No other country has both temperate Mediterranean winter and summer tropical and subtropical regions.
Mixed peel: those chewy nips of dried, candied lemon and orange rind that give Easter buns their zesty and bitter edge.
I love baking hot cross buns. But this year, searches for the peel proved fruitless, despite visiting five supermarkets and independent grocers.
Citrus peel is the latest produce to be affected by extreme weather conditions in 2023, a year marked by shortages of iceberg lettuce, and even potatoes.
Candied peel in Australia is mainly imported from Italy. In the Northern Hemisphere, unusually warm and dry conditions have contributed to a drop in 2022-23 citrus crops, which fell 13% compared to the previous season according to the World Citrus Association. In Italy, one of Europe’s major citrus growers, production fell by 21%.
“This year’s crop is one of the smallest of the last seasons, mainly due to climatic issues in leading export countries,” says Eric Imbert from CIRAD, French Agricultural Research Centre for International Development and the Citrus industry secretariat.
Climate change is affecting rainfall patterns and temperatures, and increasing the frequency and severity of extreme weather events. To survive, agricultural industries, like citrus, are having to shift, substitute and innovate.
Could climate change pose a threat to my favourite Easter treat?
It’s already a concern for citriculture in the Mediterranean, according to a study by the University of Valencia. Because even though citrus trees are hardy and can withstand higher temperatures, drought and lack of water (as well as torrential flooding) along with pests and diseases pose a major threat to growth and fruit production.
Read more in Cosmos: Ancient farms survived climate change by switching crops, storing grain
Australia produces around 768,000 tonnes of citrus annually, according to Horticulture Innovation Australia. Mainly oranges (67%), mandarins (22%), lemons and limes (9%) and grapefruit (2%).
Professor Robert Henry, an expert in agricultural innovation at the University of Queensland, says in the Northern Hemisphere, Mediterranean climatic conditions are edging northwards, which has “major ramifications” for agriculture and food crops.
Grape growers in southern France have been harvesting six weeks earlier than traditionally, for example. Somewhat controversially, the best climate for growing champagne grapes could soon be England rather than France.
In Australia, despite a strong local industry and some 27,000 hectares of orchards across every mainland state, citrus could face a future reckoning as summer rainfall and temperature patterns trend southwards.
Henry says the dividing line between predominantly winter rainfall to the south, and summer rainfall to the north, was previously in the centre of New South Wales, but climate change has shifted that boundary towards the Victorian border.
Those changes can affect crop quality and yields, create heat stress and pose biosecurity risks as diseases and pests expand their remit. Extreme weather events can test producers’ resilience.
Somewhat controversially, the best climate for growing champagne grapes could soon be England rather than France.
A Victorian catchment management authority study into the impact of climate change on Washington Navel Oranges and Afourer Mandarins shows climate change could cut fruit yields by 11% and the length of the growing season by 27% by 2050.
Citrus industry concerns also include higher overnight temperatures affecting fruit flavour by altering the balance of acid and sugar, high humidity increasing the risk of disease and the potential for rind defects.
Farmers generally have three main options to adapt to the changing conditions, Henry says.
One, move to a more desirable climate. Two, grow something different which is better suited to the new conditions. Three, try to control the environment, for example by adding wind breaks, shade, and at the most extreme by moving the crops indoors to controlled conditions with air-conditioning and lights.
When life gives you lemons …
Professor Richard Eckard leads the Climate Challenges Centre in the School of Agriculture at the University of Melbourne.
He says an advantage for Australia is the range of bioclimates and extent of north-to-south latitudes we encompass. This allows farmers to grow everything from exotic tropical fruit in the north, to dairy, cherries and apples in the south.
“There’s no other developed country in the world that has both true temperate Mediterranean winter- dominant rainfall through to true summer tropical, and subtropical all in one country,” he says.
That huge range provides an opportunity for farmers to adapt and move their crops as climate zones move south.
And there’s evidence farmers and producers are already taking up that opportunity.
“We’re growing cotton in Victoria for the first time in history in the last five years,” Eckard says.
“You couldn’t blame that on climate change alone. But climate change and a combination of cotton breeding has allowed cotton to move south quite substantially.”
The biggest concern for citrus will be the greater diversity of pests and diseases that come with a changing climate.
Even those longer-lived tree crops and vines, which require decades of forethought and planning, are gradually moving southwards.
For instance, Brown Brothers began expanding their vineyards to Tasmania, once they realised they would not be able to produce quality Pinot Noir on the mainland by 2030. Many cherry and apple growers have followed.
Henry expects the biggest concern for citrus will be the greater diversity of pests and diseases that come with a changing climate.
According to Citrus Australia, warmer winters and more conducive conditions have already seen an increase in Queensland Fruit Fly in southern Australia.
Citrus greening is an incurable disease that affects citrus trees, it’s caused by the Huanglongbing bacteria, which is spread by psyllid insects.
The disease arrived in Florida, the largest orange-producing state in the US, in the early 2000s and citrus production declined by 74%.
Luckily for Australia – for now, at least – many of the big name threats, like citrus greening, remain outside the country.
Australia’s “great opportunity,” Henry says, lies in the genetics of native wild citrus varieties, which have resistance to these major global diseases.
Henry is an expert in plant genetics, and is part of a huge program analysing the genomes of six Australian native citrus species. The best well-known is the Finger Lime, but there’s also the Kakadu, Round, Dessert, Russell River and Mount White limes.
Interbreeding these wild varieties with conventional fruits like oranges or mandarins, could unlock access to the native limes’ genetic advantages – their resistance to pests and diseases, resilience to climate changes, and novel characteristics like earlier flowering.
Globally, many growers are already breeding Australian citrus together with conventional varieties, in hopes of borrowing those genetic qualities, he says.
“Worldwide, everyone is trying to use Australian material to cope with the challenge of producing citrus. We see a lot of work, particularly in North America, using Australian material, [and] patents being taken on Australian finger limes in California.”
The added challenge for a tree crop like citrus, is that farmers need to be thinking years, even decades ahead to prepare for climate change.
“The problem we’ve got is that climate change is fairly fast, and tree crops have a long life cycle. With annual crops we’ve got the opportunity to change what we plant from year to year. But with a tree crop we’re stuck with it for decades.
“You can’t think about next year, you’ve got to think about ten years’ time, or 20 years’ time.”
“Everyone is trying to use Australian material to cope with the challenge of producing citrus.“Professor Robert Henry
For this year at least, hot cross bun bakers can breathe a sigh of relief.
Italian production might be down, but a customer service representative for dried fruit company Sunbeam Foods assures Cosmos they have secured enough Glace Mixed Peel to fully supply Australian customers this Easter.
As it happens, there’s a non-climate factor behind the bare shelves too. The two major supermarkets have delisted mixed peel from regular supply, the rep says. So, if you plan on baking some buns this Easter, and are hunting for mixed peel, try one of the independents or smaller grocers instead.
More in Cosmos Weekly
Petra Stock has a degree in environmental engineering and a Masters in Journalism from University of Melbourne. She has previously worked as a climate and energy analyst.