https://www.sunbeltrentals.co.uk/news-and-blogs/decrease-you...

> Of course, we know that fuel consumption varies drastically from machine to machine, so we’ve looked at an example of a very high utilisation rate too. We found that an 8T excavator that spent 11 hours and 3 minutes working, 1 hour and 6 minutes of which were idle, it used 89 litres of fuel and resulted in 237.4kgs of carbon emissions. 4 hours saved on that machine would be a total of 84kgs of carbon emissions on average.

https://onetreeplanted.org/blogs/stories/how-much-co2-does-t...

> To determine the amount of carbon dioxide a tree can absorb, we combine average planting densities with a conservative estimate of carbon per hectare to estimate that the average tree absorbs an average of 10 kilograms, or 22 pounds, of carbon dioxide per year for the first 20 years.

As long as they're not taking all day for one tree, I think they'll be OK.