Weather, Global Warming, Crime and CPTED

Weather is a situational aspect of crime.

Crime Prevention Through Environmental Design (CPTED) is primarily situational crime prevention. It focuses on designing interventions to change the details of design situations to reduce crime rates.

Addressing the situational consequences of weather on crime is part of CPTED.

Weather is linked to crime in many different ways (Cohn, 1990). For example, violent crime rates increase with temperature and burglary rates fall when the weather is bad (i.e. cold, raining, stormy, windy).

Researchers have identified many linkages between weather conditions and different types of crime and similar findings were seein Australia, China, Korea, India, New Zealand, South Africa, US and UK.

However, not all aspects of weather influence all crimes and there are some contradictions in the findings (Murataya &Gutiérrez, 2013).

The links between weather and particular crimes have been explained mainly by three theories:

• GAAMS theory - weather changes emotions, GAAMS is General Affective Aggression Theory (sometimes called GAMS) and has a special case of Temperature/Aggression theory (T/A theory)
• RAT theory- Routine activities change according to weather and these expose more crime opportunities. RAT is Routine Activities Theory.
• ECONOMIC theory - bad weather conditions may cause in crime from need

For example, looking at temperature.

Temperature and Crime

Evidence indicates:

As temperature increases, so does the rate of crimes of violence - with the exception of homicide.

Those that increase with temperature include assault, robbery with violence and domestic violence.

In addition, Field (1992) identified a strong link in the UK between temperature and property crime rates. However, Field found no linkage between crime rates and rainfall or hours of sunshine. He commented, however, that in the UK, rainfall may simply lead to postponing crime-related activities resulting in short-run effects that are hidden in long-run analyses.

Butke and Sheridan (2010) identified that aggressive crime in Ohio increased linearly with apparent temperature increases (especially between 9pm and 3am) with the largest responses being of non-aggravated assaults and domestic violence. The time between 3pm and midnight was most significant. They also identified that the spatial pattern of crime did not significantly change with temperature. Interestingly, while identifying that alcohol appears to be a factor in crime, they do not explore the possibility that increased night-time temperatures may result in increased alcohol consumption and this may cause of the increases in crime.

Some researchers identify an inverted 'U' shaped relationship, with violent crime also starting to reduce when the temperature exceeds a certain value.

GAAMS explains the evidence by suggesting that as people's emotions become stronger it results in increased irritability and violence. Then, as the weather becomes too hot, people feel it is too hard to be violent and simply try to survive the heat.

Routine Activity Theory (RAT) explains the evidence in terms of more people leaving their houses to do things outside which results in more overlaps between potential victims and potential offenders. Then, as the temperature increases further, people avoid going out and this reduces crime opportunities.

However, homicide rates typically do not increase with temperature.

GAAMS has difficulty explaining this. In contrast, RAT makes more sense where most homicides occur indoors: relatively unaffected by temperature increase and increased opportunities of going outside .

Property Crime in the US

Research on crime and weather in the US has resulted in contradictory findings. The reasons for this seem to be methodological rather than from facts on the ground.

Property crime in the US appears to be primarily related by pleasant weather. However, findings on the relationships between weather (mainly temperature) on violent crime and homicide rates appear contradictory (Hipp et al, 2004).

Some of the above contradictions have been resolved by Baryshnikova et al (2019) who used data based on hourly weather readings and crime data rather than the daily or seasonal reading used by others. They identified that higher frequency sampling revealed violent crime was only affected by temperature and not by precipitation. More importantly, they found that many other relationships changed and indicated the importance of using data that is more fine grained to identify effects of weather on crime.

Global Warming and Crime

A fifty year analysis (1950-1999) of crime and weather in the US during increasing global warming showed significant correlations (Rotton and Cohn, 2003).

Increases in annual temperature due to global warming correlated with increases in rates for assaults, rape, robbery, burglary and larceny (theft) - but no murder or motor vehicle theft. These are results consistent with Routine Activity Theory.

Implications are that for each 1 degree Fahrenheit increase global warming the US will expect to see:

• 1,335 to 5,347 additional assaults
• 15,197-27, 567 additional burglaries
• 225-874 additional rapes
• 16,886-43,029 additional thefts

Doctoral research at the Harvard Kennedy School identifies that the US will experience immediate increases in crime due to the climate change predicted by the IPCC A1B scenario (2010-2099) including an additional:

• 35,000 murders
• 216,000 cases of rape
• 1,600,000 aggravated assaults
• 2,400,000 simple assaults
• 409,000 robberies,
• 3,100,000 burglaries
• 3,800,000 thefts
• 1,400,000 cases of vehicle theft

These additional crimes have a current cost of between 20 and 68 billion dollars.

Weather and Crime in the UK

Researchers in the UK focused on the dynamics of weather and crime in local areas by using geographical analyses based on the application of computer-based Geographical Information Systems (GIS) that enable users to access layers of additional information (e.g. crime rates and weather) on maps and plans (Brunsdon et al, 2009).

They concluded that temperature and humidity strongly shaped spatial patterning of incidents of disorder and disturbances in the UK , but rainfall, wind speed and wind direction did not. Their work illustrated the benefits of integrating such services into GIS systems used by planners and others.

Weather and Crime in New Zealand

In alignment with studies elsewhere, Horrocks and Menclova (2014) identified that in New Zealand unexpected increases in temperature and/or decreases in precipitation are linked to increases in violent crimes. By 'unexpected' they mean different to what would be expected for the season. They also identified an inverted 'U' shaped curve in which violent crime peaked at around 27 degrees Celsius and reduced at higher temperatures. The peak temperature for property crime was lower at around 21 degrees Celsius.

Significantly, Horrocks and Menclova identified that Police already use weather as a basis for increasing policing. The data and analysis then imply that the effects of weather on crime rates are underestimated.

There is a common belief in NZ that the Nor-wester wind causes disorderly behaviour. However, review of the police data was unable to establish any special effect of the wind on the number of violent crimes committed.

Property Crime in China and the Weather

Researchers (Chen et al, 2011) investigating patterns of crime in Beijing found that robbery and burglary had differing relationships with weather conditions and time. In extreme weather conditions, both robbery and burglary rates fell as they did on public holidays and days when schools were closed.

Burglary rates had patterns that varied by season and day of week and the rates increased on days with more hours of sunlight. In contrast, robbery mostly occurred at night peaking around midnight and was independent of seasons and weather.

The above findings point towards RAT as a dominant explanation.

Weather shocks, climate change and economically driven crime

Weather can also have a direct economic effect in driving crime. This can add to the crime rate changes otherwise related to weather.

For example, in India most types of crime increases with weather shocks (low rainfall and high temperatures) that reduce agricultural output during the main growing season (Blakeslee & Fishman, 2014). This is quantitatively significant research, because of the size of the data set (over a billion people over 3 decades of economic and social change) and the consistency of the evidence and findings.

The relation with weather shocks is larger and more consistent for property crimes than violent crimes. However, high temperatures have an effect that is disproportionately high and more consistent with other effects similar to that found in industrialized countries. Also, although the economic situation in rural India has significantly improved, the effect of weather shocks on crime has remained stable. Blakeslee and Fishman draw attention to a supplementary factor, the ability (or lack of) to obtain formal insurance against adverse weather outcomes potentially drives the use of crime as a informal means of providing such insurance. They also draw attention to the evidence of linkage between weather and crimes against women and vulnerable minorities. This is potentially significant in many countries now and the near future in terms of climate changes.

Weather displaces crime in time

Most research into weather and crime focus on the long-term picture by mapping crime rates against particular weather conditions at the time. An alternative is to look at the relationships of crime changes due to unexpected weather 'shocks' of hot or cold weather. Jacobs et al, 2004) discovered that crime was displaced in time by weather. An example: if an adverse weather shock reduced crime that would be normally expected at that time, the 'extra' crime will be pushed forward to a time of better weather. Incidentally, they found that their analyses and research conclusions (that crime is displaced to other areas and other times) applied also to other 'shocks' including the 'shocks' to crime of crime prevention strategies focused on 'hot spots'.

One implication for CPTED is that short-term rapidly applied support to reduce repeat victimisation (e.g. of burglary) is likely to be significantly more effective than the same resources spread over a long period.

Subjective perception of weather is important

Most research on the relationships between weather and crime has been relatively independent of subjective perception of weather of those involved. Tompson and Bowers explored the effect of weather on street robberies in Scotland and identified that it is criminals' and victims' perception of weather that shapes their behaviour. In short, they found if weather was more or less favourable than what residents would expect then this influenced whether they would venture outdoors or not - rather than the absolute conditions. This in turn, directly affected whether victim and criminal could coincide to result in a crime.

Importantly, they found that whether the weather appeared subjectively more favourable at any point depended on many weather factors taken together (temperature, humidity, wind etc.). They coined the phrase 'Adverse-Favourable Weather Hypothesis' to refer to this crime effect from subjective appreciation of the weather compared to the norm at a particular time of year.

An additional factor they identified was fog. They found crime rates increased on weekends that were foggy. They suggested this was due to reduced guardianship because the fog reduced protective natural surveillance.

Weather and crime in South Africa

Researchers in South Africa focused on the effects of weather shocks on crime (Bruederle et al, 2017). They identified a short-term link between warmer temperatures and violent crime. Additionally, they identified a medium-term link between weather and crime which they suggest is linked to agricultural income and suggests an economic reason driving crime.

Twitter sentiment analysis, weather and predicting crime

One of the reasons for investigating the relationships between weather and crime is to predict when crime will increase or decrease depending on weather predictions. This provides a basis for managing police and crime prevention resources.

A measure of the 'sentiments' or 'in the moment feelings' of a society are potentially also of interest. This is particularly so for those using a GAAMS approach.

Twitter traffic can be analyzed to identify the moment by moment sentiments/feeling/social attitudes in a particular geographical area. Researchers (focusing on the crime context of Chicago) found that:

Adding Twitter sentiment data to predictions of crime based on weather and crime data is better than using only weather and crime data.

Implications for CPTED

The evidence of weather/crime relationships both increases the importance of using Crime Prevention Through Environmental Design (CPTED) and changes the priorities for CPTED application.

First, it becomes obvious that climate changes make it more important to increase the role of CPTED to make deep inroads to reducing crime. Then, the proportional increases in crime due to climate change (and their costs) will be proportionally much less.

Second, the evidence of weather/crime relationships suggests the need to include weather/ crime relations and change the priorities of CPTED in:

• CPTED planning development reviews
• Crime Risk Assessments used as the basis for CPTED intervention planning
• CPTED responses to addressing repeat victimisation
• Targeted CPTED responses.

References

Baryshnikova, N. V., Davidson, S. F., Wesselbaum, D. (2019) Do you feel the heat around the corner? The effect of weather on crime. University of Adelaide School of Economics Working papers, 2019-7.

Blakesslee, D. S, Fishman, R. (2014) Weather Shocks, Crime and Agriculture: Evidence from India. Journal of Human Resources. Volume 53, Issue 3, 1 June 2018, Pages 750-782

Bruederle, A., Peters, J. & Roberts, G. (2017) Weather and crime in South Africa, Ruhr Economic Papers, No. 739, ISBN 978-3-86788-859-2, RWI - Leibniz-Institut für Wirtschaftsforschung, Essen.

Brunsdon, C., Corcoran, J. & Higgs, G. (2009). The influence of weather on local geographical patterns of police calls for service. Environment and Planning B: Planning and Design, Volume 36, pages 906 - 926.

Butke, P. & Sheridan, S. C. (2010) An Analysis of the Relationship between Weather and Aggressive Crime in Cleveland, Ohio. Weather Climate and Society. Vol 2. 127-139.

Chen, P., Shu, X., Yuan, H. & Li, D. (2011) Assessing Temporal and Weather Influences on Property Crime in Beijing, China. Crime Law Soc Change, 55: 1-13.

Chen, X,, Cho, Y. &Suk, Y. J (2015) Crime Prediction Using Twitter Sentiment and Weather. 2015 IEEE Systems and Information Engineering Design Symposium.

Cohn, E. G. (1990) Weather and Crime. Brit. J. Criminol. Vol 30. No. 1.

Field, S. (1992) The Effect of Temperature on Crime. Brit. J. Criminol. Vol 32. No. 3 340-351.

Hipp, J. R., Bauer, D. J., Curran, P. J. & Bollen, K. A. (2004) Crimes of Opportunity or Crimes of Emotion? Social Forces, June 2004, 82(4):1333-1372.

Horrocks, J. & Menclova, A. (2011). The effects of weather on crime. New Zealand Economic Papers. 45. 231-254. 10.1080/00779954.2011.572544.

Jacob, B., Lefgren, L., Moretti, E. (2004) The Dynamics of Criminal Behaviour: Evidence from Weather Shocks. National Bureau of Economic Research, Working paper 10739.

Murataya, R., Gutiérrez, D. R. (2013) Effects of Weather on Crime. International Journal of Humanities and Social Science, Vol. 3 No. 10.

Ranson, M. (2012). Crime, Weather, and Climate Change. Harvard Kennedy School, M-RCBG Associate Working Paper Series. No. 8.

Rotton, J. & Cohn, E. G. (2003) Global Warming and US Crime Rates. Environment and Behavior. Vol. 35 No. 6, November 2003 802-825.

Tompson, L.A., Bowers, K.J. (2015)Testing time-sensitive influences of weather on street robbery. Crime Sci. 4, 8.