Earlier this month, the Federal Government announced it would “reduce carbon pollution by 25% of 2000 levels by 2020 if the world agrees to an ambitious global deal to stabilise levels of CO2 equivalent in the atmosphere at 450 parts per million or less by 2050”. On the surface, this looks like the move of a “climate friendly” government — an attempt to shift the international negotiations on to a path that will avoid dangerous climate change. A closer examination reveals that it is a political stunt.

The conditions the Government has placed on the 25% target give the game away. Before Australia moves to this target, the international community must agree to stabilise the atmospheric concentration of greenhouse gases at 450 ppm CO2-e “by 2050”. This is virtually impossible.

The atmospheric CO2-e concentration is currently around 460 ppm. Returning it to 450 ppm within 40 years is unrealistic. It would require global CO2 emissions to peak in the next few years and be reduced by approximately 80% on 2000 levels by 2050.

The magnitude of these cuts can be illustrated by assuming that developed countries adopt abatement targets in the order of 25% on 2000 levels by 2020, and 95% below 2000 levels by 2050. These targets are at the upper reaches of the range being contemplated by developed countries (arguably they are beyond it).

If developed countries adopt these targets, it would mean that, at a bare minimum, developing countries would have to stabilise their emissions at current levels by 2020 (i.e. around 35% above 2000 levels), and then be around 80% below 2000 levels by 2050. To put this in context, by 2020 developing country emissions are projected to be at least 80-90% above 2000 levels under business-as-usual conditions.

While some may wish for the world to shift on to these types of emissions trajectories, it does not appear achievable in the current political climate.

A 450 ppm CO2-e outcome might still be achievable but not by 2050. Optimistically it appears the earliest this could occur is in the first half of the next century.

The Garnaut Review apparently agreed with this analysis, as evidenced by the fact that its 450 ppm CO2-e scenario does not result in stabilisation until sometime after 2100. With cuts in global greenhouse gas emissions of 50% on 2001 levels at 2050, the Review’s 450 ppm scenario has the atmospheric concentration at 520 ppm CO2-e in the middle of this century.

The nature of the Garnaut Review’s 450 ppm scenario also exposes another curiosity about the proposed 25% target — the Government has not modeled the economic costs associated with this emissions trajectory. The Government boasts that the economic modelling done on the Carbon Pollution Reduction Scheme was the biggest in Australia’s history. Now it wants the public to believe it is genuinely committed to pursing a national emissions target that it hasn’t modeled.

The Government might argue the economic impact will be similar to that associated with the Garnaut Review’s 450 ppm scenario, which also has a 25% target. But the Government’s 25% scenario is significantly different. The economic impact of a scenario that results in stabilisation by 2050 is likely to differ significantly from one that has stabilisation occurring after 2100.

The question to emerge from this is why would the Government put forward a 25% target that hasn’t been modeled and is based on conditions that cannot be satisfied?

The answer is that the target was designed to do little more than appease certain lobby groups and put pressure on the opposition parties to pass the Government’s emissions trading scheme legislation.

Andrew Macintosh is the Associate Director of the ANU Centre for Climate Law and Policy.