1. July hottest ever

Not just the hottest July, we’ve just had the hottest single month since records began in 1880. It’s also been the hottest first seven months of any year, so we are heading into new territory.

David Spratt looks at the precise figures. Temperatures are often referenced to the 20th century average, or 1880. He reckons the first seven months of 2015 were a staggering 1.26°C higher than the pre-industrial level.

He also says the current El Niño could be the strongest ever, and quotes Michael Mann as saying that we really need to limit emissions to 405 ppm, which we’ll reach in about three years.

2. Warwick McKibbin spoils Abbott’s scare campaign

Tony Abbott and Greg Hunt have been talking about “massive and unmanageable costs” if we adopt Labor’s renewable energy targets. The figure of $600 billion has been thrown around as coming from the Climate Change Authority, a claim that Authority chair Bernie Fraser finds “weird” and “misleading”.

Professor Warwick McKibbin, leading ANU economist and former Reserve Bank Board member has conducted economic modelling for the Abbott Government on various emission reduction scenarios.

You can read about what he found with Lenore Taylor at The Guardian or listen to McKibbin with Fran Kelly.

Taylor puts it simply. McKibbin found that:

with a 26% target, the economy would grow by an average 2.14% a year between 2020 and 2030, under a 35% target it would grow by 2.12% and under a 45% target by 2.09%.

Not too much to ask.

McKibbin did an opinion piece for the AFR on Monday. Turns out the above is one of three ways of working out the impact on GDP. Plenty of scope for spinmeisters.

Also in terms of economic effort McKibbin places Australia near the head of the pack. But, he says, there are great uncertainties in the exercise, including technology costs and the availability of cheap international carbon credits.

3. Katrina anniversary

It’s 10 years since Hurricane Katrina struck New Orleans. It seems the place is still not fixed. Obama showed up, lauded the progress and said more needed to be done. Seems it’s the poor and people of colour who get left behind.

Joe Romm looks at the future, and concludes that New Orleans and the whole Gulf coast will become more vulnerable as warming continues. It’s more about the Gulf waters warming than sea level rise.

Josh Israel looks at the parlous state of the national levee system and identifies Sacramento as being especially at risk.

4. WA looks to a solar future

WA energy minister Mike Nahan:

“We expect that the bulk of generating capacity during sunlight hours in the [Perth] metro area in about 10 years time will be provided by rooftop solar,” said Nahan in a speech to an energy conference in Perth.

“That’s the reality. So it is going to provide the bulk of additional capacity going forward.

“Solar will also displace a lot of the existing [coal-based] capacity. It’s low-priced, it’s democratically determined and it’s something we’re committed to facilitating.”

Amazing, from someone who used to rubbish renewable energy when he was at the IPA.

5. 2°C is not safe

The Climate Council has released a report Growing Risks, Critical Choices with the key message:

The scientific underpinning for the 2°C policy target being a “safe” level of climate change is now weaker than it was a decade ago. The scientific case for a 1.5°C limit is more consistent with our current level of understanding, bolstering the case for even more urgent action.

And:

A very strong and rapid decarbonisation of the global economy could stabilise the climate system below 2°C, while a business-as-usual scenario could lead to temperature rises of 4°C or above by the end of the century, threatening the viability of modern society.

The world must almost completely decarbonise in the next 30-35 years, and the vast majority of fossil fuels be left in the ground, if we are to have any hope of tackling climate change effectively.

Recently we lokked at whether 1.5°C was attainable. Probably not.

6. Stranded assets

Success in the Paris climate talks could leave $100 trillion worth of stranded assets, according to Citigroup.