Essential climatic variables: Photosynthetic activity (NDVI)

One of the ways of knowing whether climate change is already affecting the biodiversity of an area is by studying time series of climatic variables.
This post analyses the time series of photosynthetic activity from 2001 to 2021. One way to observe photosynthetic activity is by calculating a spectral index of satellite measurements. The NDVI (Normalized Difference Vegetation Index) has been used as it is the most common index in these cases.

One way to know the photosynthetic activity by means of satellite information is by using photosynthetic indices. The most widely used is the Normalized Difference Vegetation Index, known by its acronym as NDVI.
NASA, through its AppEEARS platform, makes data from a satellite sensor (MODIS) with the values of this index available to the public. Among the different options, one which provides biweekly information with a spatial resolution of 250 meters has been chosen. The information has been analyzed for the period from January 2001 to December 2021.
It has been observed that, although there are strong seasonal variations for values of photosynthetic activity, the trend of the mean and minimum photosynthetic values is upward for the period of time analyzed.
When comparing the NDVI values of each of the last 3 years (2019, 2020, 2021) with the average of the period 2001-2018, it is observed that in recent years the photosynthetic activity has been significantly higher than the average in all months, with the exception of November 2019.
This information could indicate that recent winters are shorter, leading to photosynthetic activity starting earlier and ending later than the historical average.
If this trend is confirmed, it would be an indicator that climatic alterations are already present in the study area and, therefore, would have implications for the biodiversity and habitats found there.