## 2 Materials and Methods  
### Search Term Selection  
Climate change and its mitigation could be defined with one or more of the following eight Japanese terms, namely Kankyou Mondai (Environmental Issues), Chikyu Ondanka (Global Warming), Kankyou Bijinesu (Environmental Business), Kyotogiteisho (Kyoto Protocol), Eko Pointo (Eco-point), Maibagu (My Bag), Shoene (Energy Conservation), Eko Jutaku (Eco House). While [PERSON] and [PERSON] [13] chose three keywords (Global warming, Climate change, Pollution) to study the public interests in environment, here we chose five terms that are relevant to mitigation policy: Chikyu Ondanka, Kyotogiteisho, Eko Pointo, Maibagu, Shoene (Table 1). **Chikyu Ondanka** represents the current environmental problem. After the Intergovernmental Panel on Climate Change [14] reported that global warming results from human activity, many researchers have become interested in this subject. Most scientists agree that the warming in recent decades has been caused primarily by human activities that have increased the amount of greenhouse gases in the atmosphere [15]. We chose Chikyu Ondanka term to assess the general public's awareness of the global environmental problem. Average monthly searches of this term on Google in Japan were about 201,000. **Kyotogiteisho** was initially adopted by 39 industrialized countries in 1997, and became effective in 2005. It is the first international binding agreement to combat global warming by requiring Annex 1 countries to fulfill their obligations of reducing greenhouse gases emissions during the first commitment period (2008-2012). Monthly searches of this term on Google in Japan average about 33,100. With this search term, we can evaluate the degree to which the Japanese public is interested in climate change mitigation policies. \begin{table}
\begin{tabular}{l c c} \hline \multirow{2}{*}{**Search Term**} & \multirow{2}{*}{**Related to Climate Change Mitigation**} & **Average Local Monthly** \\  & & **Searches** \\ \hline
**Chikyu Ondanka** & Keyword concerning climate change & 201,000 \\ Global Warming & & \\ \hline
**Kyotogiteisho** & Keyword concerning commitment to & 33,100 \\ Kyoto Protocol & reducing climate change & \\ \hline
**Eko Pointo** & Keyword concerning Domestic Policies & 1,500,000 \\ Eco-point & & \\ \hline
**Maibagu** & Keyword concerning Domestic Policies & 5,400 \\ My Bag & and Lifestyle & \\ \hline
**Shoene** & Keyword concerning energy saving & 368,000 \\ Energy Conservation & & \\ \hline \end{tabular} Source: Average local monthly searches were generated using Google AdWords Keyword Tool.  
\end{table} 
Table 1: Search terms and related search volumes in June 2010. **Eko Pointo** is one of the many domestic policies aimed at both reducing greenhouse gas emissions and boosting stagnant consumption to fight against the economic recession. The policy was introduced by the Japanese government to stimulate purchases of energy-efficient appliances. Under the Eco-point system, buyers of certain types of energy-efficient air conditioners, refrigerators, and television sets can exchange the points later for other goods and services worth up to nearly 40,000 pen per item. The end of this program was extended to December 2010 from the previous deadline of December 2009. The Eko Pointo search term will help us determine how effective this government policy is and the degree of public responses in such a policy. Monthly searches of this term on Google in Japan average about 1,500,000. **Maibagu** is a type of personal shopping bag that can be reused numerous times. In Japan about 30.5 billion plastic shopping bags are discarded after use each year [16], which represents about 300 bags per adult discarded yearly. As part of the country's climate change mitigation policies, \"No Plastic Bag Day\" occurs on the fifth of every month [17], a plastic bag reduction campaign has been adopted by 12 convenience store chains [18], and the My Bag campaign has been promoted.