Word: co2
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...problem is that biofuels are treated as if they were 100% carbon neutral, even though they are clearly not. When ethanol is burned, for instance, it still releases CO2 into the atmosphere. After all, the plants that go to make biofuels are made of carbon, just as oil and other fossil fuels are. Further, the use of biofuels would reduce total greenhouse-gas emissions only if their creation were to increase - or at least not displace - existing plant growth, which naturally takes carbon out of the atmosphere. For example, if the wood chips left over from logging were used...
...Indonesia and replaced with a plantation of palms to make biodiesel. That's where the accounting error crops up: we should assess the carbon lost in deforestation when we measure the greenness of biofuels, but that's not how it works under Kyoto, which simply exempts all CO2 emissions that come from using biofuels. CO2 emissions resulting from deforestation or other changes in the way we use land are not evaluated at all. The result is a huge, if accidental error in the existing global carbon accounting system - and one that now stands to be repeated...
...estimates that if the world were to meet a 50% "cut" in global greenhouse gases by 2050 under the current calculations, the necessary biofuel-crops expansion would be large enough to displace 59% of the world's natural forest cover - which would release an additional 9 billion tons of CO2 a year. "Carbon capture and storage, solar power, electric batteries - all of these alternatives have serious costs," says Searchinger. "But if you can just use up the world's carbon in forests to meet your cap, that turns out to be pretty cheap...
These scientists aren't the first to look at the chemistry of foraminifera; the fossils are abundant in ancient ocean sediments, so they're a particularly good tracer of the past. But they used a new technique to measure CO2: looking at how much of the element boron was present in the foraminifera's shells. When there's lots of CO2 in the air, there's also more in the top layers of seawater, where the relevant species of foraminifera live. That makes the water more acidic, which in turn makes the tiny animals incorporate less boron into their shells...
...reasonable, in theory, and Tripati and her colleagues made sure to use two species of foraminifera that are still around ("You can grow them in the lab," she says), just in case the effect varied from one species to another. Beyond that, they compared their own foraminifera-based CO2 estimates for the past 800,000 years with the measurements from the ice caps - and, says Tripati, "they matched to within 20 p.p.m." That makes her and her colleagues confident that the older measurements are valid as well...