Nonetheless the announcement sparked plenty of debate – ably abetted by the government – about the cost of renewable energy. But not discussed nearly as much was what our current energy supply, which is largely coal dominated, may also be costing us. The policy wonks at the International Monetary Fund have been trying to shed some light on that in recent times. Back in May they released a paper projecting that this year the world would subsidise energy consumption – mostly coal, gas and petroleum – by an astonishing $6.6 trillion. In recent weeks they released the country by country breakdown behind that headline figure.

So how did Australia fare? No prizes for guessing that China was well out in front, with a total energy subsidy of approximately $3 trillion projected for this year. Australia was never going to be in the same stratosphere. But nor is our subsidy insignificant. All up the IMF projected Australia would subsidise coal, petroleum and gas consumption by $41 billion in 2015. That is almost two per cent of our gross domestic product. Despite rapidly falling costs, on many estimates renewables still produce electricity at a higher cost than coal – if only generation costs is taken into account.

Australia's current electricity mix can supply power at about $30 to $40 per megawatt-hour, according to estimates provided by the Grattan Institute. If we were to build new fossil fuel power plants today they would produce power at about $50 to $75 per megawatt-hour based on the same Grattan model. New wind power would cost about $80 to $90 per megawatt-hour, while large-scale solar would be about $180 (Estimates by other groups put the cost of new coal power at higher rates.) But as the IMF shows, this is only part of the picture. A massive proportion of the energy subsidy identified by the IMF comes about from wider society having to bare the burden of the environment damage that burning fossil fuels causes – namely global warming and local air pollution.

The problem is that the price we pay for power and petrol largely does not reflect the cost of this environmental damage. But somebody ultimately still has to pay for it. For example, as the planet warms (largely as a result of using fossil fuels) extreme weather events, such as heatwaves and droughts, increase. Governments and communities then have to foot a growing bill to clean up after these events and to protect people from more of them. The IMF finds amid the total $41 billion Australian subsidy to coal, gas and petroleum energy use in 2015, global warming and air pollution represents about $25 billion. Other work has previously attempted to break down these types of costs to individual power plants. In April a study by two Harvard fellows estimated the social cost of the Hazelwood power station in Victoria's Latrobe Valley was $900 million a year. Many economists (and it seems the IMF) favour some form of carbon pricing so the costs of global warming can start to be accounted for. That could be a dreaded carbon tax (zombie or otherwise) or an emissions trading scheme (Labor is actually pledging the latter, though in what form and when is still very unclear).

And if the environmental costs of coal, gas and petrol are properly reflected then renewable energy should become even more competitive because of their light touch on the planet. Busy this week? Here's what you may have also missed. Tiny South Pacific nation, the Marshall Islands, set an ambitious target to cut its emissions by 32 per cent from 2010 levels by 2025 – and it wants Australia to follow its lead.

The first six months of 2015 were the hottest in 136 years of records according to the US government's weather and climate body. That puts this year on track to overtake 2014 as the hottest on record.

Prominent British Tory MP Richard Benyon launched a stinging attack on Prime Minister Tony Abbott's climate change policies, calling them a distortion of "what it means to be a conservative".

Delegations from 40 countries met in Paris last week to try and hammer out some common ground on some of the more divisive issues plaguing a potential new global climate agreement. And what you may hear about in the coming days. Former US vice president, long-time climate campaigner and one-man slide show, Al Gore, is visiting Melbourne for meetings with government and academics.