Final answer:
Global warming causes heavier rainfall and flooding due to changing global weather patterns and an increase in intense precipitation events. It also leads to rising sea levels from melting glaciers and the expansion of warmer water, which dissolves more carbon dioxide and can increase ocean acidity, rather than decreasing it. Health improvements are not a typical consequence of global warming, as it often increases health risks.
Step-by-step explanation:
The effect of global warming that is accurately described in the given options is heavier rainfall and flooding. As the global average air and ocean temperatures rise due to increased greenhouse gas emissions, several impacts are observed on the environment. One of the direct consequences of this warming is an alteration in global weather patterns, leading to more intense precipitation events.
Global warming causes glaciers to melt, contributing to rising sea levels, affecting coastal and island habitats, potentially inundating them and causing loss of biodiversity. Therefore, falling sea levels and decreases in the acidity of seawater are not effects of global warming, since warmer water also expands, adding to the rise in sea levels, and increased carbon dioxide in the atmosphere can lead to more acidic oceans. Furthermore, while global warming may lead to shifts in diseases and health risks, it is not characterized by broad health improvements; instead, it may exacerbate heat-related health problems and the spread of vector-borne diseases.