An atmosphere twice as thick at 2 bar would significantly alter Earth's climate and weather patterns. The increased air density would lead to changes in temperature variations, both daily and seasonally, likely resulting in more stable temperatures due to enhanced heat retention. Weather systems would be affected, potentially leading to more intense storms and altered precipitation patterns. Life on Earth would adapt to these conditions, possibly resulting in different physiological traits in organisms, such as increased lung capacity or modified metabolic processes to cope with the denser atmosphere. Overall, the implications of such an atmospheric change would be profound, influencing everything from climate stability to the evolution of life.