Climate Variability versus Climate Change

“Climate is what you expect, weather is what you get”
Robert A. Heinlein

Between 1905 and 2005, the average global air temperature near the Earth’s surface increased by somewhere between 0.5 and 1.0 degrees Celsius. Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C during this century (1).

To the uninitiated, this would not sound like much, but to others this suggests a worldwide catastrophe of unprecedented scale (2). Having studied this topic for about a decade now, and despite excellent scientists and experts having done their best to educate me, I still seem to belong to the uninitiated group. In this newsletter I will spell out a few of the reasons why I am not particularly alarmed by climate change.

One reason has to do with the fact that natural climate variability in any particular location is so large, that the relatively small “global warming signal” drowns in all the noise. You have to average over very large areas (millions of square kilometers), and over several decades, in order to detect the global warming signal (3). In any specific place, temperatures and precipitation may show trends completely different from the global trend.

If you are a normal person, living in a specific location, you probably won’t be able to detect the global warming signal within your own lifetime (although a lot of people may try to convince you that you are already experiencing it). For example, assuming a very strong global warming trend of 4.6 degrees Celsius during this century, a person living in La Paz would experience temperature variations similar to the ones depicted in Figure 1. This figure shows the normal daily and monthly variations in temperature, with some random el Niño events (zero mean) and a strong global warming trend added on.

Figure 1: Simulated temperature variations in La Paz with Global Warming, now – 2050

For comparison, Figure 2 includes the simulated temperatures in the absence of a global warming trend. The difference looks small, if not tiny. I am not sure how it would feel on a human body, but I suspect that it would be like the difference between living in El Alto and living in Achumani. I can’t imagine that my grand children will think it is a big deal, but if they do, they are free to move to El Alto.

Figure 2: Simulated temperature variations in La Paz with and without Global Warming, now – 2050

Of course it may not be temperature in itself that is the big problem, but rather associated events like sea-level rise. This is not going to be a problem in La Paz any time soon, but Al Gore’s book “An Inconvenient Truth” uses impressive computer generated images to show how New York, Florida, San Francisco, The Netherlands, Beijing, Shanghai, and Calcutta would be affected by a 20 foot rise in sea-levels, and uses phrases like “in Beijing and surrounding area, more than 20 million people would have to be evacuated.”

He just forgets to say that such a 20 foot increase is very unlikely to occur in neither this, nor the next, nor the following century. According to the latest IPCC scientific report, sea-levels are projected to increase by 18-59 cm this century (about 1 foot, give or take), depending on the scenario. Assuming, without any scientific evidence so far (4), that the sea-level rises would accelerate greatly in the coming centuries, the 20 foot increase may be experienced as soon as the year 2300. Or it may not(4). Anyway, I will make sure to let my great-great-great-great-great-great-great grandchildren know that they maybe should think about selling the summerhouse near the beach that my father built, because by the time they have great-great-great-great-great-great grandchildren themselves, the house may be at the beach. “Evacuation” is not exactly the word I would use for this process.

Al Gore also talks a great deal about natural disasters, which are expected to be amplified by climate change. He mentions that in 2005 there were so many hurricanes that for the first time in history, we ran out of letters in the alphabet, and had to start using Greek letters to name the last hurricanes of the season. He writes that “Hurricane Wilma was the strongest hurricane ever measured. It traveled back eastward from Mexico’s Yucatan Peninsula to southern Florida, causing massive damage and leaving thousands without water or electricity for weeks.”

I feel sorry for the people who were adversely affected, of course, but what about the 3 billion people in the rest of the World who have never had electricity at all? Or the 1.1 billion who never have gotten piped water installed in their houses? Their problems seem to be on a completely different scale.

For the record, I am not part of any oil company disinformation campaign. Actually, I pretty much accept the scientists’ explanation of what is going on, and what is likely to happen with the climate during the next century (especially the low-end projections), but it is a mighty big leap from there to “it is our ability to live on planet Earth – to have a future as a civilization – that is at stake.

Statements like “The world has less than a decade to change course. No issue merits more urgent attention—or more immediate action” (5) seem not only to be scientifically unsubstantiated, but also to ignore the fact that we right now have at least a billion very poor people living in conditions that we would not want for our own descendants, whereas our descendants are likely to be unimaginably rich.

If the World economy keeps growing at the rate it has done the last 28 years (with global warming and all), then the average person would be more than 500 times richer (in real terms) in the year 2300 than now. Thus, instead of a dollar per day, the poverty line might be $500 per day, and the average reader of this newsletter might easily earn more than a million dollars per month.

This is just a conservative estimate, because the global real per capita income growth rate has actually been consistently increasing during the last millenium. So, even if it is difficult to imagine, your descendants in the year 2300 may be earning a million dollar per week, and even a million dollar per day would not be uncommon.

Any policy that weighs the interests of the unimaginably rich people of year 2300 higher than the desperately poor of year 2008, would be a very odd policy, and should be hard to defend.

How alarmed should we really be climate change? Leave your thoughts below.

Lykke Andersen is the Director of the Center for Economic and Environmental Modeling and Analysis (CEEMA) at INESAD

(1) Fourth Assessment Report of the Intergovernmental Panel on Climate Change. See

(2) Al Gore, for example, says that “it is our ability to live on planet Earth – to have a future as a civilization – that is at stake” in his 2006 book “An Inconvenient Truth.”
(3) According to personal communication with one of the lead
coordinating authors of the latest IPCC Working Group 1 report, Jens Hesselbjerg.
(4) The IPCC Working Group 1 report suggests that it would take millennia. On p. 752 of Chapter 10 it says: “the Greenland Ice Sheet would largely be eliminated, raising sea level by about 7 m, if a sufficiently warm climate were maintained for millennia.” On the same page it says “The Antarctic Ice Sheet is projected to remain too cold for widespread surface melting, and to receive increased snowfall, leading to a gain of ice…In current models, the net projected contribution to sea level rise is negative for coming centuries.”
(5) Introduction of the 2007 Human Development Report from UNDP. See:


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