There is no area in global warming discussions where AGW advocates have done more to shoot down their own credibility than in the absolutely egregious science and absurd claims that have been made about the potential negative effects of global warming. If AGW advocates are frustrated that skeptics question their science and their credibility, they need to look no further than their own claims on global warming effects, which are so easy to prove wrong that it causes people like me to question everything else they say.
Whenever global warming is discussed in the press, the consequences are all universally bad. Floods, famine, drought, pestilence, disease – they are all commonly predicted results of global warming. But it is worth noting that in the 1970’s, when climate scientists and the press were in a panic over global cooling, the predicted results were… floods, famine, drought, pestilence, disease. The implication is that we currently happen to be balanced on the knife edge of exactly the optimum world temperature for mankind. Any change warmer or cooler results in net negative consequences.
This, of course, seems an odd coincidence. Since man evolved into homo sapiens, he has experienced a wide range of cooler and warmer temperatures than we experience today. It seems frankly amazing that in the mid 20th century we happened to be sitting at the absolute ideal temperature for modern technological society and agriculture. Now, I guess you can argue that our society has made enormous investments based on the locations of the best crop lands, the height of the oceans, the typical paths of storms, etc., and that shifts in any of these would force an expensive restructuring of these investments. However, it is also worth noting that from the bottom of the Little Ice Age to say 1980, the world warmed at least a degree, and no one really noticed! Everyone was still talking about cooling!
So I think that any honest analysis of the effects of global warming would have to acknowledge that there are likely both positive and negative effects. While some areas may experience heat-induced droughts, other will be wetter as more moisture from the oceans is evaporated. While some crops will struggle, others, particularly in northern latitudes, will thrive due to longer growing seasons. For each crop of vegetables that wilt in a heat wave there will be a crop of citrus that didn’t freeze. While more may die from the heat, fewer will die from the cold. These may still net to a negative sum, but that net sum will be substantially less negative than a one-sided look at only the downsides of warming would arrive at.
One reason that warming impact analysis is hard is because while we may talk about the world warming a degree or two, the world does not warm evenly. Most climate models show the most warming on dry winter nights (Siberian winters, for example, get a disproportionate share of the warming). An extra summer degree in Arizona would suck; an extra winter degree in Siberia would probably be welcomed, and would likely extend growing seasons.
In the rest of this chapter, I will spend some time with a number of the most common “scary results” from global warming.
In An Inconvenient Truth, Al Gore claims that oceans will rise twenty feet due to global warming. Helpfully, a number of websites have been created to show what parts of the world (including much of Florida) would sink beneath the oceans like Atlantis with a 20-foot rise in sea level.
Fortunately, even most AGW supporters believe that Gore is wildly exaggerating, at least for any time period less than a couple of centuries. The Fourth IPCC report (see chart below) predicts sea level rise by the year 2100 of … 12-15 inches. And remember that this is based on forecasts of both CO2 production and climate sensitivity to CO2 that are arguably high by a factor of two or more. From the fourth IPCC report (different columns are for different starting CO2 forecasts):
By the way, to give a sense of scale, the IPCC estimates that the oceans have already risen about 0.2 meters in the last 130 years or so:
One other interesting thing you can see from the sea level forecast chart is that even the IPCC considers ice melting virtually irrelevant. That is because most of the surface level increase is from thermal expansion of the water as the oceans warm. In the A1B case, for example, net worldwide ice melt raises oceans by about 4 inches in the next hundred years.
This last conclusion may seem crazy to anyone who has watched the media of late or seen Mr. Gore’s movie. Images of ice crashing into the ocean and sea ice retreating are common fodder for global warming visuals. But the fact is that ice, like everything else in climate, is complicated.
- North Pole: Arctic sea ice melting is totally irrelevant to ocean surface levels. Since the ice floats, even a 100% melting of the Arctic ice will not change sea level one bit, just as ice melting in your glass of water does not cause your glass to overflow.
But some may argue that this ducks the question. Does current, well-documented retreat of artic ice sheets provide independent confirmation of the magnitude of AGW? In fact, though ice sheets are retreating, this seems to be part of a two hundred year trend that began long before man was burning fossil fuels in any quantity:
- Alpine Glaciers: We know that many Alpine glaciers around the world are retreating. Some of this is surely from global warming, but some is also from fluctuations in precipitation. In many cases, we have documented evidence that these glaciers have been retreating since the 19th century, and that they have been less extensive in the past.
Reid A. Bryson is Emeritus Professor and founding chairman of the University of Wisconsin Department of Meteorology—now the Department of Oceanic and Atmospheric Sciences and a member of the United Nations Global 500 Roll of Honor. When asked about the retreat of Alpine glaciers, he says, “What do they find when the ice sheets retreat, in the Alps? A silver mine! The guys had stacked up their tools because they were going to be back the next spring to mine more silver, only the snow never went,” he says. “There used to be less ice than now. It’s just getting back to normal.”
Alaska Geographic published a chart of the retreat of the glaciers at Glacier Bay, Alaska, showing most of the retreat occurred before the 2nd half of the 20th century:
One special note should be made of the glaciers on Kilimanjaro, because their retreat over the last 125 years has been well-documented and played a starring role in An Inconvenient Truth. Analysis has shown that most the glacial retreat at Kilimanjaro occurred before 1953 (and therefore before most recent warming) and that the retreat has more to do with moisture in the air than with global warming. One wonders why the movie, with glacial retreats around the world that are provably due to warming, would focus on one that is probably not due to warming.
· Greenland: Greenland has a lot of ice, and there is not much doubt that if it all melted, the oceans would rise a lot. However, we know that in the middle ages, Greenland was much warmer and had less extensive ice coverage (thus the name Greenland and the successful attempt to farm it for over a century)
While there is a lot of discussion about whether the Medieval Warm Period extended worldwide, most accept that it did cover the North Atlantic, including Greenland. Boreholes, such as the Dahl-Jensen below, seem to prove out our historical information, showing a temperature peak around the year 1000.
· Antarctica: Something like 80-85% of the world’s ice is in Antarctica. And no one really thinks it is melting or going to melt. In fact, if you look at the marks on the IPCC chart above for the contribution of Antarctic ice to ocean levels, it has a net negative impact, which means the IPCC actually expects the Antarctic ice sheet to grow, not melt.
Whoa, that can’t be right! Mr. Gore showed those videos of ice retreating in Antarctica. Well, yes, sort of. Scientists expect that global warming will make the sea currents that circle Antarctica a bit warmer, leading to more precipitation and more snowfall on the continent. Besides, Antarctica is so damn cold that raising temperatures a few degrees is not going to melt anything.
The one exception is the Antarctic Peninsula, which sticks out into the warmer oceans. This land area, representing about 2% of the Antarctic land mass and even less of its total ice sheet, is expected to warm and lose ice while the other 98% gains ice.
Guess what? Mr. Gore chose that little 2% to illustrate his movie. Was he ignorant of the choice he was making, or did he know exactly what he was doing, telling the literal truth (that the peninsula is melting) but leading viewers to the wrong conclusion overall about Antarctic ice?
By the way, one last interesting fact that frankly, scientists don’t fully understand is the fact that the South Pole is really not experiencing any warming. While the warming at the north pole exceeds the global average, the south pole shows little or no anomaly.
Alter Hurricane Katrina, the media storyline focused strongly on the role global warming may have played in increasing hurricane power and activity. Lost in the rush to blame global warming was the fact that Katrina, when it made landfall, was not even a category 5 hurricane, and its devastation was due more to a city sited below sea-level that did a poor job of managing its storm protection.
In fact, many hurricane experts do not agree with the argument that warming oceans can lead to more and stronger hurricanes. In fact, hurricane activity is more related to the difference in temperatures between the cold and warmer waters, a difference AGW theory says should decrease rather than increase. So is there reason to believe hurricanes are on the rise as global temperatures warm? The answer, as shown below, seems to be no:
But what about storm damage? It certainly seems like recent hurricanes have resulted in far more economic damage. And they have, but for the simple reason that over the last several decades, Americans have put billions of dollars of expensive homes and other facilities in vulnerable Gulf and Atlantic coast locations. Several years ago, Dr. RA Pielke and CW Landsea (that can’t really be the name of a scientist studying coastal strikes by hurricanes) attempted to correct hurricane damage numbers for the density and value of coastal real estate:
By this reckoning, it is hard to see any trend.
Another claim Mr. Gore makes in An Inconvenient Truth is that 2004 was the most active year for tornadoes ever in the United States, and that there has been a steady trend in increasing tornados as the globe has warmed.
And certainly if you look at the raw numbers, you might be worried:
But there is a little something Mr. Gore fails to mention. During this time period, from 1950 to 2000, the technology and network for detecting tornados has improved vastly. From the NOAA
With increased national doppler radar coverage, increasing population, and greater attention to tornado reporting, there has been an increase in the number of tornado reports over the past several decades. This can create a misleading appearance of an increasing trend in tornado frequency. To better understand the true variability and trend in tornado frequency in the US, the total number of strong to violent tornadoes (F3 to F5 category on the Fujita scale) can be analyzed. These are the tornadoes that would have likely been reported even during the decades before Dopplar radar use became widespread and practices resulted in increasing tornado reports. The bar chart below indicates there has been little trend in the strongest tornadoes over the past 55 years.
Oops! In fact, tornado frequency seems to be falling as temperatures warm. Do you think this was another honest mistake, like with Antarctica, or did Mr. Gore purposefully obfuscate the real story?
Another argument is that global warming will lead to more temperature extremes, particularly record sweltering highs. That seems logical enough, but Bruce Hall actually compiled the data and found something interesting. He created a data base for each state which shows in what year that state’s monthly temperature records were set. So for each state, he has the years when the twelve monthly high temperature records were set (e.g. year of highest Arizona Jan temp, year of highest Arizona Feb temp, etc.) and the years when the twelve monthly low temperature records were set. Here, for example, is his data for Arizona:
So, for example, the record for the highest July temperature was set in 1905 at Parker, Arizona with a scorching 127 degrees. The entry in his database would then be Arizona-July: 1905. He notes that there is a bias in the data toward more recent years, since if the record was set in 1905 and tied in 1983, only the newer 1983 date will show in the data. I would also observe that this data is uncorrected for urban heat island effects (as cities urbanize they get hotter, and effect that is different than CO2-cause global warming and is usually corrected for in global warming studies). There is also a bias towards the present in having more measurement points today than 100 years ago: More measurement points means that, over a state, one is more likely to pick up the true high (or low).
Though I have other problems with the anthropogenic global warming hypothesis, I have never really doubted that the world has warmed up over the last century. So even I, a skeptic, would expect a disproportionate number of the all-time high temperatures to be in the last decade, particularly without UHI correction and with the bias discussed above. The global warming folks would argue that the effect should be doubly pronounced, since they claim that we are seeing not just a general heating, but an increase in volatility (ie more extreme variation around the mean).
But Hall doesn’t find this when he graphs the data. Take the 600 state monthly high temperature records that exist on the books today (50 states times 12 months) and graph the distribution of years in which these records were set:
Assuming about 120 years of data, you should expect to see a high temperature record on average in a database of 600 records at 5 per year, which is precisely where we have been of late and well below the record years in the thirties (remember the dust bowl?) and the fifties. It seems to actually show a reduction in temperatures or volatility or both.
This may seem impossible – how can the mean increase without causing a lot more new highs? But remember what we discussed earlier – global warming is expected to be seen disproportionately in nighttime and winter temperatures. This means that the mean can increase even as daytime summer highs don’t increase much. In a sense, is the lows, not the highs, that are getting higher.
Vincent et al in 2005 did a study of temperature trends in South America from 1960-2000. What they observed is exactly what we discussed here: The number of warm days and cold days did not really change. The warming trend showed up as a decrease in cold nights and an increase in warm nights, meaning effectively that the diurnal (across 24 hours) temperature variation is narrowed.
It’s a little hard to be scared by this.
Biologist Josef Reichholf was interviewed recently in der Spiegel. He is a strong conservationist, and certainly has his axe to grind with industrial society. In fact he blames industrial agriculture and modern development for problems that species face.
Many species are certainly threatened, but not by climate change….Many species have already fled from the countryside to the cities, which have been transformed into havens of biodiversity. We are also seeing another interesting phenomenon: Major cities, like Hamburg, Berlin and Munich, have formed heat islands where the climate has been two or three degrees warmer than in the surrounding countryside for decades. If higher temperatures are truly so bad, why do more and more animals and plants feel so comfortable in our cities?
On the contrary, there is much to be said for the argument that warming temperatures promote biodiversity. There is a clear relationship between biodiversity and temperature. The number of species increases exponentially from the regions near the poles across the moderate latitudes and to the equator. To put it succinctly, the warmer a region is, the more diverse are its species.
OK, but what about those polar bears? We have all seen the media pictures of bears stranded on blocks of ice, as if all the arctic has melted out from under them. Well, it turns out that polar bears have survived much warmer conditions. We know polar bears existed as a separate species at least 125,000 years ago, and in the intervening years, there have been periods where Arctic sea ice melted completely during the summer months. And yet polar bears still exist today. Polar bears may be threatened by man’s hunting and encroachment on its hunting grounds, but not likely by our fossil fuel combustion.
AGW fear-mongering also extends to breathless predictions of increases in “tropical” diseases. Reichholf also takes on this canard:
Many people truly believe that malaria will spread as temperatures rise. But malaria isn’t even a true tropical disease. In the 19th century, thousands of people in Europe, including Germany, the Netherlands and even Scandinavia, died of malaria, even though they had never gone abroad. That’s because this disease was still prevalent in northern and central Europe in previous centuries. We only managed to eliminate malaria in Europe by quarantining the sick, improving hygiene and draining swamps. That’s why I consider it virtually impossible that malaria would return to us purely because of climate change. If it does appear, it’ll be because it has been brought in somewhere.
Most of the world’s leading tropical disease experts tend to agree with Reichholf. In fact, I would argue that diseases like Malaria are not diseases of the tropics but diseases of poverty and under-development. Malaria is prevalent in Africa not because Africa is hot but because Africa is poor. Asian tropical countries that have developed substantially over the last several decades have also greatly reduced malaria. In fact, as I will discuss in later sections, by reducing world economic growth and slowing development in the third world in the name of CO2 reduction, we will actually increase rather than reduce these diseases.
One of the recent hysteria’s has been that global warming will cause the Gulf Stream to collapse as Atlantic circulation patterns are radically altered, thus leading to the freezing of Europe. More sober scientists have since essentially said “nevermind.” The Gulf Stream and Atlantic circulation patterns are far more robust than this theory assumed, and, even if the Gulf Stream changes, proponents of the theory were overestimating the dependence of Europe on Gulf Stream warming.
Interestingly, we may eventually decide that other non-climate effects of CO2 production actually present more tangible environmental threats. In particular, recent studies have shown that more atmospheric CO2 is causing the PH of ocean surface layers to drop (ie become more acidic) leading potentially to coral kills and substantial changes in sea life. At the same time, physicist Freeman Dyson argues that stratospheric cooling from man-made CO2 is much more a problem than surface warming, and is much more measurable and provable. These topics are beyond my scope at this point, but something we may see more of in the future.