Extreme weather: an integral part of the Earth’s climate
Written by Dr Madhav L. Khandekar
It is important to realize at the outset that extreme weather events – heatwaves, droughts, floods (localized or larger scale), rainstorms, tropical cyclone landfalls and so on – are an integral part of the Earth’s climate system.
Throughout the recorded history of the Earth’s climate, extreme weather events have always occurred, the result of largescale atmosphere–ocean circulation patterns and their complex interaction with local weather and climate elements. As an example, the El Niño–Southern Oscillation (ENSO) phenomenon in the equatorial eastern Pacific Ocean has been linked with global weather and climate anomalies (Kiladis and Diaz 1989; Ropelewski and Halpert 1989).
Such weather and climate anomalies can lead to an extreme weather event, depending on how the ENSO phase evolves over the equatorial Pacific. For example, a moderate-to-strong El Niño event leads to a drought in the Indian summer monsoon season (Khandekar and Neralla 1984), while a strong La Niña (the inverse of El Niño) usually produces good monsoon rains.
A strong La Niña also brings colder winters over western Canada (Shabbar and Khandekar 1996). Even without an (extreme) ENSO phase, large-scale atmosphere–ocean patterns can and do produce strong interactions between high-latitude colder air and low-latitude warmer air, resulting in a commonly observed mid-latitude weather system called a ‘frontal cyclone’. Depending on how they evolve, these cyclones produce a variety of extreme weather events: heavy rains, snow and extreme cold, coastal storms and associated strong coastal winds and so on.
Standard textbooks in meteorology provide a number of examples of extreme weather events associated with frontal cyclones. For example, Petterssen (1958) gives the example of the weather in North America on 20 December 1955, with extreme cold conditions over the Midwest and cold Arctic air carried into many southeastern US states as well. The book by Palmen and Newton (1969) provides an example of an ‘upper-air cut-off low’, which moved westwards from Siberia and produced extreme cold weather over central and northern Europe from 8–15 November 1959.
Such an atmospheric circulation system can also develop in the western US, producing extreme weather events such as sustained cold spells in the Midwest and/or heavy rains in the north-eastern states. The textbook by Battan (1980) provides an interesting set of data on the number of deaths due to hurricane landfalls, tornado outbreaks and lightning strikes in the coterminous USA.
This dataset is presented below in Table 1. Of particular interest is the number of deaths due to lightning strikes in the USA: about 200 per year. Surprisingly, this number is larger than the combined deaths due to hurricane landfalls and tornado outbreak over conterminous USA.
The IPCC on extreme weather
The IPCC is a body of scientists and environmentalists that was established by the United Nations in 1988 to provide periodic assessments of climate change and its possible (adverse) impacts on various regions of the Earth.
In its first comprehensive report (IPCC 1996), a reference to concentrations of greenhouse gases in the atmosphere and in particular increasing concentrations of carbon dioxide was made, with a link to global mean temperature using a now somewhat notorious phrase: ‘the balance of evidence suggests a discernible human influence on Earth’s climate’.
The Third Assessment Report (IPCC 2001) explicitly included a table of extreme weather events that it said were impacted by climate change. This is reproduced in Table 2 (see GWPF link below). Among the extreme weather events identified by the IPCC as being affected by climate change are heatwaves, rainstorms (accompanied by localized or regional flooding), droughts, hurricanes and tropical cyclones. The IPCC also categorically stated that there would be ‘fewer frost days and colder nights’ in a warmer future climate.
The IPCC does not provide any physical rationale for the alleged increased incidence of these extreme weather events, but a simple (perhaps deceptively so) explanation is sometimes given by the IPCC and its supporters: a warmer climate will hold more atmospheric moisture and this can lead to enhanced thunderstorms and/or rainstorms in some areas while producing dryer areas and hot weather elsewhere.
This simple statement has now been morphed into a hypothesis that ‘a warmer future climate will lead to increased extreme weather events in future’. The IPCC documents do not provide a long-term climatology of extreme weather events, nor do they make any assessment of past extreme weather events.
The latest IPCC (2013) ‘Summary for Policymakers’ (SPM), which was released in Stockholm Sweden on 26 September 2013, provides an assessment and update on extreme weather, since the last (IPCC 2007) assessment and the Special Report SREX (2012) on ‘Managing the risks of extreme events and disasters to advance climate change adaptation’.
The SPM makes only general statements such as ‘the number of cold days and nights has decreased since 1950 and heat waves have increased in parts of Europe, Asia and Australia’. Chapter 2 of 8 the Working Group I (WGI) report makes more specific statements, such as the ‘number of heavy precipitation events over land has increased since 1950’ (high confidence), while assessment of observed trend in drought (on global scale) has ‘low confidence’.
Also longterm change in tropical cyclone activity is now assessed with only ‘low confidence’. This latest assessment on extreme weather is a significant departure from its previous (AR4) assessment where ‘higher confidence’ was attributed to an increasing trend in tropical cyclone activity and increasing global-scale drought (see Table 2 below from IPCC 2001). Elsewhere in Chapter 2 are general statements on decreasing snowfall amounts over land, fewer frost days and melting of Arctic sea ice and the cryosphere.
The IPCC continues its theme of a warmer present and future climate ushering more hot weather extremes.
The reality of climate change, as we shall discuss below, is that there have been increasing cold weather extremes in recent years, which have been totally ignored by the IPCC and its adherents. Chapter 2 of the IPCC WGI (AR5) entitled: ‘Observations: atmosphere and surface’, makes no mention of cold weather extremes of recent years.
There have, however, been news reports of hundreds of deaths due to extreme cold weather in central and eastern Europe, northern India and parts of South America in the last six years. Regional as well as international news media (TV, newspapers, internet blog ect) have reported cold weather extremes in various parts of the world. Also, several peer-reviewed papers on the increasing severity of cold weather extremes over Europe and elsewhere have also appeared in the literature in the last few years.
None of these is mentioned anywhere, either in the SPM-AR5 or in Chapter 2 of the WGI. The IPCC scientists, while sifting through hundreds of peer-reviewed papers, appear to be completely oblivious of the reality of climate change. It is tempting to ask on what planet the IPCC scientists live and how they can be ignorant of what has happened to the real climate in the last few years.
The above is an extract from the full paper, ‘The Global Warming – Extreme Weather Link: A Review of the State of the Science,’ (Madhav L. Khandekar), published at the Global Warming Policy Foundation (GWPF) located here.