Oxford University scientists say they have analysed data from two deadly heatwaves in 2003 and 2018 as well as four floods between 2000 and 2016 that cost an estimated $US18 billion ($A23 billion) in losses.

They found at least half the total damages and deaths could be attributed to climate change.

Friederike Otto, director of Oxford University's Environmental Change Institute and one of the study's authors, said far more data needed to be collected and analysed worldwide for the true consequences of climate change to be understood.

If metrics were agreed, "I think it would become far more obvious to everyone that the impacts of climate change are real and not something that will happen in the future and to someone else," Otto said.

"They are upon us and costing lives here and now."

The authors looked at the two specific British heatwaves because the influence of climate change on them had already been analysed, although others also occurred in the time frame.

Under the 2015 Paris Agreement, which aims to limit global warming to "well below" 2 degrees Celsius compared with pre-industrial levels, more than 190 countries must submit action plans.

They include not just targets to reduce climate-heating emissions but ways to adapt to more extreme weather and rising seas.

About 5.2 million homes and other properties in England are at risk of flooding, according to Britain's Environment Agency, as sea levels have risen 16 cm in Britain since 1990.

The new study, published in the scientific journal Climate Risk Management, said other countries also faced extreme weather costs exacerbated by climate change, both human and financial.

For example, in Puerto Rico the increased intensity of Hurricane Maria in 2017 led to the deaths of up to 3670 people, it noted.

Separately, Stanford University researchers in January found climate change boosted the cost of flood damage in the United States by $US75 billion over the past three decades, accounting for a third of all losses.

Australian Associated Press