According to a recent opinion poll conducted by Nielsen/Oxford University, global concern about climate change has decreased in the past two years. The survey, which involved over 27,000 Internet users in 54 countries, found that only 37 percent of respondents were "very concerned" about climate change, down from 41 percent in a similar poll conducted two years ago. The decline in concern was attributed to the world economic slowdown. In the United States, the number of individuals who were very concerned about climate change dropped from 34 percent to 25 percent. President Barack Obama aims to reduce US greenhouse gas emissions, primarily from the burning of fossil fuels. He plans to attend the Copenhagen meeting with over 100 world leaders to work towards a new UN agreement. China, the largest emitter of greenhouse gases, saw an increase in the number of people who are very concerned about climate change, rising from 30 to 36 percent. The survey showed that Latin America and Asian-Pacific countries had the highest levels of concern, with the Philippines at the top with 78 percent, likely due to being hit by Typhoon Ketsana in September. The poll did not include most African countries. Eastern Europe had the lowest level of concern for global warming, which is attributed to human emissions of greenhouse gases from burning fossil fuels. In a recent survey, Estonia had the lowest level of concern about climate change, with only 10 percent of respondents expressing significant worry. Jonathan Banks, Business Insights Director Europe at the Nielsen Co., suggested that concerns about climate change may be increasing due to the focus on the Copenhagen summit. He noted that economic struggles had temporarily diverted attention from environmental issues, but as the recession eases, he expects climate change to become a top priority once again. The survey revealed that globally, air and water pollution, followed by climate change, were the top three environmental concerns among the population.