Thanks, a lot more of you have sent in comments. I will be responding to a number of you, but I’m behind so please be patient. On the list, I want to stick to the topic: what does science really tell us about climate. Only a few of the comments I’ve received relate directly to the science and the evidence. The other comments are interesting, but I want to stick to our topic and see if we can achieve any kind of agreement.
One of the articles I posted, about expanding polar ice caps, was misleading. Two of you sent in articles revealing that these expanded ice caps are unusually thin. Thanks for that, and I accept the correction. And let me emphasize I’m not trying to prove there is no global warming. I want to understand what the science really says, and if global warming turns out to be real, I’ll be glad to accept that. So far, the evidence seems to be the other way.
The first question is whether or not we are experiencing any kind of alarming warming. Here we have the satellite data for the past 29 years, which is the most accurate data we have for atmospheric temperatures:
We see that there a small increase in temperature in the north, and none in the south, over the past three decades. And during these decades Co2 emissions have been skyrocketing. On this time period at least, we are not seeing a strong effect from Co2.
And in the past ten years, we have been seeing a decline in temperatures:
Here’s a corresponding graph from ground stations, compared with Co2 increases:
Now let’s look at a longer timeframe, the past 1,000 years:
We are definitely not seeing a hockey stick. We are nowhere near the temperatures of the Medieval period, and recent warming is simply a gradual continuation of a warming that has been going on since the end of the Little Ice Age.
Here’s a longer timeframe, the past 10,000 years, since the last Glacial period:
What we see here is a regular pattern of oscillating temperatures, most likely caused by variations of solar activity. And it appears that we are approaching the maximum of the current oscillation, indicating that a downward trend is likely to begin soon. Indeed, if the past ten years are any indication, the downward trend may have already begun.
The fact is that temperature records do not show any cause for alarm. Perhaps a case can be made that something unusual is going to happen from recent Co2 emissions, but that case would need to be based on something other than actual experience with temperature. And from studies I’ve seen about regulatory mechanisms, I don’t think the case can be made. That is, however, another subject.
In response to these temperature facts, I’ve seen two arguments raised. One says that heat is being stored in the ocean, and we’ll see the heating from it later. As we see in the following documentary, warmer oceans lead to accelerated evaporation, redistributing the heat, and it is not at all clear what other regulatory mechanisms are acting. There is a question mark here, but no proven cause for alarm.
I’ve also seen arguments trying to minimize the existence of the Medieval Warm Period, trying to claim it was localized. The following documentary responds to that, and it also shows there is no indication of any rise in sea levels. This is an easy-to-watch documentary, and very interesting.
Global Warming – Doomsday Called Off
CBC NewsWorld documentary (5 parts)
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