School of Earth Sciences - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 56
-
ItemUncertainty in temperature projections reduced using carbon cycle and climate observations(Nature Research, 2013-08-01)The future behaviour of the carbon cycle is a major contributor to uncertainty in temperature projections for the twenty-first century1,2. Using a simplified climate model3, we show that, for a given emission scenario, it is the second most important contributor to this uncertainty after climate sensitivity, followed by aerosol impacts. Historical measurements of carbon dioxide concentrations4 have been used along with global temperature observations5 to help reduce this uncertainty. This results in an increased probability of exceeding a 2 °C global–mean temperature increase by 2100 while reducing the probability of surpassing a 6 °C threshold for non-mitigation scenarios such as the Special Report on Emissions Scenarios A1B and A1FI scenarios6, as compared with projections from the Fourth Assessment Report7 of the Intergovernmental Panel on Climate Change. Climate sensitivity, the response of the carbon cycle and aerosol effects remain highly uncertain but historical observations of temperature and carbon dioxide imply a trade–off between them so that temperature projections are more certain than they would be considering each factor in isolation. As well as pointing out the promise from the formal use of observational constraints in climate projection, this also highlights the need for an holistic view of uncertainty.
-
Item
-
ItemHuman-induced rainfall changes(Nature Research, 2014-08-01)Southwest Australia has become increasingly dry over the past century. Simulations with a high-resolution global climate model show that this trend is linked to greenhouse gas emissions and ozone depletion — and that it is likely to continue.
-
ItemNo Preview AvailableTHE ROLE OF ANTHROPOGENIC FORCING IN THE RECORD 2013 AUSTRALIA-WIDE ANNUAL AND SPRING TEMPERATURES(AMER METEOROLOGICAL SOC, 2014-09)
-
ItemNo Preview AvailableThe Copenhagen Diagnosis(Elsevier Science, 2011)
-
ItemNo Preview AvailableTHE CONTRIBUTION OF ANTHROPOGENIC FORCING TO THE ADELAIDE AND MELBOURNE, AUSTRALIA, HEAT WAVES OF JANUARY 2014(AMER METEOROLOGICAL SOC, 2015-12)
-
ItemNo Preview AvailableNonstationary Australasian Teleconnections and Implications for Paleoclimate Reconstructions(American Meteorological Society, 2013)The stationarity of relationships between local and remote climates is a necessary, yet implicit, assumption underlying many paleoclimate reconstructions. However, the assumption is tenuous for many seasonal relationships between interannual variations in the El Niño–Southern Oscillation (ENSO) and the southern annular mode (SAM) and Australasian precipitation and mean temperatures. Nonstationary statistical relationships between local and remote climates on the 31–71-yr time scale, defined as a change in their strength and/or phase outside that expected from local climate noise, are detected on near-centennial time scales from instrumental data, climate model simulations, and paleoclimate proxies.The relationships between ENSO and SAM and Australasian precipitation were nonstationary at 21%–37% of Australasian stations from 1900 to 2009 and strongly covaried, suggesting common modulation. Control simulations from three coupled climate models produce ENSO-like and SAM-like patterns of variability, but differ in detail to the observed patterns in Australasia. However, the model teleconnections also display nonstationarity, in some cases for over 50% of the domain. Therefore, nonstationary local–remote climatic relationships are inherent in environments regulated by internal variability. The assessments using paleoclimate reconstructions are not robust because of extraneous noise associated with the paleoclimate proxies.Instrumental records provide the only means of calibrating and evaluating regional paleoclimate reconstructions. However, the length of Australasian instrumental observations may be too short to capture the near-centennial-scale variations in local–remote climatic relationships, potentially compromising these reconstructions. The uncertainty surrounding nonstationary teleconnections must be acknowledged and quantified. This should include interpreting nonstationarities in paleoclimate reconstructions using physically based frameworks.
-
ItemNo Preview Available
-
ItemNo Preview AvailableINCREASED LIKELIHOOD OF BRISBANE, AUSTRALIA, G20 HEAT EVENT DUE TO ANTHROPOGENIC CLIMATE CHANGE(AMER METEOROLOGICAL SOC, 2015-12)
-
ItemNo Preview AvailableFuture Australian Severe Thunderstorm Environments. Part II: The Influence of a Strongly Warming Climate on Convective Environments(AMER METEOROLOGICAL SOC, 2014-05)Abstract The influence of a warming climate on the occurrence of severe thunderstorm environments in Australia was explored using two global climate models: Commonwealth Scientific and Industrial Research Organisation Mark, version 3.6 (CSIRO Mk3.6), and the Cubic-Conformal Atmospheric Model (CCAM). These models have previously been evaluated and found to be capable of reproducing a useful climatology for the twentieth-century period (1980–2000). Analyzing the changes between the historical period and high warming climate scenarios for the period 2079–99 has allowed estimation of the potential convective future for the continent. Based on these simulations, significant increases to the frequency of severe thunderstorm environments will likely occur for northern and eastern Australia in a warmed climate. This change is a response to increasing convective available potential energy from higher continental moisture, particularly in proximity to warm sea surface temperatures. Despite decreases to the frequency of environments with high vertical wind shear, it appears unlikely that this will offset increases to thermodynamic energy. The change is most pronounced during the peak of the convective season, increasing its length and the frequency of severe thunderstorm environments therein, particularly over the eastern parts of the continent. The implications of this potential increase are significant, with the overall frequency of potential severe thunderstorm days per year likely to rise over the major population centers of the east coast by 14% for Brisbane, 22% for Melbourne, and 30% for Sydney. The limitations of this approach are then discussed in the context of ways to increase the confidence of predictions of future severe convection.