Which one of the following is not a potential impact of global warming?

The assertion that increased crop yield, particularly of citrus fruits, is not a potential impact of global warming reflects the understanding that while some specific crops may initially benefit from climatic changes, the overall trend of global warming is complex and can lead to detrimental effects on agriculture in general.

Global warming influences various factors—temperature, precipitation patterns, pests, and diseases—all of which can affect crop yields. While it is possible that certain regions might see short-term increases in yield due to warmer temperatures, the overarching impacts of climate change often result in more challenges than benefits. Changes in climate can lead to extreme weather events, such as droughts and floods, which are detrimental to crop production. Furthermore, altered growing seasons might not favor the long-term growth of citrus and other crops, undermining the idea of sustained increased yields.

In contrast, the loss of biodiversity, sea level rise, and increases in human morbidity and mortality rates are consistent and well-documented consequences of global warming. Loss of biodiversity stems from rapid changes in habitats and ecosystems unable to adapt, while sea level rise is a direct result of melting ice caps and thermal expansion of seawater. Increased human morbidity and mortality can arise from heat waves, respiratory issues due to poor air quality, and greater spread of