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Dear Sen. Daines: Natural variability isn't the last word on climate science

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Politicians recently visiting the Lolo Peak fire tried to put the blame for the fire on lawsuits filed by environmentalists. Sen. Steve Daines did mention the role of climate change, but only to say that the climate has always changed.

Well, yes, obviously. Changes in Earth's temperatures and resulting climate have often been driven by forces beyond human control, and many such changes occurred well before humans existed. These familiar natural forces have changed the climate from hot to cold and from cold to hot, all without a lick of help from man, woman or child.

For example, it's become plain that large volcanic eruptions can cast killing chills across the planet, crushing crops and making people miserable. For another example, El Niño—perhaps the most widely known expression of natural variability—periodically releases ocean heat that has a rippling effect across much of the planet.

So, yes, Daines' remark wasn't entirely hot air. Natural forces are clearly capable of changing the climate.

A recent attention-getting study turned up evidence that an earlier planetary hot spell was driven by volcanic magma under an extensive Siberian coalfield. Geologists put that initial study to the test and have twice confirmed that the hot magma scorched the coal above, thereby releasing lots of carbon into the atmosphere, which then increased atmospheric and oceanic temperatures. The resulting heat created extinctions long before there were humans to blame.

It's the real world out there, with more than one thing going on at a time, so it's no shocker that the forms of natural variability don't always act alone.

One recent study cites evidence that natural variability in the form of a sulfur-loaded volcanic eruption may have had its cooling influence on North America complicated by the warming influence of another natural variation, El Niño.

All in all, and independent of any single line of evidence, the science on natural variability of climate is as good as it gets. Natural variation of climate is real, is influential, and isn't going away.

A 2007 analysis in Science succinctly summarized the situation: "Rising greenhouse gases are changing global climate, but ... natural climate variations will have a say."

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Natural climate variations will have a say, but they're not the only voice in the climate choir, as Daines might have us believe.

Modern interest in the influence of greenhouse gases had its start with a hunch explored by mathematician Joseph Fourier in the 1820s. Fourier wondered why Earth isn't too cold to support life. After all, the planet spins on its axis, turning half the globe away from sunlight every night. Why doesn't everything just freeze in the dark?

Fourier wasn't sure, but it was known by his day that our atmosphere is made up of several kinds of gases. That was enough to make him wonder if some of those gases might somehow hug enough heat to keep the planet from deep freeze. A contemporary journal published Fourier's hypothesis, but it wasn't until about 1860 that physicist John Tyndall put it to the test. With some simple experiments, Tyndall found that two atmospheric gases—water vapor and carbon dioxide±—were especially good at holding heat.

Thirty years later, in the 1890s, a new normal had been established. The burning of coal was commonplace, and there was reason to suspect that it was enabling additions of carbon dioxide above the atmosphere's normal levels. Curious about the consequences, physical chemist Svante Arrhenius put together a simple little model to estimate where it might lead.

With Arrhenius' calculations, modern scientific climate prediction was off to an early start, even before the end of the 19th century. Although primitive compared to the climate calculations of today, Arrhenius' model predicted a warmer world, with an eventual loss of ice and snow. We're seeing his model tested in the real world today, as glaciers shrink, Arctic sea ice retreats and rainfall in mid-winter months signals a world too warm for snow.

None of which contradicts the science on natural variability. Earth is and will remain susceptible to natural variability capable of forcing its climate into change, in one direction or another.

Nor does natural variability contradict the science pioneered by Fourier 200 years ago. It's still the real world out there, in all its complexity, and politicians shouldn't be allowed the luxury of using natural variability as a smokescreen.

Lance Olsen runs a climate listserv for agency and university scientists and conservation group staff.

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