Saturday, April 4, 2009

Global Warming Conclusion (Incomplete)

*Note: make sure you click on the hyperlinks to see the figures. For the sake of expediency I am temporarily using figures from authors (primarily Mann and Kump, 2009), but will soon replace the most important figures with my own versions.

*Note: Some sections of this blog are simply notes, placeholders for sections that I still must write. Some of the notes follow those of one of my colleagues, Jonathan Gilligan, who is an expert on global warming. But I am anxious to start posts on other subjects, so this will be the final blog on global warming, even though I haven't completed the first draft on that topic.

How Will Global Warming Affect us in the Future?, or What changes are likely to occur in the near future, and what will be the consequences?

How Sensitive is the Climate to Changes in CO2 concentration?

"Climate scientists compare model predictions with estimated changes in average temperatures in the northern Hemisphere derived from proxy data. The proxy temperature estimates match the model simulations well when the assumed equilibrium climate sensitivity is 2-3°C, meaning that a doubling of atmospheric CO2 concentrations will lead to a roughly 2-3°C warming of the globe (this is the famous hockey-stick figure produced by Mann):

Northern Hemisphere Temperature Changes over the Past Seven Centuries

The most likely changes in the near future are represented by the IPCC (2007) "middle of the road" A1B emissions scenario (pg. 86). CO2 emissions will peak in the year 2050 (pg. 104a), and atmospheric CO2 conc. Will level off at ~550 ppm (pg. 104b). The corresponding increase in temperature between 2000 and 2100 is 3 deg. C (pg. 88), causing sea level to rise ~0.8 m = 31.5 /12=2.625 ft. (pg. 99). This will cause the global loss of 2223 km2 of land, $944 billion and 145 million lives (pg. 111).

Known Consequences: Sea Level Rise

Projected sea level rise

  • Sea level rise: 4” in 20th century, 8-28” in 21st; Large areas will become flooded, including much of south Florida and many inhabited Pacific islands (entire countries). Flooded coastline
  • Increases in coastal erosion: Up to 260 ft on open beaches
  • Landward shift of existing estuaries
  • Disastrous impact on existing developments along coastal zones

Potential Impacts of Global Warming

  • Doubling greenhouse gas concentrations ↑ avg. global temp 1.5–9°C (IPCC 2007).
  • Global warming leads to significant changes in rainfall, soil moisture
  • Agricultural activities and world food supplies affected greatly by climatic factors
  • Global warming affects the frequency, intensity, and distribution of natural hazards such as hurricanes and other storms
  • Higher incidence of weather extremes (high T, floods and drought); causes ↑ in weather-related deaths)
  • Migration of plants and animals to higher latitudes
  • Economic losses from seal level rise and storms; could bankrupt insurance companies
  • ↑ in infectious diseases and respiratory illnesses
  • Countries that contribute the most to climate change will suffer the least.

Reducing the Impact of GW

  • Identify the historic changes that have occurred
  • Predict the potential changes in the future
  • Political commitment: Reconcile the conflicts between the
    • environmental need for reduction of greenhouse gases
    • economic demands for more fossil fuel
  • Mitigate: reduce the emission of CO2 until it stabilizes at 550 ppm (scenario A1B)
    • Use fossil fuels releasing less CO2
    • Use alternative renewable energy
    • Conserve energy
    • Store CO2 in forests, soils and rocks (sequestration of CO2)
  • Economists say that cost of emissions reductions will be less than the economic damage in the absence of mitigation
  • SCC = Social Cost of Carbon: cost to society of emission of one metric ton of carbon (equiv. to 10,000 miles of driving). Integrated assessment models estimate that SCC = $30; this cost would be made up by a 9 cent per gallon tax on gas.
  • Is it fair for rich developed nations to decide whether action is worth taking, when it is the poor developing countries that will suffer the most?


The approach many people take to climate change is similar to the approach they take when driving in a lane that is about to close. Prudent people change lanes when they see the warning sign; the probability that they will be able to change lanes without slowing down is high because they have a lot of time and therefore opportunities to change lanes. However, some people won't change lanes until they are forced to when their lane ends. Because they didn't make good use of the warning sign, they have only one chance to change lanes. The probability of their being able to change lanes without slowing down or stopping is low, and they may find it very difficult to change lanes and get back up to speed. They may even get in an accident. They miss most of the opportunities to make change easy. Likewise, if we keep driving down the same path and don't heed the warning signs about global warming, and change our lifestyles only when we are forced to, we will miss most of the opportunities to make change easy, and we may be forced to drastically slow down (greatly decrease our consumption rates and quality of life) in order to make the change.

People who say that we don't have to worry about making changes to the earth, or that the changes we make may even prove beneficial, should think of this analogy: the earth is a complex system that we don't understand. Making changes to it without knowing the consequences is like an untrained mechanic bashing the working engine of a flawless Ferrari with a wrench in hopes of improving it's performance. The Ferrari is a complex system of working parts, and almost certainly any change that is made to a Ferrari in perfect working condition will have deleterious effects. In fact, breaking one part of the engine can lead to other parts breaking down if it is kept operating (and we can't stop the earth system from operating in order to repair it). An induced oil leak in the Ferrari would cause a breakdown of the lubrication system, and the resulting friction would lead to overheating and deformation of the mechanical parts, leading to an irreversible failure of the engine system. Our tweaking of the much more complex earth system, with its many working connected parts, could lead to the failure of individual parts, or in the case of a domino effect failure of complete subsystems (atmospheric or oceanic circulation patterns, ecosystems, etc.). The precautionary principle states that we would be unwise to make global-scale changes without having any idea of what the consequences will be. As Donald Rumsfeld said, there are the known knowns, the known unknowns, and the unknown unknowns. In the case of global climate, we know there are known unknowns, and there are almost certainly some unknown unknowns.

Humans have adapted to the earth's surface environment over several million years; Homo sapiens have existed since the beginning of the Holocene epoch 10,000 years ago. During that time the earth's climate has been relatively stable (*check). However, the rates of change of atmospheric CO2 concentration and global temperature are greater than at any time in earth's history, and if continued will outpace the ability of plants and animals to adapt by migration and certainly by evolution (which occurs at a much slower pace). Humans may be able to adapt through use of technology, but much of human society cannot afford the costs of these technologies, so the death rate in poor undeveloped countries will skyrocket. This is one of the great injustices of global warming: those most responsible for global warming (e.g., U.S. citizens) are likely to suffer the least from it. We are wealthy, so we can afford to buy and operate another air conditioner, to import bottled water and food, etc.. Another injustice is intergenerational: we may be making many areas of the earth uninhabitable for our offspring. Almost certainly, life will be more difficult for the next generation, who will be burdened not only with the consequences of global warming, but also an enormous financial debt (witness the exploding budget deficit of the federal government) and shortages in key resources such as oil. The current generation must look for ways to soften the blow that will be delivered to our offspring as a result of our actions and decisions. Most parents make sacrifices for their children’s welfare; the truly responsible parents also make sacrifices for their children’s future (e.g., saving money for them to go to college). We must now make other kinds of sacrifices, ones that will make our lifestyles more sustainable and therefore easier for our children to maintain. We will discuss this in great detail in the coming chapters.

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