Has global warming stopped?

Recently reappearing is the oft-repeated claim that global warming has stopped so we don't need to worry any more about emissions of carbon dioxide and other gases into our atmosphere. This claim is at best naive; at worst it's simply fraudulent.

One way to understand how our universe works involves looking at evidence through the lens of preconceived principles, cherry-picking those data that satisfy us and rejecting those that do not. If reality contradicts preconceptions, this technique leads to confirmation of what we already think we know rather than an understanding of what is really happening.

A different lens involves looking at the evidence and drawing conclusions from what it tells us. This technique, called science, allows us to understand what is really happening even if it is inconvenient and seems to challenge preconceptions. I explore the question of slowed global warming through the second lens.

What Is the atmospheric warming trend?

NASA's Goddard Institute for Space Studies global temperature data from 1880 to 2012 reveal a clear upward trend with over a 99 percent the probability that this upward trend is real. The basis for arguing a slowing is the claim that since 1998, the upward trend has slowed or stopped. The year 1998 is selected because it was the hottest year on record at that time, and was above the warming trend of the decade. This is almost certainly because 1998 was an El Niño year.

However, the data for 1998-2012 show a continued upward trend, though slightly shallower, with a probability still greater than 70 percent. Science requires analyzing all the data in a set, not cherry-picking subsets of the data because they show trends we want. This is not science.

If cherry-picking data is legitimate, then asking what the pattern would be if 1998 had just been typical of the trend of the decade is equally legitimate. By replacing the actual value of 1998 with the average from the two preceding and succeeding years, a trend is revealed that is steeper again, with over a 90 percent probability.

Claiming atmospheric warming has stopped is false.

The rest of the story

Global warming occurs because:

Incoming short wave radiation from the sun (largely the visible range) passes through our atmosphere and reaches the Earth's surface.

This energy is transformed into longer wavelength energy that radiates back outwards.

Some of this energy is trapped in gas molecules in our atmosphere warming our planet enough for it to support life as we know it.

As the concentration of these heat-trapping gas molecules increases, the atmosphere's ability to retain heat increases and our atmosphere warms.

Importantly, only about 2 percent of this heat energy contributes to atmospheric warming. Fully 96 percent of it enters the oceans but because of water's properties, much more energy is required for warming than is the case with rapidly warming air. Confirm this by heating saucepans of water and air on your stove and see which warms fastest.

Oceans serve as heat sinks for the energy that is trapped at the planet's surface; but because of water's properties oceans are warming much slower than the atmosphere. Even so, a recent study indicated that oceans warmed faster in the last 60 years than in the last 10,000 years. Because we are land-dwellers, we think of air temperature as the most important component of global warming, but it is not. Our oceans are serving as far greater heat energy sinks than is the atmosphere. Retention of oceanic energy continues unabated.

Besides considering evidence regarding the warming atmosphere and oceans, we must also consider the array of other phenomena resulting from of the carbon pollution we are emitting:

  • Loss of ice at the poles and from glaciers.
  • Reduction in critical snowpack providing irrigation and drinking water for much of the world's populations (including us).
  • Species extinctions and range adjustments of wildlife.
  • Expanding zones for crop and human disease organisms.
  • Increasing fire season length with increased area burned.
  • Increasing frequency of severe weather events.
  • Threats to agricultural and forestry production.
  • Acidification of the oceans, compromising marine species and human fisheries.

Even if we think the probability of continued carbon pollution problems is small, the risk should they happen suggests it is critical to address the cause. If we wish to leave future generations a planet that can support them to anywhere near the extent it supports us, we should acknowledge and address the problem. Rejecting evidence because it challenges preconceived notions is risking our collective future

Dr. Alan Journet of Jacksonville is co-facilitator of Southern Oregon Climate Action Now. He will present a lecture titled "A Waning Warming; What's Up With That?" from 6 to 6:30 p.m. Tuesday, Nov. 26, in the Adams Room of the Medford Library, 205 S. Central Ave.

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