Storms have taken lives in the Caribbean, and caused chaos in the UK - climate change is eroding certainties across the globe

As tens of thousands people suffered through a flooded and powerless Christmas in Britain, 5,000 miles away unexpected weather was also unleashing havoc on the Caribbean.

Torrential rains on Christmas Eve, with 15in falling in 24 hours, led to dramatic floods and landslides that washed through St Vincent and the Grenadines, St Lucia and Dominica. So far eight people in St Vincent and five in St Lucia have died, water and electricity are down and thousands of properties have been damaged. The clean-up bill is expected to be in the millions.

The crisis cut short the holiday of the prime minister of St Vincent, Ralph Gonsalves, who happened to be in storm-hit London, after a trip to see the pope in Rome. Gonsalves - whose cousin was killed in a landslide during the rains - said it was "a disaster of a proportion the likes of which we have not seen in living memory". The secretary general of the Organisation of American States, Jos� Miguel Insulza, also noted the "unreasonable nature" of the rains, and said "the flooding raises once again the impact of climate change in the Caribbean region".

Many years ago, during a rainy spell in Britain, a South African colleague at my office grumbled that Britain didn't have a climate - it only had weather. I chuckled at the time, but it seems that this now goes well beyond the UK. Unmoored from what usually happens during a given season, we are increasingly vulnerable to the brutal force of extreme weather events at short notice.

The Caribbean's climate does involve a rainy period - it is part of the hurricane season, which starts around June and usually lasts until around mid to late November. The 2013 hurricane season was the quietest in 30 years, with only two storms, and they did not even reach an intensity of category three or above. With regards to these recent rains, public opinion appears to agree with Gonsalves: these downpours were unprecedented.

There is no doubt that something is amiss in the tropics, and has been for some time. For instance, in 2011 in the north-east region of Colombia, the rain almost never stopped, and floods devastated the country, with hundreds of thousands of homes damaged and millions of people left suffering. And Trinidad and Tobago, too, has been experiencing severe and often unexpected flooding in the past few years, due to heavy rains.

The Caribbean is on the receiving end of the effects of climate change - it has to adapt and respond to the consequences, even though it has contributed little to the problem. Like other island nations, rising sea levels are a particular threat. A recent report by the Inter-American Development Bank claims that the tourism industry could lose some $900m a year (�550m) by 2050, and that flat, non-volcanic islands like the Bahamas are considered especially vulnerable.

There is also the risk that more people on the islands will choose to live abroad - if they are not evacuated first. But erosion is not something from a computer model - it's happening now. For instance, Varadero, Cuba - where more than a million tourists descend every year - has lost between 40,000 and 50,000 cubic metres of shoreline (430,000 to 537,500 sq ft), and a recent report says around 84% of the island's beaches are threatened.

For the Caribbean, unpredictable weather and eroding beaches could harm the vital tourism trade. In addition, the islands have a range of environmental issues to tackle, from mining in Jamaica to deforestation in Haiti. There is a rich ecosystem across the region - forests and biodiversity above water, and precious coral reefs and aquatic life below - that is increasingly under threat. The islands are trying to cope, earmarking scarce funds to deal with these challenges, set against a backdrop of economic struggle and often poor infrastructure. But moves have long been under way in places such as Belize, Dominica, and Costa Rica to encourage eco-tourism. The Caribbean Community Climate Change Centre was set up in 2005, which involves most of the Caricom members (18 of the English-speaking states of the Caribbean, as well as Haiti and Suriname), and most islands have scientists monitoring changes in climate patterns, and taskforces to attempt to deal with the consequences.

Whatever you think about climate change, the onset of erratic and extreme weather erodes any pretence of certainty. Modern life, as recent events in Britain have shown, has no time for floods, storms, downed power lines, delayed trains or flights - but this is our future. So in this sense, small islands, whose tribulations are often are ignored, are really the canaries in the coal mine.

This Christmas the impact of climate change reached across the Atlantic: developed and developing worlds were brought together in a misery of rising flood waters. We ignore what is happening to the places on the frontline of this changing climate at our peril.

The Guardian