Quote from newbunch:
This is what you didn't actually answer:
What is the correct average global temperature?
What year/time period average should we use to determine the correct temperature?
What happened to the global climate before this most recent trend?
Is global warming bad or good? (Maybe is not a good answer)
And what caused the previous temperature change? And the one before that?
And what about global warming on Mars?
If there is global warming and it is bad, how much would it cost man to stop/reverse this trend?
Or will the trend reverse on its own?
And would the money be better spent on other things?
You made comments of each group of questions, but didn't actually answer them.
Some of the questions can only be properly answer with appropriate scientific background knowledge. Most questions don't have a clear cut yes or no answer. Are you really interested? That will bore everyone to death.
I'll try to answer the first two questions together because they are the same nature. If you're not bored and want more then I can try the others.
What is the correct average global temperature?
What year/time period average should we use to determine the correct temperature?
The short answer is that there is not a uniquely defined average global temperature. This is similar to the question "what is the correct index for the market average?" Just because there are dozens of market indices doesn't mean that you won't know whether the market went up or down in the past 10 years. Likewise, there are many ways to examine whether the global temperatures went up or down in the past decade or in the past century.
You can use daily close, weekly close, or even monthly close to measure whether the market is going up or down. Over the period of many years, whether you use daily close or monthly close matters very little. But you have to be consistent. You cannot use daily close for one year, and monthly close for the next. Same goes for the global temperature. You can take the high of the year or the low of the year, or the average temperature on same 12 days of each year. But you cannot compare temperatures in January to temperatures in June. Take a look at this figure below
It gives three sets of reconstructed historical temperatures. These were data using different methods. They are like three different marke averages. At any given year the difference between the three sets can be huge. These differences can have many causes. Part of that may be related to the accuracy or reliability of the particular method. Part of that could be due to random events happened locally at the place where the data was recorded. But the nature of random events are such that they do not influence the overall trend. Indeed, the overall trend of all three curves is the same.
Correction: There are actually 5 curves. But 2 of them don't go back as far as the other three. That may have to do with the limitations of the method used or the availability of the data.
So the question should be reframed as "If we don't have a unique standard for an average global temperature, how do we know that it's going up?"
The answer to that question is, we compare apples to apples and oranges to oranges. If all of them show the temperature going up, then we have "global warming."
