Act now or the costs of addressing key environmental issues will increase significantly. ThatÃ¢â‚¬â„¢s the message from the Organization for Economic Cooperation and Development (OECD) in its Environmental Outlook to 2030. The report identifies four priority areas where urgent action is needed: climate change, biodiversity loss, water scarcity and the impacts on human health of pollution and toxic chemicals. It highlights a mix of policies that can address these challenges in a cost-effective way. By 2030, world GDP is projected to nearly double from todayÃ¢â‚¬â„¢s levels. The OECD analysis shows that it would cost just over 1 percent of that growth to implement policies that can cut key air pollutants by about one third, and contain greenhouse gas emissions to about 12 percent, instead of 37 percent growth under the scenario without new policies. OECD also recommends use of market-based instruments, such as green taxes, efficient water pricing, emissions trading and polluter-pay systems. However, more stringent regulations and standards, such as for transport and building construction, are also needed.