For those who aren’t sure what this means, it has to do with the so-called urban heat island effect. There’s no doubt that development around old temperature monitoring stations affected the readings. What was once a grassy field now has a blacktop parking lot next to it, or a large city around it.
The question is, how to account for this effect? Did the increase in human activity raise the temperature readings by half a degree, or one degree, or some other number? The issue is far more complex than it suggests. There is no way to experimentally prove the effect. A study would have to have an experimental group where the environment around the thermometer was changed. The study also has to have a control group where the environment was not changed, and the results of the two different groups are compared. But you can’t do that. Each measuring station is in a different place and different things affect the temperature. You can’t be certain that the urban heat island effect is the reason the temperature increased.
What is certain is that the urban heat island effect requires some downward adjustment of the temperature readings. The readings might have to be reduced by one degree, or more, or less, to correctly reflect local changes. But Darwin’s temperatures were adjusted upwards. The airport went from a military base in 1941 to its present activity of 1,500,000 passengers on 56,000 annual flights.
That activity should increase the readings measured by the thremometers. They should be adjusted downward. They were adjusted upward.
