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An Inconvenient Truth?

An issue sparking much debate in recent years is that of climate change. On the one hand we have Al Gore and the majority of scientists saying we must do something before it’s too late, on the other hand we have the skeptics who say there is no climate change, and in between we have people saying climate change is real but not man-made, or people who are altogether indifferent. (You can read what Californians think about the matter in this recent PPIC survey.)

Here I’ll explore the two main positions and the implications on us as individuals and as communities.

Many of us have seen the movie “An Inconvenient Truth” (watch trailer here) describing Al Gore’s campaign to raise global awareness of climate change issues. He brings convincing data supporting the idea that changes in temperature follow human actions. For example, Figure 1 shows changes in temperature, dust concentration and CO₂ concentration over the last 400,000 years. The three values seem to follow the same trend, suggesting higher dust and CO₂ concentrations are correlated with a rise in temperature. In Gore’s words, "it is now clear that we face a deepening global climate crisis that requires us to act boldly, quickly, and wisely". These actions can take the form of scaling back on energy consumption and adopting renewable energy technologies.

 

Figure 1. Source: Petit et al. 1999, Nature, 399: 429-436

Some protagonists from the other side claim the climate changes are actually governed by the sun’s activity, taking the prevention of global warming out of our hands. Here is just a sample of scientists who oppose the common view, and their respective reasoning (a full compilation can be found here):

1. Ocean currents (William M. Gray)
2. Cosmic rays (Henrik Svensmark)
3. Natural Causes (Marcel Leroux, Willie Soon)

Another view is that the changes in climate are related to solar activity. One of the leaders of this camp is Prof. Nir Shaviv from the Hebrew University, who in a 2008 paper published in the Journal of Geophysical Research argued this point. The sun’s activity has an 11 year cycle during which there are small changes in the total solar irradiance (TSI). These in turn cause variations in global energy, and therefore in global temperature. But the temperature variations associated with the solar cycle variations are about 5 to 7 times larger than just those associated with the TSI variations, implying the existence of an amplification mechanism strengthening the solar effect on climate (you can read more about this paper and its implications in Shaviv’s blog).

Figure 2. Using the oceans as a calorimeter to measure the net irradiance variations associated with the solar cycle: Sea Level (solid line, shaded region denotes error range) vs. Solar Activity (dashed line). Source: Shaviv’s blog. 

When I attended a conference on these issues several years ago, where both cases were presented, each in turn convinced me. You may feel the same after reading the information presented here, which may result in your asking: So, where does that leave me? Do I use renewable energies or not? Do I reduce my carbon footprint or not?

Well, if you ask me, while I’ll keep following the debate on the causes of temperature change, I don’t feel the need to side with one or another of the positions. We can argue ad infinitum whether or not we are responsible for global warming or have nothing to do with it, but putting climate change aside, there are many valid reasons for us to make changes in our lives, on the personal, community, state and global level, which will decrease air pollution and aid in the wiser use of energy resources.

Don’t you agree it’s pretty incredible that just by installing a photovoltaic system you can make an impact? Installing systems such as those offered by SolarEdge contributes to improved health by reducing pollution, affects global politics by reducing oil dependency, creates jobs in the green sector and promotes many additional positive causes. This cartoon by Joel Pett really says it all: