Energy Futures for Australia

Project 2.1

Background

The climate of the Earth has warmed by about 0.7oC over the past century, and particularly through the last few decades (Figure 1). It is now the view of mainstream science that the substantive cause of the warming has been the accumulation of greenhouse gases in the atmosphere, with most of the change being in carbon dioxide concentrations. These increased concentrations are the result of a variety of human interventions, of which the most important are the combustion of carbon-based fuels, coals, oil and gas, from which the world community derives a very large proportion of its energy, and land-use change. Thus future climate change, the means of energy production and usage, and land use change are deeply entwined.

In the last five years, there has been an explosion of scientific publications that now relate this general warming trend to changes in the character of climate around the world, rainfall amount and seasonality, storm intensity and coastal impacts, biological responses such as plant and animal distributions, seasonal behaviour such as flowering, breeding and migration, and consequential human impacts on insurance, infrastructure damage, health, etc.

In Australia and New Zealand, ecosystems in which changes related to the climate have been observed include semi-arid woodlands, Eucalypt savannas, rain forest/woodland, subalpine, mangroves and coral reefs. The genera in which change has been observed include birds, Antarctic beech, mammals, insects (including genetic changes), sea urchins, marine mammals, fish, and invasive species. The behaviour of plants and animals observed to change include flowering phenology, earlier migration and egg laying and seed production.

Figure 1. Average temperature at the Earth’s surface. Source: http://www.cru.uea.ac.uk/cru/info/warming/

Work by CSIRO and others indicates that through this century temperate-zone Australia may experience warming from 1990 of 0.7 to 5.0ºC by 2070, with an accompanying increase in the frequency of extreme higher temperatures (up to 3 times as many days per year over 35ºC) and decrease in frequency of minimum temperatures below 0ºC. This is expected to affect: plant growth and life cycles, such as seed setting and flowering, animal species through health and food resources; human well being as a result of increased disease vectors; fire risk; stress on ecosystems of tourism and ecological value; and the scale and pattern of energy use.

Areas critically important to Australia’s agricultural, horticultural and livestock production can also expect generally lower rainfall and, coupled with higher temperatures, a reduction in soil moisture. This may reduce agricultural productivity, and impact on the water supply needed to balance energy and potable water supplies, environmental stream flow and agricultural usage. Water security may turn out to be a key climate risk along with changes to biodiversity and agricultural production, fire risk and tourism impacts.

Thus there is an early indication that we can anticipate widespread impacts of further climate change through this century with effects to be felt as early as the next decade or so. The complexity of these impacts and remaining uncertainty makes evaluation of both the social and economic impacts of such changes difficult. We urgently need to build on studies of these impacts to establish an assessment of how such changes will impact on social and economic futures.

The key question for Australia and indeed the rest of the world is not how much will the climate change, but how much change to the climate represents an acceptable risk? This is a difficult question to answer, for what is an acceptable risk from a particular global warming depends on how that warming manifests in regional change and the capacity of societies regionally to cope.

Globally, there is a growing consensus, both scientifically and politically, that a warming through this century of about 2oC may involve unacceptable ecological and economic risk. Even a temperature rise of 2oC already commits the Earth to significant climate change and associated ecological, economic and social risk. This is not widely understood as very few in the community appreciate that global annual average temperatures do not vary from year to year by any more than a few tenths of a degree. Indeed warming that took place from the last ice age, 25,000 years ago, when sea levels were 80 m lower, ice and snow covered half of the Earth, and the ecosystems around the world were totally different, to the present state was only about 5oC. Climatologists therefore see this 2oC change in this context; that is, we will experience in this century 40% of this historically observed and understood change since the last ice age.

In order to mitigate the currently understood risks attendant upon global warming the International Panel on Climate Change has indicated the need for the world community to achieve cuts of around 80% on 1990 global emissions over the course of the 21st century. As an interim target we believe that Australia would be wise to plan to reduce its emissions by of the order of 60% by 2050.

Much has been written about aspects of the climate change problem, but nowhere has an attempt been made to develop an analysis that brings to together all of the issues that need to be considered in formulating a policy framework that can be implemented at acceptable cost.