Although my post today applies to research conducted studying climate and rainfall in the UK and Canada, it’s not far-fetched to apply the same logic to anywhere in the world. The findings of a study by the journal “Nature” has found that greenhouse gas emissions are increasing the frequency of extreme rainfall totals as a result-in the risk of flooding. The combination of computer modeling and real-world data prove the link between greenhouse gas emissions and the frequency of high storm totals in terms of rainfall in the Northern Hemisphere. Twice in the last decade the UK has seen flooding far beyond anything previously documented, with the autumn rains in 2000 being the highest recorded since record-keeping in England and Wales all the way back in 1766.

A team from Oxford University compared two computer models, one representing the atmosphere as it actually was/is whilst simultaneously running a model which excluded carbon dioxide and similar gases due to man-made causes. Those rainfall projections were then studied in terms of their impact on the river basins across the country. Oxford researcher Pardeep Dall led the study and stated:

“We looked at how greenhouse gas emissions affected the odds of a flood, we found that the emissions substantially increased the odds of a flood occurring in 2000, with about a doubling of the likelihood.”

In a similar and related study, experts in Canada and the UK examined the frequency of heavier rainfall events that have been documented between 1950 and 2000 throughout much of the northern hemisphere. Naturally as you’d expect there were variations from one location to the next and year-to-year, but the aggregate proved that intense rainfall has become more common over the period of time studied. Researchers cite that the only thing that would account for such a trend is the gradual increase in temperatures that has been tracked due to greenhouse gas emissions.

“In North America, precipitation extremes correspond to the El Nino effect in pretty characteristic ways, where some regions get heavy rainfall while others receive less extreme precipitation. But we don’t see these spatial variations in our study, and our models don’t generate that kind of spatial structure either. The evidence is leading us in another direction, to a phenomena that influences precipitations in a global scale – and the only thing we can think of is the changing composition of the atmosphere.”

While science has long been able to prove that warmer weather naturally leads to wetter weather the link to more frequent heavy rains had yet to be documented to such a degree. Not only does the total rainfall annually tend to creep upward but the evidence of extreme events leading to flooding rises to the same degree, some analysts are suggesting that the model even underestimates the potential for heavy floods in the future. There is a consensus that more research needs to be completed with improved record-keeping from all regions of the world to better illustrate to governments what future planning is necessary. There are also the economic impacts of flooding where damage is intense, insurance policies increase and of course flood defenses need to be upgraded globally especially along river basins. The data is of most use with future urban planning and allowing for better precaution to be taken when building near flood plains.