“From a pool of more than 27,000 research papers, the researchers selected 202 for meta-analysis”
The headline says an average of 5°C. The text says “as much as” 5°C, and that is for botanical gardens, the best case in the set. Street trees manage 3.8°C and parks 3.2°C. The same paper ties 62,862 European deaths to the summer heat of 2022, which makes a shade tree the cheapest public health program a city can buy.