Monday, August 11, 2014

Weather Vs. Climate In Global Warming

Sharknado - more than enough said, but I can’t resist.
Without having seen the “film,” I don’t think I can give a
good review, but I know enough to know that a flood of
sharks would do more damage than a single tornado full
of sharks. As with all falls, it’s the landing that does the
damage, so I would guess there would be a lot of shark
parts to clean up later. Do you think a sharknado is
caused by global warning?
Here in the Midwest, the fall and winter of 2013-2014 was a doozie. There were ice storms, snowstorms, sleet storms, and at least one Sharknado. My shovel and patience got quite a work out. But this was followed by a particularly mild summer, which by coincidence has included a second Sharknado. As of mid-August, we’ve only had one day where the temperatures got above 90˚F (32.2˚C).

Some people say that this is proof that global warming is a government/liberal/ commie/hippie/satanic conspiracy. I hate to burst your Oliver Stone bubble, but that’s just not so – and it doesn’t prove global warming is true either. Let’s take a short look into climate and weather and see if we can pick out a few trends.

Number one, and this is a point for the conspiracy theorists, global warming and climate change are as natural as day following night, as dogs chasing cats, or as Justin Bieber doing something socially or morally reprehensible. The Earth has gone through countless shifts in climate.

The Cambrian Explosion took place 550 million years ago, and the average global temperature at the time was 25˚C (77˚F). This was the period when the number of types of multicellular animals increased greatly over a relatively short period of time. All of our current phyla of animals were born in this era, so speciation obviously doesn’t have a problem with heat.

During the Middle Carboniferous Period 330 million years ago, the average temperature on Earth decreased from about 20˚C to 15˚C. Yet animals grew to huge sizes, like dragonflies with 6-foot wing spans, even though the temperature was dropping. By the Permian period the average global temperature was only 10˚C (50˚F).

You can see that through geologic history, there have been
many warm and cold periods in Earth’s history. We can’t
blame human technology for all of them. But that doesn’t
mean we aren’t affecting our rate of temperature rise now.
You can see that we are now near a low point, and that’s
What humans evolved to live in. The next warming trend
will be our first – can we survive it?
Ice ages have been plentiful too, with multimillion year periods where the global temperature was low. Today, the average global temperature is about 14˚C (57.2 ˚F), so we’re much closer to another Disney movie about a sloth and a mammoth than we are to a period similar to an ant under the magnifying glass.

But don’t conclude that this means we have nothing to worry about. We are in a period of global warming. Over the last 100 years, the average global temperature has risen 1.53 degrees Celsius. This may not seem like much, but it’s faster than any time in the previous 1400 years, and we don’t know how high it might go.

Number two, even if global warming and cooling are natural events, the rate at which they occur doesn’t have to be. The number of things man is doing to influence the rate of global warming is staggering (called anthropogenic warming). Burning fossil fuels that release carbon dioxide and other gases that trap the heat radiating from the earth and not letting it escape to space is just the beginning.

As humans, we breathe, and after we stop breathing - we decay. These processes release greenhouse gases as well. O.K., these are natural, but with the population explosion, there‘s a lot more breathing and decaying going on.

And more people need more food. Livestock are great producers of greenhouse gases methane and CO2 primarily (see this post). Even growing crops contributes to global warming. The fertilizers with nitrogen contribute to production of more nitrous oxide – right – laughing gas. This escapes to the atmosphere and is one of the worst greenhouse gases - not very funny.

We need to figure out to what degree human actions altering what might be a natural increase in temperature. The vast majority of scientists agree that we are accelerating the rate at which the temperatures around the world are rising. Many studies have compared the rate at which temperature rise and the amount of carbon dioxide in the atmosphere changed during historical periods of warming and now. They are going up faster now, and there doesn’t have to be a ceiling. Score one for the climate change supporters.

This sums up the difference between climate and weather
very well. The average weather, ie. what you expect for a
certain time of year, is the climate. What actually occurs on
any given day is the weather. The old song lyric, “It don’t
rain in Indianapolis in the summertime,“ refers to climate
not weather, because I got rained on today.
This brings us to point three – changes in global temperature aren’t given as one year compared to some other year in the last century, or any single year for that matter. The changes are best understood and are reported as deviations from what is considered normal over a longer period of time.

Here is the biggest point so far – climate and weather is not the same thing. Weather is what you see is happening when you stick your head out the window. Climate is considered an average of the weather for a certain place over the last 30 years. A single hot summer or single cold winter doesn’t really make much of a difference when it's included in a 30 year average. The trends over time are what are important.

Last year’s nasty winter or this year’s mild summer aren’t refutations of global warming any more than catching one 20 foot shark means that all the fish in the ocean are huge, deadly, and good movie material. It’s just one point of data that has to be looked at with all the others.

Things we can agree on: Global warming, whether natural, man made, or a combination of the two, can result in warmer weather. The warmest ten years on record have all occurred in the last three decades (calculated as rise over the 100 year average). Also, we can agree that the warmer weather can lead to stronger storms. Typhoons and hurricanes build up over warm ocean water; the warmer the water, the stronger the storms.

What isn’t so evident is whether global warming leads to an increase in the number of tropical storms. Two fairly recent papers (here and here) make opposite predictions. One says the increase in global temperature has and will lead to more storms. The other says the trend will be toward fewer storms as the temperatures rise.

Lake Erie is the shallowest of all the Great Lakes. The
deepest spot may be 210 feet, but it averages only 62 ft deep
overall. It’s almost the smallest of the Great Lakes (4th of 5)
but is still the 10th largest lake in the world. Because of its
shallow depth, it freezes over almost every winter. Since
the Erie Canal was built for trade, this seems to have been
quite the cog in the works.
Global warming can even lead to stronger winter storms. In 2006, the huge amount of snowfall in the Ohio, Pennsylvania, and New York was attributed to the fact that Lake Erie didn’t freeze over – the first time this was ever recorded. Less ice cover meant more water was available to evaporate into the clouds and become lake effect snow. Therefore, one could just as easily argue that bad winters are support for the idea of global warming.

One last thing we should agree on – the Earth itself doesn’t care if it’s cold or hot. The Earth will go on, speciation will go on, with new species evolving in adaptation to new conditions and filling niches left by species that couldn’t hack it. If humans are going to adapt and survive, we’d better find a way to do it that doesn’t contribute to further warming – just turning the AC on high won’t help the situation.

Contributed by Mark E. Lasbury, MS, MSEd, PhD
As Many Exceptions As Rules

Bender MA, Knutson TR, Tuleya RE, Sirutis JJ, Vecchi GA, Garner ST, & Held IM (2010). Modeled impact of anthropogenic warming on the frequency of intense Atlantic hurricanes. Science (New York, N.Y.), 327 (5964), 454-8 PMID: 20093471

Knutson, T., Sirutis, J., Garner, S., Vecchi, G., & Held, I. (2008). Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions Nature Geoscience, 1 (6), 359-364 DOI: 10.1038/ngeo202

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