The Intergovernmental Panel on Climate Change’s (IPCC) synthesis report recently landed with an authoritative thump, giving voice to hundreds of scientists endeavouring to understand the unfolding calamity of global heating. What’s changed since the last one in 2014? Well, we’ve dumped an additional third of a trillion tonnes of CO₂ into the atmosphere, primarily from burning fossil fuels. While world leaders promised to cut global emissions, they have presided over a 5% rise.
The new report evokes a mild sense of urgency, calling on governments to mobilise finance to accelerate the uptake of green technology. But its conclusions are far removed from a direct interpretation of the IPCC’s own carbon budgets (the total amount of CO₂ scientists estimate can be put into the atmosphere for a given temperature rise).
The report claims that, to maintain a 50:50 chance of warming not exceeding 1.5°C above pre-industrial levels, CO₂ emissions must be cut to “net-zero” by the “early 2050s”. Yet, updating the IPCC’s estimate of the 1.5°C carbon budget, from 2020 to 2023, and then drawing a straight line down from today’s total emissions to the point where all carbon emissions must cease, and without exceeding this budget, gives a zero CO₂ date of 2040.
