Satitoa, Samoa

Exiting Neumayer Station III, you are transported from the deep freeze of Antarctica to the tropical breeze of Satitoa, Samoa located at 171º 22' W/ 14º 1' S. Don’t worry, although the longitude has changed to 171º W, you are still on a path to Bremerhaven.

The centerpiece of the exhibit room is a traditional open thatched roof structure called a fale. The fale design is an engineering solution for comfort in a sunny, warm, wet, breezy tropical climate. It was difficult to find construction trades people in Europe who had the knowledge and skills needed to build a fale. Two of the local residents of Satitoa, whom Axel Werner befriended, traveled to Bremerhaven to construct the fale.

The fale overlooks a lagoon. Standing in the fale, you gaze over a white sand beach to blue waters that sparkle in the tropical sun. Off the coast, a tropical reef is teeming with life. Tropical reefs are often referred to as the rainforests of the ocean because of their biodiversity. The coral reef habitat sustains a variety of animals some of which are important food sources for the Samoan islanders.

The original village visited by Werner and Goldberg no longer exists. After a tsunami destroyed the village in 2009, the inhabitants resettled further inland. The tsunami was unrelated to climate change, however, there are other events taking place are related to changes in climate that made the move inland a necessity.

As an island in the Pacific, Samoa is particularly vulnerable to changes in sea surface temperatures in the Pacific Ocean. Precipitation patterns change with the naturally occurring changes in ocean currents known as El Nino Southern Oscillation (ENSO). However, storm intensity precipitation variability is increasing as sea surface temperatures increase.

Warmer ocean water evaporates more quickly from the surface raising the water vapor concentration in the air above the water. More water in the atmosphere can lead to cloud formation. More water in the air has the potential to increase the chance of rain. Although evaporation of surface water leads to increased salinity, the return of freshwater as rain reduces salinity. Unlike Antarctica, the problem is not changing ocean salinity, rather it is increasing cycling of water between the ocean and atmosphere driven by heating. Sunlight drives water evaporation from sea surfaces. Because of Earth’s axial tilt, incoming solar radiation is the most direct and intense in tropical regions.

Warmer ocean water has other impacts as well. As seawater warms, the kinetic energy of water molecules increases. As the kinetic energy increases, water molecules spread out causing the volume to expand. Seawater expansion contributes to global sea level rise. Rising sea levels may cause flooding and beach erosion. Silt in the water from beach erosion affects coral reefs by blocking sunlight needed by photosynthetic zooxanthellae that live on corals and produce nutrients and energy for corals.

Warmer water temperatures also impact the symbiotic relationship between zooxanthellae and corals. When temperatures are 1º to 2º C higher than normal for 5 to 10 days, zooxanthellae abandon the coral. If conditions remain too warm, even if water is clear and shallow, the zooxanthellae do not return. When corals become deprived of nutrients they begin to turn white and die. Warmer ocean surface temperatures are one cause of coral bleaching.

Another factor affecting ocean life is ocean acidification. The acidity of a substance is measured using a pH (potential of hydrogen) scale from 0 to 14. Substances with a pH less than 7 are called acids. Substances with a pH of 7 are neutral. Substances with a pH greater than 7 are bases. Acidity refers to an acid alkalinity refers to a base. Acidification describes processes that result in lower pH measurements, even if the altered pH is still equal to or greater than 7.

Prior to the Industrial Revolution, the average pH of ocean water was 8.2. The alkalinity of ocean water depends on chemical reactions taking place in the water. Oceans serve as a sink for atmospheric carbon dioxide. When carbon dioxide mixes with ocean water it forms carbonic acid. Rising concentrations of carbon dioxide in the atmosphere correlate to lower pH levels in ocean waters. The current average pH of ocean water is 8.1. That may not seem like a big difference, but the pH scale is based on powers of ten. A 0.1 change in pH is a 25% reduction in alkalinity and increase in acidity. Lower pH levels affect survival of corals and animals with calcium carbonate shells.

The signs of climate change in Samoa are alarming. A downed electrical line pole indicates the power of recent storms. Flood waters lapping at the steps of the church are a sign of sea level rise. Ocean reef productivity has declined as the result of warmer ocean temperatures and acidification. Could that light bulb in Bremerhaven be connected to sea level rise, ocean acidification, increased storm intensity, and coral bleaching in Samoa?

• Look for clues to answer the question.

• Examine the photo to identify factors that influence the climate of Satitoa.

• Use Google Earth to develop a sense of place.

• Analyze the data and the climograph to observe patterns in rainfall and temperature.

• Use the dig deeper resources to gather information to understand the processes behind climate change.