By Dimity Williams Dimity Williams attended the Four Degrees conference as a Doctors for the Environment Australia member (and CAHA member) and shares main messages here. The presentations are at http://www.fourdegrees2011.com.au/ "It was an excellent conference with international speakers updating attendees on the latest climate science and coincided with the release of the government's carbon tax package. The premise of the conference was to describe the 4 degree world our politicians are planning for and in so doing motivate us for mitigation. In this they certainly succeeded as the science is very grim. Key messages for me were:

• Australia is the most vulnerable continent to climate change impacts
• The current CO2 concentration is 392 ppm (pre-industrial 280); the current level of warming is one degree above pre-industrial levels
• There is an enormous disconnect between the international agreement to limit global warming to 2 degrees (450ppm) and the current policies which see us (with a fossil fuel intensive model) reaching 4 degrees warming by 2070 - and hence 8 degrees by 2300. No human life at this temperature.
• We need to peak global emissions by 2020 to have a 2/3 chance of limiting warming to 2 degrees
• Global damage is a highly non-linear function of global warming ie. once certain tipping points are crossed there is no way to reverse them and a cascade starts ie. the Greenland ice sheet loss may be triggered at 1.5-2.5 degrees
• Preliminary evidence suggests that once global temperature is over 5 degrees it will rapidly accelerate above 10 degrees
• This is the CRITICAL DECADE for action to avert dire climate change; a strong mitigation future is technologically and economically feasible but is it politically feasible?

All speakers can now be heard on the conference website and I highly recommend you spend some time listening for yourself. See link: http://www.fourdegrees2011.com.au/ Excellent sessions were: Session 4- Australia at 4 degrees Excellent discussion of heat waves and El Nino impacts recently by CSIRO /BOM scientists Session 5- Australian Biodiversity impacts Australia has 7-10% of global biodiversity; we are the most vulnerable continent because we are flat and have nutrient poor soil. This means that species migration is especially great ie. with one degree warming, species need to move 100m altitudinally and 125km south; this is difficult as many of our rivers run east-west

• Australia currently has the highest mammal extinction rate in the world. For every 1 degree of warming 100-500 species of bird will become extinct. Ecosystems can only withstand <0.1 degree temperature increase per decade (current rate 0.13deg C; 0.46 at higher latitudes)
• In addition to mitigation, the answer here is to protect more land, restore some of what's lost and understand that landscape level management is more important than individual species ie. protect ecosystems

Session 6- Australian Marine impacts

• Oceans maintain climate by absorbing CO2, generating O2 through marine plants and absorbing heat. They also supply our food and generate income through tourism and food supply
• Impacts due to climate change include warming, acidification and a reduction in oxygen content
• The Great Barrier Reef (GBR) generates $6 billion/year and employs 63,000 people- second largest employer in QLD. GBR is the most biodiverse ecosystem in Australia and is especially vulnerable to global warming as we see mass coral bleaching and acidification of the ocean
• 80% world's coral reefs are at risk of disappearance at 1.5 degrees warming
• Coral reef safety threshold crossed at the latest at 336ppm in 1979
• As the ocean has warmed, species have migrated south, today at 1 degree of warming marine organisms have moved 100km south and there is 50% less coral cover now than 50yrs ago
• By 2030 we can expect annual mass coral bleaching- the reef does not always recover from this ie. most pacific reefs bleached in 1998 have not recovered.

Session 9- Health impacts by Professor Tony Mc Michael The issue is not adaptation to 4 degrees of warming as this will not be possible- the need is to strengthen our resolve to mitigation

• Australia's lack of action on climate change is causing thousands of deaths in the third world
• Causal paths for health impacts are:

1. Environmental health hazards, 'exposures'- extreme temperatures and extreme weather events; increased concentrations of air pollutants and aeroallergans 2. Loss of and change in environmental functions 'services' - lower food yields, reduced fresh water, change to natural constraints to infection, reduction in nature's buffers ie. forests and reefs, psychological effects Tony asked "What do economists eat?" We don't just catch fish to sell them as a commodity; we catch them as a food source to maintain our health. Session 15- Mitigation- Can we? An excellent solutions-focussed session. I especially enjoyed the presentation from Anna Skarbek from CLIMATEWORKS whose answer was clearly 'Yes we can! There was also an address by Greg Combet, Minister for Climate Change and Ross Garnaut discussing the carbon tax package. Next steps I personally would prefer to attend a conference where we talk about limiting global warming to 1.5 degrees as 2 degrees sees us accepting the loss of entire countries (ie. Maldives, Pacific islands etc) and I wonder if the scientific community is allowing itself to have its parameters set by the political agenda? I would also like to see some research focus on mitigation rather than just the adaptation focus of the NCCARF and a place for science and health experts not just economists on key advisory groups like the Climate Change Authority."