The Five Horses of Climate Change

In the Christian Book of Revelation (Chapter 6) there is a famous scene in which four horses and their riders are released into the world: white, red, black and pale horses.  They are interpreted in various ways, most popularly as Plague, War, Famine and Death. 

Some might consider it overly dramatic to talk about the ‘climate apocalypse’ and I hope they are right.  Nonetheless, updating the horsemen might provide a memorable framework for climate adaptation.  Of course climate change releases a different set of horses and riders into the world than the wrath of the Roman Empire - heat, fire, flood, tide and storm tide.  As I've been working on this series, we are experiencing most of them - heatwaves across the south of the country, bushfires in Victoria, Western Australia and Tasmania, floods in North Queensland and cyclones forming off the coast to our East and West. And through it all, the sea keeps rising inexorably.... So here are the five horses.

1.       The Sweaty Horse – Heat

The first horse is whipped into a lather of sweat, panting and suffering due to extreme heat, and can barely put one hoof in front of the other.  It badly needs a cool drink, or even better a swim, followed by a long rest in the shade of a spreading tree. 

Increased temperatures are the most obvious consequence of climate change (it’s often called ‘global warming’, after all!) and also have the biggest impact on human wellbeing.  The Australian Government’s State of the Climate Report 2024 tells us that average temperatures across Australia have increased by around 1.5 degrees since 1910 when records began.  But the big issue is not so much the overall temperature increases as the increase in heat waves and days of extreme heat.  In 2019, our warmest year so far, there were 33 days when the average national maximum temperature was over 39 degrees, more than any other year between 1960 and 2018.  The percentage of ‘extreme heat days’ increased from 2% in the years 1960-1989, to 11% in the years 2000-2023. 

Of all our extreme weather events, heat has the most widespread health impacts.  The Australian Institute of Health and Welfare estimates that over 7,000 people were hospitalised due to the effects of extreme heat between 2012 and 2022.  People most at risk are those who are vulnerable for other reasons – young children who can easily become dehydrated, frail older people or other people with health conditions. 

Read more about adapting to heat here.

2.       The Fiery Horse – Bushfire

The second horse is terrified, with a singed mane from the flying cinders, desperately trying to escape the raging fire. 

The risk of fires is determined by heat, low rainfall, low humidity, and high fuel loads.  In the southern half of Australia, average temperatures have increased while average rainfall has decreased, and more intense rainfall events have led to rapid plant growth and increases in stuff that can burn as it dries out.  All of these things are measured through the Forest Fire Danger Index, and across many Australian regions the number of days that this index is 'high' or 'extreme' has increased, particularly in spring and summer.  This has resulted in more frequent and more intense bushfires of which the Black Summer fires of 2019-20 are the worst so far.

Bushfires obviously have a huge impact on the natural world and also destroy property, rendering people homeless for extended periods.  Health impacts include direct impacts from the fire (burns, etc) and also the impact of smoke which can extend far beyond the communities directly affected by fire.  The AIHW estimates that between 2012 and 2022, 894 people were hospitalised due to the effects of bushfires. The Black Summer of 2019-20 resulted in the destruction of approximately 3,000 properties, 33 deaths from the direct affects of fire and around 450 deaths as a result of smoke inhalation, many of which were far from the fires themselves as smoke blanketed much of the country. 

3.       The Muddy Horse – Flood

The third horse is coated in mud up to its shoulders, sodden and exhausted from struggling to high ground or taking its rider to safety. 

Rainfall patterns have changed across Australia – average winter rainfall in the south-east and south-west (where the ‘normal’ wet season is in winter) has decreased, while average summer rainfall in the north has increased.  These impacts are important in themselves in terms of food production and water supply, but the particularly important thing for housing is the frequency and intensity of extreme rainfall events, where lots of rain falls in a short time.  The average intensity of short-duration rainfall events across the country has increased by around 10% since 1979.  There has also been an increase in sustained heavy rainfall events which lead to widespread flooding, such as those in the summer of 2021-22 that led to flooding in much of eastern Australia.

Major flooding can have massive impacts on both health and on property.  For instance, Deloitte estimated that in the South-East Queensland floods in February/March 2022, 13 people were killed, around 200 hospitalised and 19,000 residential and commercial properties were damaged. 

4.       The Sea-Horse – Sea Level Rise

The fourth horse is not really a horse at all, swimming about in the rising tides, driven ever-further inshore in search of the shallow habitats it calls home. 

As the polar icecaps melt, sea levels around the world are slowly rising – both because there is more water floating free rather than contained in ice, and because the water expands as it warms.  Global sea levels have risen by approximately 22cm since 1900, and this increase has accelerated in recent decades with an average rise of around 4cm per decade since 1993.  As well as meaning that the sea is gradually creeping further up the shore, it increases the damage caused by exceptionally high tides and by storm surges.  Sea level also exacerbates flood events in coastal river systems as higher tides reduce the rate at which floodwater flows through the river system. 

All this means that if you have housing near the coast, you need to be aware of what the impacts might be, and plan ahead.  Since about 80% of Australians live within 50km of the ocean, this might well be you! The damage probably won’t occur in a catastrophe (although we have recently seen cliff-top houses collapsing into the sea after storm surges, which may or may not be climate change related) but it will be a slow burn.

5.       The Wind-Blown Horse – Storm and Cyclone

The final horse is very much a tropical beast although its range has extended gradually southwards along with other tropical creatures as the climate warms.  It is looking damp, dishevelled and a little panicky after getting caught in a cataclysmic tropical cyclone. 

Climate change has an impact on cyclones, although it is not all bad news.  It seems so far that the number of cyclones each summer across northern Australia has declined in recent decades.  However, those that do form are more intense, with stronger winds, more rain and greater stability meaning they can last longer. 

When a cyclone hits a town it can be a seminal event in that community’s life - Cyclone Tracy in Darwin in 1975, Cyclone Larry in Innisfail and Babinda in 2006, or Cyclone Debbie in 2017 which caused damage and flooding along a path from the Whitsundays into South-East Queensland and Northern NSW. 

Read more about adapting to cyclones here.

Writing About the Five Horses

Prompted by Clive Hamilton and George Wilkenfeld's book Living Hot, I've been researching and writing about each of the five horses and what housing organisations should do respond to the changes we know are under way. Each one is a big subject on its own so I'll be giving a few pointers and then sharing various resources you can use to learn more on each issue. Join the mailing list at the bottom of the page if you want to be kept up to date.

Resources

The basic climate data in this report comes from the State of the Climate Report 2024, produced by CSIRO and the Bureau of Meteorology.

Data on health impacts comes from the Australian Institute of Health and Welfare.

Information on the Black Summer Bushfires comes from a report published by Natural Hazards Research Australia.

SEQ flood impacts data comes from the Queensland Government’s Reconstruction Authority. You can also read my own reflection on flooding in Brisbane here.

There’s lots of sources of information on the various historic cyclones – I started with the Wikipedia page for each, and it’s easy to go down the rabbit hole from there!

Basic information on coastal impacts of climate change, and mitigation measures, can be found at CoastAdapt.