Lightning as a measure of global warming

[Loren Booda]

1. Is an annual increase of lightning strikes worldwide a measure of global warming?

2. What has been the correlation between such discharges and temperature in recent decades?

 

[Xnn]

Don't remember seeing anything about this in the IPCC reports. But here is an article referencing a NASA study:

http://www.sciencedaily.com/releases/2007/08/070830105911.htm

This information can be derived from the temperatures and humidities predicted by a climate computer model, according to the new study published on August 17 in the American Geophysical Union's Geophysical Research Letters. It predicts that in a warmer climate, stronger and more severe storms can be expected, but with fewer storms overall.

and

The models do not directly simulate thunderstorms and lightning. Instead, they evaluate when conditions are conducive to the outbreak of storms of varying strengths.

and

The study found that continents warm more than oceans and that the altitude at which lightning forms rises to a level where the storms are usually more vigorous.

These effects combine to cause more of the continental storms that form in the warmer climate to resemble the strongest storms we currently experience

Interesting that fewer storms are predicted, but those that do form are more severe.

 

[Xnn]

http://www.sciencedaily.com/releases/2008/12/081227214927.htm

The frequency of extremely high clouds in Earth's tropics -- the type associated with severe storms and rainfall -- is increasing as a result of global warming, according to a study by scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

For every degree Centigrade (1.8 degrees Fahrenheit) increase in average ocean surface temperature, the team observed a 45-percent increase in the frequency of the very high clouds. At the present rate of global warming of 0.13 degrees Celsius (0.23 degrees Fahrenheit) per decade, the team inferred the frequency of these storms can be expected to increase by six percent per decade.

That study found an increase in the global rain rate of 1.5 percent per decade over 18 years, a value that is about five times higher than the value estimated by climate models that were used in the 2007 report of the Intergovernmental Panel on Climate Change.

 

[Loren Booda]

Would you say that global warming leads to more turbulence in the atmosphere?

 

[Xnn]

Overall, Global Warming is expected to result in fewer storms which implies less turbulence. However, the storms that do form are expected to be stronger and more severe, which implies more turbulence.

So, I wouldn't say that Global Warming clearly leads to more turbulence, although it probably does.

 

[.:Endeavour:.]

In been a correlation between thunderstorms and Global Warming is hard to actually know. You have to do research and try to find if there are any lurking variables that will explain the phenomenon. Mostly because you are dealing with nature, there is more than meets the eye. Is like saying classical music increases better grades, is this a correlation or is there a lurking variable that will explain the situation? It might be true or not, but you have to create a nonbias experiment to get adecuate results.

 

[Andre]

Don't remember seeing anything about this in the IPCC reports. But here is an article referencing a NASA study:

http://www.sciencedaily.com/releases/2007/08/070830105911.htm
.

which states:

Previous climate model studies have shown that heavy rainstorms will be more common in a warmer climate,..

I wonder what happened to the scientific method. The models seem to have overtaken it. They appear to demonstrate now what's going to happen. In the good old days models were a tool to work out an idea to formulate a prediction, which needed to be checked against reality. Now what would happen if reality is different. Model right, reality wrong?

Nevertheless, the expectation of stronger storms is obviously based on a stronger gradient or lapse rate in the atmosphere caused by more effective greenhouse effect near the Earth surface, which enhances convection. But this also activates several different negative feedbacks,
1: the increase of energy in a storm must be balanced by a decrease in energy at the Earth surface hence a decrease in temperature.
2: The stronger gradient, causes an increase of the tropopause altitude, bringing the warmer greenhouse gasses to an higher altitude, where the out radiation rate to space is increased.
3: the increase in cloud cover increases reflectivity, decreasing the temperature at the surface

See also this thread for substantiations.

 

[Xnn]

which states:
is obviously based on a stronger gradient or lapse rate in the atmosphere caused by more effective greenhouse effect near the Earth surface...

Actually, CO2 is most effective at the top of the cloud layer.

Anyhow, the IPCC reports that lapse rate is a negative feedback:

In AOGCMs, the water vapour feedback constitutes by far the strongest feedback, with a multi-model mean and standard deviation for the MMD at PCMDI of 1.80 ± 0.18 W m–2
°C–1, followed by the (negative) lapse rate feedback (–0.84 ±0.26 W m–2 °C–1) and the surface albedo feedback (0.26 ± 0.08 W m–2 °C–1). The cloud feedback mean is 0.69 W m–2 °C–1 with a very large inter-model spread of ±0.38 W m–2 °C–1 (Soden and Held, 2006).

And negatively correlated with water vapor!

Because the water vapour and temperature responses are tightly coupled in the troposphere (see Section 8.6.3.1), models with a larger (negative) lapse rate feedback also have a larger (positive) water vapour feedback. These act to offset each other (see Box 8.1).

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf