Google that phrase and you get 1,270,000 hits. Here is a sample of some of the first links in that list.
Aug 23, 2004
“Scientists at the National Center for Atmospheric Research say global warming will bring about more frequent and more intense heat waves in the United States and Europe.”
Oct 14, 2008
“August 2003 was the warmest August on record in the northern hemisphere, but according to the projections of the Intergovernmental Panel on Climate Change (IPCC), even more extreme weather events lie ahead. By the end of the century, the world’s average temperature is projected to increase by 2.5-10.4 degrees Fahrenheit (1.4-5.8 degrees Celsius). As the mercury climbs, more frequent and more severe heat waves are in store.”
July 8, 2010
“Exceptionally long heat waves and other hot events could become commonplace in the United States in the next 30 years, according to a new study by Stanford University climate scientists.”
July 10, 2010
“Targets set by policy makers to slow global warming are too soft to prevent more heatwaves and extreme temperatures in the United States within a few years, with grim consequences for human health and farming, a study has warned.”
Undated from NOAA
“more intense, more frequent and longer-lasting heat waves.”
Oh, but the warmists will complain that these are not peer reviewed papers. But these are:
Science 5 December 2003:
Vol. 302 no. 5651 pp. 1719-1723
Modern Global Climate Change
Thomas R. Karl and Kevin E. Trenberth
Modern climate change is dominated by human influences, which are now large enough to exceed the bounds of natural variability. The main source of global climate change is human-induced changes in atmospheric composition. These perturbations primarily result from emissions associated with energy use, but on local and regional scales, urbanization and land use changes are also important. Although there has been progress in monitoring and understanding climate change, there remain many scientific, technical, and institutional impediments to precisely planning for, adapting to, and mitigating the effects of climate change. There is still considerable uncertainty about the rates of change that can be expected, but it is clear that these changes will be increasingly manifested in important and tangible ways, such as changes in extremes of temperature and precipitation, decreases in seasonal and perennial snow and ice extent, and sea level rise. Anthropogenic climate change is now likely to continue for many centuries. We are venturing into the unknown with climate, and its associated impacts could be quite disruptive.
“Even with these uncertainties, the likely outcome is more frequent heat waves, droughts, extreme precipitation events, and related impacts (such as wild fires, heat stress, vegetation changes, and sea level rise) that will be regionally dependent.”
Science 13 August 2004:
Vol. 305 no. 5686 pp. 994-997
More Intense, More Frequent, and Longer Lasting Heat Waves in the 21st Century
Gerald A. Meehl and Claudia Tebaldi
A global coupled climate model shows that there is a distinct geographic pattern to future changes in heat waves. Model results for areas of Europe and North America, associated with the severe heat waves in Chicago in 1995 and Paris in 2003, show that future heat waves in these areas will become more intense, more frequent, and longer lasting in the second half of the 21st century. Observations and the model show that present-day heat waves over Europe and North America coincide with a specific atmospheric circulation pattern that is intensified by ongoing increases in greenhouse gases, indicating that it will produce more severe heat waves in those regions in the future.
GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L02202, doi:10.1029/2003GL018857, 2004
“Model results suggest that under enhanced atmospheric greenhouse-gas concentrations, summer temperatures are likely to increase by over 4C on average, with a corresponding increase in the frequency of severe heat waves.”
This should be enough sampling to make the statement that AGW theory predicts there will be more heat waves in the summers ahead.
What is the definition of a heat wave? There really isn’t a formal definition, but Environment Canada’s is more than 2 days in a row above 32C. Thus a “heat wave” are days when the summer TMax is at its highest.
This is easy enough to check to see if indeed TMax has been increasing by looking at the summer daily TMax for specific locations. One cannot use anomalies for this test. The definition is specific to a definitive temperature – hot. Hence specific locations of daily TMax will be needed to check this.
This analysis will look at locations on opposite sides of the planet, Canada and Australia. The stations picked were based on location on their respective continents as well as having the longest possible recordset. Three locations from each continent were picked spanning as much of their continent as possible.
Each location will have three tests run to cover the bases on what a “heat wave” is. The first test will be tracking the highest TMax reached for each year to see if that has been increasing. The second test will count the number of “hot” days for each year, that is, over a threshold temperature. The third test will look at which years are setting daily record highs.
Ottawa, Ontario, Environment Canada Station 4333.
Figure 1a: Yearly Highest Summer Tmax. Summer being June to August. The trend is clearly dropping on the hottest years.
Figure 1b: Number of days above 29.9C. Trend is clearly for fewer hot day
Figure 1c: Record setting years for July. It is clear that the early 1900’s dominate the record setting temps. Only 6 of the 31 records are after 1950. The all time high of 37.8C was July 4, 1921 and July 30, 1916. Notice the latest year, 1995 (July 14) is one of the lowest temps in the list of records.
Muenster, Sask, EC Station 2973
Figure 2a: Summer yearly Tmax. Notice the distinct increase from 1904 to 1946. Down over all from 1936 to 2009, and completely flat since 1970.
Figure 2b: Count of summer days above 29.9C. Clearly the 1930s and 1940s have more days 30C and above than the recent years. Clearly there are not more hotter days in the last 30 years than at the middle of the 1900’s.
Figure 2c: Record temperature days for July. Notice the years are mostly before 1950, only 9 years after 1950 were record days, with the highest of 41.1C July 19, 1941 dominating.
Fort St James, BC, EC Station 588
Figure 3a: Summer yearly Tmax. There is a modest increase from 1900 to 1940. Completely flat over all since 1900.
Figure 3b: Count of summer days above 29.9C. There are slightly more days at the beginning of the 1900’s, but over all there is no change in the number of hot days.
Figure 3c: Record temperature days for July. Notice the years are mostly before 1950, only 8 years are after 1950 were record days, with the highest of 36.7C July 17, 1941.
The trend is clear for Canada, there is no indication of any kind of increase in Tmax in the summer. In Ontario summer Tmax is dropping, where as elsewhere it’s flat, no increase in hot summer days. Record setting hot days are mostly prior to the 1950’s.
Darwin, Station 014015
With Darwin being so close to the Equator, they essentially have summer all year. This graph shows the monthly highest Tmax range for the years 1941 to 2010, which is all the available data. This is going to be a problem because from mid 1940’s to mid 1970’s is acknowledged to be a cooler trend after the increase from 1900 to 1945. Not having that range at this location means there is no way to know if any warm trend after 1975 is unusual and didn’t happen prior to 1941.
Figure 4a: Tmax range per month. Red is the highest TMax, blue is the lowest TMax with the black line the average of all the points between those two. October is the hottest month for Darwin with August the coolest, if low 30C can be considered “cool”.
Figure 4b: Hottest yearly Tmax, regardless of month. There is a modest increase from 1941 to 2010. Though flat since 1970, there is a significant increase in Tmax since 1995, though not above the all time high in 1982.
Figure 4c: Count of October days above 35C. Since 1995 there has been an increase in the number of days, corresponding to the increase in Tmax over the same period.
The next figure would be record temperature days for October, like whatwas done for the Canadian stations, but this dataset is way too small. There is no way we can know if any of the temps since 1941 have anything record breaking without longer data. Record breaking days is more of an accounting issue than a temperature trend issue. With such a short dataset it is meaningless.
Alice Springs, Station 015590
Like Darwin, a short recordset. This graph shows the monthly highest Tmax range for the years 1941 to 2010, which is all the available data.
Figure 5a: Tmax range per month. Red is the highest TMax, blue the lowest TMax with the black line th average of all the points between the other two. January is the hottest month for Darwin with July the coolest.
Figure 5b: Hottest yearly Tmax, regardless of month. There is a modest steady increase from 1941 to 2010. Notice 2010 was one of the coolest summers, getting to “only” 41.3C.
Figure 5c: Count of October days above 42.9C. Seems to have peaked in 1998, are we seeing a cycle?
As with Darwin, there is no way we can know if any of the temps since 1941 have anything record breaking without longer data.
Melbourne, Station 86071
Now we have a nice long recordet, from 1855 to 2010 This graph shows the monthly highest Tmax range all years.
Figure 6a: Tmax range per month. Again, highest TMax is in red, the lowest in blue with the average in black. Feburary is the hottest month with July the coolest.
Figure 6b: Hottest yearly Tmax, regardless of month. Over the entire range the trend is completely flat. No increase. Blue line is the 10 year moving average. There is no reason to attach any significance to the trend on the right. The last 30 years contained both the coolest summer (35C in 1984) as well as the highest (46.4C in 2009)
Figure 6c: Count of Feburary days above 39.9C. No trend. Having a longer dataset definitely is required to get the “big picture.”
Figure 6d: Record setting dates for Feburary. Half the years are before 1950, 14 days are after 1950. 2009 was quite the anomalous year, with a record high of 46.4C on the 7th of Feb. There is no indication from this data that any other recent years built up to 2009.
What does this sampling of stations tell us about the predictions of more heat waves? It’s pure speculation. There is no indication that there is any kind of increase in the summer maximum temperatures.
If these stations on opposite sides of the earth are not a fair representation of what’s going on globally, it begs the question. Which locations are these climate scientists looking at that do have summers increasing temperatures?