The debate over global warming can be distilled to two basic questions:
(1) Is the earth undergoing an unusual period of warming? and,
(2) Is the warming caused by the man-caused increase in atmospheric CO2 concentration (and if so, what can we do about it)?In this post I address the first question: is the planet warming? Even many “skeptics” say that it is. You can google “climate change” and find graphs showing a sharp warming trend in recent years, and easily convince yourself that global warming is real. A scientist, however, must consider not only these graphs, but how they were constructed – the raw data, the methodology – to determine their validity.
I have done so, and I've concluded that global warming is NOT happening. Or more accurately, there is no reliable evidence that it is happening. The figures and "facts" used to demonstrate global warming are unreliable and the analyses invalid, while the voluminous reliable data show that the warming trend claimed by global warming proponents does not exist.
First let's start with the famous “hockey stick” graph. There are several versions of this graph, produced by different climatology groups, and they show the same thing: from the year 1000 until about 1900 the “global temperature” has varied mildly up and down, but from 1900 onward it skyrockets (hence the term “hockey stick”).
This graph, constructed mostly by Michael E. Mann, has been so criticized and discredited for its bad methodology and mathematics that it is now considered totally bogus and bordering on scientific malpractice. In fact, Mann's statistical algorithm has been shown to produce that “hockey stick” shape even when fed random data. Any conclusions based on this or similar graphs should be discarded.
Now that the issue of the "hockey stick" graph is out of the way, let's address a real scientific problem. How does one calculate the average "global temperature"?
The reality is that it is so difficult to determine the average temperature of an entire planet that it's reasonable to say there is no such thing. Of course scientists try to calculate it anyway and this is done through several means, which can be divided into two categories: direct measurements, typically limited to modern times, and temperature reconstructions, for hundreds to thousands or millions of years ago. For this post I will limit the discussion to modern direct measurements.
The problem is that the meteorological stations cover only a tiny fraction of the global land surface. To extrapolate an average temperature for the entire planet from this sparse and sporadic data requires generous assumptions and mathematical calculations which, to my knowledge, have only been publicly described in a qualitative way. Nevertheless, some scientists have used this data, and found that their calculated "global temperature" has been rising rapidly in recent years:
The above “global temperature” graph was originally produced by Dr. James Hansen. Dr. Hansen runs NASA GISS, and is responsible for nearly every graph and study cited by global warming proponents. He is also a famous climate activist who argues that CEOs of fossil fuel companies should be put on trial for "high crimes against humanity and nature". He is the same Dr. Hansen who, along with actress Daryl Hannah and 30 other climate activists, was arrested in June 2009 in a protest at a coal mining facility in West Virginia. His strange behavior and climate activism should not necessarily disqualify his research, but it is clear he is not following the impartiality and professionalism that should be expected of respectable scientists.
Look at the above figure in detail. It traces the “global temperature” from 1880 to today using a single line. The green “error bars” on the graph are not really error bars – they don't reflect uncertainty in the “global temperature” calculation, but “account only for incomplete spatial sampling of data”. I've already mentioned the impossibility of calculating an average “global temperature”, but even without that understanding any honest scientist could point out that this graph is absurd. The number of meteorological stations and the fraction of global area covered have changed dramatically from 1880 to today. Therefore any comparison of global averages necessarily draws from vastly different data sets from year to year. Despite the best efforts of the researchers, this will skew the averages over time. The construction of this graph is an interesting exercise for curiosity's sake, but it cannot be relied upon to draw conclusions about global climate.
To further demonstrate this point, take a look at this video, which shows how the temperature network has grown since the 1890s, and then dwindled in modern times:
Every scientist knows that when half the data points are thrown out it is bound to skew the results.
Furthermore, as I mentioned earlier, the raw station data must be thoroughly processed and manipulated to yield an average "global temperature". NOAA has published the temperature difference between the raw data and the processed numbers used in their climate figures. The result is their "adjusted" data shows an additional 0.5 degree (F) temperature increase over the past 5 decades that is not present in the raw data:
Reliable temperature measurements show no warming
The only reliable and scientifically accurate way to determine temperature trends is to limit our analysis to consistent data sets. By this I mean temperature measurements made using a single reliable method, at a single location or over a consistently-well-covered region of the globe, for an extended period of time. It just so happens that many such data sets exist, and they offer no evidence of global warming.
The most reliable and consistent temperature record in existence uses a single measurement method over a very large contiguous area and length of time: the meteorological record of the United States of America. I have downloaded the data and plotted it with no modification:
As you can see, there is no warming trend in the United States. This fact is well-known, but global warming proponents claim it is an anomaly – that for reasons unknown the USA is not experiencing global warming. Is it a coincidence that the single most reliable temperature record in the world shows no warming and is discounted as an unexplainable anomaly, while the dubious and scientifically-invalid calculation of “global temperature” shows warming and is heralded as fact? (Also note that the USA graph includes the artificial 0.5-degree warming that, as shown above, NOAA added to the raw data.)
If the lack of warming in the USA temperature record is really an anomaly, then what about other consistent temperature records from around the world?
Graphs of individual temperature stations from around the world are available online. I have downloaded data from 18 stations at random. The areas sampled include eastern, western, and northern Canada, Alaska, the Arctic, the Antarctic, Australia, Europe, Greenland, Iceland, Egypt, northern and sub-Saharan Africa, and South America. I limited my sampling to mostly stations in rural areas (to avoid the urban "heat island" effect), and those with uninterrupted data extending back most of a century. An example is shown below: data from Anchorage, Alaska, and Reykjavik, Iceland. The complete set is available here.
Not one shows a dramatic warming trend. In not one location are today's temperatures unusually warm. This is a small sample of the total number of stations, but what is the probability that 18 stations selected at random would show no evidence of warming if a dramatic warming trend really exists? Or is it more likely that, as I have argued, the graphs of "global temperature" are bogus and global warming is not really happening?
The ice caps are not melting
Direct temperature measurements are not the only consistent means of determining global climate trends. Global warming proponents often claim that the melting of the polar ice caps is strong evidence for global warming. Amazingly, global sea ice data from NOAA proves just the opposite: the ice caps are not melting and global warming is not happening.
There is one more consistent data set: global satellite temperature measurements. Since 1979 a series of satellites in orbit have been monitoring global temperatures. The satellite data provide probably the best estimate of global atmospheric temperature trends. I have downloaded the satellite data directly from the source and plotted it below:
Where is the dramatic warming trend? The satellite data looks nothing at all like Hansen's "global temperature" graphs. It is clear from the above plot that any evidence of warming is inconclusive at best, and there is a slight cooling trend since the temperature peak in 1998. (Note: the two large spikes in the TLS data are the result of volcanic eruptions.)
Conclusion: Global warming is NOT happening