What Is Climate Change?

Climate change describes a change in the average conditions — such as temperature, wind and rainfall — in a region over a long period of time.

Our Earth’s climate has always been changing and adapting, even before humans came into the picture. However, scientists are now finding that the earth is rapidly warming at an unusual pace. The video below demonstrates how quickly the world’s average temperature has increased over the past 30 years compared to previous climatic changes. 

 

  • There are lots of factors that contribute to Earth’s climate. However, human activity has been found to be the main player in the Earth’s increased warming over the past 50 to 100 years, since the industrial revolution.

    Certain gases in Earth’s atmosphere block heat from escaping. This is called the greenhouse effect. These gases keep the Earth warm like the glass in a greenhouse keeps plants warm. Human activities such as burning fuel to power factories, cars and buses are changing this natural greenhouse. 

    The European Project for Ice Coring in Antarctica (EPICA) has provided historic records of CO2 in our atmosphere dating back as far as 800,000 years. The below graphs from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) show atmospheric CO2 concentrations from 800,000 years BC  to 1 BC, and for the last 2017 years AD. These changes cause the atmosphere to trap more heat than it used to, leading to a warmer Earth. 

    Graph 1 - Co2 Concentrations

     

    Source: CSIRO

    The below graph shows the factors that have contributed to major changes in the global carbon budget from 1870 to 2016. On the left we can see the sources of increasing carbon dioxide in our atmosphere, these are oil, coal, gas, cement and land use change.  There are some “sinks” that counter off these increases. These are labeled as ocean or land sinks, which absorb carbon dioxide. The end result is an increase in carbon dioxide levels from 288ppm in 1870 to 403ppm in 2016.  There is an imbalance which represents a gap in understanding and estimates. Visit CSIRO for more information.

    Graph 2

     

    Source: CSIRO

  • Half a degree may be the difference between a world with coral reefs and Arctic summer sea ice and a world without them. The below diagram from the special IPCC report highlights the difference an extra half a degree can make by 2050.  

    Half a degree

     

    Source: Cool Earth

  • RCP stands for ‘Representative Concentration Pathway'.

    RCPs try to capture future trends in our climate. They make predictions of how concentrations of greenhouse gases in the atmosphere will change in future as a result of human activities. So, to understand how our climate may change in the future we need to predict how we will behave. Will we continue to burn fossil fuels or will we have made the switch to renewable energy? Will we keep having 1.9 babies per couple or will population growth decline? Will industries remain carbon intensive?  

    The answers to these questions will determine whether concentrations of greenhouse gases in the future will be high or will start to decline. Currently human activities are emitting 42 billion tonnes of carbon dioxide into the atmosphere each year.  The four RCPs attempt to capture future trends - they range from very high (RCP8.5) through to very low (RCP2.6) - and allow scientists to model climate change, build scenarios and plan for a positive future.

    Check out a visual explanation on Coast Adapt's website.

    If the high concentration scenario is followed (which is where we currently are tracking), Australia could warm by as much as 2.8°C to 5.1°C (above the climate of 1986-2005) by 2090. This level of warming is slightly higher than the global average warming of 2.6°C to 4.8°C, estimated by the Intergovernmental Panel on Climate Change (IPCC) in its Fifth Assessment Report. 

  • Let's break it down:

    •   Climate affects our ecosystems.

    •   Climate impacts our communities.

    •   Climate defines economies.

    Climate and our ecosystems

    Australia’s complex and beautiful ecosystems respond and adapt to the climates they experience. Therefore, any changes in climate will lead to changes in these ecosystems. 

    Wave energy, tidal range, sea level rise, altered rainfall, extreme weather, increased atmospheric carbon dioxide and higher water temperature can significantly alter our forests, coasts and reefs.

    Our coastal ecosystems are being affected:

    Australia’s coastline includes a diverse range of coastal ecosystems; marine, estuarine, coastal interface, terrestrial and freshwater environments. Climate change, is already altering our coastlines and if not mitigated and managed, will directly affect the safety and longevity of our coastal ecosystems and their communities

    • As things heat up, our coastal ecosystems struggle to adjust:

    • Sea level rise is pushing our coastal ecosystems landward.  In developed areas we are seeing beaches and other coastal ecosystems lost as hard infrastructure is built to save property. Some plants can’t retreat as quickly as the sea level is rising.  

    • Increased temperatures cause heat stress to plants and animals which can affect survival, growth and reproduction. 

    •  Many species will move southwards or upwards in response to rising temperatures. However, the food sources or habitats they need may not exist within their shifting climatic range.  

    • A change in biodiversity will cause big changes in our ecosystems

    • Lots of corals on our reef are not able to  survive small temperature increases ( 1-2 degrees) and many have already experienced unprecedented bleaching and die off.

    • Significant declines of giant kelp off the eastern and southern coasts of Australia have been linked to rising sea temperatures. In fact, there is only a small percentage of kelp left in our seas.

     

    Climate and communities

    Australia’s climate has shaped the location of the communities that we see dotted across our map today. We have built homes and grown businesses in areas with abundant water availability, favourable climate and accessibility.

    As the climate rapidly changes and becomes increasingly unpredictable, past understanding of weather extremes can no longer be used as a guide to the future, putting our communities at higher risk.

    An understanding of our variable climate, including weather extremes, is already written into planning and building regulations but, moving forwards, considering increased climate risk, these will need to be flexible and evolve over time to keep our communities safe. 

    An increase in hotter days could lead to poor health and deaths within our communities, particularly amongst the vulnerable population. Climate change will also alter disease (types and patterns) and how they spread throughout our community. 

     

    Climate and economies

    The climate has a leading influence on economies; as the climate changes it could put financial risk and strain on many industries, businesses and individuals:

    Industries: The productivity of many coastal industries, such as fisheries, are linked to climate factors such as sea surface temperatures and patterns in coastal currents. 

    Infrastructure: Climate is a key factor in the design, location and operation of infrastructure that supports economic activity. 

    Insurance: Climate risk, including extreme weather, is a key determinant of the affordability and availability of insurance cover. 

    Tourism: Australia’s coast is one of the major drivers of our thriving tourism industry. The Great Barrier Reef alone receives around 2.3 million international and 1.8 million domestic visitors every year. 

    Transition: As we adapt to climate change and move towards low carbon economies via introduction of carbon pricing, energy storage advancements and changing customer preferences for low-carbon products our economies will benefit from opportunities, become more diverse and more resilient.