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Speaker 1: Welcome to brain Stuff from How Stuff Works, Pay brain

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Speaker 1: Stuff Lauren Vogelbaum. Here. You might remember when in Republican

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Speaker 1: Senator James Inhoff of Oklahoma set out to refute the

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Speaker 1: quote hysteria over global warming by tossing a snowball around

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Speaker 1: inside the US capital. The obvious implication was, how could

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Speaker 1: the climate be changing that radically from humans burning fossil

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Speaker 1: fuels and pumping greenhouse gases into the atmosphere, since we

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Speaker 1: still have snowfall and chilly temperatures on a winter day.

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Speaker 1: But even if you're not a U. S. Senator from

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Speaker 1: an oil producing state, you might be wondering how it

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Speaker 1: is that scientists can predict climate trends over many years

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Speaker 1: but can't predict what the weather will be three weeks

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Speaker 1: from today. The reason is that weather and climate are

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Speaker 1: two very different things. Basically, whether it is what happens

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Speaker 1: today or tomorrow or this week, it's the day to

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Speaker 1: day variations. Climate, meanwhile, happens over many years. It's the

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Speaker 1: combined long term average of weather events. Scientists look at

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Speaker 1: climate in terms of fixed thirty year periods. Right now,

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Speaker 1: for example, scientists are comparing the daily temperature to the

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Speaker 1: period that started in nineteen eighty one and ended in one.

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Speaker 1: They'll shift forward ten years and start comparing temperatures to

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Speaker 1: the period between nine and twenty and so on. Scientists

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Speaker 1: rely on thirty year periods because it's an amount of

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Speaker 1: time that's long enough to produce meaningful comparisons, but just

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Speaker 1: short enough that any changes that occur will be subtle

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Speaker 1: without being imperceptible. Twenty years might not show enough change,

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Speaker 1: and fifty years might be too drastic. To make sense

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Speaker 1: of those, thirty year periods help us put the weather

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Speaker 1: on a particular day in the right context. Comparing the

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Speaker 1: temperature on December to the same day a hundred years

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Speaker 1: ago wouldn't provide that much useful information because the climate

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Speaker 1: was too different then, but comparing it to the average

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Speaker 1: of the temperature readings for every December five between nine

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Speaker 1: and twenty ten, when the climate conditions were pretty much constant,

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Speaker 1: makes it possible to say whether a given to number

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Speaker 1: five is an unusually cold or warm day. We spoke

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Speaker 1: with Jonathan Martin, a professor of atmospheric and oceanic studies

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Speaker 1: at the University of Wisconsin Madison. He explained or trying

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Speaker 1: to compare apples to apples when it comes to prediction.

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Speaker 1: Whether in climate are also very different. Weather forecasting, Martin explains,

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Speaker 1: is based upon observation of conditions that are already occurring

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Speaker 1: in real time in the atmosphere. Because those conditions only

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Speaker 1: exist for a short time, whether it can be reliably

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Speaker 1: forecast only over relatively short periods of ten to fourteen

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Speaker 1: days at most, though Martin said that's theoretical, My confidence

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Speaker 1: ends at day eight. Envisioning climate, in contrast, is much

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Speaker 1: more low resolution. Scientists are trying to project what the

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Speaker 1: trend will be over a long period, not what the

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Speaker 1: weather will be like on a specific day fifty or

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Speaker 1: a hundred years from now. That involves gathering and crunching

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Speaker 1: huge amounts of data in powerful computers and doing modeling.

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Speaker 1: We also spoke with Jeffrey S. Duke's director of the

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Speaker 1: Climate Change Research Center at Purdue University. He said, in

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Speaker 1: one sense, climate does not affect weather. It's a description

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Speaker 1: of the weather over a long period. You could turn

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Speaker 1: that around and say that climate provides you with information

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Speaker 1: about how likely you are to get a given type

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Speaker 1: of weather at a given time of year. But historically

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Speaker 1: the climate has been determined by the weather over long periods.

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Speaker 1: He continued In another sense, though, climate for a given

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Speaker 1: location is determined by a bunch of factors, such as

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Speaker 1: the latitude and position on the planet, which affects how

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Speaker 1: it is influenced by the circulation of the atmosphere and oceans,

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Speaker 1: and the daytime heating of continents. Climate is also influenced

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Speaker 1: by the composition of the atmosphere, the transport of water

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Speaker 1: from soil to air by plants, and other factors. On

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Speaker 1: a given day, the sum of all these influences determines

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Speaker 1: the weather, but as some of these larger scale factors

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Speaker 1: change over time, they will drag the weather and the

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Speaker 1: climate along with them. In recent years, some of the

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Speaker 1: sharp distinction between weather and climate has blurred slightly as

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Speaker 1: scientists have used increasingly phisticated models and accumulated knowledge in

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Speaker 1: an effort to figure out the extent to which some

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Speaker 1: specific weather events, say a hurricane, a heat wave, or

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Speaker 1: a monster snowstorm, is actually a function of climate change

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Speaker 1: driven by humans releasing greenhouse emissions into the atmosphere. By

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Speaker 1: running thousands of computer simulations, they can conduct what if experiments,

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Speaker 1: seeing how the atmosphere would behave if you removed one

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Speaker 1: factor or another. Although such analysis is still a work

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Speaker 1: in progress, Martin thinks that eventually it will be possible

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Speaker 1: to determine the extent to which specific weather events are

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Speaker 1: influenced by climate change. Some of that research is already

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Speaker 1: bearing results. The National Oceanic and Atmospheric Administration presented a

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Speaker 1: paper in December in which they concluded that three extreme

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Speaker 1: weather events in that year's record global heat, extreme heat

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Speaker 1: over Asia, and unusually warm waters in the Bearing Sea

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Speaker 1: would not have been possible without human caused climate change.

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Speaker 1: Today's episode was written by Patrick J. Keiger and produced

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Speaker 1: by Tyler Clang. For more on this and lots of

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Speaker 1: other stormy topics, visit our home planet, how stuff Works

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Speaker 1: dot com. M