Should average global temperature increase by more than 4 degrees Celsius, one or several parts of the climate system could tip to a new state. Experts' estimates of the probability of tipping vary, and it also remains uncertain by how much global temperature will increase in the future.
But - as the authors report in the Proceedings of the National Academy of Sciences online early edition - these uncertainties do not imply that far-reaching events caused by global warming are unlikely.
An international team of researchers lead by Elmar Kriegler of the Potsdam Institute for Climate Impact Research (PIK) elicited the opinions of 52 climate scientists about the sensitivity of five so-called tipping elements. Tipping elements are parts of the climate system which, through human interference, can change quickly and irreversibly. In the current study the sensitivity of the following tipping elements is evaluated: Atlantic thermohaline circulation, El Niño phenomenon, Amazon rainforest, Greenland, and West Antarctic ice sheets.
43 experts estimated upper and lower bounds for the probability of those elements undergoing dramatic changes, given three different global warming scenarios: a warming by less than 2°C, by 2 - 4°C, or by an extreme of 4 - 8°C until 2200. "Strong global warming of more than 4°C by the year 2200 so far does appear to be a clear possibility", Kriegler says.
The analysis of the survey is now published in the online version of the US American "Proceedings of the National Academy of Sciences". If temperatures were to increase by 2 - 4°C then - so the scientists estimate - at least one element will tip with a one in six chance. If global temperatures were to increase even further then this probability increases to more than one in two (56%). In such a warming scenario the majority of respondents consider the probability of a complete melting of the Greenland ice sheet and a large-scale die-back of the Amazon rainforest to be particularly high. "The results show that the estimated probabilities increase strongly parallel to the progressive scenarios of future warming" Kriegler summarises the expert survey.
The authors write that expert elicitations have occasionally been criticised for not contributing new scientific information as long as they are not backed by new data, modelling or theories. However, in the context of risk analysis such surveys have proven to be a useful tool to summarise expert knowledge for decision makers. "We do not prescribe society specific climate policy measures," says Hans Joachim Schellnhuber, director of PIK, and coauthor of the article. "But the results of the survey provide further evidence for the need of ambitious climate protection in order to minimize the risks of far-reaching consequences for our entire planet."
Reorganization of the Atlantic Thermohaline Circulation: Most of the experts believe that the ocean circulation will remain stable under small future warming. However, if global temperatures were to rise by more than 4°C experts see a significant increase in the probability of a collapse of the existing system of Atlantic circulation.
Increased occurrence of the El-Niño phenomenon and large-scale die-off of the Amazon rainforest: Even if intense warming should occur some experts do not expect any change of the El-Niño phenomenon. Others estimate that El-Niño will become more frequent. The continued existence of the Amazon rainforest depends on these potential changes, because the El-Niño phenomenon causes drought in the Amazon region. In case of increased recurrences of El-Niño models indicate that large parts of the rainforest will die off. Most experts assume a one in two chance for a large-scale die-back of the rainforest in case of warming by more than 4°C.
Complete melting of the Greenland Ice Sheet: Even for a warming by less than 2°C some of the respondents see the risk of a complete melting of the Greenland ice sheet. For a strong increase of global temperature by more than 4°C almost all experts expect a melting of the ice sheet with a high probability of more than one in two.
Disintegration of the West Antarctic ice sheet: There are significant uncertainties in our knowledge about the response of the ice sheet to further warming. Therefore, experts differ in their estimates of the probability of its disintegration. Higher probability estimates may have been motivated by recent findings of acceleration of inland glaciers following the disintegration of ice shelfs on the West Antarctic peninsula.
Article: Elmar Kriegler, Jim W. Hall, Hermann Held, Richard Dawson, and Hans Joachim Schellnhuber (2009). Imprecise probability assessment of tipping points in the climate system. Proceedings of the National Academy of Sciences, Online Early EditionFor further information please contact the PIK press office:
Uta Pohlmann | idw
Novel method for investigating pore geometry in rocks
18.06.2018 | Kyushu University, I2CNER
Decades of satellite monitoring reveal Antarctic ice loss
14.06.2018 | University of Maryland
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
20.06.2018 | Materials Sciences
20.06.2018 | Materials Sciences
20.06.2018 | Materials Sciences