Imagine the scenario: a sudden, massive rise in sea level inundates the low-lying vineyards of the Veneto plain, destroying millions of Prosecco vines. And a wave of mighty hailstorms decimates the vines whose grapes become Champagne.

In these days of unpredictable climate change, that just might happen.

What then for the lovers of sparkling wine?

While Prosecco and Champagne are by far Britons’ favourite fizz, there are so many alternatives.

Almost all of the best follow the champagne or “traditional” method: to a still base wine a “dosage” of sugar and yeast is added to prompt a second fermentation in heavy, deep-punted bottles.

Cava, crémants and much new world fizz follow this method.

For Prosecco – and plenty of cheap sparklers – the second fermentation is in pressurised tanks, very big for run-of-the-mill results, small ones for posher bottles. There are other methods, too, but these are the most common.

In the froth of enthusiasm for Prosecco, Cava has been somewhat overlooked – unfairly, as the winemakers in the production region, inland from Barcelona, turn out both good basic wines and fine smarter ones.

Crémant is the rest of France’s answer to champagne, widely made in such regions as the Loire Valley, southern Rhône, Jura and Languedoc.

Traditional champagne grapes, particularly chardonnay, usually dominate, but often there are local varieties in the blends.

Cool-climate Tasmania is source of some of the new world’s best fizz – Australia’s first recorded sparkling wine was made there nearly 200 years ago, so perhaps Down Under isn’t so new, after all.

The 1985 joint venture between Roederer and Tasmania’s Heemskerk was an early example of many champagne house links in distant locations, particularly California.

There is traditional-method fizz, as well, from less likely places – Brazil, for example, or Portugal. And England! Our sparkling wine has much in common with Champagne, and the best can beat its continental challengers in blind-tasting competitions.

Points to remember: good “alternative” fizz spans the price spectrum, and quality/price ratio can be as variable as with Champagne and Prosecco.

I’ve chosen some wines from good sources, at different price points (prices are rounded). Among them are a couple of unusual Champagnes I couldn’t resist including.

Soft, almost dangerously drinkable Brut 1415 Moingeon, Méthode Traditionelle Blanc de Blanc is a stylish Burgundian; Serge Mathieu brut rosé champagne is quite deep pink, a seriously dry, savoury food accompaniment (£11, £29, fromvineyardsdirect.com).

Waitrose own-brand cava brut is a crisp, fresh and pleasantly fruity bargain, while Janz Premium Cuvée is a lovely example of Tasmania’s style, lingering long (£7, £17).

Two high-end highlights, only from waitrosecellar.com, are Poillot Cuvée Val Colas Robin 2012 Brut Nature, a rare champagne made from 100% pinot blanc, nutty and savoury, and Hambledon Première Cuvée Brut, (£30, £40), complex and smooth, a top example from England’s vineyards.

Fine value-for-money fizz is made in southern France by Paul Mas – Prima Perla Grande Reserve is an appealing example – and Balfour 1503 rosé, perfumed and attractively summer fruited, is another English star (£9.50, £20 – both mix-six price, Majestic).

The pick of M&S’s alternative fizz is Ferrari Brut from Trento, northern Italy, frothy yet seriously celebratory (£20).

And for a splendid choice of crémants, go to The Wine Society.