Despite the strong conclusions of the international and Australian scientific communities there are people yet to be convinced that human-induced climate change is likely to or already having adverse impacts.

Climate scientists tend to focus on what might happen decades into the future based on scenarios of varying future greenhouse gas emissions. However, the starting point can be today, as measured by environmental trends of rising temperatures, longer droughts, depleted water resources, more heatwaves, shifting storm tracks, rising sea levels and more extreme events.

While it is natural to attribute increasingly severe weather-related events to human-induced climate change, science cannot be 100 per cent certain for any individual event. Rigorous science deals in changing probabilities and risk. The science community says the chances are high that increasing greenhouse gas concentrations are at least partly to blame for more extreme conditions.

We can therefore weigh up the costs already being incurred which are likely due at least in part to climate change already experienced.

The present drought in south-eastern Australia has been ongoing since at least 2001.

In September 2007, the total surface water stored in the Murray Darling Basin was only some 2 cubic km, or about 23 per cent of capacity. Cumulative loss of groundwater has been about ten times as much. Even average to above-average rainfall will not restore the situation to non-drought conditions for many years.

This ongoing drought has resulted in low or zero irrigation allocations, leading to serious impacts on irrigation farmers and their communities, including local unemployment and some loss of rural populations. Losses of biodiversity have occurred with the death of river red gums and the drying of wetlands, and dire consequences for the lakes at the Murray mouth including the Coorong.

According to scientists in the joint CSIRO and Bureau of Meteorology Centre for Australian Weather and Climate Research (CAWCR) human-induced climate change is likely to be a major cause of this “drought”. This is due to two factors: decreasing rainfall associated with increasing surface pressure in the region, with the rainfall belt moving further south, and increasing evaporative losses from plants and remaining wet surfaces.

Attribution of this long-term “drought” to human-induced climate change is greatly strengthened by global climate model results that indicate that for a greenhouse-warmed world the rainfall belts in both hemispheres will move poleward. Drying is thus predicted to occur in “Mediterranean-type” climates (climate with winter rainfall maxima) in southern Europe, California, southern Africa and Australia, as has been observed.

As average temperatures rise due to global warming so too does the frequency of extreme high temperatures.

A major heat wave in 2003 is well documented for Europe. There were an estimated 35,000 additional deaths. In 2008 Adelaide experienced a heat wave with 15 days over 35˚C, estimated to have a frequency of 1 in 3000 years based on the past record.  

The southeast Australian heatwave of late January 2009 caused an estimated 374 excess deaths in Victoria according to the Victorian Dept. of Human Services, more than twice the 173 deaths in the bushfires of “Black Saturday”, 7 February, and damaged crops. Adaptive measures could reduce damage or deaths from heat waves, but at some cost.

South-eastern Australia has experienced in the last decade three major outbreaks of widespread bushfires, in 2003, 2006 and 2009. This is unprecedented in recorded Australian history. While individual outbreaks of widespread fire have occurred before (1851, 1898, 1926, 1939, and 1983), never has this happened several times in the one decade. Clearly this is related to the prolonged dry conditions in southeastern Australia which has greatly reduced fuel moisture, increasing fire intensity and spread.

In addition to property and lives lost (in 2003, 530 houses and 4 lives; in 2009, 1800 houses and 173 lives), there are losses of infrastructure, disruption of activities and other costs to the economy (schools, small businesses, farms, tourism, etc.). Losses or changes in natural ecosystems will follow.

Reliable estimates of the total cost of the 2009 bushfires are not yet available, but a preliminary estimate from Allianz Insurance put insured losses at about $1 billion. The Melbourne Age on 28 June 2009 reported total losses at about $1.6 billion and insured losses at some $940 million.

The increasing frequency of so-called “natural disasters”, including coastal storm damage and flooding, has already led to significant coastal erosion, with responses already from insurance companies and local and regional governments.
 
Insurance companies are used to the concept of uncertainty and risk. They manage their risk by adjusting insurance premiums or refusing coverage, especially of damage due to seawater effects. Local and state governments are also learning to reduce their risk of claims of negligence, lack of due diligence, and compensation, as well as acting out of concern for the welfare of their constituents.

The all-party House of Representatives Committee on Climate Change, Water, Environment and the Arts recently released a unanimous and extensive report on management of the coastal zone. It identified the threat to property values, the liability of public authorities and private landowners, responses to possible withdrawal of insurance, and the possibility of governments prohibiting continued occupation of land or future building development on properties due to sea hazard. The report noted that 80 per cent of the Australian population lives in the coastal zone, and some 711,000 addresses are within three kilometres of the coast and less than six metres above sea level.

According to this report, quoting from an Insurance Council of Australia submission, “Preliminary estimates of the value of property in Australia exposed to this risk range from $50 billion to $150 billion. The figure depends upon the extent of sea level rise assumed (in the order of 1 metre to 3 metres) and the effectiveness or otherwise of potential mitigation measures. Even if paid for over 50 years this amounts to a cost to replace these assets of some $1 billion to $3 billion per annum in real terms.”

Similar estimates come from the Department of Climate Change, namely “up to $63 billion of existing residential buildings are potentially at risk of inundation from a 1.1 metre sea-level rise with a lower and upper estimate of risk identified for between 157,000 and 274,000 individual buildings.”

Property owners and developers are already facing new design rules and restrictions such as greater minimum heights above sea level, building design requirements and even portability of dwellings.

Such considerations suggest that many seaside and estuarine property owners who have invested in land or in holiday or full-time residences (especially marina developments) are, or soon will be, facing higher insurance premiums, increased restrictions on development and reduced property values. Some may soon have to “retreat” further from the coast, since defensive measures such as sea walls will in many cases be too costly or prohibited.

Climate change impacts and costs are thus not merely something for future generations to bear, but are being experienced now.  We are committed to large and growing costs arising from the impacts of climate change to date, and a virtual guarantee of rising losses in the near future.

For most people there appear to be two options – leave it to future generations and avoid any cost today or grasp the environmental and economic insight science is offering, by way of impacts, adaptation and renewable energy and sequestering technologies.

In reality, climate change impacts are already costing lives and billions of dollars. These costs will increase rapidly if we do not act to reduce greenhouse gas emissions.

By Barrie Pittock