Interpretation
Controls
1. Dropdown - Select a Month
2. Mouse hover over countries - shows temperature difference
3. Mouse click on counties - shows the temperature variation line graph.
4. Mouse hover on line graph - shows exact temperature recorded
To start the analysis, select a month from the dropdown. The resulting choropleth World map encodes the difference
in the average temperature for all the countries between the year 1890 and 2010. The color encoding is based on the values of the temperature
difference. Darker color shows higher temperature difference and lighter color shows less temperature difference.
For example:
Select month - January. Hover over Canada. You will see the exact value of temperature difference in Fahrenheit.
Temperature difference calculation sample:
Canada
Average Temperature January in 1890 = -16.65°F
Average Temperature January in 2010 = -1.94°F
Difference = 14.71°F
Now click on any country. On the left side you will see the line graph showing the temperature variation for the selected country.
The x-axis encodes the years in which the temperatures are recorded and y-axis shows the temperature values in Fahrenheit. The y-axis values are dynamic according
to the selected country and the month. The range for y-axis is calculated by finding the maximum and minimum temperatures recorded for a country over the
period 1890-2010.
Hover over the line to see the exact values of the temperature in the corresponding year.
Data and Processing
GlobalLandTemperaturesByCountry.csv data set is used for creating this choropleth visualization. This visualization is representing temperature variation for different countries, between years 2010 and 1890 for each month.
- Eventhough the original data set had details from year 1743 - 2013, most of the data was missing for the years beyond 1890 and after 2010. So I filtered out data for those years using Tableau-filtering, for the 'dt' field.
- For the pop-up line graph in Visualization-1, I am showing data for every 10th year from 1890. For this, I again filtered out the data to represent only the the specific years that represent the 10th year.
- The data was missing for Antartica entirely. So I filtered it out using Tableau.
- A calculated field called 'Temperature in Fahrenheit'
was added using Tableau's calculated field, to convert temperature in degree celsius to fahrenheit. The calculation was 'Temperature * 1.8 +32'.
- I removed the column 'Average Temperature Uncertainty' manually from the csv file as I am not using this field for any calculation.
- After all the filterations mentioned above, the final data set had the size 5.7 MB.
Discussion
This is a choropleth map that encodes the temperature difference data for all countries. The color encodes the temperature difference value for each country. The darker colors show high temperature variations and
lighter colors show low temperature variations for each month.
Refer the 'Interpretation' section to see how this choropleth world map can be analyzed. Also refer to, how the temperature change is calculated for a country.
From the analysis of the choropleth, we can see that there is a notable increase in temperature for every country in the world for every month. When the dropdown values are changed to do the analysis, we can see that months
March and April show a wide range of colors in the choropleth. This means that the world has witnessed the maximum temperature variations in the 2nd quarter of the year. The changes can be seen minimal in the 3rd quarter.
Now consider the line graph visualization generated for each country by mouse click on the desired country. Consider the data for United States. We can see that the temperature changes
in US is less during the winter season. But for the entire fall season, the temperature has been gradually increasing. Consider the month of August for US. From the line chart,
we can clearly observe that, in January 1890, the temperature used to be 67°F. But for the year 2010 August, the temperature recorded was 71.06°F. This is about 4°F change.
The above mentioned observation about US can be generalized to all counties. For the fall quarter, every country is showing a steady increase in temperature. There are so many other noticeable things also.
For Brazil, the temperaturehas been seen rising for almost every month. For the colder countries like Canada, Greenland, Russia can be seen with very high temperature difference for winter.
To conclude, the detailed analysis of the choropleth visualizations shows that there has been a gradual by significant rise in
temperature across the world. This make me say that the temperature change is real and people should take immediate steps to protect the Earth for future generations.