The Galapagos Islands are a volcanic archipelago located west of Ecuador in the Pacific Ocean. Credit: European Space Agency
While most of the world’s oceans are warming due to climate change, a new study by CU Boulder explains how the water around the Galapagos remains cold and gets colder.
Posted in Climate PLOS, the study shows that not only does the eastward flowing cold equatorial ocean current provide the Galapagos with a buffer against Pacific Ocean warming, but that current has been getting stronger for decades. In fact, the waters off the west coast of the Galapagos have cooled 0.9 degrees Fahrenheit (0.5 degrees Celsius) since the early 1990s.
Kris Karnauskas said, “There is a push and pull between the greenhouse effect that causes warming from above, and the cold ocean current. Right now, the ocean current is winning — it not only stays calm, it gets colder year after year,” said Kris Karnauskas, lead author. For the study, he is an associate professor in the Department of Atmospheric and Oceanic Sciences and a fellow at the Collaborative Institute for Research in the Environmental Sciences (CIRES).
This phenomenon is a reason for cautious optimism for the world’s second largest marine reserve, the island’s biodiverse ecosystem that includes many endangered species and a UNESCO World Heritage Site.
If corals do not bleach and die in these waters off the west coast of Ecuador, and the marine food web does not struggle as it does in warmer waters nearby, the flora and fauna of the Galapagos could help replenish faltering ecosystems and keep the fisheries in the region functioning.
“Since the Galápagos Islands have been relatively unaffected by climate change so far, it is worth looking at the Galápagos Islands as a potential location to try to put some climate change mitigation efforts into it,” Karnauskas said.
But as it is one of the few remaining places in the world’s oceans that is not currently warming, it is also likely that the waters off the west coast of the Galapagos will need additional protection from overfishing as well as the pressures of increased ecotourism.
“Human pressures on this area and this mechanism of keeping it alive are paradoxical,” Karnauskas said. “It is a major resource that must be protected.”
Climate PLOS (2022). DOI: 10.1371 / journal.pclm.0000056″/>
Observed sea surface temperature trends. a, Sea surface temperature trend (°C per 39 years) from January 1982 through December 2020. The black lines are the mean sea surface temperature, defined every 0.5 °C; The deepest ocean is 23 degrees Celsius. b, as in a but removing the effect of large ENSO events before calculating the trend. c , the same as in a but for January 1993 through December 2018. The color scale next to b applies to all three directional (ac) maps. d, Histogram of SST trends across the globe (one per square kilometer), with minimum and mean SST trend in the GCP region (white squares in ac) indicated by blue lines. e, Mean SST time series within the GCP region relative to the region west of the GCP (extending from GCP to 100° W) with two (black line) and five (red line) low-pass filters to remove high-frequency noise. The blue curve shows the portion of the 2-year low-pass filtered time series running from January 1993 through December 2018. Credit: Climate PLOS (2022). DOI: 10.1371 / journal.pclm.0000056
geology accident
The Galapagos Archipelago may appear insignificant from space, like several small points in the eastern Pacific Ocean. But it is their location – exactly on the equator – that makes them so important.
Since the Earth rotates on an axis, this subtle equatorial current in the Pacific Ocean is also stuck at the equator, trapped by the force of the planet’s rotation. This current under the ocean surface is moving rapidly from west to east, and its cold waters are rich in nutrients. When it hits the Galapagos, some of this water is pushed to the surface and the chemical reaction of photosynthesis causes an explosion of food for all kinds of organisms.
So while the islands lie in the tropics, the cold ocean current crashing into them creates a cooler and more stable environment for coral reefs, as well as the marine animals and birds that usually live near the poles. The endangered Galapagos penguin, Galapagos fur seal, and Galapagos sea lion thrive on these islands, which are described as a “living museum and display of evolution” by the UNESCO World Heritage Convention.
Galapagos penguin. Credit: Derek Keats
Posted in August in Geophysical Research Letters, another paper by Karnauskas, and University of Colorado Boulder colleague Donata Gilio associate professor of atmospheric and oceanic sciences used data from thousands of floating ocean sensors, in place since 2000, to monitor and confirm that this hidden current in the Pacific Ocean is responsible for the cold waters that are rising . from below to encircle and support the thriving island ecosystem.
cold stream booster
Karnauskas used various data, when he was at the Woods Hole Oceanographic Institution a decade ago, to show up in The nature of climate change How cold ocean currents can protect certain islands or coastlines from the harmful warming effects of climate change. This new study shows that not only does this prove in the Galapagos – but that the cold current is getting stronger.
“There is clear evidence that has emerged since 1982 that this current has grown stronger and the cold water on the western shores of the islands is getting colder,” Karnauskas said.
Light-footed crab (Grapsus grapsus) from the Galapagos Islands. Credit: NOAA Photo Library
But why is this cold ocean current getting stronger?
This current, which begins near Australia, is already among the strongest in the world. Using a recently developed high-resolution ocean model, Karnauskas concluded that its continued cooling is caused by changes in winds across the equator.
While this acceleration of the subtle equatorial current is consistent with simulations of future climate change, according to Karnauskas, it is not yet clear whether this trend can be directly attributed to human-caused climate change or whether it is the result of natural cycles.
Are the Galapagos Islands safe forever? Not quite, Karnauskas says.
El Niño (the warm phase of a recurring climate pattern across the tropical Pacific) is a temporary threat – shutting off the cold current every two years, causing penguin numbers to collapse. While El Niño occurs independently of the cold current, it offers a glimpse of what could happen without it.
“The concern is that if there are changes in the future in this stream, it could be really devastating to the ecosystem,” Karnauskas said.
If the oceans continue to warm the way they used to, Karnauskas says, this safe haven from climate change may no longer continue.
“What the data shows very clearly is that it is pending so far,” Karnauskas said. “That doesn’t mean it will last forever.”
Study identifies when the Galapagos Islands developed their unique environment
Kristopher B. Karnauskas et al, Where is the temperature in the Galapagos Islands?, Climate PLOS (2022). DOI: 10.1371 / journal.pclm.0000056
Christopher b. Geophysical Research Letters (2022). doi: 10.1029/2022GL098744
Christopher B. Karnauskas et al., Tropical sanctuary amid tropical warming, The nature of climate change (2012). doi: 10.1038/nclimate1499
Presented by the University of Colorado at Boulder
the quote: Strengthening the cold ocean current that protects the Galapagos Islands from climate change (2022, October 13) Retrieved October 13, 2022 from https://phys.org/news/2022-10-cold-ocean-current-buffers-galpagos.html
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Originally published at San Jose News Bulletin
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