I watched some of the Congressional hearing yesterday on Data or dogma? It consisted of evidence from four people who I shall politely describe as contrarians (Judith Curry, John Christy, William Happer, and Mark Steyn) and one person who had more mainstream views (David Titley).

I turned on just as Mark Steyn was pontificating about the scientific method and how great scientists of the past would be appalled by what’s going on today. Steyn is quite a commanding speaker, but utterly clueless about science and the scientific method. Judith Curry spoke a bit about being tossed out of the tribe. I didn’t hear John Christy say anything. William Happer, unsurprisingly, promoted CO 2 and suggested that hospitals now measure temperature the same way as satellites. This would only be true if hospitals were interested in the temperature of the air around you, at different distances from your skin. David Titley did very well, in trying circumstances, and I thought some of the Democrat senators were pretty well informed. Eli was live blogging, while Stoat points out that

when you’ve got so few scientists you’re willing to listen to that you’re obliged to invite Mark Steyn to speak, then you’re the one pushing Dogma.

Ted Cruz ended the hearing with seven facts that the witnesses had laid out, to which there had been no effective response. This could be because, with only one non-contrarian, it was pretty hard to rebut all of the gish-gallop. On the other hand, it could be because some of the “facts” are not worth responding to, or he simply didn’t understand the responses when given. I thought I might respond, here, to these supposed sevens facts.

CO 2 is good for plants.

This is at best a simplistic truism. Plants, of course, need CO 2 , but that doesn’t make it good under all circumstances. As I understand it, some plants will indeed thrive under higher CO 2 concentrations, others probably will not. Also, as David Titley pointed out, there are many other factors, such as heat stress and changes to the water cycle, that need to be considered. At the end of the day, this isn’t necessarily about showing that something will be definitively good or bad, but trying to understand how things will change, and the consequences of those changes.

The Earth is greening.

Well, yes, the biosphere is taking up about 25% of our emissions. This is quite a substantial fraction of the total mass of the biosphere, so it is no great surprise that there has been greening. However, if you want more context, it’s worth reading Randa Myneni’s responses to Matt Ridley’s claims in an interview with Roger Harrabin.

There have been periods in the past when there has been more CO 2 in the atmosphere than there is now, and this was before the industrial revolution.

Well, yes, there have indeed been periods in the past when atmospheric CO 2 concentrations have been higher than now. However, this was before humans were even present. Also, there is no suggestion that the only way CO 2 levels can increase is through human activity. It’s simply what is causing it to happen now. In fact, part of our understanding of how our climate will respond to increasing atmospheric CO 2 concentrations comes from studing climate change in the past. There is no inconsistency here.

Satellite and balloon data demonstrate no significant warming whatsoever for the last 18 years.

Well, this just illustrates a lack of understanding of what is meant by “no significant warming” and ignores swathes of other data that indicate that we have continued to warm. The satellite data is also very noisy, so typically requires quite a long period of time (more than 18 years) for a trend to emerge. Also, 1998 was a particularly warm year because of a large El Nino, so the “no warming for 18 years” is a cherry-pick. You can look at all of this yourself, using the Skeptical Science trend calculator.

Satellite data is the best evidence we have.

Well, this is a bizarre thing to say, as it almost certainly is not. Eli has a post on why we shouldn’t trust some of the satellite datasets. Even Carl Mears at RSS says

A similar, but stronger case can be made using surface temperature datasets, which I consider to be more reliable than satellite datasets (they certainly agree with each other better than the various satellite datasets do!).

In truth, we have lots of different pieces of evidence that, together, indicate that we are warming and that the dominant cause of the recent warming is us.

Sea levels rose more in the first half of the 20th century, than in the 2nd, prior to the significant increase in CO 2 .

I think this comes from Judith Curry who is picking a single study that showed that the rate of sea level rise may have been higher than now, for a short period of time, earlier in the 20th century. It’s discussed in more detail here, but most studies indicate that the rate now is higher than at any other time in the 20th century, and that it is now probably more than twice the 20th century average. Also, even if there were a period when it was faster, sea level rise is a straightforward consequence of thermal expansion and the melting of land ice. If we continue to add CO 2 to the atmosphere, we will maintain a planetary energy imbalance, the energy in the system will continue to rise, and sea levels will continue to rise due to both thermal expansion and melting of land ice. It’s as simple as that.

Apocalyptic computer models are profoundly wrong.

Well, no, they are not. You can read our Medium article, which includes a discussion of why climate models are skillful. You can also watch Gavin Schmidt’s TED talk. As David Titley said during the hearing all models are wrong, but some are useful. The claim that climate models are profoundly wrong is just silly, and calling them apocalytic is stupid.

Well, I think that’s all I can face. If anyone wants to add more in the comments, feel free.