Atmospheric rivers set to increase UK winter flooding

Jul 24, 2013

The prolonged heat wave that has bathed the UK in sunshine over the past month has given the country an unexpected taste of summer that has seemed to be missing in recent years.

However, a new study published today, 24 July, in IOP Publishing's Environmental Research Letters, has provided warnings that will chime with those accustomed to more typical British weather.

According to the study, winter flooding in the UK is set to get more severe and more frequent under the influence of climate change as a result of a change in the characteristics of atmospheric rivers (ARs).

ARs are narrow regions of intense moisture flows in the lower of the atmosphere that deliver sustained and heavy rainfall to mid-latitude regions such as the UK.

They are responsible for many of the largest winter floods in the mid-latitudes and can carry extremely large amounts of water: the AR responsible for flooding in the northwest of the UK in 2009 transported 4500 times more water than the average flow in the River Thames in London.

The researchers, from the University of Reading and University of Iowa, found that large parts of the projected changes in AR frequency and intensity would be down to thermodynamic changes in the atmosphere, rather than the natural variability of the climate, suggesting that it is a response to anthropogenic climate change.

To reach these conclusions, the researchers used simulations from five state-of-the-art climate models to investigate how the characteristics of ARs may change under future climate change scenarios.

Firstly, they used the to see how accurately they could simulate the ARs that occurred between 1980 and 2005. The five models did this successfully and were deemed capable of projecting how future ARs will develop under different scenarios.

The models were then used to simulate future conditions under two scenarios – RCP4.5 and RCP8.5 – that represent different, yet equally plausible, scenarios for future increases in greenhouse gas concentrations in the atmosphere. They projected changes that would occur between 2074 and 2099.

Each of the five models simulated an increase in AR frequency. For the RCP8.5 projections, which represents stronger increases in greenhouse gas concentrations than RCP4.5, there was a striking level of consistency in the magnitude of change in AR frequency – all models showed an approximate doubling of the number of future ARs compared to the simulations for 1980 – 2005.

The models also projected an increase in intensity of the ARs, meaning an AR impacting the UK in the future is projected to deliver more moisture, potentially causing larger precipitation totals.

Lead author of the research, Dr David Lavers, said: "ARs could become stronger in terms of their moisture transport. In a warming world, atmospheric water vapour content is expected to rise due to an increase in saturation water vapour pressure with air temperature. This is likely to result in increased water vapour transport.

"The link between ARs and flooding is already well established, so an increase in AR frequency is likely to lead an increased number of heavy winter rainfall events and floods. More intense ARs are likely to lead to higher rainfall totals, and thus larger flood events."

Explore further: NASA study projects warming-driven changes in global rainfall (w/ Video)

More information: iopscience.iop.org/1748-9326/8/3/034010/article

add to favorites email to friend print save as pdf

Related Stories

Projected U.S. water use likely to increase as climate warms

Jan 29, 2013

Despite increases in efficiency, water demand in the United States is likely to increase substantially in the future if climate continues to warm, new projections indicate. Brown et al. project future water use to 2090 based ...

Warming to shift heavy rainfall patterns in the UK

Nov 20, 2012

(Phys.org)—It appears that it's not just us Brits who are fascinated with the UK weather. A group of researchers from Germany has taken to investigating the potential changes in extreme rainfall patterns ...

Floods to become commonplace by 2080

Jan 08, 2009

Flooding like that which devastated the North of England last year is set to become a common event across the UK in the next 75 years, new research has shown.

Recommended for you

Image: Grand Canyon geology lessons on view

3 hours ago

The Grand Canyon in northern Arizona is a favorite for astronauts shooting photos from the International Space Station, as well as one of the best-known tourist attractions in the world. The steep walls of ...

First radar vision for Copernicus

3 hours ago

Launched on 3 April, ESA's Sentinel-1A satellite has already delivered its first radar images of Earth. They offer a tantalising glimpse of the kind of operational imagery that this new mission will provide ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

ormondotvos
not rated yet Jul 24, 2013
Recent SciAm article shows pix of Central Valley of California turned into a lake, ten feet deep at Sacramento, from an AR in 1851.

This would destroy half the state's agronomy if it happened now, not to mention hundreds of billions in housing, warehousing and homes. It would help flush the soil of pesticides and salts from decades of irrigation, though. Fresh new mud, and lots of it!

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

First radar vision for Copernicus

Launched on 3 April, ESA's Sentinel-1A satellite has already delivered its first radar images of Earth. They offer a tantalising glimpse of the kind of operational imagery that this new mission will provide ...

Image: Grand Canyon geology lessons on view

The Grand Canyon in northern Arizona is a favorite for astronauts shooting photos from the International Space Station, as well as one of the best-known tourist attractions in the world. The steep walls of ...

Book offers simplified guide to shale gas extraction

The new book, "Science Beneath the Surface: A Very Short Guide to the Marcellus Shale," attempts to offer a reader-friendly, unbiased, scientific guide needed to make well-informed decisions regarding energy ...

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...