Motivation: wanted to observe how the climate changed during the past 40 years for different regions in the world.

Select a location on the map to access post-processed statistics, and use the menu to select another continent. Data from MERRA-2 is used for temperature statistics from the years 1980 to 2016. The pvgis and ninja parts use the timespan 2005 till 2015 for temperature data, so we also provide data on this time-span for comparison. Both yearly and monthly overviews are included. Specifically:

• Temperature statistics, including minimum, mean and maximum temperature in degrees Celsius. Also percentiles are provided. For example a percentile value of 95% indicates that 95% of temperatures are lower than this value, and 5% are higher than this value.
• Heating degree days (HDD) and cooling degree days (CDD): Higher heating degree values occur with colder temperatures, indicating a higher energy need for space heating. Higher cooling degree days occur with higher temperatures, indicating a higher energy need for space cooling if an air conditioner is present. A balance point of 15.5 degrees Celsius is used for heating degree days, and a balance point of 21 degrees Celsius for cooling degree days.
• Rainfall (precipitation) statistics, showing yearly rainfall expressed in millimeter. Monthly statistics show month with minimum rainfall (dryest), month with maximum rainfall (wettest) month, mean (average) rainfall, and percentiles.

This data spans countries, states, provinces or regions. Sub-regions of these enetities can differ significantly with respect to temperature or rainfall. Also the MERRA-2 climate re-analysis models can deviate from measurements. Still they give a good indication of past climate patterns.

Main observations

Since 1850 the atmospheric concentration of CO₂ has risen by about 40 percent to 408 parts per million (ppm), whereas it fluctuated between 200 and 300 ppm in the past 800 thousand years and since 1980 global temperatures on earth started increasing significantly [1]. Also when we look at local data we see higher temperatures:

• In cool climates the number of heating degree days decreases significantly, which corresponds to warming of the climate.
• In warm climates the number of cooling degree days increases significantly, which also corresponds to warming of the climate.
• This change occurs for most countries, whether they have a dense population or not. Hence this warming is not due to random weather fluctuations and unlikely to be caused by urban heat island effects alone.

Acknowledgement: The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) was developed by the Global Modeling and Assimilation Office and supported by the NASA Modeling, Analysis and Prediction Program. Source data files can be acquired from the Goddard Earth Science Data Information Services Center (GES DISC). In this work we use land area weighted MERRA-2 climate data, as provided on renewables.ninja. Many thanks to NASA and the Renewables.ninja team for open access to this data.

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