article_snippet: We focused on changes over 40-year periods, which is similar to the lifetime of houses and human-built infrastructure such as buildings and roads,' said lead scientist Dr Steve Smith, from the  Pacific Northwest National Laboratory in Washington. '
article_snippet: We focused on changes over 40-year periods, which is similar to the lifetime of houses and human-built infrastructure,' said lead scientist Dr Steve Smith, from the  Pacific Northwest National Laboratory in WashingtonWashington.
article_snippet: The new study started off by calculating how fast temperatures changed between 1850 and 1930, a period when the amount of fossil fuel gases collecting in the atmosphere was low.
article_snippet: Over the 900 years preceding the 20th century, 40-year warming trends rarely showed an average rate much higher than 0.1°C per decade, The new study found.
highlights_snippet: Figure is more than double the 900 years preceding the 20th century .
  