The Earth’s Sensitivity to Greenhouse Gases is Greater Than We Realized

The Earth’s climate appears to be more responsive to the pollution caused by greenhouse gases than previously assumed, making it harder to keep global temperature increases below 2°C.

This is concerning news for global efforts to combat climate change, according to Gunnar Myhre from Cicero International Climate Research Centre in Norway.

Researchers have long been aware that releasing greenhouse gases into the atmosphere can lead to climate warming with widespread consequences. However, the extent of potential warming due to these emissions remains uncertain. Specifically, how sensitive is the Earth’s climate to this pollution?

The primary uncertainty arises from how clouds react to warming atmospheres, as shifts in cloud systems could exacerbate warming through feedback loops.

Most predictions regarding warming by the century’s end are derived from climate models that incorporate various sensitivity assumptions. The model utilized by the Intergovernmental Panel on Climate Change indicates that if atmospheric concentrations double compared to pre-industrial levels, warming could range between 2°C and 5°C, prompting organizations to adopt a median estimate of 3°C.

Myhre and his team sought to align climate model predictions with satellite data showing the Earth’s energy imbalance—a measure of excess heat within our climate system, reflecting its sensitivity levels.

They discovered that less sensitive climate models, which suggest that the Earth’s climate is more resistant to greenhouse gas emissions, did not align with satellite data collected since the turn of the millennium. According to Myhre, models asserting that the Earth’s climate is less resistant to these gases are “more common.” He added, “Models predicting minimal warming are increasingly rare.”

The findings challenge the reliability of climate models forecasting warming below 2.9°C with doubled greenhouse gas concentrations. Instead, the data imply that warming beyond this threshold is more probable for the same level of pollution.

This has been corroborated by recent record-high temperatures observed both on land and in the sea since 2023, described as “strong climate feedback” in the atmosphere by Myhre.

A more sensitive climate necessitates a quicker reduction in emissions to maintain the same temperature trajectory. In essence, the world must accelerate decarbonization efforts to meet its climate commitments.

Johannes Kuas from the University of Leipzig in Germany argues that the study presents a “very plausible contention” that the Earth is indeed more sensitive to global warming than some models suggest, stating it “reduces the margin” for model estimations that scientists should follow. “It highlights the urgent need for political action against climate change,” he emphasized.

Richard Allen from the University of Reading in the UK notes that “natural climate change” could also be part of the narrative, by pointing out that satellite records date back only to 2001. Nevertheless, he describes the study as “rigorous” and adds, “there is further evidence that simulations predicting less warming are increasingly unrealistic in the long-term.”