rationalskepticism.org

Once again, science is shown to work. The laborious process in which scientists check and recheck their work and subject their ideas to peer review has led to another success. An independent test of global warming data has confirmed a groundbreaking 2015 study that showed warming was faster than prior estimates.

Because of its inconvenient findings, the study’s lead author Thomas Karl was subjected to harassment by Lamar Smith (R-TX), chair of the House Science Committee, in an effort to impugn his credibility. But now Karl and his co-authors have been vindicated.

Let’s take a step back and discuss the science. Measuring the temperature of the Earth is hard. There are many locations to measure and many choices to make. Should we measure the temperature of the ground? Of the ocean waters? How deep in the water? If we measure air temperatures, what height should the measurements be taken? How many locations should we make measurements at? What happens if the instruments change over time or if the location changes? What happens if a city grows near a measurement location and the so-called urban heat-island effect grows? How do we estimate the temperatures in areas where no measurements exist?

These and many other questions make measuring global warming challenge. Different groups of scientists make different decisions so that depending on the institution, they will get a slightly different temperature result.

But this diversity is also a good thing. It turns out that it doesn’t matter whose results you use – NASA, NOAA, The Hadley Centre in the UK, the Japanese Meteorological Agency, or the Berkeley Earth group – they all report a warming world. However, the rates are slightly different. So, one persistent question is, which group is most accurate? Whose methods are best?