Super typhoon Goni caused multiple deaths and millions of dollars’ worth of damage when early this week it became the most powerful storm to make landfall in the Philippines for seven years.
Just days after the devastation left by Goni’s 225kph winds, Hurricane Eta struck Central America with almost as much power, triggering floods and deadly landslides.
What made Eta’s formation especially notable was that it was the 28th named storm in this year’s Atlantic hurricane season – a joint record.
It brings to the fore concerns that tropical cyclones – also called typhoons or hurricanes, according to geographical location – are becoming increasingly common because of climate change.
According to Tom Matthews, a lecturer in climate science at Loughborough University in the UK who researches extreme weather events, the scientific consensus is that the number of tropical cyclones will drop, but the proportion of high category ones – like Goni and Eta – will increase.
“With greater warming, the average intensity moves upward, so the tropical cyclones become more intense on average, and that suggests we should expect to see tropical cyclones emerge that are stronger than anything we’ve seen before,” Mr Matthews says.
Climate modelling predicts wind speed in the most intense tropical cyclones to increase by about 5 per cent – which means 16 per cent more power.
For every 1°C rise in global average temperature, a 2013 study suggested there would be a 25 to 30 per cent rise in category four and five storms, which are the most severe.
Indeed, the forecasts of climate models are now a reality, says Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment, part of the London School of Economics.
“It was a key paper published earlier this year, in May, that showed that we can now see a trend in many basins of the world towards the stronger tropical cyclones. That’s something that’s just started to emerge,” he said.
As well as becoming more powerful, tropical cyclones will drop more rain because a warmer atmosphere can hold more moisture – 7 per cent more for each 1°C temperature increase – and will act on a higher seas as sea levels rise, so storm surges will reach further inland.
“In the last couple of years, there’s been key research showing, particularly in the Atlantic basin ... rapid intensification, where storms very quickly go from weak to strong. We’ve seen that in the last couple of days with Hurricane Eta,” Mr Ward says.
There is also the risk that, thanks to climate change, tropical cyclones could more often coincide with heatwaves, compounding the dangers.
“The world that we’re moving into, yes, it means more of the familiar,” says Mr Matthews. “It may also mean some novel threats out there, like the interaction of climate hazards in a way we haven’t seen before.”
The downing of power grids could coincide more frequently with heatwaves in places that are already some of the warmest parts of the world – a potentially dangerous combination.
With the effects of climate change on extreme weather events already apparent, and with researchers forecasting more severe consequences to come, the question arises of what can be done to halt or mitigate them.
“Climate change is, unfortunately, locked in for the next three or four decades. The climate will continue to get worse in terms of these extreme weather events,” says Mr Ward.
“We’re going to have to adapt and become more resilient. We’re seeing better use of early-warning systems that allow you to evacuate populations before they’re hit. That’s helped to reduce the number of deaths.”
Beyond this, he says questions will increasingly be asked about how to manage populations in vulnerable coastal locations over the long term. While not realistic for major cities, moving some communities away from the coast may become necessary.
“If you look at a country like Bangladesh, which is very low lying, it can be very vulnerable to strong storms. Sea-level rises and storms are a real threat,” says Mr Ward.
“A very major hurricane hitting Miami head on, a category five hurricane hitting Miami, would cause hundreds of billions of dollars of damage, perhaps reaching a trillion dollars.
“That would cause disruption to lives and livelihoods that could have major impacts on the US economy and could affect the global insurance industry … It could possibly bankrupt the state of Florida and would have a major impact on the US economy, so even rich countries are not going to be immune to these impacts and need to take this threat seriously.”
In this context, the pressure is for nations to cut carbon emissions to net zero, something China recently declared it would do by 2060.
“In the long term, if we want to avoid the possibility of storm surges that are simply too difficult to deal with even for well-defended areas, global emissions have to go down effectively to zero,” says Mr Ward.
“It’s only when they go down effectively to zero that climate change will stop. While we continue to raise [emission] concentrations in the atmosphere, the impact of climate change will continue to get worse and become more frequent."
