More than five trillion pieces of plastic are estimated floating on the surface of the world’s oceans. It has been claimed that there is now enough plastic to form a permanent layer in the fossil record.
Another reason global warming has not been too bad yet is because the ocean absorbs most of the earth’s excess heat. But oceans are warming due to greenhouse gas emissions. According to the National Oceanic and Atmospheric Administration, half of the increase in ocean heat content since 1865 has occurred over the past two decades. Warmer water holds less oxygen, but the respiration rate of animals (except for marine mammals) increases with temperature, so they need more oxygen at the same time that less is available. A warmer ocean has less turnover (vertical water movements), which normally brings nutrient-rich water up from deep water to the plankton that photosynthesize near the surface. With fewer nutrients, they photosynthesize less and animals can’t get enough food.
Researchers have more than once warned of “dead zones” and toxic algal blooms as a consequence of changing climatic conditions. Ocean temperatures are increasing, and this in turn encourages a new set of biochemical processes.
Professor Hollibaugh and a colleague report in the journal Environmental Science and Technology that over the course of eight summers they measured peaks of nitrite, alongside massive increases in the numbers of the microorganisms that produce it, in coastal waters off Georgia.
In the Florida Keys, the U.S. Virgin Islands and Maui, coral reef degradation has caused sea floor depths to increase as sand and other sea floor materials have eroded over the past few decades, the USGS study found. In the waters around Maui, the sea floor losses amounted to 81 million cubic meters of sand, rock and other material – about what it would take to fill up the Empire State Building 81 times, the researchers calculated.
We now have a 2017 event, which is not quite as bad as 2016, but certainly worse than the first two events that we studied [in 1998 and 2002]. That is significant because it postpones any hope of recovery. The current bleaching occupies a different geographical footprint from last year, which is bad news because it means between last year and this year a much greater extent of the Great Barrier Reef has now been damaged. In 2017, the hot water was in the middle of the Great Barrier Reef, the central section; last year it was in the north.
Arctic sea ice has been rapidly declining since satellites first started tracking it in 1979, and according to NASA, roughly 13.3 percent of the ice disappears every decade. Models have projected that manmade global warming would heat the Arctic faster than it would heat more temperate regions, and observation has borne that out. The Arctic is warming at least twice as fast as the rest of the globe, and the first two months of this year both had the lowest levels of sea ice on historical record.
“To lose coral reefs is to fundamentally undermine the health of a very large proportion of the human race,” said Ruth Gates, director of the Hawaii Institute of Marine Biology
Farther south, the Bering Sea has emerged as a hot spot for warming-water studies — almost literally. Sea-surface temperatures in the Bering reached 14 degrees Celsius last summer (57 degrees Fahrenheit) and were generally 3 degrees Celsius (5 degrees Fahrenheit) warmer than normal, scientists reported.
The Blob caused the water in the eastern Pacific to be both warm and low in nutrients, “conditions that are ripe for toxin production…”