World will fail on net zero unless it ups ambition

A first of its kind study has warned that the ability for the world to drive deep decarbonization by 2050 is currently not plausible, warning the current efforts to bring about societal transformation need to be far more ambitious.

The Hamburg-based Cluster of Excellence “Climate, Climatic Change, and Society” (CLICCS) published its long-awaited study on climate futures. The study represents the first systematic attempt to investigate whether a climate future with net-zero carbon emissions is not only possible but also plausible.

The authors examined the plausibility from a technical-economic perspective, but also with regard to the societal changes necessary for such a future. The results, published as the G7 leaders meet to discuss climate change in Cornwall, found that the world will fail unless it gets more ambitious.

The study has produced a speedometer to highlight where the world currently stands in its efforts to decarbonise.

The speedometer shows the wide range of possible emissions in the year 2050 as described in existing emissions scenarios. Emissions could reach net-zero by 2050 (deep decarbonisation) or could increase up to a doubling of current emissions (very high emissions). Approximate emissions in 2020 are indicated by the speedometer needle.  Researchers found a reduced range of plausible emissions scenarios, supported by a techno-economic plausibility assessment and a social plausibility assessment indicated by the shaded bands. Increasing emissions are not yet considered in the social plausibility assessment (grey band).

“Which climate futures are plausible is not only a physical question, it is at present especially a social one,” says CLICCS speaker Prof. Detlef Stammer from Universität Hamburg. “In the Hamburg Climate Futures Outlook we investigate the transformative power of social processes and have developed a completely new method for doing so. We’ll then combine the outcomes with findings from the natural sciences, allowing us to narrow down, step by step, what’s plausible.”

The key factors being explored include, United Nations’ climate policy, national climate legislation, protests and social movements, divesting from fossil fuel industries, and media coverage. Crucially, none of the ten factors assessed in the Outlook appear to have enough momentum to reach deep decarbonisation by 2050. Yet reaching deep decarbonisation by mid-century is vital if the climate targets laid out in the Paris Agreement are to be achieved.

However, six of the drivers could foster a gradual decarbonization: “The majority of the factors we evaluated certainly support the net-zero goal. For example, the factor ‘climate policy’ has been strengthened by the USA’s re-entry into the Paris Agreement,” explained Prof. Anita Engels, a social scientist at Universität Hamburg and CLICCS Co-Chair. “At the same time, the extent to which climate protests can continue to put pressure on governments after COVID-19 will be an important aspect.” Another crucial driver is the divestment from fossil fuels. However, companies often operate under long investment cycles, which means the effects will only become ap-parent down the road.

The authors concluded that, at the moment, neither high-emissions nor low-emissions scenarios are plausible: “Studies show that very high CO2 emissions can produce tremendous economic costs. What’s more: global coal reserves are finite, and clean energy is becoming more affordable. As such, governments and companies alike will be forced to change course,” said CLICCS Co-Chair Prof. Jochem Marotzke from the Max Planck Institute for Meteorology. “However, we’re still lacking the technologies needed for the rapid and large-scale removal of carbon dioxide from the atmosphere – an essential prerequisite for cutting emissions to net zero.”

“Our results imply that global surface warming of less than 1.7 degrees Celsius by the year 2100 is not plausible, but nor is a rise of more than 4.9 degrees.”

“In the Hamburg Climate Futures Outlook, we’re not looking into what would be necessary, feasible or desirable. We’re analysing which climate futures are plausible – and which ones aren’t,” explained Prof. Marotzke, who was also one of the key contributors to the upcoming IPCC report.

“The social challenge is far greater than many people can imagine,” concluded Prof. Stammer. “As such, our findings represent a wake-up call for the political community and society at large.”

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