Is World Warming Inflicting Huge Heatwaves? • Are you completed with that?

From the Cliff Mass Weather Blog

The media exaggerate heatwaves and claim that global warming/climate change caused by human emissions of CO2 is leading to a huge, sudden increase in massive heat events. The greatest in history. Heatwaves are everywhere on the planet! Phoenix, Arizona is an often-known poster child of the new heat wave regime.

Here are a few examples of headlines, I could name dozens more.

The quiz

Before I discuss the situation, I want to give you two options to consider.

(1) Human emissions of greenhouse gases such as CO2 lead to a slow warming of the planet. In the last century, the Earth has warmed by about 1°C, and human emissions may have contributed much (but not all) to the warming. El Niño periods contribute to transient warming, but local warming due to urbanization (urban heat island) is also important. Most heatwaves are predominantly natural phenomena, with minor amplification from global warming/climate.

(2) Heat waves are predominantly caused by rising greenhouse gas emissions. Due to man-made climate change, the entire planet is experiencing unprecedented heat. Reducing greenhouse gas emissions could greatly mitigate or prevent heat waves.

Which do you think is the correct answer? The one backed by observation and peer-reviewed science?

The correct answer is (1). Heat waves are mainly caused by natural fluctuations, with humans amplifying them to a small extent. Let me prove it to you and describe some of the hype and deception going on in the media and by others.

It is important to understand that the current heatwaves are localized and much of the planet is also experiencing cooler than normal conditions. Most of the planet is NOT experiencing unusual heat.

Consider the observed temperature pattern at 11pm on Tuesday evening, or more specifically the difference in observed temperature from normal (see below). Red areas are above normal and blue/green are below normal.

The figures show that the earth experienced both heat waves and cold waves at this time.

For example the Southwest of the USA. is warm, while much of the eastern US is colder than normal. Northern Europe is cold while southern Italy experiences heat.

So, heat waves are local (and temporary) conditions, and only a small part of the world experiences abnormal heat. Greenhouse warming from greenhouse gases is much more even.

So what is causing the local warming? The answer is very clear if we simultaneously draw the upper level map (for 500 hPa, about 18,000 feet) (see below). Blue areas indicate pitting (low pressure) and red areas indicate ridge formation (high pressure).

The warm areas are closely related to the uplift at elevation, the cool areas to the upper level troughing. Grooving is associated with sinking air and warming. The opposite is the case with the trough. Ridges and valleys also exhibit wind patterns that can move tropical heat poleward (and vice versa).

Such wave patterns are quite natural. There is no convincing evidence that global warming is causing the atmosphere to become more rippled (and therefore more hot and cold waves). I have read all of the literature on this and have published myself in the peer-reviewed literature on the subject.

Wave action in the upper current was particularly large this winter and spring, resulting in more cooling in some areas and warming in others. For example the cool/wet conditions in California and the warmth in southern Canada.

Let me repeat: there is no reason to believe that this ripple is anything other than a reflection of the natural variability of the atmosphere.

As the global temperature of the planet increases slowly (by about 1°C) due to human emissions of greenhouse gases, heatwaves should be about 1°C warmer and coldwaves about 1°C weaker.

This is exactly what is observed.

Incidentally, FAR more people die each year from extreme cold than from heat waves, so global warming is actually leading to a reduction in deaths from extreme temperatures (you won’t hear much about it in the media!)

But there is something else that is currently accelerating warming.

This spring, El Niño was surfacing quickly, and El Niños are warming the planet! Below is the key indicator for El Niño: the temperature in the central tropical Pacific (range Nino 3.4). A VERY rapid and early warming in April and May.

The variation between El Nino and La Nina (cold water) is a natural model of atmospheric variability.

Would there have been major heat waves without human-caused global warming?

You bet. Certainly we have had significant heatwaves (some as severe or stronger than this month) in the past (e.g., the 1930s). Have this week’s heatwaves been slightly amplified (about 1°C) by global warming? Quite possible. So in a place like Phoenix there would have been a high of 115F instead of 117F. Pretty much the same effects.

Media deception regarding Phoenix, Arizona

The media has been particularly interested in the recent hot spell in Phoenix, citing as headline news the record number of days above 110°F.

As I will describe below, there is more than a little deception at work here. The 110 degree approach is a Prime example of misinformationand the Phoenix temperature record is highly suspect due to massive development and a huge urban heat island effect.

Cherry picking stats.

The term “cherry picking” can be defined as follows (Wikipedia):

Cherry-picking, the suppression of evidence, or the fallacy of incomplete evidence, is the act of pointing out individual cases or data that appear to support a particular position while ignoring a significant subset of related and similar cases or data that might contradict that position.

The media and some climate activist groups have touted that Phoenix has now broken the 110F mark for a record number of consecutive times. So something unusual and frightening is happening.

But why 110F? Did you wonder about this?

They did this on purpose because if they had chosen a different temperature they would have gotten a completely different answer, one where Phoenix was not abnormally warm.


Consider a choice with a difference of two degrees (112F). This year it falls to 6th place!

How about something a little more unusual (115F)? 2023 falls in 8th place

Or let’s think about more “garden variety” in the heat (105F). This year it remains in 8th place.

Do you feel deceived and betrayed? This was a deliberate attempt to pick statistics to push an agenda. Not good.

But Phoenix’s selection is even worse.

Phoenix has possibly the most pervasive and fastest growing urban heat island in the country.

Phoenix was one of the fastest growing cities in the US (see below) and all construction work (concrete, buildings, heat sources) resulted in intense warming known as the urban heat island effect.

Want to see the Phoenix Heat Island in action this week?

Below are Tuesday late afternoon temperatures. 117F at Phoenix Airport but 111F just outside the subway area. This difference is quite typical for the city.

Even if global warming had not occurred, the temperature in Phoenix would have increased significantly over time due to the city’s rapid development. Such urban heat island effects significantly degrade temperature records and lead to artificial warming.

Would you like another example? SeaTac Airport, whose third runway and local development have affected (warmed) the temperature record there.
Finally, I would like to point out that while the earth is slowly warming due to human-caused greenhouse warming, There is no evidence that heat waves are amplified or amplified beyond this baseline warming. So all the panic headlines are really unfounded.

Would you like to see an example of this? Below are the annual high temperatures in Olympia, Washington with a linear trendline added for your convenience. Annual high temperatures have increased by about 2°F, roughly in line with the global warming signal.

The claim that global warming is causing a sudden and rapid increase in heat waves may be good clickbait for the media and a powerful tool for climate activists, but that’s just not true.

In closing, I’d like to say that the headlines earlier this month that the Earth was warmer than it has been at any time in the last 125,000 years really were nonsense. But I will leave that discussion to another blog.

For more information on heatwaves, visit our Earth Temperature page on

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