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Tuesday, June 16, 2009

The USGCRP Report “Global Climate Change Impacts in the United States” Fails To Acknowledge the Multiyear Effects of ENSO on Global Temperature

The USGCRP report “Global Climate Change Impacts in the United States" was released today. Link to report:

As noted in the title, it fails to address the multiyear effects of El Nino-Southern Oscillation (ENSO) events on global temperature.

Other than explosive volcanic eruptions, El Nino-Southern Oscillation events have the greatest impacts on global climate on annual and multiyear bases. The year-to-year global temperature impacts of ENSO events are clearly visible in a comparative time-series graph, Figure 1. Also visible are the overriding effects of the 1982 El Chichon and 1991 Mount Pinatubo volcanic eruptions.
Figure 1

The multiyear impacts of the 1986/87/88 and 1997/98 El Nino events on Northern Hemisphere Lower Troposphere Temperature (TLT) are clearly visible in the TLT Time-Latitude Plot available from Remote Sensing Systems (RSS). Refer to Figure 2 and 3, which are from my post “RSS MSU TLT Time-Latitude Plots...Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone.”
Figure 2
Figure 3

A seldom-discussed, naturally occurring oceanic process called Reemergence (Refer to my post “The Reemergence Mechanism”) provides the mechanism by which the global oceans integrate the effects of ENSO events. And it only takes the cumulative effect of a very small portion (0.0045 or less than ½ of 1%) of the monthly ENSO signal, as shown in Figure 4, to reproduce the Global Sea Surface Temperature (SST) anomaly curve.
Figure 4


The USGCRP mentions "El Nino" nine times in the body of the 196-page report, but those references only pertain to global temperature on one occassion. The first reference, however, states that ENSO is independent of human activities.

On page 16, during a discussion Natural Influences, they wrote, “The climate changes that have occurred over the last century are not solely caused by the human and natural factors described above. In addition to these influences, there are also fluctuations in climate that occur even in the absence of changes in human activities, the Sun, or volcanoes. One example is the El Niño phenomenon, which has important influences on many aspects of regional and global climate.” [My emphasis.]

They acknowledged that ENSO is independent of anthropogenic, solar, and volcanic aerosol influence. That’s significant, but they provide no sources to back the statement.

On page 17, in the text of the comparative graph of “Global Temperature and Carbon Dioxide”, they wrote, “These year-to-year fluctuations in temperature are due to natural processes, such as the effects of El Niños, La Niñas, and the eruption of large volcanoes.” [My emphasis.]

Yet they fail to note the multiyear and cumulative effects of ENSO.

Page 36, during a discussion of Pacific Hurricanes, they write, “The total number of tropical storms and hurricanes in the eastern Pacific on seasonal to multi-decade time periods is generally opposite to that observed in the Atlantic. For example, during El Niño events it is common for hurricanes in the Atlantic to be suppressed while the eastern Pacific is more active. This reflects the large-scale atmospheric circulation patterns that extend across both the Atlantic and the Pacific oceans.” [My emphasis.]

That quote is important in many contexts. Much can be inferred from it. Yet they fail to acknowledge the multidecadal epochs when El Nino or La Nina are dominant. These epochs are visible in a time-series graph of smoothed NINO3.4 SST anomalies, Figure 5.
Figure 5

On page 38, under the heading of Snowstorms, they wrote, “The northward shift in storm tracks is reflected in regional changes in the frequency of snowstorms. The South and lower Midwest saw reduced snowstorm frequency during the last century. In contrast, the Northeast and upper Midwest saw increases in snowstorms, although considerable decade-to-decade variations were present in all regions, influenced, for example, by the frequency of El Niño events.” [My emphasis.]

And again, they infer multidecadal influences of ENSO, but the USGCRP have failed to account for it in their attribution of global temperature change.

There are further references of El Nino and La Nina events on pages 81, 147, 148, and 152, as they pertain to tuna stock, droughts, coral reefs, and coastal currents. No need to repeat those in this post.


Like the IPCC, the USGCRP either fails to accept the significant multiyear and cumulative impacts of ENSO on global temperatures or they chose to ignore them in their presentation of the causes of global temperature change.

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