A new study reveals that countries' exports to China and the US are major contributors to global greenhouse gas emissions. The research found that when countries export goods to China, it leads to an increase in their own carbon emissions - a phenomenon known as "carbon leakage." However, exporting to the US does not have this effect. This is significant because China has become the world's second-largest economy and largest emitter of carbon dioxide, while the US remains the largest economy but also a major polluter. The study highlights the need for countries to consider the environmental impact of their trade relationships with these two global powers.