Climate change pledges not nearly enough to save tropical ecosystems

By Jeremy Hance
16 August 2016 (mongabay.com) – The Paris Agreement marked the biggest political milestone to combat climate change since scientists first introduced us in the late 1980s to perhaps humanity’s greatest existential crisis. Last December, 178 nations pledged to do their part to keep global average temperatures from rising more than 2 degrees Celsius (3.6 degrees Fahrenheit) over preindustrial levels — adding on an even more challenging, but aspirational goal of holding temperatures at 1.5 degrees Celsius (2.7 degrees Fahrenheit). To this end, each nation produced a pledge to cut it’s own carbon emissions, targeting everything from the burning of fossil fuels to deforestation to agriculture. It seems like a Herculean task, bound, the optimistic say, to bring positive results. Yet, less than eight months later, a study in the journal Nature finds that those pledges are nowhere near as ambitious as they need to be to keep temperatures below 2 degrees Celsius, let alone 1.5 degrees. And in August, British scientists reported that this year’s record El Niño has already pushed us perilously close to the 1.5 degree milestone. Meanwhile, temperatures are not rising evenly around the planet, with the Arctic warming far faster than the tropics. That fact originally caused scientists to hypothesize that polar ecosystems would suffer more dire climate change impacts ahead of tropical habitats. But over recent years, researchers began seeing that some tropical ecosystems are being decimated by climate change far faster than expected — think coral reefs — while many more habitats may be crippled over time — think mangroves, cloud forests and rainforests — if global human effort and political willpower don’t surge quickly. Study leader, Joeri Rogelj, told Mongabay that he wasn’t surprised by his findings showing that current national carbon reduction pledges would blast past the 2 degree target, leading to global warming of between 2.6 degrees Celsius and 3.1 degrees Celsius. “The pledges currently on the table are a first step in a continuous process of pledging, reviewing, and taking stock to what they add up,” said Rogelj, a Research Scholar at the Energy Program of the International Institute for Applied Systems Analysis (IIASA). “This process has been defined by the Paris Agreement, and nations are thus expected to review and adjust their pledges in light of the best science over the coming years.” The Paris Agreement was structured from the bottom up, whereby national pledges would be reviewed every 5 years (beginning in 2020) in order to make sure that carbon cut targets are boosted as time goes by. Still, Rogelj cautioned, if pledges aren’t sufficiently ramped up – and followed through on – it will make achieving the 2 degrees Celsius goal “significantly more ambitious” after 2030. […] “We’re kidding ourselves that a 2 degree Celsius global increase will be safe for coral reefs and for the people who depend on them, given the damage we’re already seeing,” Terry Hughes bluntly stated in a Mongabay interview. “Most reefs have already bleached three or more times in less than 20 years,” explained Hughes, who is the Director of the Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies. He points to his own country’s global warming-catastrophe: the Great Barrier Reef. Super-warm waters this year led to around half of the coral in the northern section of the Great Barrier Reef dying off. In some places, nothing is left but white coral ghosts. These massive changes came far earlier than were forecast by climate models. […] Mark Urban, with the University of Connecticut, in a study last year looked at extinction risks for species linked to climate change. To get the best estimate possible, Urban analyzed findings from 131 studies. He found that currently 2.8 percent of species face extinction due to climate change — this with a warming of around 0.9 degrees Celsius. If that warming jumps to the Paris pledged 2 degrees, extinction rates could rise to 5.2 percent of all species on the planet. And if we hit 3.1 degrees Celsius this century, as projected by Joeri Rogelj’s study, which totaled up the current Paris pledges and the maximum temperature rise they could bring? Then we could lose 9 percent of the world’s species due to global warming. That’s nearly one-in-ten species facing extinction from climate change — and of course that doesn’t figure in extinction from other human induced threats like habitat degradation and destruction, deforestation, pollution, overharvesting, poaching, invasive species, or a lethal combination of any two or more of these combined with climate change. [more]