精品SM在线影片

Banner image: An endangered Gal谩pagos fur seal.听(Credit: Andrew Turner)

While most of the world鈥檚 oceans are warming due to climate change, a new 精品SM在线影片 study explains how the waters around the Gal谩pagos Islands are staying cool and getting colder.听

Published in , the study shows that not only does a cold, eastward equatorial ocean current provide the Gal谩pagos Islands a buffer against an otherwise warming Pacific Ocean, but this current has been getting stronger for decades. In fact, the waters off the west coast of the Gal谩pagos have cooled by 0.9 degrees Fahrenheit (0.5 degrees Celsius) since the early 1990s.听

鈥淭here's a tug of war going on between our greenhouse effect causing warming from above, and the cold ocean current. Right now, the ocean current is winning鈥攊t's not just staying cool, it鈥檚 getting cooler year after year,鈥� said Kris Karnauskas, lead author on the study, associate professor in the Department of Atmospheric and Oceanic Sciences and fellow in the Cooperative Institute for Research in Environmental Sciences (CIRES).听

This phenomenon is a cause for cautious optimism for the second largest marine reserve in the world, and a biodiverse island ecosystem that is home to several endangered species and designated as a UNESCO World Heritage Site.听

If corals don鈥檛 bleach and die in these waters off the western coast of Ecuador, and the marine food web doesn鈥檛 struggle like it will in nearby warming waters, flora and fauna in the Gal谩pagos could help reseed struggling ecosystems and keep fisheries in the region functioning.听

鈥淎s the Gal谩pagos so far has been relatively unaffected by climate change, it鈥檚 worth looking at the Gal谩pagos as a potential site to really try to put some climate change mitigation efforts into,鈥� said Karnauskas.听

But as one of the few places left in the world鈥檚 oceans that are not currently warming up, the waters off the west coast of the Gal谩pagos are also likely in need of additional protections from overfishing as well as the pressures of increased ecotourism.听

鈥淭he human pressures on this area and this mechanism that keeps it alive are at odds,鈥� said Karnauskas. 鈥淚t鈥檚 a major resource that should be protected.鈥�

An accident of geology听

The Gal谩pagos Archipelago may seem insignificant from space, as several tiny dots in the eastern Pacific Ocean. But it鈥檚 their location鈥攅xactly on the equator鈥攖hat makes them quite significant.听

Because the Earth rotates on an axis, this equatorial undercurrent in the Pacific Ocean is also stuck to the equator, locked in by the force of the planet鈥檚 rotation. This current under the surface of the ocean heads quickly from west to east, its cold water rich in nutrients. When it hits the Gal谩pagos Islands, some of this water is forced up to the surface and the chemical reaction of photosynthesis causes an explosion in food for all manner of creatures.听

So while the islands are located in the tropics, this cold ocean current that collides with them creates a cooler, stable environment for coral reefs, as well as marine animals and birds who normally live much closer to the poles. The endangered Gal谩pagos penguin, Gal谩pagos fur seal and Gal谩pagos sea lion all thrive on these islands, touted as a 鈥渓iving museum and showcase of evolution鈥� by the UNESCO World Heritage Convention.听

Published this August in , another paper by Karnauskas, and fellow 精品SM在线影片 atmospheric and oceanic sciences assistant professor Donata Giglio, used data from thousands of floating ocean sensors, in place since 2000, to observe and confirm that this Pacific equatorial undercurrent is responsible for the cold water that rises from below to surround and support the islands鈥� thriving ecosystem.听

A strengthening cold current听

Karnauskas used different data, when at Woods Hole Oceanographic Institution a decade ago, might protect certain islands or coastlines from the detrimental warming effects of climate change. This new study shows that not only is that proving true for the Gal谩pagos鈥攂ut that the cold current is strengthening.听

鈥淭here's clear evidence that shows all the way back to 1982 that this current has been strengthening and the cold water on the western shores of the islands has been getting colder,鈥� said Karnauskas.听

But why is this cold ocean current getting stronger?听

This current, which starts near Australia, is already among the strongest in the world. Using a recently developed high-resolution ocean model, Karnauskas concluded that its continued cooling results from changes in the winds across the equator.

While this acceleration of the equatorial undercurrent is consistent with model simulations of future climate change, according to Karnauskas, it鈥檚 not yet clear if this trend can be directly attributed to human-caused climate change or if it鈥檚 the result of natural cycles.听

Are the Gal谩pagos Islands safe forever? Not quite, says Karnauskas.听

El Ni帽o (the warm phase of a recurring climate pattern across the tropical Pacific) poses a temporary threat鈥攕hutting down the cold current every couple of years, which causes penguin populations to crash. While El Ni帽o occurs independently of the cold current, it offers a glimpse at what could happen without it.听

鈥淭he worry is if in the future there are changes in this current, it could be really devastating for the ecosystem,鈥� said Karnauskas.听

And if the oceans continue to warm the way they have been, says Karnauskas, this safe haven from climate change may not stay that way.听

鈥淲hat the data shows very clearly is that it's hanging on so far,鈥� said Karnauskas. 鈥淚t doesn't imply that it's going to hang on forever.鈥澨�