Global Warming and climate change

The overwhelming and growing scientific consensus is that global warming and climate change is a reality and a direct result of human activity. This is supported by 97% of published peer reviewed science papers. And every year more and more peer-reviewed scientific papers reach the same conclusion, meanwhile the number of papers that disagree have remained tiny in comparison.
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Today, because of excess greenhouse gases in the atmosphere from burning fossil fuels like coal, oil and gas, and from clearing land, the planet’s air and oceans are heating up at a much faster rate than ever before and our oceans are becoming more acidic. Temperature rises can appear small, but small increases translate into big changes for the world’s climate and natural environment.

Australia is particularly vulnerable to a changing climate. While we’ve previously seen natural climate variations and extreme weather such as fire, floods and droughts in Australia, there are some large-scale changes happening now that we can directly attribute to human-induced climate change. These changes include increases in average air and ocean temperature, and sea level rise, and loss of Arctic sea ice.4

Plus certain extreme events (e.g. extreme heat or flooding events) have already become more frequent or intense. We also know that all weather events are now occurring in a global climate system that is warmer and moister than it was 50 years ago, and is warming further, changing the conditions for all weather, including extreme weather.

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For more information about climate change, particularly in Australia, visit:

There is a significant amount of international and Australian research suggesting a trend towards a more extreme climate in the coming decades (noting regional variations and varying levels of certainty with respect to some types of extreme weather).

These changes threaten jobs, agricultural production, water supplies, infrastructure, industries, human lives and, ultimately, the survival of species and entire ecosystems.

Limit warming to well below 2 Degrees

In about 100 years, average surface air temperatures on Earth have already warmed by 0.74 degrees Celcius (°C), and by around 1°C in Australia. The years 2001–2012 were all among the top 13 warmest years on record.

Globally, governments have agreed to limit warming to 2°C above pre-industrial levels, however even a 2°C warming will have significant impact on our economy, health, society and environment. For example large parts of the Great Barrier Reef will be destroyed affecting our tourism industry, jobs and marine life. Our aim should be to limit warming to well below 2°C.

While the global goal is to limit warming to 2°C, a recent report prepared for the World Bank shows that the world is on the path to a 4°C rise by the end of this century, and that current greenhouse gas emission pledges will not reduce this by much.

The report does note that a 4°C rise is not inevitable and that with greater country ambition and action, warming could still be held to 2°C.

Australia can and should do its bit. Australia is an exceptionally large polluter. We are the highest per person carbon polluter among all developed countries the 15th highest overall polluter and our emissions are still rising. As a developed wealthy nation that has benefited from industrialisation, Australia has a responsibility to contribute to reducing global emissions.

 

Impacts

Extreme Weather

Extreme events occur naturally and weather records are broken from time to time. However, climate change is influencing these events and record-breaking weather is becoming far more common around the world. For example, Australia’s summer over 2012 and 2013 has been defined by extreme weather events across much of the continent, including record-breaking heat, severe bushfires, extreme rainfall and damaging flooding.

For more information please read The Climate Commission’s report “Extreme Weather”

Heatwaves – According to the Climate Commission, the duration and frequency of heatwaves in Australia have increased, and the hottest days during a heatwave have become even hotter. A severe heatwave, unusual in length, coverage and severity, affected 70% of Australia in late December 2012 and early January 2013. Temperature records were set in every state and territory and the national average daily temperature reached unprecedented levels. According to the Climate Commission it is virtually certain that extreme hot weather will continue to become even more frequent and severe around the globe, including Australia, over the coming decades.

For more information please read The Climate Commission’s report “Extreme Weather”

Extreme rainfall and drought – According to the Bureau of Meteorology, one of the most consistent results from climate modelling has been the predicted ‘intensification’ of the water cycle in association with global warming, meaning more heavy rainfall and more frequent and severe droughts.

Droughts are likely to become more severe due to rising temperatures and warmer conditions leading to increased drying associated with higher levels of evaporation. Similarly heavy rainfall and flooding is also becoming more severe as higher ocean surface temperatures leads to greater evaporation and because the atmosphere is warmer it can hold more water vapour.

However scientists note that these changes will vary significantly between different parts of Australia and between seasons. According to the Bureau of Meteorology, droughts are expected to become more frequent in southern Australia. For example the Climate Commission has reported that over the last 40 years much of eastern, southern and Southwestern Australia has become drier. Whereas, Northwest Australia has experienced a significant increase in the rate of heavy rainfall events.

For more information please read The Climate Commission’s report “Extreme Weather”

Bushfires – Recent decades have seen an upward trend in the bushfire risk rating across much of Australia. The trend towards drier and warmer conditions on the ground as a result of climate change is projected to increase the risk of bushfires. According to one study, there could be as much as 65 per cent increase in the number of ‘extreme’ fire days by 2020, compared in 1990. The risk is likely to be higher in southeast Australia.

For more information please read The Climate Commission’s report “Extreme Weather”

Cyclones – There is significant uncertainty about whether the intensity and/or frequency of cyclones in Australia have changed in recent decades. Researchers at the CSIRO suggest that climate change projections indicate that globally there will be less tropical cyclones in overall number, but that a greater number of particularly intense cyclones will occur. More intense cyclones could result in higher levels of damage to ecosystems like the Great Barrier Reef, as well as infrastructure, agriculture etc. However more research is required to reduce the levels of uncertainty around these projections.

For more information please read The Climate Commission’s report “Extreme Weather”

Coastal and Oceans

The rise in sea levels is caused by expansion of the oceans due to heat and by the addition of water to the oceans as a result of the melting and discharge of ice from mountain glaciers and ice caps and from the much larger Greenland and Antarctic ice sheets.

Around 85% of Australia’s population is settled along coastlines, often in large cities with extensive infrastructure, making sea-level rise potentially one of the most severe long-term impacts.

According to the CSIRO, the average global sea level rose by 210mm between 1880 and 2009, and is continuing to rise at a fairly steady rate of just over 3mm/year. Researchers believe this rate of rise is contributing to the flooding problems of low-lying island states like Tuvalu, Kiribati and the Maldives.

Impacts of sea-level rise include :

  1. Storm-related flooding. Even small rises in sea level can result in very large increases in the frequency of coastal flooding;
  2. More permanent flooding from higher sea levels;
  3. Erosion of the land on which buildings and infrastructure are built, and of beaches;
  4. Saltwater intrusion into aquifers, deltas and estuaries.

Global warming also has significant impact on our ocean marine life through:

  • increase in water temperature, which causes coral bleaching, interferes with marine animal growth, reproduction, and ability to survive;
  • changes to ocean currents , which effects marine animal distribution, access to food sources and reproduction;  and
  • acidification, which results from more carbon dioxide being absorbed by the ocean, and decreases the production of calcium carbonate which some corals and animals like shell fish, rely on to grow.

According to the authors of the Marine Climate Change: Impacts and Adaptation Report Card for 2012, there is evidence of extensive southward movements of tropical fish and plankton species in southeast Australia, declines in abundance of temperate species, and the first signs of ocean acidification impacts on marine species with shells.

For an easy to understand look at what is happening in our marine world, read the Marine Climate Change: Impacts and Adaptation Report Card for 2012.

Health

According to the Climate Change Commission, climate change is one of the most serious threats to Australians’ health, especially for those in our community who are already most vulnerable.

The risks to human health from climate change include :

  • injuries and fatalities related to heatwaves and other severe weather events;
  • spread of some infectious diseases from rising temperatures and changes in rainfall;
  • water and food contamination from rising temperatures, changes in rainfall patterns and extreme events;
  • respiratory allergies like asthma, which are aggravated from increased allergens (pollens and spores) in the air;
  • exacerbated respiratory and heart diseases in response to increases in some air pollutants;
  • mental health problems in those experiencing physical and economic impacts; and
  • the health consequences of population dislocation as some regions become uninhabitable.

For example, a 2011 report by PricewaterhouseCoopers states that heatwaves kill more Australians than any other natural disasters, and predicts that by 2050 an extreme heat event in Melbourne alone could typically kill over one thousand people in a few days. Very hot days and heatwaves put substantial pressure on our bodies—leading to lethargy, heatstroke, renal (kidney) failure, heart-attacks and even death.

For more information please read The Climate Commission’s report “The Critical Decade Climate Change and Health

Agriculture

Climate variability is not new for most Australian agriculture and many farmers have managed to adapt to a highly variable climate, coping with droughts, heatwaves, frosts, bushfires, and flooding. However, climate change is presenting new challenges for farmers including changing rainfall patterns and increasing risk of extreme heat and bushfire weather.

According to The Climate Commission, water demand and availability will be the most critical factor for future agricultural productivity, especially in irrigation areas. But higher temperatures and changes in the frequency and/or intensity of extremes events such as droughts, floods and bushfires will also be important.

For example, increasing temperatures are likely to have adverse effects on the productivity for beef, dairy, sheep, wool and other livestock industries as a result of increasing the frequency of heat stress which impacts on things like appetite, milk production, growth, reproduction, and mortality.

Fruit, vegetables, including wine grapes are highly sensitive to temperature, including extreme heat, and rainfall changes. As the climate shifts, some crops will not be able to be grown where they are grown now. In southern Australia, France and Germany for example grape harvesting has advanced 8 days per decade.

For more information please read The Climate Commission’s report “The Critical Decade 2013”

Wildlife and Environment

There are many immediate threats on many animals and places, from urbanisation and land clearing, to feral animals and human hunting. But the reality is that unless we act now to significantly cut our carbon pollution, climate change will result in the death of many animals.

Scientists have estimated that a 2°C to 3°C rise in global mean temperature (above pre-industrial temperatures) may see 20-30% of the Earth’s species disappear.

We have already lost the golden toadand the several species of harlequin frogsof Costa Rica, with climate change a key factor.

Animals such as the polar bear, orang-utans, tigers, pandas, marine turtles, Carnaby black cockatoos, black-flanked rock wallaby, are already at risk of extinction. The impacts of climate change will increase this risk. This would be a significant loss to the world and Australia.

Some changes are gradual like the effects of warming ocean or air temperature forcing species to move to cooler areas, which in the case of the critically endangered mountain pygmy possum, don’t exist.

Or changes could occur far more abruptly, driven by an increase in the frequency and intensity of extreme weather events such as bushfires, droughts, cyclones and heatwaves. Extreme events have larger impacts on many species because they test the limits of species’ physiological capacities.

For more information please read The Climate Commission’s report “The Critical Decade 2013”