Climate change is perhaps the single biggest issue facing the health of our communities. Severe weather conditions threaten the crops on which we depend for food and a thriving economy as well as the safety of our neighborhoods and health of our landscape. In San Luis Obispo, we have historically seen weather patterns consistent with a Mediterranean climate where we experience long, hot and dry summers with rainy, wet winters. Many of the native plants are drought-tolerant, and the cold waters and upwelling of nutrients off of our coasts provide us with a stunning amount of marine biodiversity. With greenhouse gasses on the rise, what can we expect for the seasons to come?
The Coast: According to a report released by the California Academy of Sciences in June of this year, Central California’s waters are already showing the effects of a warming planet. Surface waters have increased in temperature, sea levels are higher, winds are stronger, upwellings are more intense, there is increased ocean acidification, and shoreline erosion has accelerated. As a result, ecosystems have been thrown out of balance and organisms are struggling to adapt.
The study states that the most severe ecological disruption will come from the changes associated with upwellings, ocean temperature, sea level rise, and acidification. Upwelling appears to be increasing because of more rapid heating of land in contrast to the ocean which creates pressure gradients and strong winds, driving the process. Researchers worry that stronger currents may carry the larvae of fish and other animals out to sea, disconnecting whole populations and threatening the food web. Warm surface temperatures have heated bays and shallow waters, making for steep temperature gradients from east to west. Warmer surface waters also inhibit the vertical mixing of water and nutrients which can result in plankton blooms and areas of low dissolved oxygen, killing certain species that need oxygen rich habitats to survive and aiding in the takeover of invasive organisms.
Sea level rise has accounted for a large amount of coastline erosion as well as the change in tidepool ecosystems. Rising waters affect the ability of marine mammals to reproduce and rest, changing the living patterns for these top predators. As CO2 continues to be absorbed by the sea, waters have become more acidic, creating conditions where shelled animals cannot form their exoskeletons or even dissolve.
In regards to broader weather patterns, the El Nino oscillation cycles are expected to continue with higher temperatures than in the past. La Nina years will be wetter and warmer than average with heavy downpours becoming more frequent. Days of high fire risk are going to become more common with an extended fire season brought on by hotter temperatures and increased evaporation. Flooding and erosion from sea level rise and lack of vegetative cover will deposit more soil and sediment into freshwater systems, eventually affecting marine ecosystems as they flow out to sea. Saltwater is also expected to flow into freshwater systems as the oceans rise.