IPCC 1.5C Target Watch

[WYorksWeather]

As has been making the news lately, it looks like there's a high chance that 2023 will be the first year to reach annual average temperatures of 1.5C above pre-industrial levels in at least one surface temperature dataset, most likely Berkeley Earth.

I thought I'd make this thread to clear up what the IPCC target actually says - a lot of people seem to think that this means that 1.5C has been breached. However, the IPPC definition is a 20-year centred average, which means we're unlikely to breach 1.5C in the next few years.

However, most estimates do show that global temperatures are likely to exceed 1.5C over the long term by the early 2030s, or possibly even sooner. In terms of carbon budgets, a recent paper found that the budget has shrunk from 500GT (billion tons) of CO2 in 2020 to 250GT in 2023, thanks to continued emissions and improved scientific understanding. Global emissions are currently around 40GT/year, so that translates to around six years of current emissions, supportive of a date in the late 2020s for surpassing 1.5C.

Of course, the 'centred average' bit is tricky, since it means we can likely only declare 1.5C surpassed in hindsight.