The journal Science published research that made headlines. Titled "Avoiding ocean mass extinction from climate warming" it reviewed extinction risk for marine species in the future.

Oceans are hard to see, study, measure, and figure out. The extinction crisis underway is easiest to measure on land, where industrial and land use impacts caused more species to disappear than climate warming. But the oceans?

It's hard to imagine what the future of fish in oceans will be, when we have no idea of what they were before. Can we plan for the year 2100, when we don't have a picture of 1900?

Way, way, long ago, 252 million years ago, 81% of marine species went extinct*. 300 million years ago oceans were frigid, then continents collided into one great land, Pangea. Eroded minerals capture atmospheric carbon, flow into oceans, where marine calcification buries them. Pangea's huge scale prevented much of this, and the atmosphere's CO2 increased. Land and ocean temperatures went up.

Land collision probably triggered major volcanoes, which spewed more CO2 into the atmosphere. Very simplified models of a complex Permian climate system indicates volcanoes added enough CO2 to drive the warming impacts detected in rocks. CO2 parts-per-million could have reached 4,000 ppm, roughly 10X today's level. The mechanisms that drove oceans to lose oxygen are more uncertain. But they did, and ocean life died.

The Science study used a model of climate, nutrients, plant, and animal interactions, that successfully modeled
this 252 million year old ocean extinction. They altered it to study today's extinctions. First, a group of today's Earth system models were used to update contemporary climate and ocean conditions. Second, they used over 1000 contemporary ocean animal groups representing overall current ocean biodiversity. Then they tested how species fared when climate changes.

When oceans warm, oxygen levels drop. If that falls below a specie's capacity, it migrates to colder zones with enough oxygen, or fails. If oxygenated areas are below a critical volume, viable populations cannot be sustained.

They found that limiting warming to 2°C avoids an oceanic mass extinction loss, of the type experienced in the "Big 5" extinctions that have occured on planet Earth. At various times over the past 440 million years, these caused the disappearance of the following percent of species: 42%, 62%, 68%, 75%, and, in the one 252 million years ago, 81%. Warming of 2°C or less prevents these numbers.

A "Big 5" level ocean extinction is likely if surface air warming rises 5°C by the year 2100, and continues to rise about 3°C more by 2300. In reality we'll probably be between 2°C and 5°C.

There's something else, however. Even under the 5°C temperature scenario, ocean species losses due to warming only equal the sum of all other human-caused impacts, by 2100. In other words, half of the impact in the worst case scenario comes from massive overexploitation of marine environments, pollution and degradation. Even if we remove CO2 and keep temperature below a 2°C increase, ocean biodiversity will lose half the species of what a major extinction event would cause.

Seems like we need to understand human impacts, and what can be done about them. But if it's hard to see species loss on land, it's harder under water. Recognizing the losses that already happened will help.

That's where movies, video games, and television play a role. The size and number of fish that Tom Sawyer pulled out of the water are as unimaginable to us as the birds and buffalo back then.

With fish, successive generations of fishing people use the catch rates they grew up with as a baseline to measure change. But each generation uses better, more efficient equipment, and fishes larger areas. The result is that what look like stable catch rates mask real declines. Collecting data from 1879 onwards, researchers in Queensland, Australia found the Australian Snapper's absolute population numbers have declined by up to 90%, almost unnoticed.

Showing the real abundance 100 years ago gives us a handle to address trends 100 years into the future.

Showing the real wild west, and the real wild seas, will help. Please support this petition.

*Estimates quoted of 88–96% species extinction, often simply put as 96%, combine two extinction events. Prior to 1994, the Capitanian extinction event 260 million years ago was not known, so its impact was included in the end-Permian event 252 million years ago.