The single greatest cause of global species extinction in the next half century will most likely be:Group of answer choicesrise in sea level.global warming.urban air pollution.competition with introduced species.tropical deforestation.

The single greatest cause of global species extinction in the next half century will most likely be global warming. Here's why:

1. Global warming refers to the long-term increase in Earth's average temperature. This is primarily caused by the increase in greenhouse gases such as carbon dioxide in the Earth's atmosphere due to human activities like burning fossil fuels and deforestation.

2. This rise in temperature can lead to a variety of changes in the global climate, including more frequent and severe heatwaves, droughts, floods, and storms. These changes can make it difficult for many species to survive in their current habitats.

3. Global warming also causes the polar ice caps to melt, which leads to a rise in sea levels. This can result in the loss of coastal habitats for many species.

4. Additionally, global warming can disrupt ecosystems and food chains. For example, it can cause plants to flower at different times, which can affect the species that rely on them for food.

5. While other factors like urban air pollution, competition with introduced species, and tropical deforestation also contribute to species extinction, global warming has the potential to affect all species on Earth, making it the most significant cause.