Global warming is happening. Just look at the shrinkage of glaciers. I'm sure average temperature measurements also show a small increase, IIRC.
The trouble is the plausible hypothesis that it is due to man-made increases in "greenhouse gases".
I only alluded to to it, but you stated it almost explicitly, i.e. there are natural variations in the radiant energy from the sun which have also been documented by recordings made by satellites.
The surface record, however, continues to go up.
The surface record continues to go up. But you have to be very careful with the surface record. It is taken with thermometers that are mostly located in or near cities. And as cities expand, they get warmer. And therefore they affect the readings. And it's very difficult to eliminate this--what's called the urban heat island effect. So I personally prefer to trust in weather satellites.
You've got one record that goes back 100 years, which has got imperfections in data gathering, and then you've got a much shorter record that also has questions about data gathering, the satellite record. From a statistical point of view, you get more power out of a longer record than a shorter record, don't you?
A longer record, in general, will give you more statistical power, if there is a general overall trend. But, in fact, the surface record also shows a cooling. So, which part of the surface record are you going to believe? The part before 1940, that shows a warming, or the part after 1940, that shows a cooling? See, that's the dilemma.
The curve--as the climate modelers have it--has three segments. They would say there was a warming, a cooling, and a sharp warming now...they would say...on the land surface. And that's their problem.
Well, since we're using models to predict the future--and the only way you can predict the future is to use models--the important question is: Can these models be validated by observations? And the models very clearly show that the climate right now should be warming at about the rate of one degree Fahrenheit per decade, in the middle troposphere, that is, above the surface. But that's not what the observations show. So until the observations and the models agree, or until one or the other is resolved, it's very difficult for people--and for myself, of course--to believe in the predictive power of the current models. Now, the models are getting better. And perhaps in ten years we will have models that can be trusted, that is, that agree with actual observations
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In point of fact, the issue of whether global warming is occuring is open to debate and right the arguments made by people who contend that global warming is occuring depend in large part on the point in time they begin their measurements. For example, if you start your measurements back 800 years ago when there was an ice age, then, yes, global warming has been occuring for some time. However, if you begin your measurements 40 years ago, then it is unclear whether global warming is occuring. As for your example of glaciers melting, I believe reports have been coming out of Antarctica for sometime that the ice cap appears to be increasing there. Likewise, as a recently as a few weeks ago, we were treated to reports in the European press that the 'global warming' may result in Britain going into the deep freeze in the coming years. So, in short, you can count me as being extremely sceptical when people like David Brooks say that there is strong evidence that global warming is occurring.