Originally Posted by
TexasBob
• Carbon dioxide concentration has been continually rising for nearly 100 years. It continues to rise, but carbon dioxide concentrations at present are near the lowest in geologic history. Gotta be kidding me.
• The greenhouse effect of carbon dioxide logarithmically declines with increasing concentration. True. At present levels, any additional carbon dioxide can have very little effect. Again, kidding, right?
• During the last 100 years, temperature has both risen and fallen, including the present cooling. All the changes in temperature of the last 100 years are in normal historic ranges, both in absolute value and, most importantly, rate of change. The rate of change right now is not in any way in a normal historic range.
• Voluminous historic records demonstrate the Medieval Climate Optimum (MCO) was real and that the “hockey stick” graphic that attempted to deny that fact was at best bad science. The MCO was considerably warmer than the end of the 20th century.
• Polar bears have survived and thrived over periods of extreme cold and extreme warmth over hundreds of thousands of years - extremes far in excess of modern temperature changes. There are more factors involved than just this. You need to look at how they're actually doing now (instead of guesses), look at genetic diversity, population size, etc. to see if they can, as a species, withstand a severe change. Not really relevant to whether global warming is anthropogenic or not though.
• The 2009 minimum Arctic ice extent was significantly larger than the previous two years. The 2009 Antarctic maximum ice extent was significantly above the 30-year average. There are only 30 years of records. Again, kidding? 30 years of records? Have you heard of paleoclimate? If we only had 30 years of records about any of this stuff, we couldn't say a damn thing.