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The majority of heatwaves and almost a fifth of extreme rain storms can be blamed on human activity, a new study has warned.

Researchers say that three quarters of extreme hot weather and 18 per cent of heavy precipitation is being driven by global warming that has occurred due to man-made emissions.

They warn that as climate change pushes global temperatures higher over the coming decades, humans will become responsible for 40 per cent of extreme rainfall events.

Researchers say 75% of extreme hot weather and 18% of heavy precipitation is being driven by global warming as a result of man-made emissions. They warn that as climate change pushes global temperatures higher, humans will be responsible for 40% of extreme rainfall events (floods in Somerset in 2014 are shown)

The scientists claim it is the rarest and most destructive events that seem to be the most responsive to human influence.

Dr Erich Fischer, from the institute for atmospheric and climate science at the Swiss Federal Institute of Technology in Zurich who led the study, said: 'Climate change includes not only changes in mean climate but also in weather extremes.

'With every degree of warming it is the rarest and the most extreme events and thereby the ones with typically the highest socio-economic impacts for which the largest fraction is due to human-induced greenhouse gas emissions.

'We show that at the present-day warming of 0.85°C about 18 per cent of the moderate daily precipitation extremes over land are attributable to the observed temperature increase since pre-industrial times, which in turn primarily results from human influence.

'For 2°C of warming the fraction of precipitation extremes attributable to human influence rises to about 40 per cent.

'Likewise, today about 75 per cent of the moderate daily hot extremes over land are attributable to warming.'

The researchers, whose work is published in the journal Nature Climate Change, examined the probability that heatwaves and heavy rainfall events could be attributed to humans using 25 climate models.

The models examined the weather between 1901 and 2005 using historical simulations.

They analysed daily temperatures and daily rainfall totals from climate models and looked for events that would be expected to occur once in 1,000 days in an unperturbed climate - referred to as moderate daily extremes.

They then used the models to look at predictions of extreme weather between 2006 and 2100 under an emissions scenario that is expected to lead to 2°C of warming around the world.

While attributing individual extreme weather events such as hurricanes, floods and heatwaves to climate change is notoriously difficult, climate scientists have predicted they will become more common as the world warms.

Dr Fischer and his colleague Professor Reto Knutti, also based at the Swiss Federal Institute of Technology in Zurich, said taking a more global perspective made it easier to examine the role that human activity was having on such events.

They say their research demonstrated a strong signal for human influence in the extreme weather that is having impacts around the world today.

They found that the longer the period of the event - such as a heatwave, the greater the fraction is attributable to global warming.

The graphic above shows where the change in the probability of heavy precipitation and heatwaves compared to the pre-industrial period. If global temperatures increase as predicted, as a result of climate change, this becomes more pronounced, explained the researchers

California is in the grip of its worst drought on record, causing lake beds to dry up (as above). Around three quarters of heatwaves can now be attributed to human activity and it is likely to worsen as the climate warms

Dr Fischer said: 'A warmer and moister atmosphere does clearly favour more frequent hot and wet extremes.'

Professor Peter Stott, a scientist at the Met Office's Hadley Centre in the UK, pointed to the extreme weather that has happened in the past year - one of the warmest on record.

He said Bangladesh was hit by flooding in 2014, Australia suffered heatwaves and Kenya was battered by downpours.

California, for example, is in the grip of one of the most severe droughts on record.

He added that human-caused climate change had 'loaded the dice' in favour of heatwaves like the one that hit Europe in 2003 and the flooding that hit the UK in autumn 2000.

The models examined weather between 1901 and 2005 using historical simulations. They analysed daily temperatures and daily rainfall totals from climate models and looked for events that would be expected to occur once in 1,000 days in an unperturbed climate. Extreme rainfall is pictured in London

Writing in the journal, Professor Stott said: 'As each year goes by, evidence continues to accumulate that our climate is changing and that human influence plays a dominant role in observed warming.

'The prevalence of extremely hot temperatures is expected to increase with warming and more moisture in the atmosphere leads to a tendency towards more extreme rainfall events, changes that have been detected in the observational record.

'But what has been lacking up to now is a robust calculation of how much more likely extreme temperatures and rainfall have become worldwide.

'The idea that in a two-degree world almost half of heavy rainfall events would not have occurred were it not for climate change is a sobering thought for policymakers seeking to mitigate and adapt to climate change.'