Global warming- natural and long-term

An interesting report quoted here

The gist of the report is this- some scientists studied weather records in Philadelphia and discovered that you need a period of at least 130 years of weather data to pick that "record events" indicate a change in climate. They studied Prague's weather recirds which go back over 200 years and found that the current period of global warming goes back to before 1900, long before the contribution of carbon dioxide could be considered significant.

"Their conclusion also allows us to disqualify all comparisons of record temperatures based on a 100-year timescale or shorter as noise or hysteria. Whoever uses these weather events to prove a long-term trend is a charlatan.

The same conclusion, however, also implies that the same warming trend in Prague has existed before 1900 because the constant regime wouldn't be reached if the trend didn't exist before 1900: you need more than 130 years of the trend.

"So it is unlikely that the bulk of the warming observed in the Prague data can be explained by the influence of the global industry that was negligible 100 years ago in comparison with its current size. Instead, the 19th century data from the Czech lands played an important role for them to reveal the underlying trend which means that according to their analysis, the bulk of the post-Little-Ice-Age warming should be of natural origin."