Oceans are in crisis this Earth Day; how scientists stay optimistic

AUSTIN (KXAN) -- As people around the world celebrate Earth Day this year by planting trees and turning off a few lights, scientists look toward the oceans. According to the United Nations, the ocean has "taken the brunt of the impacts" of human-driven climate change.

Things look pretty bleak. Rising sea temperatures could lead to half of marine species going extinct by the end of the century. UN estimates found that 60% of marine ecosystems have already degraded, while up to 90% of coral reefs could be destroyed if temperatures aren't curtailed.

"I think we have to maintain a degree of optimism," said Jordan Casey with the University of Texas at Austin's Marine Science Institute. Casey is taking a closer look at the world's oceans in this month's Hot Science Cool Talks at UT.

"I just looked across the literature in the past five years, about 30% of stories are actually success stories coming out of coral reefs. So it's not all doom and gloom. I think it's important to remember that they are highly threatened, but there is some optimism for the future," Casey said.

Her work explores food webs in the oceans and how changes to our seas have impacted those webs. Her research uses DNA to determine what fish are eating and what eats them.

Coral reef loss and human impact

"When we start losing these species, the whole food web can fall apart really quickly. Every species is unique and has a role to play in a marine ecosystem. So everything matters, and losses are really a big deal for these marine systems," Casey said.

Coral reefs have seen some of the greatest impacts of climate change. Visit any reef these days and you'll find bone colored rocks, wisps of plants and fewer fish.

"When corals die, fishes that feed on the coral, obviously are impacted very quickly. We've seen in just a year, there can be 50% population declines of these feeding fishes," Casey said.

Monitoring loss

NASA has been keeping a close eye on these losses. The Coral Reef Watch map, operated by the National Oceanic and Atmospheric Administration (NOAA), shows both real time and long term monitoring of reef health.

NASA also relies on the Landsat satellites to collect images of the reefs and the ocean. The CORAL program (COral Reef Airborne Laboratory) attached a special instrument to the bottom of a commercial airplane, flew it over reefs and captured more data.

NASA also relies on several other satellites to capture data. These include NASA's Tera and Aqua satellites.

All of this loss has a direct impact on humans.

"A lot of what's on the top of food webs are fishes that we consume. For instance, in Texas, the a lot of popular game fishes, like red fish, are at the top of food webs, and they, at the end of the day, rely on the very smallest organisms, like plankton, things that people can't even see underwater, to support them," Casey said.