This is the first in a series of posts in which I look at monthly Temperature of the Lower troposphere (TLT) anomaly data from the University of Alabama- Huntsville (UAH) in different ways, which readers may find interesting and perhaps useful.
Fig. 1: Global UAH with linear trend
This is the standard presentation. It shows the linear trend as at November 2016. With every new month of data, the linear trend changes.
By calculating a running trend, that is, the linear trend from the start of the series to every subsequent data point, the trend at each point is preserved, and the trend at the final point is instantly calculated.
Fig. 2: Global UAH running trend
Figure 2 shows the historical values of the linear trend at each point, and that global temperatures are demonstrably non-linear. As I pointed out in Trending Trends: An Alternative View, each new data point will either increase, decrease, or maintain the trend. The longer the data series, the harder it will be to change the trend: the effect diminishes with time.
(An interesting result of the diminishing effect of temperature on the running trend is that it becomes possible to identify what temperatures are doing from the shape of the running trend plot- in fact, to identify a pause or plateau. To maintain the trend at say 1.2 degrees Celsius per 100 years, temperatures must continue to rise. A flat-lining running trend is evidence of increasing temperatures; a rising running trend indicates a rapid increase in temperature; but a decreasing running trend is evidence of a pause or decline in temperatures. This is not a different definition of the pause, just another indicator.)
For 10 to 15 years, the running trend swings wildly, but after this it settles. Now it becomes useful for analysis and comparison.
In Figure 2 above, note the large effect of the 1997-98 El Nino on the trend, but the 2009-10 and 2015-16 El Ninos have much less effect on the trend. They are still identifiable by the increase in trend.
Fig. 3: Regional UAH running trends
As we have seen previously, the North Polar and South Polar regions are distinctly different from the rest of the world and from each other. The North Polar region has had an increasing trend (rapidly increasing temperature) from 1994 to about 2007, then a slow down with another rapid rise in the last 12 months. All other regions have had decreasing trends since 2002-3, with an uptick in the last 12-18 months, indicating the duration of The Pause. The trend in the South Polar region has been much lower than the others, hovering about zero for the last seven or so years, and is currently negative.
For completeness, here are the running trends for continental USA and Australia.
Fig. 4: UAH running trends: USA 48 States
Fig. 5: UAH running trends: USA 49 States
Fig. 6: UAH running trends: Australia
The next plots compare Land, Ocean, and Mean running trends for the UAH regions.
Fig. 7: Global UAH running trends: Mean Land, and Ocean
Note that the mean trend is close to that of the Ocean, but since 1995 and especially 1998, the trend of global land areas is much higher. Because of the ocean’s large thermal inertia, land areas warm and cool more quickly. However, since the 1997-98 El Nino, land trends did not decrease but remained high until 2007. This graph, as any Global Warming Enthusiast (GWE) will tell you, is evidence of warming. What they won’t tell you is that it is evidence of any type of warming whether natural or anthropogenic- it is not by itself evidence of greenhouse warming.
Fig. 8: Northern Hemisphere UAH running trends: Mean Land, and Ocean
Fig. 9: Southern Hemisphere UAH running trends: Mean Land, and Ocean
Land trends in the Southern Hemisphere, unlike the Northern, did decrease after the 1997-98 El Nino.
Fig. 10: Tropical UAH (20N – 20S) running trends: Mean Land, and Ocean
Fig. 11: Northern Extra-Tropics UAH (20N – 90N) running trends: Mean Land, and Ocean
Fig. 12: Southern Extra-Tropics UAH (20S – 90S) running trends: Mean Land, and Ocean
This region warmed rapidly to 2002-3, then trends decreased.
Fig. 13: North Polar UAH (60N – 90N) running trends: Mean Land, and Ocean
Fig. 14: South Polar UAH (60S – 90S) running trends: Mean Land, and Ocean
In all tropical and northern regions, Land trends have been higher than Ocean trends since 1997-98 (2002 for South Polar and Southern Extra-Tropics). However, North Polar Ocean trends have been higher than Land since 1998. There is a greater area of ocean than land, and ocean areas have been warming more than land. This is the opposite of what greenhouse theory predicts. At the poles, where warming is expected to be greatest, only the North Pole is warming, and here the warming is not greatest over land, but over the ocean.
- Running trends are an effective way of showing the linear trend at any given month of a data series.
- They are useful for comparison and analysis after the first 10 to 15 years (the early 1990s).
- A declining running trend indicates flat or declining temperatures, thus The Pause is visible from 2002-3 to 2014-5 in all regions apart from North Polar.
- The North and South Polar regions are distinctly different from other regions and each other.
- Apart from North Polar region, all regions show land areas warming more than ocean areas, indicating warming from whatever cause.
- In the North Polar region, TLT running trends of ocean areas have been higher than land.
- These trends, especially at the poles, are not consistent with greenhouse theory.
The next post in this series will use running trends to derive running detrended data.