What is a carbon budget

TL;DR

Explanation

If we want to keep the temperature rise to a target, using the wizardry of maths and some nerdy science we can work out how much more greenhouse gases can be added to the atmosphere before we hit that target.

Have you ever tracked your calories? Calories eaten, calories burnt and then what do you weigh. We are eating too much and not doing anywhere near enough exercise, the atmosphere is getting fat. Carbon fat.

Instead of a target of “Net-Zero by 2050”, our focus should be “How much do we have left in the carbon budget for 1.5°C?”.

If the focus was on the remaining carbon budget we’d realise there’s not much left. We’re creating carbon emissions faster and faster instead of slowing down. Like car heading for a cliff but we’re hitting the accelerator instead of the brakes.

The time based targets of 2050, and then 2030 (for a progress check) are not fixed. We can burn through our budget more quickly, or more slowly. Climate change delayers act as if these are fixed in time targets and use them so they can make as much money as possible until 2049 where they think we can then just stop making carbon emissions. This is completely wrong because the problem is based on cumulative emissions, not the amount of emissions at a single point in time. We’re filling the bathtub.

OK so if we have a global carbon budget, who gets to spend it? That’s part of the challenge of a just transition.

If governments were serious

Each year the Australian Federal Government hands down a budget - proposed spending and expected tax revenue for the financial year ahead, and some projections for the years after that. This is the effect of various government policies such as tax rates and government spending and the health of the economy overall. Each year media outlets feverishly publish Winners and Losers articles to grab your attention - how much better or worse off are you going to be based on this budget? I’m not a fan of this approach.

However. If the government was actually serious about climate change, each year a Carbon Treasurer would present the carbon budget. How much did we spend. How much is left. What are our adjustments going forward. What policies are we ending, what are we adjusting, what are we bringing in new. There’d be a similar national media campaign and excited reporting of the Winners vs Losers but in carbon terms.

To be fair the Australian Government has started to make this a custom with the first Annual Climate Change Statement to Parliament delivered in 2023. The first, in 2023! Except it seems it wasn’t as forthcoming and transparent as it should have been, and there was certainly no mainstream reporting of it.

Further reading

Global Carbon Budget FAQs

Global Carbon Project Key Messages 2023

Global greenhouse gas budgets (CSIRO)

8 things Chris Bowen didn’t tell you about Australia’s climate failure 30 November 2023