Part 1 here, part 2 here. In our previous two posts, we looked at the oldest thermometer temperature record, CET (central England temperatures), to determine if the last decade exhibited "unprecedented" absolute temperature changes versus the past (it did not). This post is going to look at whether the last decade was exhibiting "runaway" ("accelerated," "accelerating," "galloping," etc.) warming versus the historical past, as an add-on to Luboš Motl's previous findings.
In his analysis, he found that the growth (trend/slope) of temperatures for the last 10 years (2000-2009) was not exceptional versus the past. Using Excel, we've calculated additional growth rates (trends/slopes) that provide more time-period data points to analyze for those who are interested, plus a new, 'purty' graph. (click on the images to enlarge)
Examining the above grids on the left, there are only 4 years (see red rectangles) from last 10 years that exhibit 'top-ten' warming growth (degrees per century growth rate from the trend/slope). As can be seen, for the 30-year time periods, years 2007, 2006 and 2008 achieved top-ten slots but the rest of grid was taken up by 18th century years. Other than the year 2004 in the 10-year time period, the grids are void of recent years that we were told represented galloping warming.
Moving on, the graph on the right is displaying all 60-year periods and their respective growth trends (degrees per century growth rate). The right-side of the curve reveals the most recent years having 60-year spans of faster warming. But is this warming acceleration exceptional or extraordinary versus the past? Again, the early to mid-18th century (left-side of curve) truly is the era of unmatched "accelerated" warming, and unprecedented, absolute temperature change, as 'C3' posts (parts one & two) have documented.
Why did we choose the 60-year time periods to graph? It's now been 60+ years since CO2 emissions have exploded (1946 was the first large jump in human CO2 emissions). Global warming alarmists claim that years of human CO2 emissions have caused a "runaway" growth in temperatures. Even after 60+ years of CO2 growth, that claim rings hollow when compared to the pre-industrial growth rate of temperatures.
As an aside, you may have noticed that the trends got smaller as the time periods grew in number of years. In the case of ten-year trends, the top figure is 52.3 degrees per century. For sixty-year periods, the respective figure is 2.6 degrees per century. For the entire series, 351 years, the trend falls to 0.26 degrees per century. Those are huge differences in the slope of the trend line. That is why global warming alarmists are fixated on short-term trends that they love to extrapolate out into the future. But 350 some years from now, the actual trend line from 2010 on will look more similar to the 0.26 per century than say, the 52.3 degree/century trend - it's just the 'nature' of things when viewed in longer timescales.
Summary for the three CET posts: Temperatures in central England are at their warmest since 1659 (just forget about the the winter of 2010 for now). In contrast to previous temperature history, during the latter part of the 20th century or the beginning of the 21st century, have central England temperature changes been "unprecedented"? The answer is a definite no. In contrast to previous temperature history, during the latter part of the 20th century or the beginning of the 21st century, has the central England temperature trend (growth rate) been "galloping"? The answer is a definite no.
Are the CET dataset, trends and temperature changes a perfect proxy for global temperatures. The answer is no. Do they provide a good insight to the historical past of global temperatures and their long-term dynamic behavior? The answer is a strong yes. If long-term global temperatures were available from 1659 on, the general trends and absolute change characteristics we found for the CET would be similar to what a global temperature dataset would likely produce. Does this mean one could accurately calculate what global temperatures were some 350 years ago based on these CET findings? Wish it were so but the answer is a resounding, "no way."
