April showers bring May flowers and it also brings changes to the sea level! This April we are going to dive in (and maybe jump in a few puddles along the way) to the science behind how rainfall affects the oceans and vice versa. The water cycle is very important in understanding how water moves between reservoirs. We know that when water gets warm it begins to evaporate, leaving the ocean and entering a new reservoir–the atmosphere! As water collects in the atmosphere, forming clouds, beads of water eventually cool down, gather, and drop from the sky as precipitation, or rain! Typically the winds from Earth’s rotation will carry these clouds over land before precipitation occurs. During this brief period there is slightly less water in the ocean than normal because it is in the atmosphere or on land. This does not mean that an abundance of rain will permanently lower the current sea level. 

There are many effects of climate change but one of the most concerning is the rise in sea level. As more heat is trapped by our atmosphere due to the increase of greenhouse gases, that heat is continuously reflected back towards our Earth. This lowers the albedo, the ability to reflect light, of ice caps. Ice in the Arctic and Antarctic poles are now absorbing light rather than reflecting it, which is melting them into the ocean, the added water causing the sea level to rise. When April showers bring downpours of water over our lands, the rate of sea level rise lowers slightly. But like the seasons and Earth’s rotation, evaporation and precipitation are simply part of a cycle. The rising of sea levels from ice melt, however, is a process that usually spans millennia, which humans have accelerated within decades.

Climatologists are currently studying what happens when ice melt raises sea levels and when oceans warm. On the one hand, higher temperatures caused by climate change increase evaporation rates, the freshwater heading towards land in the form of a cloud, and excess salt is left behind. This process makes salty, hot parts of the ocean saltier than normal. On the other hand ice melt is dumping tons of freshwater that was previously locked away in the ice, back into the ocean. As freshwater is added, the concentration of salt lowers in these areas. Scientists are hypothesizing that changes in salinity, due to climate change’s impact on ice melt and the water cycle, could change the Earth’s oceanic currents. We rely on these currents to create a habitable climate for us to live in, and without them and the distribution of hot water from the tropics and cold water from the poles, our perception of climate might change completely. The Jet Stream, an oceanic current that happens to bring April showers in Spring, might move, change, or stay exactly the same and it all depends on the severity of global warming. The next time you jump in a puddle or are locked inside during a thunderstorm, you can thank the water cycle and oceanic currents for bringing a piece of the ocean right to your doorstep!