Palaeoclimate Consortium

Since the 1960s, scientific understanding of our global environment and its climate has undergone a remarkable transformation. We are now increasingly aware that the world around us is dynamic, and quasi-stable only in the short-term. Recognizing the challenge of human-induced climate change, the Intergovernmental Panel on Climate Change (IPCC) was established in 1988 and released its most recent Fourth Assessment Report (AR4) in 2007. The AR4 conclusions are startling: by 2100 global temperatures are estimated to increase between 1° and 6.5°C compared to 1990, accompanied by a sea level rise of between 0.18 and 0.58 metres. This relatively large range in projections is partly due to chaotic climate variability and to uncertainties in emissions but another significant factor is the paucity of instrumental data with which to test them; published records only allow a robust reconstruction of global temperature back to 1850 but appear to show a ‘gradual’ warming trend of around 0.8°C with an associated sea level rise of 0.18 metres. A major source of concern is the extent to which the historical record captures processes representative of future change, specifically whether one or more components of the climate system may pass a threshold in the future, resulting in them operating in an extreme different state (perhaps irreversibly).

A wealth of geological, chemical, and biological records (so-called ‘natural archives’ or ‘palaeo’), clearly indicate large-scale and abrupt shifts in the climate system took place prior to the historical record. The forcing associated with these changes appear to have been relatively small, implying the associated thresholds (often described as ‘tipping points’) are considerably smaller than generally supposed. When and where these tipping points in the climate system may be reached is an area of great uncertainty. By extending historical records, palaeoclimate data can provide critical insights into external and internal forcing of the climate system, thereby reducing uncertainties in predictions for the region.

Australia is a country distinguished by lack of water, and high interannual climate variability but where historical records only extend back to 1880. The region is potentially highly-sensitive to abrupt changes caused by the passing of tipping points within different components of the climate system.  For instance, the El Niño-Southern Oscillation (ENSO) and changes in the location of the Intertropical Convergence Zone (ITCZ) strongly influences the distribution, timing and intensity of rainfall across large parts of the continent and their future behaviour in a warming world remains unclear. Further south, while climate models predict that subtropical regions will expand with an increase in global temperatures, bringing more arid conditions to heavily populated areas, recent trends indicate an expansion of the same order of magnitude as that predicted for the end of this century (5° to 8°), resulting a ~20% reduction in winter rainfall over the southwest of Western Australia and costing more than $500 million in the development of new water sources. In high latitudes, the region south of 45°S has the potential to have extra-regional impacts: a collapse of the West Antarctic Ice Sheet (WAIS) would lead to a global sea level rise of several metres; while movements in the location and intensity of westerly airflow over the Southern Ocean may change the balance of the region from a greenhouse gas sink to a source (most notably carbon dioxide, CO2), amplifying the effects of global warming. The extent to which increasing aridity, greater variability, carbon feedbacks and rising sea levels will impact Australia are some of the most challenging problems facing the nation today.

The Palaeoclimate Consortium is a new national collaborative program of research which aims to plug this key knowledge gap. By investigating abrupt change as recorded in ice, marine and terrestrial sequences, the Consortium seeks to integrate these with high-precision dating and state-of-the-art climate modelling to better understand the mechanisms and impacts of past change on annual to centennial-timescales, thereby reducing the uncertainty of projections. Members of the Palaeoclimate Consortium work together closely on common periods of time during which abrupt change took place in the recent geological record. Researchers are drawn from leading research institutions and universities across Australia, including:

Co-ordinator

Modelling

Ice

Marine

Terrestrial

Impacts