The cost of losing greenery?

Tan Ping Hau Today Online 25 Jun 13;

The seriousness of the haze situation leads one to ponder whether the natural greenery we have lost over the years could have cushioned the blow. Trees not only provide oxygen but cleanse the air of greenhouse gases. Transpiration, which introduces water vapour into the air, contributes to rainfall.

Singapore’s green lungs could be our best defence against pollution and the haze, without being dependent on wind directions and rain. But it appears that, over the years, we have lost a significant amount of natural forest to property development and roads and replaced them with parks like Gardens by the Bay and the Punggol Waterway park.

Are there studies being done about how much forest we have lost over the years and how much impact this has had on our ability to mitigate air pollution and the haze?