In 2004, Tokyo (Otemachi) had as many as seventy heat days, registering a record high. A heat day is defined as a day that marked a high of $ 30^{\circ} $ C or higher. (The average number of tropical days per year from 1971 to 2001 was forty-six.) According to the Tokyo Fire Department, a total of 793 people were rushed by ambulance to hospitals within Tokyo due to heat illness during the period between May 1 and September 30 in 2004. (The mean value from 1996 to 2005 is 472 people.) If such extreme hot weather happens more frequently due to global warming in the future, heat-illness victims will probably increase further.

### b. Formation of high-intensity tropical cyclone and increasing frequency of heavy rain

There is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures, and the frequency of heavy precipitation events has increased over most land areas (IPCC AR4 WG1 report).

In August 2005, Hurricane Katrina, which hit the Southeastern part of the United States, was a Category 5 hurricane, the highest level under the Saffir-Simpson Hurricane Scale. Katrina caused catastrophe, claiming the lives of more than 1,300 people. According to the ISDR (International Strategy for Disaster Reduction), the damage caused by Katrina within the United States is estimated to be 125 billion dollars (or about 14.4 trillion yen). The NOAA (National Oceanic & Atmospheric Administration of the U.S. Department of Commerce) reported that in 2005 a total of twenty-eight tropical storms formed (tropical storms are defined as tropical cyclone that have a maximum wind speed of 17.2m/s or faster) in the zone stretching from the Northern Atlantic Ocean to the Caribbean Sea, far exceeding the norm in this zone (19), and that fourteen of them developed into hurricanes (defined to be tropical cyclone that have a maximum wind speed of 32.7m/s or faster). If global warming further raises sea-surface temperatures in the tropics in the future, the frequency of high-intensity tropical cyclone is likely to increase.

In Japan, it is also reported that heavy rains are occurring more frequently than ever. According to the “Report on Climate Change 2005” issued by the Japan Metrological Agency, the number of days that have a daily precipitation of 100mm or greater and 200mm or greater respectively increased 1.19 times and 1.46 times, from the 1901-1930 period to the 1975-2004 period.

According to a global warming projection conducted by the Metrological Research Institute, an affiliate of the Japan Meteorological Agency, it is likely under a future warmer climate that the northward progression of the North Pacific High slows down to prolong the rainy season (Baiu) gradually, possibly until as late as August.

### c. Sea level rise

According to the IPCC AR4 WG1 report, the total 20th-century rise is estimated to be 0.17 [0.12 to 0.22] m. The report says that warming causes the thermal expansion of seawater and ice sheet melting contributing to sea level rise.

Southern Pacific nations are already suffering coastal erosion and the danger of land submergence in many shores. One of them is a small, 26-square-kilometer island nation, Tuvalu, which has a total population of about 10,000 people. Tuvalu is consists of nine atolls, scattered ranging from lat.5 to 10 degrees south, and a half of its habitants is living in its capital, Funafuti. Fogafale Island, where Funafuti is located, is less than 1.5 meters above sea level on average, and has recently started to suffer frequent flooding especially during the period from January to March when the tide level is relatively high. Some of the palm trees on the shore are already unable to stand up, and have fallen into the ocean. We could

Hurricane Katrina

Photo: courtesy of NOAA

With a minimum central pressure of 902hPa, Katrina marked the central pressure of 920hPa when it made its landfall.

Funafuti atoll suffering coastal erosion (in Tuvalu)

Photo: courtery of Shuichi Endo (NGO Tuvalu Overview)