Sunday, July 15, 2012

The Heat Returns

Here in Iowa, we just emerged from an 8-day stretch when the daytime temperatures exceeded 95 degrees each day. The heat index on several of those days topped 100, easy. It was damn hot.

The sizzler broke last week, and temperatures regressed to seasonal averages of mid-80s for a few days. It felt downright refreshing.

That respite has ended. Today, the heat has returned, and it will be with us for at least a few days. Temps will reach the high 90s, according to the National Weather Service, and with a southerly wind bringing moisture from the Gulf of Mexico, the heat index on those days almost surely will be north of 100ยบ. Again.

Iowa gets hot in the summer, of that there is no doubt. And it's not unusual for the thermometer to register in the 90s – or even the high 90s. But generally that occurs in August, Iowans tell me, and it's a wave or two, and that's it. Already, though, we had a prolonged heat wave that began in June and now one that's ripening this month.

I think about the onset of heat, the drought in Iowa – on pace to be the worst in more than two decades, the epic drought in Texas last year, the wildfires ravaging New Mexico, Colorado, California and other areas of the western U.S., and I wonder how anyone – and I mean anyone – doubts global warming.

At this point, you just have to be plain ignorant to disbelieve that our country is baking, and that we have put her in the oven. I'm tired of listening to folks who willfully ignore evidence, as if they were grade-school children afraid of getting cooties.

The facts, please:

• The average temperature across the contiguous United States for the first six months of this year has been the warmest on record — and by a considerable sum — dating back to 1895, according to a monthly report released Monday by NOAA’s National Climatic Data Center.

• The past 12 months (July 2011 to June 2012 ) have been the warmest on record for the mainland United States, according to NOAA. During that period, the nation averaged a temperature of 56.0 degrees, 3.2 degrees higher than the long-term average. According to the report, every single state in the contiguous US except for Washington saw warmer-than-average temperatures during this time period.

• This decade, and the decade prior (meaning the entire 21st century) has been the hottest decades in the instrumental temperature record. From NOAA: "Including 2011, all eleven years of the 21st century so far (2001-2011) rank among the 13 warmest in the 132-year period of record. Only one year during the 20th century, 1998, was warmer than 2011."

Now, we know that climate is about trends, over longish time spans, whereas weather is tracking what happens day to day, or week to week. Weather, in other words, is a subset of climate, a blink of an eye compared to a night's sleep. And while the points above don't necessarily prove the U.S. is getting hotter, it and the other accumulating phenomena do show the trend is going that way, and that the probability for extraordinary happenings – be they floods, drought, heat, tornadoes, hurricanes, ice melting on glaciers and in the Arctic, etc. – is increasing. Unfortunately, this falls right in line with what climate scientists have forecast. And it will get worse, their models show.

If that doesn't grab you, then let's just consider the basic science and go from there:

We know there are a host of natural variables that have influenced the Earth's climate since the planet's formation. As you may know, these include: changes in the Earth's orbit around the sun, the tilt of its axis, its "wobble," the intensity of the sun, the amount of CO2 in the oceans and/or the atmosphere, volcanic eruptions, impacts from meteors, global wind patterns, circulation in the ocean, regional phenomena such as El Nino and La Nina, etc. The effects of some variables are pretty well known; the effects of others not so. Climate scientists also are studying how each variable works, and how (or whether) they work in tandem is still being studied. The bottom line is the Earth's climate is incredibly complex and mysterious. There is a lot to learn.

That said, there is a lot that we do know. Climate scientists have been able to tease out the most pronounced natural variables that influence the Earth's climate with great clarity. Those biggies include the effects of eccentricity, precession, axial tilt and the sun's intensity. For example, the advent of Ice Ages that you reference (and relatively warm periods between them called interglacials) are caused primarily by the Milankovitch cycle, which is governed by some of these processes I cited earlier in this paragraph. The elevated CO2 that marked the dinosaurs' reign (and other periods in the Earth's history) were caused by natural factors, such as volcanism or a meteor impact.
These natural variables continue to influence our planet's climate, no question. And the scientific models take all of them into account. The reason why they are predictive models, and not fool-proof analyses, is that we don't know fully the extent that these variables influence climate. But the models are getting better, and thus, more accurate at predicting changes. In fact, they have accurately predicted the warming that we are seeing in the Arctic, the drought that is frying the American Southwest, etc.

What none of the models can account for is that natural variables alone have caused the changes to climate that we have witnessed since the Industrial Revolution and that we are seeing today. And that's where the rubber meets the road. Something else is causing these changes, beyond the natural influences. And that something is us. It's our burning of fossil fuels that is increasing the concentration of CO2 in the atmosphere. CO2, as I am sure you know, warms the air. That fact is indisputable. And that's a good thing, for without CO2 and other greenhouse gases, our little planet would be far too cold to support human life. But there's such a thing as too much of a good thing, and that's what is happening now. We have put our planet in the oven and are slowly baking it.

The cost of ignoring global warming and our role in it has become too high to deny any longer. The cost of doing nothing to prevent drastic changes to our planet's climate has become too high to stand idle. Even if all those climate scientists and all those models are wrong, wouldn't you feel better if we did something in the face of what appears to be a calamity on the horizon than if we did nothing?

Well, wouldn't you?

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