Final answer:
China is the current top emitter of greenhouse gases, surpassing the United States, which historically had contributed the most but now is in second place.
Step-by-step explanation:
The student is asking which country is the current top emitter of greenhouse gases. According to the provided reference materials, China is today's largest emitter of carbon dioxide (CO₂), producing approximately 9.4 gigatons (Gt) per year, placing it ahead of the United States, which emits about 5.15 Gt per year. Despite historical cumulative emissions being highest from the United States, recent data clearly indicates that China has surpassed the US and other nations to become the leading contributor to greenhouse gas emissions in contemporary times. It's important to note that while high-income countries like the United States have historically contributed significantly to greenhouse gas emissions, developing nations are now increasing their share, largely due to their economic growth and use of fossil fuels.