacques Vabre, which has almost 100 boats attempting to cross the Atlantic, had to be postponed for most of the fleet because of Storm Ciarán. They may be delayed in port by as much as a week because of challenging developing conditions. Sailors everywhere were commenting on the pressure during Ciarán dropping so low that their barometers bottomed out. Storm Ciaran has set a new record for the lowest mean sea level pressure recorded in England and Wales. The Met Office has confirmed that a record for November, unbroken for more than 100 years, was set in Plymouth. The previous record in England was 959.7 hPa (mb), set in 1916. That though was broken with a value of 953.3 hPa (mb) in Plymouth, while Teignmouth in Devon also saw pressure get as low as 955hPa (mb).

Jersey and Brittany were most seriously affected by the storm, with Jersey likely hit by a massive tornado and Brittany getting the full force of a category 4 storm. Germany and the Netherlands had fallout next while parts of Italy had 200 mm rain in only 3 hours causing massive flooding. 

Now, a fourth extratropical system is to pass south of us as it heads for Spain this time. The historic storm Ciarán is dissipating over the North Sea, and a new rapidly developing Atlantic storm Domingos is already on the way for Western Europe. Wind gusts up to around 150 km/h and high waves will spread towards northern Spain and western France Saturday afternoon. 

Ocean Currents

The Gulf Stream, aka Atlantic meridional overturning circulation (Amoc) which runs up the East Coast of the US before crossing over to us, brings us the warm waters that keep our climate at this high latitude (51-55 N) temperate, is slowing down. If it slows down much more, or God forbid stops, we'd have a climate catastrophe here. And scientists are warning that we are approaching a tipping point. 

Sea Surface Temperatures (SST)

Sea Surface Temperatures (SST) have exhibited worrying anomalies this year. Global average SSTs remained at record high levels for the time of year throughout April, May, and June 2023, a situation that continued into July 2023, with the largest SST anomaly for any July on record. 

With increasing SST, coral reefs are dying off and sealife is becoming endangered or moving off into new territories where cooler ocean temperatures can be found. Several large fish kills have been reported this year among species that don't typically migrate very far. For us in Ireland, it means reduced catches of cod and herring, potentially the end of salmon farms, and increased catch of anchovies, hake, and sardines. Tuna have been coming to the waters off Mayo and Donegal, and basking sharks have returned here to mate. The EU quotas can't be adjusted to match in time. The waters off the west coast of Ireland were 5C warmer than average this year. 

Warming waters also increase the frequency of phytoplankton blooms. Large blooms can be beneficial for marine life and fisheries, but harmful algal blooms can be toxic to living creatures or harm the environment in other ways. A recent study found that warming temperatures cause certain phytoplankton to change from carbon absorbers to carbon emitters, a potential and unanticipated climate-induced tipping point. Some phytoplankton are mixotrophs, meaning they can get energy either through photosynthesis or by eating other organisms. When they perform photosynthesis, they take carbon out of the atmosphere; but when they eat other organisms, they end up emitting more CO2 than they absorb. Warming waters tip them toward the latter. 

In NSW Australia 20-30m fish died in March after floods in the region. A combination of factors including a shift in farming practices and extreme heat contributed and not for the first time. 

Surface Air Temperature (SAT)

Researchers at the EU's Copernicus unit reported that the start of June saw global surface air temperatures rise 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial levels for the first time. While Earth had the hottest August and September on record, heatwaves were recorded in both the Northern and Southern hemispheres, with record surface air temperatures across multiple countries.

An intense heatwave was scorching South America at the beginning of the spring season as temperatures in several countries broke September and October records. Countries like Brazil, Peru, Bolivia, Paraguay, and Argentina have all recorded their highest September temperatures after months of unusually warm winter this year. And of course, we learned that El Niño has set in and it will likely fuel further global temperature increase. 

Temperatures were reported to be reaching up to 43C in Paraguay, 41C in Brazil, Bolivia and Argentina this week. Western Paraguay’s Filadelfia city saw 44.4C (112F). Scientists expect up to 45C in Paraguay, Bolivia, and Argentina, 43C in Brazil, 40C in Peru, and many records broken.

A new World Weather Attribution study concluded that climate change made the prolonged extreme off-season heat in South America more likely. The extreme late winter and early spring heat in South America would have been virtually impossible in a world without human-caused climate change. The WWA study found that climate change made the prolonged heat at least 100 times more likely and 1.4-4.3ºC hotter.

Wildfires broke out along the outskirts of densely populated regions of Argentina. Although they have mostly been brought under control, the region remains at high risk of wildfires as the temperatures continue to soar and drought conditions persist. Wildfires were also reported across Bolivia, in Paraguay, and throughout Brazil, including in Bahia, Pantanal, and the Amazon.

Cruisers planning to visit these regions should be prepared to deal with weather extremes in previously temperate climates. Heat-related illnesses and deaths have been mounting with the increasing temperatures. The effects of heat on the body are well documented. It strains the heart and kidneys, causes headaches and confusion, disrupts sleep and slows cognition. Kidney dysfunction is a common affliction of young outdoor workers. 

Heat Action Plans that include early warning and early action, awareness-raising and behaviour-changing can reduce morbidity and mortality. It is important for sailors who spend long periods in warming climates to learn to recognise the signs and symptoms of heat exposure and what to do to quickly manage the situation. A bath of cold water has been proven to be the most effective way of quickly lowering your core body temperature. The quicker you can receive cold water immersion, the less risk of death and organ damage.

Of course, wildfires have become more common as the temperature rises and rainfall becomes erratic. They are not usually of concern to cruisers until you look at what happened in Lahaina this year. The marina was completely destroyed in a flash and all boats sank. Had you been on your boat there, you may not have had a chance to escape. Several years ago, when our boat was in Galicia, Spain, wildfires came perilously close to the marina while we were away. 

Floods and droughts

So much else on earth affected by climate change will also affect cruising routes and options. Floods and droughts are already changing choices. Anchorages become untenable when flood waters bring debris down from the land, and canals become impassable when drought reduces water depth. The Panama Canal just today announced a third round of reduced traffic through the canal and long delays for vessels that do not pre-book. The vast quantities of rainfall in pockets -- a year's worth in one day -- can have massive impact on a place that cruisers frequent. Granted a boat floats, but witnessing the devastation of a population can be traumatic to say the least. 

Drought and floods also affect food availability in many regions where agriculture is becoming unsustainable. People who have nothing will have nothing to share with cruisers arriving in remote regions without access to supply ships. Water shortages in drought-stricken areas may pose access problems and ethical dilemmas, so water-making facilities are almost mandatory now. 

Sea level rise also affects the cruising routes as towns and villages along the routes become inundated and islands submerged. We are long past mitigation and are now in the adaptation phase. Of course, melting sea level ice also makes the NW and NE passages navigable for longer periods. Antarctica is another story. On September 10, 2023, sea ice in the Antarctic reached an annual maximum extent of 16.96 million square kilometers (6.55 million square miles), setting a record low maximum in the satellite record that began in 1979. 

Air Currents

The jet stream has been wobbling back and forth in cycles of about 5 to 6 weeks. In periods when the Azores High or the Scandinavian High get stuck over us, we get 6 weeks of settled weather now. When the jet streams wobbles back, we get six weeks on nonstop depressions as happened in July and August this year, effectively destroying most cruising plans. Visiting yachts were stuck in harbours like Rossaveal for a week at a time unable to move up the coast. 

Disease Spread

Another worrisome effect of climate change is the expanding territory of infectious agents and their carriers. For example, mosquitos are moving north in the Northern Hemisphere and diseases like malaria, chikungunya, and zika are appearing in places where they never were before. Similarly for tick-borne diseases like Crimean-Congo Hemorrhagic fever. Vaccinations are being expanded and the medical kit needs to be revised. 

The spread of disease around the world has never been more evident than in the last few years with the outbreak of the Covid-19 pandemic and Avian flu. Close to 7 Million people have died from Covid worldwide. Estimating how many birds have died is almost impossible but experts say it's in the millions. 

Ice extent

As the long dark winter sets in, Arctic sea ice extent has increased at a faster-than-average pace. By the end of October, the ice cover had reached the Siberian coast, while open water persisted along the coasts of the Beaufort and Chukchi Seas. In the Antarctic, the spring decline in extent has been quite slow, but the extent at the end of October remains at record-low levels for this time of year.

Wave height

A study has shown that globally averaged ocean wave energy since the late 20th century has increased at a median rate of 0.27% per year. However, since 2000, that globally averaged increase in the rate has risen by 0.35% per year.

So every time we cross an ocean, the likelihood of encountering bigger waves packing more energy is increasing. 

Storm tracks 

The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) commented that:

It is likely that circulation features have moved poleward since the 1970s, involving a widening of the tropical belt, a poleward shift of storm tracks and jet streams and a contraction of the northern polar vortex … for the years since the 1970s, it is virtually certain that the frequency and intensity of storms in the North Atlantic have increased.

The seasonality of storms must also be considered, with storms beginning earlier and tracking even later in the seasons, so plenty of time must be allowed for conditions to settle before venturing out. 

Extreme cyclones are increasing in frequency and, as seen with Hurricane Otis that struck Acapulco Oct. 25, 2023, they are increasing in intensity and moving faster over warming waters. Otis went from Tropical Storm to Category 5 in less than 12 hours, striking in an area rarely before targetted by a tropical cyclone.  

A study published as a preprint in 2021 presents the first assessment of changes to objectively identified cyclones, their intensities, and associated wind speeds in the newest generation CMIP6 models. 

• Cyclone numbers are projected to decrease globally in both winter and summer seasons.
• In the Northern Hemisphere winter, there is a projected poleward shift of the North Pacific storm track, an extension of the North Atlantic storm track into Europe, and a decrease in activity over the Mediterranean. In summer a reduction in storm track activity is projected hemispherically.
• In the Southern Hemisphere, a robust poleward shift of the storm tracks is projected for both seasons in a symmetric manner around the hemisphere.
•  The most extreme cyclones will have higher intensities (higher vorticity/lower MSLP) for both seasons in the SH and for NH winter, whereas the strongest summer cyclones in the NH will weaken slightly.
• The strongest cyclones will have stronger wind speeds throughout the troposphere for NH winter and both seasons in the SH. 
• The area of extreme wind speeds will increase in future winters and the area of intense wind speeds in extreme cyclones will increase by up to 40% by the end of the century.
• Extreme cyclones are projected to intensify at a faster rate than average-strength cyclones in the winter.

Trade winds

Jimmy Cornell has issued a revised Cruising Routes to take into account the shift in wind patterns that sailors have been relying on for hundreds of years. He says the Atlantic which is the most traveled ocean route has seen a great shift in wind patterns for the times of the year when most sailors cross. Today, it is almost essential to drop way south to the Cape Verdes when crossing from Europe to the Caribbean before finding enough wind to cross. We saw when assisting sailors during Covid that vessels returning to Europe had to sail straight north before turning east.

The Pacific trade winds strengthened in the 1990s and the enhancement of southeast trade wind is less than that of northeast trade wind. 

El Niño

We have entered an El Niño year which is predicted to accelerate climate change faster than any event before. Global temperatures are likely to soar to record levels in the next five years, the World Meteorological Organization (WMO) has warned. This would briefly push us above Paris Agreement targets which urge limiting global temperature increase this century to 1.5°C.

What this means to the cruising sailor is an ever-increasing unpredictability of the conditions at any given place and at any given time. So although forecasting in general has improved for the longer term, the forecasting for micro regions remains highly unpredictable. 

Conclusion for now

I'm writing this for myself so that I can try to understand how to interpret what I see and hear. I think I've covered enough for now. I'll pick it up again as I see changes to the expected progression of climate weirdness. See you then.  

I am certainly not a climate or weather expert. I'm a biochemist by training so don't rely on my interpretations.