3. There has been an increase in the amount of greenhouse gases in recent years.

Краткое пояснение: Текст начинается с описания последствий глобального потепления, таких как «The effects of global warming are becoming more and more noticeable with the passing of the years. The number of floods, storms and heatwaves has increased as a result of carbon dioxide (CO2) and other greenhouse gases». Это прямо указывает на увеличение выбросов парниковых газов.