## 1 Introduction  
Concerns over the effects of global warming led to the adoption of the Kyoto Protocol in 1997. Becoming effective in February 2005, the Kyoto Protocol to the United Nations Convention on Climate Change (UNFCCC) is aimed at mitigating global climate change by reducing global greenhouse gas emissions during the first commitment period (2008-2012). Annex 1 countries, which include 39 industrialized countries, committed to a reduction of 5.2% of greenhouse gas emissions compared to their levels in 1990. Agreeing to cut 1,163 million tons of carbon dioxide, representing 6.0% of greenhouse gas emissions, Japan proposed the following reduction options: 1.6% reduction under the Kyoto mechanisms, 3.9% reduction using forest carbon sinks, and the remaining 0.5% via domestic measures [1,2]. However, because emissions continued to rise after 2005, Japan must reduce emissions by 14.5% in 2007 to meet the 6.0% reduction commitment made in Kyoto in 1997 [3]. Under the domestic measures, Japan introduced and implemented various policies that would result in huge domestic emission reductions. These policies include implementing ecologically friendly lifestyle programs such as My Bag, CoolBiz, WarmBiz, My Bottle, My Chopsticks, Eco House, and Eco Building; using energy-efficient products such as light-emitting diode goods and eco-car; utilizing natural energy sources such as solar power and biomass; participating in local environmental activities; and amending environmental laws. Furthermore, since the adoption of the Kyoto Protocol, Japan has also revised various energy-use laws and promoted policies to address global warming and use new clean energy sources. Until recently, assessments of the public responsiveness towards climate change mitigation policy were conducted through questionnaire surveys [4, 5, 6, 7, 8, 9]. Although questionnaire surveys provide useful assessments, there are other methods that consume less time and costs. The emerging information and communication technology (ICT) makes it possible to assess public responses through the use of an online query-based approach. Nevertheless, studies using such an approach were not available despite rapid increase of internet users. The number of internet users has dramatically increased in recent years. According to Miniwatts Marketing Group [10], there were approximately 1.80 billion internet users worldwide in December 2009, with about 90.91 million internet users in Japan at the end of 2008 [11]. As of September 2008, the number of searches had reached 5.9 billion in Japan [12]. Taking advantage of ICT and the increase of internet users, we can assess the public responses to climate change mitigation policies in Japan by analyzing the search terms performed by the internet users. Using ICT tools can also reduce time and associated costs compared to the conventional studies.  
The purpose of this study is to assess public responses on proposed climate change mitigation policies in Japan by using the online tools, namely Insights for Search, AdWords Keyword Tool, and Timeline View provided by Google Inc. The paper is structured as follows: justifications for selecting search terms and online tools are described; analytical results for each search term under various search categories are discussed; and finally, we discuss our conclusions and suggestions for further study.