In reference to the removal of the tree, Loraine said:
"Tragic to read this, but suspect the likes of Messrs Campbell, Pike, Saper will see this as an Eco Victory"
You quoted this and we discussed whether the tree was removed for a new left filter lane or a cycle lane.
You were adamant that the tree was removed for a cycle lane.
Thus the question is, does a cycle lane provide an "eco victory" when it includes the removal of a tree which provided an "environmental benefit that that particular tree contributed".
Loraine suggests it does not because a tree can absorb toxins.
In my earlier answer I focused on CO2 sequestration. To give an example:
If the cycle lane results in one school run switching from car to bike - assuming 180g of CO2 per mile, 1.5 mile one way journey (6 miles per day), then over a school year (180 days) that would reduce CO2 emissions by nearly 200KG, equivalent to the annual CO2 sequestration of around 8 mature trees.
You don't need 1,000 people a day to switch from a car to a bike, just one family changing one trip of just 1.5 miles could justify a tree removed for a bike lane.
You say that CO2 is a greenhouse gas and not a pollutant (some would disagree with you on that point) and thus any environmental benefits of reducing CO2 emissions must be disregarded.
Looking at other particulate pollutants, PM2.5 and PM10 for instance which are interesting because electric cars produce these as well, an average car emits circa 2KG of these particles per year (assuming 10K miles per year) in a roughly 60:40 split of PM10 to PM2.5.
The 8 million trees in London are estimated to "trap" between 1,000 to 2,000 tonnes of these particulates per year. Assuming 1,500 tonnes, then an average tree captures just under 0.2KG per year.
Taking the school drop example, which would be just over 1,000 miles per year, that would produce just over 0.2KG of fine particulates if driven.
Further, these particulates are not permanently trapped and absorbed like gases, they can be re-released.
In answer to the central charge of whether I believe a bike lane is an "Eco victory", even if it includes the removal of a tree, then I would say that I do.
Trees provide a lot of environmental benefits and are aesthetically beautiful so should not be removed without good reason and replaced where feasible (I understand 3-4 trees are being planted on CHR to replace the one being removed).
The built environment would be more pleasant and healthier if we had fewer cars, fewer car lanes and more trees.
As an example, this is an image of the former Electric Theatre from the 1920s with 4 trees lining the pavement outside:
The same scene today with one tree remaining:
The old bus stop is now redundant and there's space for 2 or 3 trees on the pavement and further space for trees to screen the road and the cycle lane at the end of the floating bus stop. I hope we use the space to plant them.
Ed Saper ● 1722d