Daniel P. Ahn, Adjunct Fellow for Energy
Determining the "most urgent" global environmental issue is somewhat subjective; many would argue that carbon emissions and climate change is the most pressing issue. Others are just as passionate about deforestation, water scarcity, groundwater contamination, loss of biodiversity, landfills, ocean acidification, air quality… the list goes on. Many of these issues are interrelated; climate change could make a good case simply because it embraces so many other global issues and the potentially negative consequences are so dramatic in scale, but one can easily argue for the urgency of many other concerns.
In terms of the best way to address the issue, again the answer is necessarily complex. By its nature, environmental issues tend to be negative externalities in the sense that the costs are borne by society as a whole instead of solely affecting those responsible for the problem. Hence those responsible are tempted to free-ride and pass on the problem to the rest of society, who must all come together to coordinate and deal with the issue. Once these issues become global, it becomes even more difficult to address because of the multitude of nations and societies involved.
Economists tend to believe in the power of markets and the power of incentives to change human behavior. Hence, we tend, in principle, to favor "Pigovian" taxes that put a specific economic cost to an environmentally harmful activity. But efficiency by itself will not get very far without political and social support.