Comment on New Satellite-Observed Temperature Dataset

A new piece of scientific research hit the presses last week. It reported finding more warming in one of the (several) satellite-observed temperature histories of the earth’s lower atmosphere than had been previously reported. As these satellite-measured temperatures were the recent subject of comments made by presidential candidate Ted Cruz, a lot of scrutiny and interest surrounds these new findings—findings which seemed to refute some of Cruz’s assertions.

In researching his story on the new study, the Associated Press’s Seth Borenstein solicited my opinion about them and how they may alter climate change skeptics’ way of thinking about the satellite-observed temperatures—temperature datasets which had previously shown precious little warming over the past nearly two decades.

I was happy to offer my thoughts, and equally happy to see some of them reflected in Seth’s AP story. Given topical and length constraints, understandably, Seth had to be selective.

But I do have a bit more to say about the new research finding besides that it “shows ‘how messy the procedures are in putting the satellite data together.’”

Many of my additional thoughts were included in my broader email response to Seth’s initial inquiry and, with his permission, I am reproducing our correspondence below.

To Seth’s summary of my thoughts, I’d add “but even considering the new findings, the complete collection of satellite- and weather balloon-observed temperature histories of the earth’s atmosphere  indicate that climate models are projecting too much warming in this important region.”

Again, my thanks to Seth for reaching out to me in the first place. Here is out question and answer exchange:

Chip, 

Seeing that the climate doubter community has hinged so much on RSS and saying there has been no warming post 1997 _ despite NOAA heat records in 1998, 2005, 2010, 2014 and 2015 _  you’ve seen the RSS update that shows there has been warming in the last 18 years. I’m wondering what your thoughts are on it. Will you and those in your community keep using RSS, even if it shows no warming. Add to that the UAH record warming in February. Are satellites now contradicting the climate doubter community?

Thanks,
Seth

 

Seth,

Thanks for soliciting my opinion.

I can’t speak for the climate doubter community, however that is defined.

Personally, my doubts are not that human-caused climate change as a result of greenhouse gas emissions is not occurring and that a temperature rise as a result is not detectable in large spatial averages, but I have doubts that the change is taking place at the rate projected by the collection of climate models and that its effects are currently detectable on most smaller scale climate/weather metrics.

So with that out of the way, I’ll give some opinions as to the new RSS results and their importance to my way of thinking…

First off, as I have tweeted (https://twitter.com/PCKnappenberger/status/705515578325270529), the overall 1979-2014 trend in the RSS v4 MT data is still pretty far beneath the climate model expectations…far enough to continue to indicate a sizable discrepancy that needs further scientific attention.

Second, the trend in the new RSS v4 MT now makes it the mid-tropospheric (MT) dataset (including other satellite based and weather-balloon based) that has the greatest trend over the 1979-2014 period (see the same tweet mentioned above, as well as this one, https://twitter.com/PCKnappenberger/status/705472903458914305 which shows the old and new RSS data in comparison to weather-balloon compilations).

Given these two things, I don’t think it helps settle any questions regarding the temperature behavior of the mid-troposphere.

But what it does do is shed more light on just how messy the procedures are in putting the satellite data together.  Decisions, guided by science but not specifically defined by it, occur at many points in the procedure. The new RSS paper, again highlights how sensitive the final results are to those decisions. It is good that we have many different groups involved in assembling both the satellite history and the weather-balloon history. That these different groups provide answers that are pretty close to each other helps not to lower the uncertainty in any single result, but that the general result is not indicative as to what is going on in the MT.  The new RSS v4 now lies outside the old envelop of these collective findings. It’ll either prove to move the science in a bit of a different direction, or prove to be an erroneous result.  Time will tell. 

As to the impact on the “pause,” IMO there was too much being made about the “pause” in the first place. No serious student of climate science thought that it would last forever.  The important thing about it was that it provided a challenge to climate science and prompted enhanced research into natural climate variability, climate sensitivity, and other important aspects of climate science. So that it’s now over comes as no surprise.  But, once the El Nino warming subsides, I think we’ll probably see a continuation of the modest (below model mean) rate of warming.

I hope this is useful.  If you have any further questions, I’d be more than happy to try to answer them.

-Chip

In addition to Seth’s story for the AP, more reactions about the new satellite-study can be found at Watts Up With That, Climate Etc., and at Roy Spencer’s blog, among others.