Which type of fresh water is at risk of increased salinity as Earth warms?
1. mountain streams
2. glaciers
3. coastal lakes
4. snowpacks
3. coastal lakes
To determine which type of fresh water is at risk of increased salinity as Earth warms, we need to consider the effects of global warming on the different sources of fresh water.
1. Mountain Streams: Mountain streams are usually fed by melting ice and snow. As the Earth warms, glaciers and snowpacks melt at a faster rate, providing a continuous flow of freshwater to mountain streams. Therefore, it is less likely that mountain streams would experience increased salinity due to global warming.
2. Glaciers: Glaciers are enormous masses of ice formed by compacted snow over many years. With rising temperatures, glaciers are melting at an accelerated pace. However, the melting ice from glaciers doesn't directly contribute to increased salinity. As the glaciers melt, they release freshwater into rivers and lakes, which helps maintain the balance of salinity levels.
3. Coastal Lakes: Coastal lakes can be at risk of increased salinity as Earth warms. Rising sea levels, which are a consequence of global warming, can lead to saltwater intrusion into coastal lakes. When seawater infiltrates these freshwater bodies, it increases their salinity levels, potentially posing a threat to the local ecosystems and their freshwater sources.
4. Snowpacks: Snowpacks act as natural reservoirs, storing frozen water during winter and slowly releasing it as freshwater during the warmer months. As Earth warms, snowpacks tend to diminish in size and melt earlier in the year. This can lead to reduced freshwater availability during dry seasons, but it does not directly influence salinity levels.
In summary, while mountain streams and snowpacks are not directly at risk of increased salinity with global warming, coastal lakes can be negatively impacted by the rising sea levels, potentially causing a rise in salinity. Therefore, the correct answer is 3. Coastal lakes.