Experts quantify melting glaciers' effect on ocean currents

May 25, 2011

A team of scientists from the University of Sheffield and Bangor University have used a computer climate model to study how freshwater entering the oceans at the end of the penultimate Ice Age 140,000 years ago affected the parts of the ocean currents that control climate.

A paper based on the research, co-authored by Professor Grant Bigg, Head of the University of Sheffield's Department of Geography, his PhD student Clare Green, and Dr Mattias Green, a Senior Research fellow at Bangor University's School of , is currently featured as an Editor's Highlight in top US journal, Paleoceanography. The study is the first of this kind for the time period.

The research found that freshwater entering the ocean from sheets can weaken the climate controlling part of the large-scale ocean circulation, with dramatic climate change as a consequence. During the period of the study, the experts noted that the dropped by up to two degrees over a few centuries, but changes were not uniform over the planet, and it took a long time for the climate to recover after the ice sheets had melted completely.

The team argues that it is not only the volume of freshwater being released from the melting which is important but also the state of the freshwater: icebergs act to reduce the ocean circulation less than , but the effects of icebergs last for longer periods of time. The effect is similar to the difference between adding very cold water to a drink or adding an ice cube or two.

The study also shows that at the end of the more recent Ice Age 20,000 years ago, the was more sensitive to ice sheet collapses than during the earlier period.

Professor Grant Bigg, Head of the University of Sheffield's Department of Geography, said: "An important component of the work is that it shows that the impact of freshwater releases from past, or future, ice masses depends critically on the form - whether fresh water or icebergs - and the location of the release.

"The Arctic has been surrounded by extensive glaciations several times in the past and this study has shown that large-scale changes in such Arctic ice sheets could affect the climate in places far from the release site. Our work also suggests that the Pacific Ocean may have been more sensitive to major changes in past glaciations than previously realised. We plan to investigate this possibility more in the future."

Dr Mattias Green from Bangor University, added: "With meltwater- similar to adding water to your drink, the water spreads out quickly and has an immediate effect, but it is also absorbed quickly into the rest of the . In a similar way to your ice cube, the icebergs drift along and melt more slowly. This means the immediate impact is weaker, but they are there for a longer time and distribute the water over a larger area.

"Our results lead us to conclude that a future sheet collapse, that might happen in Antarctica or Greenland, would have climatic consequences, but the exact impact needs to be evaluated in each case."

Explore further: Study: Ocean tides once spread massive icebergs

Related Stories

Study: Ocean tides once spread massive icebergs

December 8, 2004

Connection between changes in ocean circulation and future climate remains a matter of great interest Labrador Sea ocean tides dislodged huge Arctic icebergs thousands of years ago, carrying gigantic ice-rafted debris across ...

Melting of Floating Ice Will Raise Sea Level

August 4, 2005

When ice on land slides into the ocean, it displaces ocean water and causes sea level to rise. People believe that when this floating ice melts, water level doesn’t rise an additional amount because the freshwater ice displaces ...

Sea level rise of 1 meter within 100 years

January 8, 2009

New research indicates that the ocean could rise in the next 100 years to a meter higher than the current sea level - which is three times higher than predictions from the UN's Intergovernmental Panel on Climate Change, IPCC. ...

Greenland and Antarctic ice sheet melting, rate unknown

February 16, 2009

The Greenland and Antarctica ice sheets are melting, but the amounts that will melt and the time it will take are still unknown, according to Richard Alley, Evan Pugh professor of geosciences, Penn State.

Quantifying melting glaciers' effect on ocean currents

May 20, 2011

(PhysOrg.com) -- A team of scientists from Bangor University and the University of Sheffield have used a computer climate model to study how freshwater entering the oceans at the end of ice-ages 140,000 years ago, affected ...

Recommended for you

New study sheds light on end of Snowball Earth period

August 24, 2015

The second ice age during the Cryogenian period was not followed by the sudden and chaotic melting-back of the ice as previously thought, but ended with regular advances and retreats of the ice, according to research published ...

Earth's mineralogy unique in the cosmos

August 26, 2015

New research from a team led by Carnegie's Robert Hazen predicts that Earth has more than 1,500 undiscovered minerals and that the exact mineral diversity of our planet is unique and could not be duplicated anywhere in the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.