German scientists carried out flight observations on passenger aircraft fitted with 'lean-burn' engines. Their findings indicate that curbing soot emissions from aircraft may not inevitably lead to a reduction in contrails, which stand as one of the major contributors to climate warming within the aviation sector. This implies that further research is imperative to comprehend and alleviate the climate impact stemming from jet engine emissions.

Previously, it was widely assumed that the adoption of lean-burn engines, known for their ability to cut down on soot emissions, would result in a decrease in the warming effect caused by contrails. However, this notion lacked the backing of real-world data. The study unveils that simply altering the engine's combustion mode may not suffice to diminish contrails. Although lean-burn engines emit soot levels that are 1,000 times lower than those of rich-burn engines, the formation of contrails does not witness a significant decline.

When it comes to fuel type, the number of ice crystals in contrails produced by using low-sulfur fuel is fewer than those generated with conventional sulfur-containing fuel. Nevertheless, when ultra-low-sulfur fuel is employed, other vapors and lubricants still give rise to contrails. The researchers emphasized the necessity for in-depth research aimed at reducing ice formation within contrails. These discoveries shed new light on strategies to lessen the aviation industry's climate impact by modifying fuel composition and engine combustion modes.