by Staff Writers
Stockholm, Sweden (SPX) Jul 12, 2017
Accounting for a vegetated and less dusty Sahara reduces the variability of El Nino during the Mid-Holocene to closer to that which is observed in several paleoclimate records. This is shown by researchers at the Department of Meteorology at Stockholm University in a recent study, published in Nature Communications.
Changes in the El Nino Southern Oscillation (ENSO) - an important driver of large-scale climate variability - have broad impacts on society and eco-systems globally. Both observations and model simulations suggest that with the current trend in global warming, we may see changes in ENSO behaviour. Understanding how ENSO has varied historically and the causes of this variability is paramount for predicting the future.
Many paleoclimate records from the warm Mid-Holocene (4,000 - 7,000 yrs BP) show that variations in ENSO were reduced by 30%-60% compared to pre-industrial times. This is not accurately captured by most climate models, which show a modest reduction of 10% using only changes in the Earth's orbital parameters.
Our study accounts for a vegetated and less dusty Sahara. This reduces the variability of the Mid-Holocene ENSO with up to 25% compared to the pre-industrial, more than twice the decrease found by using orbital forcings alone, says Francesco S.R. Pausata, researcher at the Department of Meteorology at Stockholm University (MISU).
In the study four model simulations with varying forcings were compared, from using orbital parameter changes alone to a simulation that included orbital forcings, added vegetation and reduced dust emissions. The researchers found a tight link between the intensity of the climatological West African Monsoon, the strength and position of the Walker circulation and the variability of ENSO.
The results of the study show that the strengthening of the West African Monsoon, associated with the greening of the Sahara, alters the tropical Atlantic mean state and variability. This in turn affects ENSO activity through changes in the Walker circulation, explains Francesco S.R. Pausata.
Therefore, vegetation and dust feedbacks are important players in amplifying ENSO's response to insolation forcing.
More proxy records from both the Pacific and the Atlantic Ocean are critically needed to capture the natural variability of ENSO and its teleconnections with the Atlantic basin. These will provide a better understanding of the ENSO spatio-temporal characteristics through time. Together with improved model simulations that account for vegetation and dust changes, this will improve our prediction of future climate change, Francesco S.R. Pausata concludes.
Suva, Fiji (AFP) June 2, 2017
The head of upcoming UN climate talks vowed Friday that the fight against global warming would continue despite Washington's "unfortunate" decision to abandon the Paris climate deal. Fiji Prime Minister Voreqe Bainimarama, who will serve as president of the COP 23 talks in Germany later this year, labelled the US move "deeply disappointing". "While the loss of America's leadership is unf ... read more
Water News - Science, Technology and Politics
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|