Yesterday, Bill Shorten’s repeated failure to come clean on the cost of Labor’s economy-wrecking emissions target was finally explained.Bill Shorten and Labor have resorted to relying on four-year old modelling done by Professor Warwick McKibbin to detail the cost of their policy, including claiming that there will be “no additional cost” to meet Labor’s 45% target relative to the Coalition’s 26% target. This is despite Labor needing 1.33 billion tonnes of abatement - nearly four times the 328 million tonnes needed under Coalition policy. As Professor McKibbin himself said, “raising the target reduction from 28 per cent to 45 per cent would almost double the cost to the economy...by 2030, you’re well and truly worse off. It is twice as costly for twice the target.” The Australian, 11 July 2017Bill Shorten and his energy and climate spokesperson Mark Butler are trying to pull an outrageous con job on the Australian people.Patricia Karvelas: When will we see your full modelling for how it will effect the economy?Mark Butler: I don't understand why it's inappropriate for us to rely upon [Professor McKibbin's] modelling that the Australian Government commissioned.ABC, 17 April 2019Well, here are a few reasons Mr Butler, for a start:1. Professor McKibbin himself has said his modelling, done in 2015, “did not model Labor’s policy”. Twitter, 19 March 20192. Professor McKibbin’s modelling did not cover the entire economy, excluding around 30% of Australia’s emissions including fugitives from manufacturing, mining and oil and gas production. These are the sectors that will be hit hardest by Labor’s new carbon tax.3. Bill Shorten himself has previously dismissed Professor McKibbin’s modelling as “just complete rubbish” and implied the modelling results were made up. ABC Lateline, 1 December 20154. Professor McKibbin’s modelling assumes a carbon price of US$5 per tonne, rising to US$10 in 2030, much lower than current international prices of around US$30 per tonne and far below forecast prices for 2030. Professor McKibbin: “If the price of offsets in the world is higher than we assume, that effect is gone. We don’t know what the price of offsets will be in 2030. These numbers are not precise in any sense.” The Australian, 18 April 2019The Labor Party’s desperate insistence on relying solely on modelling from 2015 proves the terrifying truth: if elected, Labor is committing this country to an economy-wrecking emissions target and no one in the Labor Party has done the numbers on what the consequences are.The Coalition has stepped through - to the last megatonne and the last dollar - how we are going to meet our international obligations.Bill Shorten isn’t telling us the truth about how much Labor’s reckless target will cost - because he actually has no idea.If Bill Shorten can’t tell you the truth about his policies, how can Australians trust him?