Background: Climate Change

Climate change is the most significant environmental challenge facing governments and communities around the world. This challenge will require the ACT Government and community to adapt to a changing environment and undertake preventative actions to build resilience and minimise impacts on our natural and urban environments. In recognition of the need for urgent action, the ACT Government declared a state of climate emergency in May 2019.

Climate change is caused by increases in the amounts of greenhouse gases and aerosols in the Earth’s atmosphere. The majority of greenhouse gases come from the burning of fossil fuels, which release carbon dioxide gas to the atmosphere. Climate change is a global challenge with all greenhouse gas emissions, regardless of source and location, contributing to the total atmospheric concentrations which drive local climatic conditions. This means that greenhouse gas emissions from the ACT have an impact on the global environment, not just the local region.

Greenhouse gas emissions are exacerbated by population growth and a range of human activities, including those that drive energy and resource demand and land clearing, which reduce the uptake of carbon dioxide. Consequently, government and community actions are fundamental to reducing emissions including minimising vehicle use, cutting back the consumption of goods, choosing products that are better for the environment, and improving recycling and reuse.

Whilst many climate change impacts are inevitable given the existing levels of greenhouse gases in the atmosphere, it is vital to reduce emissions to minimise the severity of climate change for the generations to come. The future impacts of climate change will depend on the degree to which we can mitigate greenhouse gas emissions today.

It is important to understand the drivers and impacts of climate change in order to develop strategies that address the risks they pose. Building resilience in the social and environmental systems of the ACT is a core part of achieving this, as it allows us to focus on maintaining the desired values of the ACT’s environment despite the effects of climate change.

Advice from the international scientific community is that if we are to avoid the most catastrophic effects of climate change, the increase in average global temperature must not exceed 2 °C above pre-industrial levels.^[1] Beyond 2 °C warming there is a risk that the climate system will pass an irreversible tipping point, beyond which the task of stabilising global warming becomes impossible. This would mean an increasingly extreme and unpredictable global climate.

For more, see Expert Commentary – The State of Canberra’s Climate.

Impacts of climate change on the ACT

Climate change has significant natural, social and economic repercussions for the ACT driven by increased temperatures, decreased rainfall, and the greater risk of extreme weather events and fire. These have severe consequences for ecosystem health and biodiversity, aquatic ecosystems, ecosystem services, and human health and wellbeing.

The broad impacts that climate change has on the ACT region are well known. These impacts are shown in the infographics below as they relate to biodiversity and ecosystem health, the urban environment, and primary production.

Impacts on the ACT community

Recent research has found that one-third of the Canberra community have low or very low resilience to climate change and are highly vulnerable to the likely negative impacts.^[2] Resilience was generally linked to income levels with low-income community members being the most vulnerable. This was particularly the case for heat where 36% of people live in homes that perform poorly in heatwaves. The study also found that nearly 40% of Canberrans have low resilience to extreme weather events due to lack of preparedness.

Climate change has also been shown to have a significant impact on medical costs and the economy. A study of the Adelaide community’s response to hot weather found that for every degree above the threshold of 33^oC, medical costs increased by over 40% and lost work days by nearly 75%.^[3]

Benefits of urban trees

Urban trees are key for the Canberra community’s climate change resilience. They provide many benefits including:

• climate regulation through shading and cooling
• decreased heat impacts
• reduced energy consumption for home cooling
• CO₂ uptake
• reduction of dust, pollution, wind and UV radiation
• management of storm water run-off, and
• support for biodiversity by providing habitat and refuge on hot days.

For more, see Cooling Our City: Trees and Urban Heat. 

Climate drivers

The ACT’s climate is determined by atmospheric conditions and sea-surface temperatures. The main drivers of natural climate variability include (but are not limited to) the El Niño–Southern Oscillation (including La Niña cycles), the Indian Ocean Dipole, and the Southern Annular Mode which influence climate across south-eastern Australia. Changes in the frequency and duration of these drivers cause year-to-year variations in temperature and rainfall.

This natural climate variability is now significantly influenced by human-induced climate change. Evidence of global and regional warming caused by greenhouse gas emissions is incontrovertible.

Greenhouse gas emissions

Greenhouse gas emissions from human activity have increased since the pre-industrial era, mainly through the combustion of fossil fuels and widespread land clearing, with emissions now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the past 800,000 years. The high atmospheric concentrations of these gases have been the dominant cause of the observed changes to climate conditions since the mid-20th century.

Global efforts through the United Nations Framework Convention on Climate Change, including the Paris Agreement, aim to keep the global average temperature increase to well below 2 °C and to pursue efforts to keep warming to below 1.5 °C. Achieving this target will require a significant cut in global greenhouse gas emissions. This is dependent on both regional and local actions to reduce emissions. Whilst the ACT’s emissions are only a fraction of that produced globally, the effect of cumulative reductions from local actions across the world will make substantial contributions to minimising the severity of climate change in the future.

The ACT Government has legislated greenhouse gas emissions reduction targets under the Climate Change and Greenhouse Gas Reduction Act 2010. The legislated targets are for percentage reductions from 1990 levels and include:

• 50% to 60% reduction by 2025
• 65% to 75% reduction by 2030
• 90% to 95% reduction by 2040, and
• net zero emissions by 2045.

Greenhouse gas types and sources

The majority of greenhouse gas emissions come from energy, transport and industry. Those emitted by human activities and measured in the ACT are:

• carbon dioxide from burning fossil fuels (coal, natural gas and oil), solid waste, trees and wood products, and also as a result of certain chemical reactions (such as the manufacture of cement).
• methane emitted during the production and transport of coal, natural gas and oil, livestock and other agricultural practices, and from organic waste decay in municipal solid-waste landfills.
• nitrous oxide from the combustion of fossil fuels and solid waste, and also from agricultural and industrial activities, and
• fluorinated gases, including hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride and nitrogen trifluoride, which are synthetic gases that are emitted from a variety of industrial processes.