According to a recent opinion poll conducted by Nielsen/Oxford University, global concern about climate change has decreased over the past two years. The survey, which included over 27,000 Internet users in 54 countries, found that 37 percent of respondents were "very concerned" about climate change, compared to 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 percentage of those very concerned about climate change dropped from 34 percent to 25 percent. President Barack Obama is aiming to reduce US greenhouse gas emissions, specifically from the burning of fossil fuels. He plans to attend a meeting in Copenhagen with over 100 world leaders in an effort to negotiate 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. Latin America and Asian-Pacific countries showed the highest levels of concern, with the Philippines topping the list at 78 percent following Typhoon Ketsana in September. The survey did not include most African nations. Eastern Europe had the least concern about global warming, often attributed to human emissions of greenhouse gases from burning fossil fuels. In Estonia, only 10 percent of people reported being very concerned, ranking the country at the bottom. Jonathan Banks, Business Insights Director Europe of the Nielsen Co., mentioned that concerns about climate change might be increasing with the spotlight on Copenhagen. He stated that economic troubles had temporarily shifted attention away from climate change, but as the recession starts to fade, the Copenhagen summit is expected to bring this important issue back to the forefront. The survey revealed that globally, air and water pollution, followed by climate change, were the top three environmental concerns for people worldwide.