ZHAI HAIJUN/CHINA DAILY

However, scientists warn that these weather phenomena are becoming more frequent and more powerful. Two deadly superstorms late last month, thousands of miles apart, once more raised the question of whether humankind has contributed to this trend through greenhouse gas-induced climate change.

Typhoon Hato, which struck southern China, killing 18 people and forcing thousands to evacuate their homes, was the worst storm to hit the region in half a century. Days later, Hurricane Harvey made landfall in Texas, bringing with it what officials described as "unprecedented" flooding to the populous US state. The storm forced the closure of 10 oil refineries that employ tens of thousands of people and normally handle up to 2 million barrels a day.

Climate change skeptics routinely argue that such natural scourges long predate the era in which fossil-fuel burning is said to have accelerated global warming. Research, however, points to human activity playing a role. A US study published last year indicated that typhoons affecting heavily populated regions of East Asia had become up to 15 percent more intense and up to four times more frequent as a result of climate change.

Wei Mei, a marine scientist at the University of South Carolina and co-author of the study, said at the time: "The intensification is strongest for typhoons that tend to make landfall because of the stronger warming of the coastal waters near East and Southeast Asia." According to Wei, the typhoons striking the Chinese mainland, Taiwan, Japan and the Korean Peninsula will intensify further because of the faster warming of waters of 20 degrees north.

An update earlier this year from the Geophysical Fluid Dynamics Laboratory in New Jersey cautiously reported it was premature to conclude that greenhouse gas emissions had already had a detectable impact on Atlantic hurricane or global tropical cyclone activity. However, human activities may have already caused changes that are not yet detectable.

The GFDL said it was likely that by the end of the century manmade global warming would contribute to more intense and destructive storms and there was a better than even chance that there would be more of them.

Similar studies in the past prompted the debate on climate change and led to a near-global consensus, expressed in last year's Paris climate change agreement, on taking action to curb the temperature rise.

Climate change deniers are now in a minority, although they received a boost with the election of US President Donald Trump, a climate skeptic. He has suggested in the past that the data behind some climate change research might have been manipulated. There are now allegations of a cover-up of some research－to favor the climate change deniers. ExxonMobil, the world's largest energy company, is defending itself against accusations that it downplayed its own research indicating the existence of manmade global warming.

US legal authorities are looking into whether the company misled the public, an allegation which the energy giant denies. ExxonMobil says it now acknowledges that climate change is real and that it even urged Trump not to pull out of the Paris Agreement, which he nevertheless did.

It is now left to China and the European Union to take the lead to combat climate change, the issue on which the two have shown the greatest solidarity in a more than decade-old partnership.

Some argue that we may already have reached the point of no return, where no amount of reduction of greenhouse gases will prevent potentially catastrophic global warming. That may be overly pessimistic. But data suggesting last year might have been the hottest year on record, coupled with this season's superstorms, are reminders that time for action may be running out.

The author is a senior editorial consultant for China Daily. harveymorris@gmail.com