How does rising atmospheric CO2 affect marine organisms?

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The Fire History of California's Lake Tahoe Basin
Beaty, R.M. and Taylor, A.H. 2009. A 14,000-year sedimentary charcoal record of fire from the northern Sierra Nevada, Lake Tahoe Basin, California, USA. The Holocene 19: 347-358.

What was done
Based on high-resolution charcoal analysis of a 5.5-m-long sediment core extracted from Lily Pond (393'26"N, 1207'21"W) in the General Creek Watershed on the west shore of Lake Tahoe in the northern Sierra Nevada in California (USA), as well as a 20-cm-long surface core that "preserved the sediment-water interface," the authors developed a 14,000-year record of fire frequency.

What was learned
Beaty and Taylor report that "fire episode frequency was low during the Lateglacial period but increased through the middle Holocene to a maximum frequency around 6500 cal. yr BP," which "corresponded with the Holocene temperature maximum (7000-4000 cal. yr BP)." Thereafter, as the temperature gradually declined, so too did fire frequency decline, except for a multi-century aberration they describe as "a similar peak in fire episode frequency [that] occurred between c. 1000 and 600 cal. yr BP during the 'Medieval Warm Period'," which they say was followed by an interval "between c. 500 and 200 cal. yr BP with few charcoal peaks [that] corresponded with the so-called 'Little Ice Age'." Ultimately arriving at the present, they found that the "current fire episode frequency on the west shore of Lake Tahoe is at one of its lowest points in at least the last 14,000 years."

What it means
As for the future, the two researchers state that "given the strong relationship between climate and fire episode frequency, warming due to increased levels of greenhouse gases in the atmosphere may increase fire episode frequency to levels experienced during the 'Medieval Warm Period'." And since the part of the planet they studied is currently experiencing one of the lowest levels of fire frequency of the last 14,000 years, it is clear that it is currently nowhere near as warm there now as it was during the Medieval Warm Period, when the air's CO2 content was much lower than it is today.

These facts stand out in sharp contrast to the climate-alarmist claim that the world's current level of warmth is greater than it has been at any other time over the past one to two millennia, which claim has also been debunked by numerous scientists working in many other parts of the world (see our Medieval Warm Period Project). As a result, this ever-accumulating body of data makes us wonder why it is currently so cool, especially if CO2 is the tremendous warmth-producing greenhouse gas the world's climate alarmists claim it to be.

Reviewed 22 July 2009