Chapter 5
The Frightening Numbers
Prediction is very difficult, especially about the future.
— Niels Bohr50
Scientists can tell us what the general effects of global warming will be, partly because of what has happened during warm periods in the past, and partly because the effects of the current warming can already be seen and measured in things like retreating glaciers and shifting habitats.
But scientists cannot tell us with absolute certainty the things many young people really want to know. How will climate change affect my house, my family, my
community, my livelihood? Which will be the “good” places to live when it is time to get a job, buy a house, raise a family? Exactly when will these changes take place? In my lifetime? Or not until my children’s generation?
One of the biggest problems with proposing action on climate change is that scientists are often unable to make specific predictions. And yet they are constantly asked to do so. Governments want hard facts before they introduce unpopular legislation that will force reductions in greenhouse gas emissions. Insurance companies want to know how much they may have to pay out for climate-triggered disasters. (Insurance claims from hurricane damage in the US in 2004 and 2005, for example, came to $90 billion.51) Investors and consumers want to know where to put their money. (Invest in wind energy or the Scandinavian wine industry? Spend extra for a hybrid car? Build a house on a hillside or by the shore?) And the media looks for short, attention-grabbing statements that will fit into a newspaper headline.
So climate centers do issue predictions (or “projections,” as they prefer to call them), based on computer models called General Circulation Models (GCMs). Researchers feed pieces of information into powerful supercomputers (the newest can perform quadrillions of operations a second) — data on the amount of greenhouse gases in the atmosphere, the location of land and water, soil depth, the earth’s rotation and orbit and many other factors. Sophisticated computer programs then apply the laws of physics to simulate the interactions between land, water, sunlight, air, ice, etc., and determine what the climate will be like over the next months, years, decades and even centuries.
Computer models are far from perfect — critics say their results are so broad as to be next to useless — because no matter how sophisticated the model, it can never factor in the many, many complexities that affect climate. A tiny physical, chemical or biological action can cause turbulence in the air or water that may trigger major reactions somewhere else. This notion that a small random change can affect a larger outcome is called chaos theory, and climate is a prime example of how it works, because it is affected by millions of random events. This is the phenomenon that allows it to be dry over your house, but raining over your friend’s house two blocks down the street.
Climate models also cannot resolve all the small-scale processes and features that drive day-to-day weather and, ultimately, climate. They cannot, for example, properly take into account the shape, height, thickness and size of clouds or predict what kinds of clouds there will be. Clouds are just too complicated. Some produce precipitation, some do not. Some block incoming solar radiation, some block outgoing heat. Climate models also cannot represent the effect of every heat-absorbing town or city, every valley or mountain.
As well, climate scientists can’t say exactly when or how warming may be offset by human forces (such as technological advances or changes in practice that result in reduced emissions) or natural forces (such as solar or volcanic activity). It is extremely difficult, for instance, to estimate how much carbon dioxide we will continue to produce — something that depends on how much our population and economies grow, whether we cut or plant forests, whether we develop alternative energy sources or invent a new way to make energy.
Today, atmospheric carbon dioxide levels are about 390 ppm. Even if we stabilize or reduce greenhouse gas emissions, the level would still rise to 450 ppm by 2100, because of the carbon dioxide already in the atmosphere and because carbon sinks are not keeping up with current emissions. If we continue to increase greenhouse gas emissions at the present rate (called the “business as usual” scenario), atmospheric carbon dioxide levels will double by 2100.52
And if emissions increase even faster,53 the news will be much worse.
As carbon dioxide levels rise, here are a few things climate models are predicting:
Average Global Temperatures Will Rise
All climate models say that temperatures will continue to rise. The most recent climate models predict that average global temperatures will rise by 3°C (5.5°F) by 2100,54 a rate of warming that has not occurred in at least 10,000 years.
Not every place in the world will become just a little bit warmer at the same time. Almost all land areas will likely warm more than the predicted average, and the biggest warming will occur in the northern polar regions. The changes will also not happen evenly or steadily. Despite the fact that 2004 was the sixth-warmest year on record, for example, in the northern hemisphere the spring of 2004 was one of the coldest.55
Sea Levels Will Rise
The IPCC predicts that average sea levels will rise by about 40 cm (15.75 inches) by 2100. New research suggests the rise will be even greater — a meter (3 feet) or more.56 Most of it will be due to the water warming and expanding, but about one-quarter of the rise will be caused by runoff from melting ice.57
No one predicts that the ice at the poles will melt completely, but with sufficient warming the West Antarctic Ice Sheet (WAIS) — a mass of ice propped up by island “pillars” — could become unstable enough to collapse and slide into the ocean, causing global sea levels to rise by several meters.
Snow and Ice Will Melt
As the Arctic and Greenland ice sheets melt, and with increased precipitation and river runoff, cold, fresh water will be released into the North Atlantic. A large enough influx would dilute the saltiness of the Gulf Stream. The current would become less salty and therefore less dense and no longer sink. Instead it would weaken and eventually stall, no longer bringing warm water from the southern Atlantic. The predictions vary, but some models expect the Gulf Stream will weaken by 20 to 50 percent by 2100, and some say the current will stall entirely in two hundred to three hundred years.62 One study reports that the ocean circulation in the North Atlantic has already weakened substantially.63
The results of a stalled Gulf Stream are uncertain, but many scientists think it could mean the collapse of the North Atlantic fisheries64 and cooler weather in some of the most heavily populated and economically active areas of the world (Great Britain could have a climate similar to that of Labrador), affecting everything from shipping (rivers and harbors would freeze up earlier) to crops (which would be more vulnerable to frost) and heating costs.
Modelers also predict that half the mass of mountain glaciers and small ice caps will melt by 2100.
Precipitation Patterns Will Change
Over all, annual precipitation will increase during the twenty-first century. But where will this precipitation fall, and when? Increased precipitation is predicted, for example, in Antarctica in winter, and in southeast Asia in summer. Australia, Central America and southern Africa, on the other hand, will receive less rainfall. The Mediterranean will receive less rain overall but more variable summer rainfall, increasing the likelihood of drought and flash floods. Increased drying during the summers in continental Africa and the North American prairies will reduce both the amount and quality of fresh water for irrigation, hydro power, water transportation and drinking.65
Vegetation Zones Will Shift
As climate zones shift, plant species will move into new growing areas, and the mix of species within areas will change. Most plants migrate at a rate of, at most, 1 kilometer per year,66 but if the planet warms by only 2°C (3.5°F) over the next century, species will have to migrate seven times faster.67 In intensively farmed mountain areas in countries near the equator, such as Ecuador and Rwanda, growing zones will move uphill.68 In the mid latitudes, agricultural zones are expected to shift 200 to 300 kilometers (320 to 480 miles) for every degree Celsius of warming.69
For humans, one of the biggest concerns is the future of the world’s cereal crops. There will be a longer frost-free season, and therefore longer growing season, in Canada, Scandinavia, Iceland and Australia. In western China, models predict the farming season will be extended by as much as one month. But in the North American prairies, the Mediterranean, Latin America and southern Africa, warming will be accompanied by decreased precipitation, which may mean there is not enough water for crops.
Scientists predict that global warming will not likely affect the world’s total food supply in this century. However, it will affect where food grows. Parts of the world already struggling, such as tropical and sub-tropical areas, will have fewer cereal crops. And if temperatures go up more than a few degrees Celsius, there will be an overall drop in agricultural activity, an increase in food prices around the world, as well as increased risk of famine in some developing countries. Warming of only 2°C (3.5°F) would, for example, make it too hot to grow coffee in Uganda — the base of the country’s economy.70
Animals Will Migrate and Adapt — or Not
Some animals will not be able to migrate or adapt quickly enough to survive the effects of climate change. At the current rate of warming, the Great Barrier Reef will be wiped out within fifty years.71 One study predicts that as a result of global warming, one-quarter of all land plants and animals — 1 million species — will either be extinct or becoming extinct by 2050.72 It would be the largest mass extinction since the disappearance of the dinosaurs 65 million years ago.
And what about humans? No one predicts that the human race will be wiped out because of climate change. But global warming is expected to increase threats to human populations, especially those already on the margins. People who live in tropical countries will likely face poorer water and air quality. One study predicts that by 2050, 150 million people will be displaced because of global warming — 100 million due to sea level rise and flooding and 50 million because of drought.73 Most models predict that disease-carrying species like mosquitoes and ticks will move with the warmer climate zones, bringing infectious diseases. Malaria already kills 2 million people each year, and 300 million to 500 million a year are affected. As the mosquito-borne disease moves into new territory, including Australia, North America and southern Europe, the local population’s natural immunity will at first be very low, increasing the mortality rate.
The predictions are alarming. Maybe too alarming? When the third IPCC report was released in 2001, some critics claimed that it painted an overly bleak picture of the future. But other studies have issued findings that are even more troubling.
Here are just a few examples:
Avoiding Dangerous Climate Change Symposium75
A conference held in Exeter, England, in 2005 brought together one of the largest groups of climate change scientists since the 2001 IPCC report. Although the 2001 IPCC report predicted that the West Antarctic Ice Sheet (WAIS) was so cold that it would not melt for centuries, experts in Exeter reported early signs that the ice sheet could already be disintegrating.
Hadley Centre for Climate Prediction and Research76
In 2001 the British government commissioned the Hadley Centre (one of the world’s main climate modeling centers) to study the effects of climate change and its consequences, especially for Great Britain. The report took several years to complete and predicted that by the 2040s more than half of European summers will be warmer than that of 2003 (the year a heat wave killed more than 30,000), and by 2060 a summer like the one of 2003 would be considered unusually cool.
Arctic Climate Impact Assessment77
At the end of 2004, the world’s eight Arctic nations, including the US, released a 1,200-page study prepared over four years by more than three hundred scientists. The report suggested that the Arctic is warming at almost twice the rate of the rest of the world. The amount of sea ice is shrinking and the Greenland ice sheet is melting. The report predicts that in the next hundred years, Arctic temperatures will rise 4° to 7°C (7° to 12.5°F), and the permafrost line will retreat 300 kilometers (480 miles) north.
More recent studies reveal that both the Greenland ice sheet and the West Antarctic Ice Sheet are melting much more quickly than previously thought. Though the IPCC predicted that global sea levels would rise no more than a meter (3 feet) by the end of the century, new research predicts melting ice from Greenland and Antarctica will cause sea levels to rise several meters by 2100.78
Climate Change Around the World —
Some Predictions74
Nobody knows for sure precisely how high carbon dioxide levels will rise, or what exactly will happen as a result. But climatologists are certain about one thing. Although some people will initially benefit from climate change (some industrialized countries, for example, will enjoy longer growing seasons), in general, global warming will bring more harm than good to humans.79 The problem is not just the fact of global warming — something the planet has experienced many times before. It is the speed of the warming, and the impact this will have on a crowded planet.
50. Niels Bohr, physicist and Nobel Prize winner, 1885-1962.
51. Agnes Sinai, “The Cleanliness Business,” Le Monde Diplomatique, March 2006.
52. According to the 2007 IPCC report, CO2 levels will range from 535 to 983 ppm by 2100, 41 to 158 percent higher than current levels. IPCC, Climate Change 2007: The Physical Science Basis.
53. At the current rate of increase, the International Energy Association (IEA) expects greenhouse gas emissions to increase by 60 percent by 2030. Patrick Brethour, “IEA Says Policies Inadequate, Emissions Will Jump 60%,” Globe and Mail, October 27, 2004.
54. According to the 2007 IPCC report, average global temperatures will rise 1.8 to 4°C by 2100. An increase in the frequency of heat waves and events of heavy rainfall is “very likely” (probability greater than 90 percent). It is “likely” (probability greater than 66 percent) that there will be an increase in areas affected by droughts and in the intensity of tropical storms.
55. The central and northeast US, for example, experienced a much colder than average summer. WMO Statement on the Status of the Global Climate in 2004, World Meteorological Organization.
56. Justin Gillis, “Rising Seas, and a Looming Catastrophe,” New York Times, November 21, 2010.
57. The IPCC calculations do not consider the disintegration of the Greenland or West Antarctic ice sheets, which are losing 150 square kilometers (58 square miles) of ice each year. Kennedy Warne, “Dance of a Dangerous Sea,” Canadian Geographic, October 2008.
58. Mauri S. Pelto, “Recent Global Glacier Retreat Overview,” North Cascade Glacier Climate Project, August 30, 2011, www.nichols.edu/departments/glacier/glacier_retreat.htm.
59. Susan Joy Hassel et al, “Impacts of a Warming Arctic,” Arctic Climate Impact Assessment (ACIA), www.amap.no/acia/.
60. F.S. Chapin et al, “Role of Land-Surface Changes in Arctic Summer Warming,” Science, October 28, 2005.
61. Mark Lynas, “Hot News,” This Overheating World, Granta, Fall 2003.
62. Quirin Schiermeier, “A Sea Change,” Nature, January 16, 2006; Houghton, 136.
63. Although most climate models do not predict a significant slowdown until the end of the century, a recent study reports that circulation in the north Atlantic has weakened by 30 percent over the past fifty years. H.L. Bryden et al, “Slowing of the Atlantic Meridional Overturning Circulation at 25°N,” Nature, December 1, 2005.
64. Collapse of fisheries will be largely due to the depletion of North Atlantic plankton stocks by up to 51 percent; plankton form the base of the marine food chain. Andreas Schmittner, “Decline of the Marine Ecosystem Caused by a Reduction in the Atlantic Overturning Circulation,” Nature, March 31, 2005.
65. Filippo Giorgi, “Climate Change Hot-Spots,” Geophysical Research Letters, April 21, 2006.
66. Houghton, 170.
67. Mark Lynas, High Tide: The Truth About Our Climate Crisis (New York: Picador, 2004), 23-24.
68. Moving 500 meters up a mountain is like moving 250 kilometers north. Jonathan Weiner, The Next One Hundred Years: Shaping the Fate of Our Living Earth (New York: Bantam, 1990), 178.
69. United Nations Framework Convention on Climate Change (UNFCCC), Beginner’s Guide, 1994, www.unfccc.org/resources/beginner.html.
70. Mark Maslin, Global Warming: Causes, Effects and the Future (Osceola, Wisconsin: Voyageur, 2002), 53.
71. Queensland Centre for Marine Studies, www.marine.uq.edu.au.
72. Number of species “committed to extinction” is estimated at 15 to 37 percent. Chris D. Thomas et al, “Extinction Risk from Climate Change,” Nature, January 8, 2004.
73. Houghton, 187.
74. (Northwest Passage) “Impacts of a Warming Arctic,” Arctic Climate Impact Assessment, 2004, www.amap.no/acia/. (Polar bears) National Geographic, September 2004. (Great Lakes) Government of Canada, www.adaptation.nrcan.gc.ca. (Missouri and Upper Mississippi basins) Houghton, 160. (Louisiana) National Geographic, October 2004. (British Columbia) Government of British Columbia, www.for.gov.bc.ca/hfp/mountain_pine_beetle/. (Peru) International Strategy for Disaster Reduction, www.eird.org. (Southern Europe) Houghton, 130. (China) World-wide Fund for Nature, quoted in Houghton, 152. (South Pacific) Michael C. Howard, ed., Asia’s Environmental Crisis (Boulder, Colorado: Westview, 1993), 13-14. (Nile) Lynas, 113-14. (Coral reefs) Andrea G. Grottoli et al, “Heterotrophic Plasticity and Resilience in Bleached Corals,” Nature, April 27, 2006.
75. Avoiding Dangerous Climate Change, www.stabilisation2005.com.
76. Hadley Centre, Uncertainty, Risk and Dangerous Climate Change: Recent Research on Climate Change Science from the Hadley Centre, December 2004, www.metoffice.com/research/hadleycentre.
77. “Impacts of a Warming Arctic,” Arctic Climate Impact Assessment (ACIA).
78. Julian A. Dowdeswell, “The Greenland Ice Sheet and Global Sea-Level Rise,” Science, February 17, 2006; Jonathan T. Overpeck et al, “Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise,” Science, March 24, 2006.
79. “More people are projected to be harmed than benefited by climate change, even for global mean increases of less than a few °C.” IPCC, Climate Change 2001: Impacts, Adaptation, and Vulnerability, (Cambridge: Cambridge University Press, 2001), 8.