A PWF reader has sent us ‘a succinct piece of science based on data measurements, not modelling’ produced by the BOM and CSIRO(pdf).
The following info comes from peer reviewed data on temperature, rainfall, sea level, ocean acidification and carbon dioxide and methane levels in our atmosphere. The key points are listed and maps/charts can be viewed on the pdf file.
TREND IN MEAN TEMPERATURE 1960 – 2009
1. All of Australia has experienced warming over the past 50 years.
2. Some areas have experienced warming since 1960 of up to 0.4 degrees C. per decade, resulting in total warming over the five decades of 1.5 – 2 degrees C.
RECORD OF HOT DAY MAXIMUMS AT AUSTRALIAN CLIMATE REFERENCE STATIONS
1. The number of days with record hot day maximums has increased each decade over the past 50 years
2. There have been fewer record cold days each decade
3. 2000 – 2009 was Australia’s warmest decade on record
TREND IN ANNUAL RAINFALL 1969 – 2009
1. Trend over five decades of increasing rainfall in many parts of northern and central Australia
2. Trend over five decades of rainfall decreasing across much of southern and eastern Australia
RISING GLOBAL MEAN SEA LEVEL
1. The rate of sea level rise increased during the twentieth century
2. During 1993 – 2009 the sea level rise has been 1.5 to 3mm per year in the south and east of Australia and 7 to 10mm in the north and west
ANNUAL AND TEN YEAR MEAN SEA SURFACE TEMPERATURE FOR THE AUSTRALIAN REGION
Sea surface temperatures around Australia have increased 0.4 degrees C. in the past 50 years
The world’s oceans currently absorb about 25 per cent of the carbon dioxide generated by humans – about 40 per cent of this is absorbed in the Southern Ocean. The CO2 absorbed by the ocean makes the ocean more acidic. Recent research shows that ocean acidification decreases the ability of marine plants and animals to form shells. Such effects are now being observed at the base of the food chain in the Southern Ocean. This has far-reaching implications for the health of ocean eco-systems around the world.
Global greenhouse gases such as carbon dioxide and methane in the atmosphere have risen rapidly over the last century.
CARBON DIOXIDE CONCENTRATIONS MEASURED AT CAPE GRIM, TASMANIA
The Cape Grim baseline air pollution station operated jointly by CSIRO and the Bureau of Meteorology in north-western Tasmania provides vital information about changes to the atmosphere in the southern hemisphere. This chart shows the increase in CO2 concentrations measured at Cape Grim over the past 35 years.
Australia will be hotter in the coming decades
Australian average temperatures are projected to rise by 0.6 degrees C. by 2030. If global greenhouse gas emissions continue at current levels, warming is predicted to be in the range of 2.2 to 5.0 degreesC. by 2070. Warming is projected to be lower near the coast and in Tasmania and higher in central and north-western Australia. These changes will be felt through an increase in the number of hot days.
Much of Australia will be drier in coming decades
In Australia compared to the period 1981-2000, decreases are likely in the decades to come in southern areas of Australia during winter, in southern and eastern areas during spring, and in south-west Western Australia during autumn. An increase in the number of dry days is expected across the country, but it is likely that there will be an increase in intense rainfall in many areas.
It is very likely that human activities have caused most of the global warming observed since 1950
There is greater than 90% certainty that increases in greenhouse gas emissions have caused most of the global warming since the mid-20th century. International research shows that it is extremely unlikely that the observed warming could be explained by natural causes alone. Evidence of human influence has been detected in ocean warming, sea-level rise, continental-average temperatures, temperature extremes and wind patterns. CSIRO research shows that higher greenhouse gas levels are likely to have caused about half of the winter rainfall reduction in south-west western Australia.
Climate change is real
Our observations clearly demonstrate that climate change is real. CSIRO and the Bureau of meteorology will continue to provide observations and research so that Australia’s responses are underpinned by science of the highest quality.
You can go to www.csiro.au for the brochure ‘The Science of Climate Change’ and web page ‘Climate Questions and Answers’ and other information about adaptation and mitigation.
Telephone 1300 363 400