The user's device is the largest emission source, and above all its manufacture, which accounts for 30 to 45% of the impact, against 20 to 30% for use, 15 to 25% for the data centre and 10 to 20% for the network. The country of hosting also matters: a server in France emits 7 to 8 times less than one in Germany and 10 to 15 times less than one in Poland. On the page side, images account for about 35% of the weight of a median page and JavaScript for about 25%, but weight is only an indication: the load placed on the processor of the visitor's device counts for as much.
Read the source article: Website carbon footprint: how to calculate and reduce it