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Heat Waves - Are They Becoming More Common?

By Joe D'Aleo
Monday, July 27, 2009

It has been a typical post La Nina hot late spring and summer in the southern plains and across the Deep South. Recently the heat built back into the Intermountain West and even the Northwest but the first half of summer has been unusually cool from the north central across the Midwest and Great Lakes to the Northeast, with some locations the first half of meteorological summer averaging 5F or more below normal. Although a warmer, more seasonably humid and wet early end of July is likely in the east as the Bermuda high presses inland, it will not last and it will remain cool to the west and in the end it will not be remembered as a hot summer. Indeed, in many areas, it may be remembered as “a year without a summer.”


Many farmers point back to 1992 as the most similar summer. It was a volcano summer (post Pinatubo). More on that next week.




The UN, NOAA and the EPA in their analyses based mainly on climate modeling, made the following claims:


Widespread changes in extreme temperatures have been observed in the last 50 years. Globally, cold days, cold nights, and frost have become less frequent, while hot days, hot nights, and heat waves have become more frequent.


Severe heat waves are projected to intensify in magnitude and duration over the portions of the U.S. where these events already occur, with potential increases in mortality and morbidity, especially among the elderly, young and frail.



There is no indication that record heat is increasing in frequency, in fact the data shows a precipitous decline in the number of heat records in recent decades. The early 20th century dominates the heat statistics for the United States and the world.


The forecasts are based on GCMs that have failed to catch the cooling this past decade and that even the IPCC Lead Author modelers like Kevin Trenberth agree “None of the models used by IPCC are initialized to the observed state and none of the climate states in the models correspond even remotely to the current observed climate. In particular, the state of the oceans, sea ice, and soil moisture has no relationship to the observed state at any recent time in any of the IPCC models.” IPCC Lead Author Trenberth in Nature 2007 weblog.  (Harvard Astrophysicist Willie Soon “…garbage in, gospel out”)



This for example is Hansen’s model bases forecast from 1988 senate testimony versus reality. Even his scenario C not shown which assumed CO2 was held steady (not the case) had more warming than observed. The UAH MSU satellite data here is used. 




The IPCC 2001 model projected warming reinforced in the 2007 update, also is failing to show the observed cooling. In this case the temperature is a blend of NOAA, Hadley land and ocean and satellite data from both RSS and UAH.





One of the model’s key features promised by Ben Santer is the warm spot in the middle atmosphere in low and middle atmosphere. Top left cross section. Satellites and weather balloons show this is not present (bottom left), falsifying the greenhouse models.





The Hadley based trends are similar to the satellite trends on the short term. Satellites go only back to 1979. Over the longer term the land based data is contaminated seriously by station dropout mostly rural (we now use 1079 stations compared to over 6000 in 1970). a tenfold increase in missing months, poor siting of instruments (90% of the 1000 US climate station surveyed the last two years have been classified as poor to very poorly sited based on the governments own criteria) and no adjustment for urbanization despite dozens of peer review papers pointing to the critical importance of this adjustment. These render long term (century) trend analysis unreliable but for short term trends, these issues can be ignored. You can see the down trend for Hadley and satellite is the same for the last 8 years.





The presumption that global heat waves and extremes have increased in frequency is not supported by the official government data. NOAA’s NCDC shows that record high temperature by continent have occurred mainly in the 1880s and early 1900s, with only 1 post 1950 (Antarctica in 1974).





In the United States, there has been almost a total absence of new statewide records. There was no evidence of extreme warming based on temperature extremes. This analysis using NOAA data was compiled by InfoPlease through 2004 and updated with NOAA record page.




The methodology biases the month/year point of the record to the latest incident of the record temperature.  If an old record is tied or surpassed, the record goes to the latest date.  Because these records are based on absolute temperatures and tie-goes-to-the-latest methodology, there is no favoring earlier points after a reasonable time has passed and 129 years and 2,354,250 daily observations is more than reasonable. In fact, the methodology actually biases toward the latest occurrences because it is a replacement methodology, not an additive one.  


When examined on a state by state basis, the 1930s jumps out as the warmest decade with 24 state records. 37 records occurred before the 1970s.





In Des Moines, Iowa, a continental climate far away from any large scale maritime influence, one would expect to see the effects of global warming extremes most. However that is not the case in the peak heat months of June and July. The last record highs in the months of June and July were in 1988. Here again, the 1930s dominate with 33 of the possible 61 record daily highs.




In Central Park, New York, where urbanization warmth is certainly an issue, the peak warmth again occurred early in the period with 100F days peaking in the 1930s and 1950s and 90F degree days the 1940s, a secondary maximum occurred in the 1990s but the number of extreme heat days with one summer to go has declined this decade.


Source NWS Central Park90F days, 100F days



The heat was clearly most dominant in the middle of the 20th century with “secondary smaller max in recent decades. There is no evidence of an increasing trend.


The state record lows actually peaked in the 1960s and 1980s but were very low early and late in the record. Combined with the record high, this decade is unusually benign with an absence of extremes, not an increase. Fewer record lows with no corresponding increase of record highs actually is a benefit not a liability as it reduces need for heating (energy).




In summary, the increasing heat wave notion comes entirely from model forecasts, models which are failing.





The claim that warming increases morbidity rates is also a myth. Dr. Robert Mendelsohn, an environmental economist from Yale University argues that heat-stress deaths are caused by temperature variability and not warming. Those deaths grow in number not as climates warm but as the variability in climate increases. The deaths are greater in northern climates when sudden heat waves occur and were the populace has not adapted to heat. Excess deaths are greatest in metropolitan areas among the elderly and when the nighttime readings stay high (80F) or greater and the heat lasts more than a few days. After an event like that the populace adapts.


As Nico Stehr and Hans von Storch in an essay in 2005 noted: Adaptation, by contrast, works. Precautionary and preventative measures are effective in preventing fatalities from heat, for example. While a tragedy occurred in Chicago in mid-July 1995, with more than 700 “heat deaths,” in the same summer the so-called “hot weather health warning watch system” saved the lives of about 300 people in the city of Philadelphia. The occurrence of extremely high temperatures in Philadelphia in 1993 and 1994 prompted the development of an efficient warning system and social networks that benefited the elderly and other persons at risk.


What does this mean? In reality, it was the isolation of elderly people in Chicago who did not know how to help themselves, or the poverty (and thus also: helplessness), which was much worse in this region ten years ago, that led to the high number of fatalities.”


A similar story can be said for the heat waves in Europe in 2003. The timing of the event (summer vacation where most families went to the oceans while mostly the elderly remained in homes without air conditioning) led to excess premature deaths. Subsequent hot days in more recent years have not brought the same results.

Indur Glokany in Death and Death Rates Due to Extreme Weather Events, in 2007 showed deaths from all extremes for 1979-2002. It showed death from extreme cold continues to exceed death from extreme heat.





Death Risk may be increased by policies that limit reliable traditional energy sources in favor of renewables such as wind power which increase the likelihood of brownouts and blackouts. It is during the normal heat waves, that energy demand is the greatest. Also during extremes of heat and cold, high pressure dominates, causing winds to be below the threshold for energy generation. This has already been shown in Texas, California and the UK (see link). This policy not the weather if implemented would put the population at enhanced risk.





Goklany, I.M.; Straja, S.R. 2000. U.S. death rates due to extreme heat and cold ascribed to weather, 1979–1997. Technology, 7S, 165–173.


Ching-Cheng Chang, Robert O. Mendelsohn, Daigee Shaw: 2003, Global warming and the Asian Pacific, Edward Elgar Publishing, ISBN 1843764199, 9781843764199, 307 pages (Chapter 11)


Hall, B. Hall of Records: 2009 Bruce Hall web site - supporting analysis here and here


Mendelsohn, R., Nuemann, J.E., 1994,  Impact of Climate Change on United States Economy, Cambridge University Press, Cambridge


Trenberth, K. 2007: Predictions of climate. Posted on Climate Feedback, The Climate Change Blog, June 4, 2007.