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The age of ancient iron artifacts can be measured by using carbon component contained in metal iron that was included during the iron producing or iron reprocessing stages. To extract carbon from iron artifacts in a form of CO2, a quartz tube has been used for metal iron combustion at the temperature of 1000°C for about 15 hours. We tested the quartz tube combustion method successfully of metal iron in a fine flake condition of almost 1mm in size. Almost 87 % recovery in average for 24 samples from a standard iron material was attained when metal iron weight is about 25% of CuO used as an oxidizer. The CO2 of about 1mg carbon was changed to graphite and 14C dated with the HVE 14C-AMS system at Nagoya University as well as NEC 0.5MV compact AMS at Paleo-Lab Co. Ltd. One of the common iron artifacts in Japan is Japanese sword, owned traditionally by samurai, a Japanese warrior, and used during battles. At the present time, Japanese swords are one of excellent art collections, and many fake swords exist in the market. Traditionally, Japanese sword has been authenticated by experts based on visual outlook of them and judged real ones out of fakes. A more scientific method was required for judging the original sword. We have analyzed several iron flakes of about 1mm in size collected from Japanese swords in the course of grinding and re-sharpening them. The analyzed swords were believed to have produced in the 5th century and after, by the name of the manufacturer inscribed on the surface of the sword, and/or by the traditional judgment by experts. The obtained 14C dates for the sword samples were calibrated with IntCal20 and compared with the authorized production dates by visual analysis. The 14C ages were almost consistent with the traditional judgments. We consider that 14C dating is a useful tool to certificate the visual judgment of the swords by experts and to accept existing historical documents about them. In addition, iron rust samples are commonly excavated from archeological sites in Japan and in foreign countries. We have tested four rust nail samples from archeological sites in India, to collect carbon component successfully by the quartz tube in the same way as pure metal iron. The nail samples were covered by rust on the surface, but the samples should contain metal portion, because they reacted on the magnetic filed. The carbon content of the rust nails was from 0.2 to 0.5 % in weight ratio, similar to that of pure metal iron samples. The obtained 14C ages were consistent with their archeological chronology.

The Tokachi Plain in Hokkaido, Japan, has always been a stable food supply base for Japan, supported by large-scale agriculture, including dry-field farming, mainly of beans and potatoes and dairy husbandry since 1875. In 2021, the authors performed pollen analysis, AMS14C dating, vegetation and soil property surveys on a 1.6 m deep borehole obtained in a wetland forest at an altitude of 275 m in Memuro-cho, Fushimi, at the foot of the eastern Tokachi side of the Hidaka Mountains in 2002. The study clearly shows the characteristics of vegetation changes. In regard to the changes that occurred in the Fushimi wetland, tephra released from volcanoes in the distance was thickly piled up, changing into a wetland with Lysichiton camtschatcense, on which a cool-temperate deciduous broad-leaved forest was established, and the pollen zone D was formed. The AMS14C age at a depth of 1.44 m is 2310–2112 cal BP ± 2σ (95.4%) (NUTA2-27097). Below this point, in the pollen zone A, coniferous trees receded and deciduous broad-leaved trees predominated. Samples from 1.0 m depth (sample No. 51) to 1.4 m depth (sample No. 69) contain a small amount of Selaginella selaginoides spore (pollen zone B). In addition, the C pollen zone includes a little more spruce (maximum value of 35% at a depth of 72 cm, sample No. 39) and Abies sachalinensis. On the other hand, in Churui, located 40 km southeast of the aforesaid site, the molar teeth and almost the entire bodyʼbone of the Palaeoloxodon naumanni’ were excavated in 1969. The result from the pollen analysis on the stratum 17c-5, performed by Ohe and Kosaka (1972) and Hoshino et al. (2021), where the bones were discovered, indicates that the climate of Churui was milder than that of Fushimi, because there used to be a Fagus crenata forest there. The period turned out to be 120,000 years ago. In recent years, while global warming has become a serious social issue, there was a time in the past when the climate was much warmer., 北海道十勝平野は1875年以降、豆類、馬鈴薯中心の畑作、酪農など大規模農業による日本の食料供給基地である。その日高山脈東部十勝側山麓部にある芽室町伏美の標高275mの湿性樹林で、2002年に深さ1.6mのボーリングコアを得て、花粉分析を行い、2021年AMS14C年代測定と周辺の現在の林相・植生調査・土性調査により花粉種属から林相と林床植生の推移の特徴を明らかにした。伏美湿性地は、遠隔テフラ堆積物が厚く堆積してミズバショウのある湿地となり、この上に落葉広葉樹を主とする冷温帯性の落葉広葉樹林が成立し、花粉帯Dを形成した。深さ1.44mでのAMS14C年代は2310–2112calBP±2σ(94.9%)（NUTA2-27097）であった。この年代測定点の下で針葉樹が減少し落葉広葉樹が優勢である（A花粉帯）。深度1.0m（試料番号51）から深度1.4m（試料番号69）はコケスギランの胞子を少量伴う（B花粉帯）。なお、C花粉帯はトウヒ属やや多く（試料番号39深度72cmで最大値35%）、トドマツもやや多い。一方、ここより南東40kmの近距離にある忠類ナウマンゾウ臼歯とほぼ全身の発掘が1969年に行われ、その骨の産出層準17c-5から得られた花粉分析結果（大江・小坂,1972）と星野ほか（2021）は、ブナを伴い今回の伏美より温暖な気候を示し、その時代は12万年前であった。近年、地球温暖化が社会問題になっているが、より温暖な気候に見舞われていた時代が過去に存在していたのである。