Climate Change

Conference Presentations:

Climate Change

Introduction

The issue of climate change and sea level rise is well documented, and has been the subject of much research in recent years. The results of this research have contributed to growing acknowledgement and understanding of climate change, but there remains a degree of uncertainty about the magnitude and timing of its impacts. This uncertainty means that governments, industry and communities need to be prepared for a range of future scenarios.

Background

Climate systems are dynamic, reflecting changes across geological, yearly, or seasonal timescales. In recent decades, scientists have expressed concerned about the rate and nature of climate change.

FAQs

What is Climate Change?
What is the Greenhouse Effect?
What is Global Warming?
Will there be changes to the Global Climate?
What does 'climate change' mean in Australia?
What does 'climate change' mean in Tasmania?
What are the Future Projections of Climate Change?

Climate Change Toolkit

Click here to access the Climate Change Toolkit, which offers links to a range of websites, articles, tools and resources to help Councils understand and address the issue of climate change.

Climate Change Consultation - Summary Report

Throughout 2007 the Local Government Association of Tasmania conducted extensive consultation with Tasmanian councils on the issue of climate change. The results of this consultation process have been collated and released as a Summary Report, which can be viewed by clicking here.

What is Climate Change?

Although the term 'climate change' can refer to any variation in climate, weather or atmospheric conditions, in recent times the term has taken on a more specific meaning.

Now when people say 'climate change' they are talking about changes in climate that are a direct result of human activity. It is this human-induced climate change that is often meant by the term 'climate change'.

In the context of environmental policy, 'climate change' is usually applied interchangeably with the terms 'global warming' or 'the greenhouse effect' to refer to human-induced changes in climate.

What is the Greenhouse Effect?

The greenhouse effect is a natural process that sees the Earth's atmosphere insulate the Earth.

Incoming solar radiation (short-wave radiation) is absorbed at the Earth's surface. The Earth's climatic system then redistributes this energy around the globe, through atmospheric and oceanic circulation patterns. Energy is then radiated back from the Earth's surface into the atmosphere as long-wave radiation (see figure 1).

Over time there is an approximate balance in this incoming (short-wave) and outgoing (long-wave) radiation. Changes to this balance, such as changes in the amount of radiation received or lost by the system, or changes to the distribution cycles within the system, can affect climate.

Water vapour and other gases in the atmosphere absorb or reflect some of the incoming (short-wave) radiation and much of the outgoing (long-wave) radiation. This process, known as the "greenhouse effect", regulates the Earth's temperature.

The Theory of Global Warming

Human activities, particularly industrial and post-industrial practices, have lead to an increase in greenhouse gas concentrations in the atmosphere. An increase in greenhouse gases in the Earth's atmosphere means that less long-wave radiation is released into space. Instead, the long-wave radiation is trapped in the atmosphere, and redirected back to Earth, causing a heating at the Earth's surface. This warming of the lower atmosphere and Earth's surface produces changes to the Earth's climate system.

This process has become known as 'global warming' or the 'enhanced greenhouse effect', and is what is often referred to when people talk about 'climate change'.

The Greenhouse Effect

Changes to the Global Climate

With an enhanced greenhouse effect there will be large changes to the global climate.

The global climate system is complex. It includes interconnected sub-systems and processes. The effects of global climate change will be equally complex, with each change in the climate system leading to successive responses and variations. Much of the uncertainty in projecting climate change is in understanding this process of successive responses within parts of the system.

Climate change is already being observed in a range of climate variables, such as: temperature, rainfall, atmospheric moisture, snow cover, land and sea ice, sea level, wind patterns and ocean circulation patterns.

The heating of the Earth's surface and atmosphere affects these climate variables to produce extreme weather and climate events. This may include drought, storm surges, increased wind speeds, increased incidents of cyclones and tropical storms, and changes in the range of these weather events.

These climate variables will show different effects of climate change in different regions of the world. Much of the research on climate change has been done at the global level, and offers projections and modelling of global climate change.

The impact of climate change at the local and regional level will vary over time, and in different places. This further complicates the issue of climate change, particularly for planners and policy makers.

Gradually more research is being undertaken at the regional and local level that can help us understand what climate change will mean for Australia, and even Tasmania.

What does 'climate change' mean in Australia?

The past century has shown an average temperature increase in the Australian continent of approximately 0.7ºC. This includes a greater rate of increase in the last 50 years, with the temperature increase 0.15ºC per decade since 1970. This is in line with rates of average global temperature warming.

The vast size and topographic variability of Australia means that there has been no discernable trend in rainfall since 1910. Projections of future climate change for the Australian region reinforce this, with increases in rainfall expected in some areas and decreases in others.

What does 'climate change' mean in Tasmania?

Changes to the global climate system will be felt differently around the world. Whilst global climate change may reflect increased global temperatures, the re-distribution of extra energy may mean large temperature increases in some regions, and only moderate temperature increases (or even temperature decreases!) in other regions.

The complexity of the global climate system, and the complexity of regional and local (micro) climates mean that it is very difficult to predict the long-term impact of climate change at the local scale.

Broad projections of Tasmania's future climate indicate only a slight increase in minimum and maximum temperatures, with minimum temperatures increasing more than maximum. However, it is anticipated that there will be a greater degree of warming in winter and early spring, with more temperature increases in the east than in the south-west. Overall warming in Tasmania will be less than the Australian and global average.

Whilst the annual rainfall totals for Tasmania are unlikely to change greatly, there will be changes to the seasonal and spatial patterns of rainfall. A decrease in spring, summer and autumn rain is expected in most areas of the state.

Greater wind speeds (particularly during winter, early spring and early summer) and slightly higher temperatures are likely to increase water evaporation.

Future Projections of Climate Change

Understanding climate change is complicated by the multiple variables that contribute to and interact with climate systems. This is even more difficult when trying to project future changes in climate.

To help manage the uncertainty, and better understanding climate change, a range of scenarios have been developed to explain the potential effects that climate change can have on natural and human systems, and the influence that human systems will have on climate change.

More reliable observations of climate, along with improvements to climate models are enhancing our ability to project climate change impacts at the global, regional and local levels.

Global climate models are used to simulate all of the relevant processes that govern climate systems. Future scenarios for the factors that contribute to climate change (such as greenhouse gases and aerosols) are then input. The climate models then produce projections of future climate change based on how the global climate might respond to the new (greenhouse gas) scenarios.