Australian Archaeology 34:29-33 CLIMATE CHANGE, SEA-LEVEL RISE AND THE ARCHAEOLOGICAL RECORD M.J. Rowland There is an urgent need for heritage researchers and managers to address the issue of climate change and its impact on archaeological sites. Yet, it was apparent from discussions at the Australian Archaeological Asso- ciation's annual conference at Townsville in 1990 and a recent workshop in Canberra initiated by the Depart- ment of the Arts, Sport the Environment and Territories (DASET) (May 1991) that few heritage researchers are fully conversant with greenhouse issues, and that the process of discussion has only just begun. The DASET workshop will result in a publication outlining a range of potential climate change impacts on heritage resources and a strategy for dealing with these. As a contribution to these discussions this paper attempts to provide an introduction to greenhouse literature and issues, and in particular outlines some of the potential impacts of greenhouse effects on Aboriginal coastal sites. Green- house impacts need to be considered in the context of other ongoing impacts and these will be addressed in an upcoming review of coastal sites in Queensland. THE GREENHOUSE EFFECT The greenhouse effect is a natural phenomenon in which gases within the earth's atmosphere trap some of the warming energy of the sun. Without this 'blanket' of gases the earth's temperature would be ca 33°C lower than it is and too cold for life. However over the last several decades humans have increased the amount of these gases, particularly carbon dioxide (C02), methane (CH4), nitrous oxide (N20) and added a new family of gases - chloroflurocarbons (CFCs) , resulting in an enhanced greenhouse effect. This increase in gases has arguably lead to an increase in world temperatures, acid rain, ozone depletion, changing climates and rising seas. A potential enhanced greenhouse effect was recognised as long ago as the 1 850s (Christie 1 990; Grove 1 99O), while ironically in the 1960s and 1970s evidence was being gathered which suggested evidence of planetary cooling and debate centred around the question of whether or not the world was heading toward a new ice age (Pearman 1 988). Nevertheless the mid-1 970s and early 1980s saw a rapid increase in the volume of evidence and research indicating global warming. Literature relating to the enhanced greenhouse effect is both voluminous and complex and it is sometimes diffi- cult for the layman to separate the 'hard' from the 'soft' scientific data. The media has shortened, simplified and sensationalised the evidence and deatt with worst case scenarios (Pittock and Pearman 1989). The review pre- sented below is only a brief outline of some of the more reliable literature. A seminal meeting in the climate change debate held at Villach, Austria in 1985 (Bolin et al 1986) concluded that by 2030 world temperatures would have risen by be- tween 1.5 and 4.5"C and that by 2050 sea-levels would also have risen by between 20 and 140 cm as a result of melting of land-based ice and thermal expansion of the ocean. The potential flooding of low-lying land and river deltas, movement of saltwater into fresh water aquifers and surging seas causing erosion were high- lighted as potential impacts. A major meeting organised in Australia to discuss these issues found support for changes at the lower end of the temperature and sea- level range of scenarios (Pearman 1988). The most recent and influential publications on climate change (and the ones to which archaeologists might refer) are the three summaries produced by the Inter- governmental Panel on Climate Change (IPCC). These documents suggest that given business-as-usual condi- tions (ie no control over emissions of greenhouse gases), global temperature will rise at about 0.3"C per decade (uncertainty range 0.2"C to 0.5OC) resulting in a global mean temperature of about 1 "C above present by 2025 and 3°C by 2100. Control of emissions might reducethis by 0.1-0.2"C per decade. Sea-levelswill rise about 6 cm per decade (uncertainty range 3-10 cm) resulting in a rise of about 20 cm by 2030 and 65 cm by 2100. Again this will be reduced by emission controls. It is recognised that regional climatic impacts will be vari- able. Given the above figures a possible scenario for Austra- lia's climate in 2030 is as follows: Temperature - Annual mean temperature will in- crease 1-2°C in northern coastal areas, 1-3°C in southern coastal areas and 2-4°C in the interior.