The researchers studied the uncertainty in reducing certain gases that contribute to global warming. They looked at different scenarios to see how much these gases could be reduced and how it might impact climate goals. Their findings show that meeting strict climate targets may be harder due to uncertainties in reducing these gases. There are different estimates for the costs and effectiveness of the gases' reduction, making it more challenging to reach climate goals. The goal of limiting global warming to 1.5 or 2 degrees Celsius could be tough without clear plans to tackle these uncertainties.