This week sees the 4th annual Climate Week across the UK, with over 1600 events happening across the country. Climate change is not something that is limited to national borders or political boundaries, it is something that affects every country on the planet and every living thing on it. The Galapagos Islands are no different and their unique and isolated location does not protect them from the future threats posed by a changing climate.
Air temperature increase
The Intergovernmental Panel on Climate Change estimates a global increase in air temperature of between 1.8°C and 4°C. Because the Galapagos Archipelago lies on the equator, it is likely to see at least a 2°C increase.
Sea temperature increase
As air temperature increases so too does sea surface temperature (SST). A change in the SST can alter the currents which so many Galapagos species directly or indirectly rely upon. Warm water has fewer nutrients and is far less productive than cooler water. If less nutrients are available for phytoplankton, the primary producers of the sea, the entire marine food web has the potential to collapse, and populations of marine iguanas, Galapagos penguins, fish, sea lions and seabirds could decline rapidly.
An increase in both air and water temperature will result in increased evaporation and therefore more rainfall. This may precipitate down on the Islands in intense showers, leading to flash floods and causing erosion issues. Alternatively, it could prolong the wet season, disrupting the breeding cycles of many bird and reptile species.
Sea level rise
One of the most pressing issues for some species is a rising sea level. Many animals, such as Galapagos penguins, flightless cormorants, marine iguanas and turtles, rely on the shorelines around islands for resting, nesting or breeding. A rise in sea level will greatly reduce areas available to do this, putting these vulnerable species at even greater risk.
The increase in carbon dioxide (CO2) being released into the atmosphere since the industrial revolution has resulted in a greater absorption of CO2 by the oceans. This process increases the acidity of the water which greatly affects reef building corals as well as other marine species which produce calcium carbonate shells such as mussels and clams. It has been estimated that corals could disappear from Galapagos within the next century.
Increased and stronger El Nino occurrences
El Nino is a natural phenomenon that affects the whole of the Pacific. The weakening of normally strong westerly currents allows warm waters to spread east, leading to increased rainfall and warmer temperatures in South America (including Galapagos). It is predicted that climate change will alter the occurrence of El Nino by making it more frequent and more severe, increasing the impact that it has on many Galapagos species.
Whilst climate change itself wont introduce new terrestrial species to Galapagos, the species that have already been introduced may benefit from it. Introduced species are often more resilient to a changing environment, meaning that they may out-compete the native flora and fauna in times of change. Additionally, with increased rainfall the arid zone that occurs in the lowlands of many islands is likely to become wetter and more vegetated. This could open up previously uninhabitable areas for species to invade, adding to the pressure on the many endemic species that live in this region.
The effects of climate change have been been exacerbated by the increased pressures placed on the Islands from human activity. However, the human population is able to bring in measures to protect the islands and adaptations to cope with these changes. Check back tomorrow to read about the adaptation and mitigation actions that are currently underway in this fragile Archipelago.
by James Medland