Climate Models Work

Shooting down another excuse for climate deniers ....

Did you know that of all the carbon dioxide we’ve spewed into our atmosphere since the start of the industrial revolution in 1750, over half of it has been emitted in the last three decades? Probably since most of you were born. A number worth remembering. And nearly 90 percent has been emitted since I was born. That’s a sobering thought. My cohorts and I are the villains of the piece.

That accelerating rate of increase in carbon dioxide emissions is consistent with the concentrations of carbon dioxide increasing in the atmosphere and global temperatures increasing more rapidly in recent years, as shown below.

How do we know if that’s the cause of the observed temperature increase? A reader of my previous post questioned whether plant effects (e.g., deforestation) had been adequately considered. Deforestation is indeed an important effect. It releases huge amounts of carbon dioxide into the atmosphere. For example, the Australian bush-fires earlier this year more than doubled the country’s normal annual emissions of carbon dioxide.

The Carbon Cycle graphic in my last post showed that interchanges with the biosphere are indeed considered by climate scientists. The discipline isn’t confined to just atmospheric scientists. A casual look even at just the titles of the IPCC Reports give an idea of the huge scope of science involved. And if that’s not enough, deep deeper there. It’s true that early climate change models were less complete, but the modern models (they’re called Earth System Models) are improving all the time.

Even back as far as the IPCC Third Assessment Report in 2001, mankind’s contribution was obvious, as shown in the three plots below. They clearly show that the observed changes in temperature are well replicated in models, but only when both natural and anthropogenic effects are included. Natural effects include changes in solar activity, and volcanic activity. Anthropogenic influences include deforestation as well as fossil fuel burning.

A more recent NASA report also shows excellent agreement between model and measurement. It looks pretty convincing to me.

Climate change is complicated and no climate scientists would presume that we understand everything there is to know. But “the proof of the pudding is in the eating”. Our understanding of the problem is complete enough for us to be able to match theory to observation.

Bottom line. Our (only) planet is warming, and we’re to blame
(Don’t believe noisy old white men with vested interests).

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