The end of reefsClimate scientists speak of “tipping points” regarding the way the plane

The end of reefsClimate scientists speak of “tipping points” regarding the way the planet will respond to increasing greenhouse gases. Tipping points are “points of no return” – where the time it will take for the planet to recover is measured not in human lifetimes but in geologic time.There are obvious examples of these. If the Greenland or Antarctic Ice Sheets were to completely collapse, it would take hundreds of thousands of years to regrow them. If large amounts of methane-bearing ice were destabilized, releasing the methane to the atmosphere and causing runaway heating (as likely happened 56 million years ago), that is another kind of tipping point.Well I have some bad news. The 2015-2016 El Niño is a tipping point. The planet Earth is now on a path to no longer having live coral reefs.Coral are keystone species. The reefs built by their skeletons alter ocean currents, creating areas protected areas where nutrients become available and supporting entire ecosystems. They are the ocean equivalent of tropical rainforests – supporting diversity of life that doesn’t exist anywhere else on Earth.Corals are extremely sensitive. Corals are symbionts, living with a photosynthetic algae called zooxanthellae. The algae provide the coral with food; the corals provide the algae with shelter. But, this symbiosis only survives over a narrow range of temperature and acidity. If the ocean conditions change too much, typically a change of a little more than 5°C, the algae produce toxins that cause the coral to expel them. This situation removes the coral reef color, leading to the name “bleaching”.Bleaching is not necessarily fatal to all coral. During a severe bleaching event some coral will die, but enough of the algae can return to the reef to keep some polyps alive, allowing it to rebuild if conditions return to normal. A few generations later, a coral reef can recover from a single bleaching event. But that is not what humans have done.1998 saw the first “Super El Niño” of the modern era, an El Niño that broke all records for ocean conditions. 1998 was also the first global coral bleaching event; ocean temperatures were abnormally high across so many reefs around the world that it was more surprising to find a reef that didn’t have a bleaching event.Most reefs survived 1998, but things have only gotten worse since then. Global temperatures have continued going up, and as a consequence a much smaller El Niño in 2010 triggered the second officially declared global bleaching event. The 2010 El Niño was much less intense than the 1997-1998 El Niño, but because the oceans had absorbed more heat since then the smaller El Niño was enough to trigger a second bleaching event. A small El Niño triggered the bleaching in 2010, while only a record El Niño triggered it in 1998.That leads us to 2015, an El Niño that blew 1998 out of the water. In 1998, waters out of the temperature range for corals were unusual; when the coral bleaching event happened it hit corals that weren’t previously stressed. When the 2015 El Niño hit, the corals were already stressed, with a major bleaching event only a couple years ago and oceans warm enough to stress coral in-between. Then, an El Niño hit that was far beyond 1998. For many reefs, that was the last straw.For years, scientists like Kim Cobb from Georgia Tech have been surveying coral reefs like that on Kiritimati (Christmas) Island; one of the largest coral atolls in the world that happens to be found right in the middle of the Pacific Ocean where the peak of the El Niño warming hits. Dr. Cobb just returned from visiting her field sites in March and described the results as “devastating”.A bleached coral reef can survive, but so many bleachings eventually will kill the entire ecosystem. When Dr. Cobb’s team visited the island in November the corals were bleached; in March they were barren. The coral were no longer just bleached; their dead skeletons had been occupied by a “red-brown fuzz”, an algae that takes over their dead bodies. Where a live reef supports a vibrant ecosystem, this reef was a graveyard.This reef is just one of many. Reefs near Florida are experiencing their 3rd consecutive bleaching year; something that no reef has ever been known to survive. Reefs elsewhere will likely suffer the same fate as those on Christmas Island, but researchers haven’t visited them yet. But the true disaster, the global tragedy is hitting the Great Barrier Reef near Australia.Researchers regularly investigate that reef and the northern half of that reef is a disaster. Right now, more than ½ of the coral on the northern half of the reef are bleached and it is not the first stress; many may not survive. The reef is also fighting threats from tourists and from the crown-of-thorns starfish, which tends to breed more effectively during warm years.The southern half of the Great Barrier Reef may survive 2016 by an accident of weather; that part of the reef was hit by tropical cyclone Winston after it devastated Fiji (https://tmblr.co/Zyv2Js226_0LA), stirring up cold water that protected that part of the reef. That part may survive this year, but the stress isn’t going away. The Great Barrier Reef, a feature unmatched on this planet, is dying right now. Before our eyes. The Great Barrier Reef is doomed.2016 is the first year where humans can literally see that we’re witnessing the end of coral reefs. Through climate change, humans have pushed the oceans to a point where the normal extremes of temperature are so intense that the modern coral reefs will not survive. Some parts of some reefs will survive this year, but when the next El Niño hits in a few years, those parts will be even more exposed. The ecosystems that died this year are gone forever, and that is now the fate of the world’s tropical reefs.If humans stopped emitting greenhouse gases right now, the worlds oceans would still keep warming and acidifying over the next several decades. We will still lose almost all of the reefs on this planet. At this point the Christmas Island reef and those like it are already dead, and the Great Barrier Reef is on an unavoidable path to that same death. Humans can no longer stop it.We have reached a tipping point; the Earth’s coral reefs will not survive what we have done to this planet. Over geologic time, coral will find new niches and build new reefs that adapt to the new climate conditions, but that will take hundreds of thousands of years.Estimates suggest that more than 50 million people right now rely on coral reefs for their livelihoods. Those livelihoods will not survive the next few decades, if not the next 5 years. Researchers who worked for the last few decades on live reefs will now constrain the death of those reefs.I cannot sum this situation up better than Slate Climatologist Eric Holthaus, who tweeted this week: “I think our grandchildren will be astounded that coral reefs ever existed, just as we are that buffalo freely roamed the prairies.”Humans have killed coral reefs. We have killed the most vibrant ecosystems in the ocean. The next time I pick up an aluminum can discarded along the side of the street, and throw it in the recycling bin to slightly cut global carbon emissions, that’s what I’m going to think. It’s no longer enough. Coral reefs have crossed their tipping point; they’re lost. And there is nothing else I can do or say.-JBBImage credit: XL Catlin Seaview Surveyhttp://bit.ly/1SgLK0AIf you’re on twitter and not following them you should be:https://twitter.com/coralsncaveshttps://twitter.com/EricHolthausEric’s quoted tweet:https://twitter.com/EricHolthaus/status/720692690061385728Other references:http://www.slate.com/authors.eric_holthaus.htmlhttp://bit.ly/1j7fLjwUnbelievable NYTimes Article: http://nyti.ms/1S4hbLzhttp://bit.ly/1XeEH8Dhttp://1.usa.gov/1LnZXlYhttp://bit.ly/1RZZpduhttps://www.wunderground.com/climate/PETM.asp?MR=1*Yes, this post deserved 1300 words. Thank you for reading to this point; please share. Your friends may not hear of this otherwise. -- source link
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