Word: co2
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Dates: during 2000-2009
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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...
...they're right, it could be pretty bad news, even for those who already worry about rising CO2. It's generally agreed that during the earlier warm period, known as the Miocene Climatic Optimum, which occurred 15 million years ago, the global temperature was high enough to make sea levels between 80 ft. and 130 ft. higher than they are today. According to the new study, CO2 levels in the atmosphere at that time hovered at from 390 to 430 parts per million (p.p.m.). Today's CO2 level: 387 p.p.m. and rising...
...course, an increase in CO2 (or any other heat-trapping greenhouse gas) can't lead to that kind of sea-level rise unless the CO2 level stays high for a while. The latest projections suggest a rise of 6 ft. at most by 2100, even if CO2 continues to increase at the current rate. But the new study implies that failing to tamp down emissions could eventually lead to a disaster worse than most climate Cassandras have dreamed of. (See pictures of the effects of global warming...
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...