claim: Internal variability can only account for small amounts of warming and cooling over periods of decades, and scientific studies have consistently shown that it cannot account for the global warming over the past century.
evidence: Thus current evidence does not support globally synchronous periods of anomalous cold or warmth over this interval, and the conventional terms of Little Ice Age and Medieval Warm Period appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries.... [ Viewed ] hemispherically, the Little Ice Age can only be considered as a modest cooling of the Northern Hemisphere during this period of less than 1°C relative to late twentieth century levels.