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Domain: carbonbrief.org
Stories and comments across the archive that link to carbonbrief.org.
Stories · 3
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Extreme CO2 Levels Could Trigger Clouds 'Tipping Point' and 8C of Global Warming (carbonbrief.org)
If atmospheric CO2 levels exceed 1,200 parts per million (ppm), it could push the Earth's climate over a "tipping point", finds a new study. This would see clouds that shade large part of the oceans start to break up. From a report: According to the new paper published in the journal Nature Geoscience, this could trigger a massive 8C rise in global average temperatures -- in addition to the warming from increased CO2. The only similar example of rapid warming at this magnitude in the Earth's recent history is the Paleo-Eocene Thermal Maximum 55m years ago, when global temperatures increased by 5-8C and drove widespread extinction of species on both the oceans and land.
However, scientists not involved in the research caution that the results are still speculative and that other complicating factors could influence if or when a tipping point is reached. The threshold identified by the researchers -- a 1,200ppm concentration of atmospheric CO2 -- is three times current CO2 concentrations. If fossil fuel use continues to rapidly expand over the remainder of the century, it is possible levels could get that high. The Representative Concentration Pathways 8.5 scenario (RCP8.5), a very high emissions scenario examined by climate scientists, has the Earth's atmosphere reaching around 1,100ppm by the year 2100. But this would require the world to massively expand coal use and eschew any climate mitigation over the rest of this century. Further reading: A state-of-the-art supercomputer simulation indicates that a feedback loop between global warming and cloud loss can push Earth's climate past a disastrous tipping point in as little as a century. -
The UK's CO2 Emissions Have Fallen 38% Since 1990, Faster Than Any Other Major Developed Country (carbonbrief.org)
The UK's CO2 emissions peaked in the year 1973 and have declined by around 38% since 1990, faster than any other major developed country. From a report: The most significant factors include a cleaner electricity mix based on gas and renewables instead of coal, as well as falling demand for energy across homes, businesses and industry. Declines in the UK's CO2 have persisted despite an economic recovery from the financial crisis a decade ago. Where earlier reductions were largely negated by rising imports, the past decade has seen genuine cuts in the amount of CO2 for which the UK is responsible. The factors driving emission reductions will likely continue into the future as the UK's remaining coal use is phased out by 2025. -
Antarctica Is Losing Ice Faster Every Year (qz.com)
A survey of satellite data published in the journal Cryosphere confirms what scientists have suspected for a while now: ice loss from the critical region of Antarctica is happening at an increasingly fast pace. Quartz reports: In total, researchers found that Antarctica lost roughly 1,929 gigatons of ice in 2015, which amounts to an increase of roughly 36 gigatons per year every year since 2008. (A gigaton is one billion tons.) Nearly 90% of that increase in loss occurred in West Antarctica, "probably in response to ocean warming," according to NASA. The new data analysis mostly confirms other recent research, but does so with a higher degree of precision by using a new technique that can process a larger amount of satellite data than was possible before.
West Antarctica has been losing a lot of ice in recent years, and at an ever-growing pace, while East Antarctica is losing ice more steadily. The West Antarctic ice sheet is of particular concern because, like a building that stands on an uneven foundation, it is inherently unstable, making it especially vulnerable to the warming climate. If the entire ice sheet were destabilized and melted into the sea, researchers estimate it would lead to 3 meters (9 feet) of sea level rise globally. Models suggest that under a low-emissions scenario, where the world commits to "peaking" and then steadily reducing emissions in the near future, complete destabilization of the West Antarctic ice sheet is possible to avoid. But under medium- or high-emissions scenarios, the loss of the ice sheet becomes inevitable.