The Covid-19 epidemic rages around the world and seriously threatens people’s lives and properties. At this difficult time, we should bear in mind that behind the Covid-19 there is a greater threat lurking: global climate change. Admitted that the epidemic is fierce, but it is unsustainable; however, the risks of global climate change are long-term and cumulative. This means that the duration and destruction of the global climate crisis may far exceed the epidemic.
For example, the effects of global climate changes on the natural environment challenge the decision-makers and pose provoking disaster problems, namely landslides, floods, droughts (i.e., Ma et al. 2018; He et al. 2019), which leads to catastrophic consequences and huge economic loss of properties. Therefore, it is a need to understand and investigate global climate changes.
In this project, a dataset from Kaggle (Climate Change: Earth Surface Temperature Data) was adopted (https://www.kaggle.com/berkeleyearth/climate-change-earth-surface-temperature-data) to investigate the global climate changes in the past. Three key questions are raised as follows:
1. How does the temperature change in each season?
2. What’s the temperature difference in each country in the dataset?
3. When did global warming start?
Seaonsal temperature variations
Global surface temperatures are projected to warm due to rapid increases in greenhouse gases. Several studies have investigated the global annual temperatures, both in the observational record and in climate modeling. However, analysis of temperature trends seasonally is not extensively reported. Inspired by the studies conducted by Cohen et al. (2012), recent trends in global land temperatures are seasonally dependent, which shows apparent seasonal asymmetry.
Seasonal changes are a direct consequence of the sun and earth’s relationship with it. Based on the preliminary analysis of the dataset, the land average temperature has 3180 listings with an average of 8.37 °C, in which the maximum temperature is 19.02 °C and the minimum is -2.08 °C. To investigate seasonal temperature changes, we divided the months into four seasons for investigating the characteristics of seasonal temperature changes.
In Fig. 1, it found that the spring and autumn average temperatures are very close to each other, while the summer and winter are very different. It can be found that the global seasonal temperatures are getting warmer, in which the average temperatures in each season from 1750 to 2015 manifests stable increasing. Additionally, in each season, the historical extreme land average temperatures show a significant gap between its minimum temperature and maximum one (as shown in Fig. 2). For example, the minimum average temperature in summer is about 11.63 °C, while the maximum temperature can reach up to approximately 17.54 °C.
In Fig.3 and Fig. 4, 2-dimensional and 3-dimensional scatter of summer and winter average temperatures are plotted. It clearly shows that the trend of global average temperatures presents a steady increase from 1750. Based on the computed Pearson’s correlation coefficient ( ρ = 0.19) between summer and winter data, it illustrated that the winter and summer temperature has a positive correlation between each other. To be more specific, as time goes on, the winter becomes warmer and the summer will be hotter.
Temperature difference
Temperature difference generally shows the difference between the maximum and minimum temperature values. Firstly, the top 10 countries with the highest mean temperature were listed in the following figure. It can be observed that Djibouti is the country with the highest mean temperature of 29.15 °C.
As for temperature difference, Kazakhstan presents the biggest value with 26.00 °C. Therefore, the summer is very hot and winter is relatively cold in Kazakhstan.
When did global warminig start?
The Industrial Revolution was the transition to new manufacturing processes in Europe and the United States, in the period from between 1760 to 1820 and 1840 (source from Wikipedia). The Industrial Revolution led to an unprecedented rise in the rate of population growth from fewer than 2 billion in 1900 to 7.7 billion now. Due to the major contribution from the both industrial revolution and population growth during this period, global temperatures increase on all levels.
From the above figure, it can be found that the notable global warming started after 1975. Especially, land max temperature shows a significant surge after 1975. Meanwhile, after stable increases from 1900 to 1975, land average temperature also shows an unnoticeable sharp increase after 1975. Therefore, it can be deduced that dramatic global warming started in 1975.
Conclusion
In this data blog, based on the global climate dataset, we found many interesting phenomena.
1. The spring and autumn land average temperature data are very close, while the winter and summer data show weakly positive cross-correlation, which illustrates that winter and summer land average temperature will be higher with time goes on.
2. Based on the ranking in terms of temperature difference, it can be observed that Kazakhstan presents the biggest value with 26.00 °C.
3. Global warming started after 1900 with steady increases in average temperatures and presented more and more obvious after 1975.
Author:
Dr. Derek Ma. B.eng, MSc, PhD
University of Warwick
Email: G.ma.1@warwick.ac.uk
Reference
Ma, G., Hu, X., Yin, Y., Luo, G. and Pan, Y., 2018. Failure mechanisms and development of catastrophic rockslides triggered by precipitation and open-pit mining in Emei, Sichuan, China. Landslides, 15(7), pp.1401–1414.
He, K., Ma, G., Hu, X., Luo, G., Mei, X., Liu, B. and He, X., 2019. Characteristics and mechanisms of coupled road and rainfall-induced landslide in Sichuan China. Geomatics, Natural Hazards and Risk, 10(1), pp.2313–2329.
Cohen, J.L., Furtado, J.C., Barlow, M., Alexeev, V.A. and Cherry, J.E., 2012. Asymmetric seasonal temperature trends. Geophysical Research Letters, 39(4).
