Some tiny, insignificant website called “World Net Daily” has published a glorious tirade about how climate change is a total hoax, complete with the above graph. This is a perfect example of data not burdened by pesky “facts” or “reality”.

The graph looks fairly impressive, to be sure. It seems to suggest that the “theoretical models” that predicted global warming (red zone) are completely wrong, because the actual trend in temperatures (blue zone) has been one of cooling. In fact, the “error margin” on the prediction zone and the “error margin” on the actual trend zone don’t even overlap! Wow, obviously global warming is a complete scam.

Good conservatives approve of this message. Which is why they will not be interested in the liberally biased “facts” in the rest of this article.

The actual data in this graph is taken from the monthly global mean UAH observed lower-troposphere temperature anomalies (vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt). This graph goes all the way back into the deep and distant past of the year 2005. Of course, the models that generate predictions of global warming usually go back until at least the 1970’s. The source data (click on the previous link) goes back to 1978.

By creating a trend line based only on 2005-2013, they are effectively “cherry-picking” the data. Weather data is very noisy, like the stock market or the children of liberal parents. When you observe only a very short period of time, almost anything can seem like it’s happening.

For example, in following graph we show the same experimental data with four different trend lines: one that starts from the beginning of the data set (1978), one based on data since 2000, one based on data since 2001, and one based on data since 2011.

Obviously, because of the large fluctuations in the data, you can pretty much pick a data range to predict anything you want, if the tool that you are using is linear regression. Moreover, when you pick a very narrow range of time, it creates the illusion that your “margin of error” is very small. The only reason the margin of error in the model predictions in the first graph (red area) is so large is because it’s based on modeling a much larger data set, going farther back in time.

Now, the screaming headline “global warming has exploded since 2011!” (green line) is no more nor less accurate than the headline “the world has been cooling since 2005!” (the original graph, above), because global warming is a statement about long-term trends in climate, not fluctuations in temperature that span less than a decade.

All of these, however, are just “liberal facts”. They have no place in good, conservative articles that appear on “World Net Daily”.

graph data source: http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt

graph found via: World Net Daily

related story: UNSKEWED GRAPH: Scientists split on climate change

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