Antinuclear

There’s a well-established physical law, the Clausius-Clapeyron equation, that says that a hotter atmosphere holds more moisture.

For every extra degree Celsius in warming, the atmosphere can hold 7% more water. This tends to make rainfall events even more extreme when they occur.

Another element that we can mention with some confidence is the temperature of the seas. “The waters of the Gulf of Mexico are about 1.5 degrees warmer above what they were from 1980-2010,” Sir Brian Hoskins from the Grantham Institute for Climate Change told BBC Radio 4’s Today programme.

“That is very significant because it means the potential for a stronger storm is there, and the contribution of global warming to the warmer waters in the Gulf, it’s almost inevitable that there was a contribution to that.”

Researchers are also quite confident in linking the intensity of the rainfall that is still falling in the Houston area to climate change.

“This is the type of event, in terms of the extreme rainfall, that we would expect to see more of in a warming climate,” Dr Friederike Otto from the University of Oxford told BBC News.

Analysis – Roger Harrabin, Environment analyst

Environmental lawyers are questioning whether events like Harvey should still be referred to as “Acts of God” or “Natural Disasters” as they are made worse by emissions from fossil fuels.

In a comment paper in the journal Nature Geoscience, they say legal action may be taken against countries that don’t contribute to the global effort to cut emissions.

Lawsuits seeking to apportion responsibility for climatic events have generally failed in the past.

But lawyers from the firms Client Earth in London and Earth and Water Law in Washington say that’s likely to change.

They believe a new branch of knowledge called attribution science will allow the courts to decide with reasonable confidence that individual events have been exacerbated by manmade climate change.

They believe in future governments and firms risk being successfully sued if they don’t cut their emissions.