Intensifying sun and increased CO2 a 'double-whammy' for climate change
The sun is getting stronger and Earth has only escaped a frying because plants sucked up the extra carbon dioxide, reducing the heat caught in the atmosphere. But that's all changing as the burning of fossil fuels ramps concentrations of CO2 back up. A new study, published in Nature Communications , traced how atmospheric CO2 changed over the past 420 million years, providing researchers a key clue as to how Earth's delicate heat balance was maintained. A leading Kiwi researcher said humans had already wound back the clock on CO2 by three to four million years, with current estimates at 400 parts-per-million, effectively creating a double-whammy for global warming. READ MORE: * Eating the shore: New Zealand's shrinking coastline * Sea level rise could swamp some New Zealand cities * Editorial: Doubting climate change science is no joke * Climate change education missing in New Zealand schools "At that time, temperatures were a couple of degrees or so higher than now, but sea levels were around 10 metres higher than present, worldwide," Victoria University climate scientist James Renwick said. Reversal of CO2 trends could eventually result in warming of up to 10 degrees Celcius, he said. "If we keep burning the oil and coal, we would eventually put atmospheric CO2 back where it was several hundred million years ago when the sun was a lot dimmer. With today's intensity of sunlight, the earth could get very warm," he said. "Our burning of fossil fuels is emitting, in the space of a century or two, huge quantities of carbon laid down over millions of years. The rate of release is hundreds of times faster than anything we know of from the past." The new study predicting a failure to curb fossil fuel emissions could see atmospheric CO2 levels reach concentration not experienced for 50 million years by the end of the century. Renwick said that could equate to temperatures between 7dC and 8dC higher than present, with sea level rise of 50 metres or more higher than present, a state we would be locked into for several hundred years. "Essentially all the ice on Antarctica and Greenland would melt," he said. "The issue is that tens of metres of sea levels rise, plus wholesale changes in rainfall patterns and heat extremes means that billions of people would be displaced and global food production would fall to a small fraction of what it is at present. That is, many billions of lives would be put at risk." Otago University climate scientist Jim Salinger said inaction from the likes of the United States, Australia and New Zealand was creating a dim outlook for the planet. "There is potential for a runaway effect if we don't curb emissions quickly." Salinger said to lock the same CO2 back into the ground would likely take hundreds of years, with the need to grow trees, chop them down, and bury them. "We are going into uncharted territory in terms of human existance."