The heat and extreme climate records of 2023 shocked scientists. So where are we heading? Given current trends, the world will zoom past 2°C of warming and the Paris climate goal of limiting warming to 1.5-2°C.
This is the second article in a two-part series. Read the first part here.
Climate model scenarios similar to current policies project 2°C of warming before 2050; if James Hansen is right (see Part 1) and warming sharply accelerates, it could be a decade sooner. These outcomes will be driven by the high energy imbalance, continuing high emissions, the accelerating accumulation of heat in the oceans, and decreases in short-term aerosol cooling.
Several years ago a group of eminent scientists proposed a “carbon law”, which said that keeping warming to 2°C required emissions to be halved every decade from 2020 onwards, including a halving between 2020 and 2030, plus some carbon drawdown. Instead, the level of greenhouse gases and coal use both hit record highs in 2023. And the largest national fossil fuel producers plan to keep on expanding production As a result, current government plans worldwide will likely result in emissions in 2050 almost as high as they are today, according to the UN Environment Programme’s 2023 Production Gap report.
Other analyses are broadly consistent:
The intentions of the world’s five largest fossil fuel producers are clear — and civilisation-threatening — as reported by the UN:
We are heading towards 3–4°C.
This outlook suggests Earth is heading towards 3°C of warming and perhaps a good deal more, because current climate models which project warming of around 2.7°C do not adequately account for all the system-level reinforcing feedbacks.
In 2021, the pre-eminent UK international affairs think-tank Chatham House said a “plausible worst-case scenario” is 3.5°C or more, which could be an underestimate if tipping points are reached sooner than the........