The issue focused on warming since 1975 with mention of acid rain as an explanation and authors cited Michael Mann as saying "every tree does now benefit from acid rain". However, many authors argued that acid rain should not have any negative effects on ecosystem composition or ecological impacts on trees and suggested that climate change may lead to increases in flooding and erosion on soil that cannot be corrected by limiting greenhouse gases. Some authors argued that acid rain should not increase greenhouse gas emissions because its properties may reduce impacts on ecosystems (such as lowering atmospheric