How much temperature of my city has increased?

Scientists today measure the Earth's surface temperature using thermometers at weather stations and on ships and buoys all over the world. Absolute estimates of the global average temperature are difficult to compile. Global temperature data comes from thousands of observation stations around the world, but in some regions, such as deserts and mountaintops, stations are rare. Also, different groups, analyzing the same data, use different methods for calculating the global average. These differences in methodology sometimes produce slightly different results.Data from the observation stations are compared to historical data from a long-term period (and different groups use different time spans). The differences in temperatures, called anomalies, are plotted on a grid. Some grids may be empty because there were no observations recorded. Gaps in data are treated differently by different groups(

Also, We can track significant increase in global temperatures of different levels for checking extreme changes in temperature. As you know, there are different sources of data, namely in-situ data (e.g. synoptic station), gridded datasets, the outputs of NWP models, and remote sensing products. For example, you can check Tmax of any location from 1901 to 2015 by Climatic Research Unit Presenter. In the CRUP, there is Tmax data based on Climatic Research Unit dataset. The user can load Tmax by Lat and Lon and draw trend line. If trend line be incremental, you have global warming in your location.

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