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Global Warming Discussion

What to do?

The global warming issue has been labeled the "Science of Uncertainty": (1)Although we are able to measure a significant rise in global average temperatures in recent years, we are unable to determine how much of the warming is due to the increases in greenhouse gases and how much is part of some natural cycle; (2)We are unable to predict exactly how climate will change in the future with higher levels of greenhouse gases and exactly what the impacts of climate changes will be on humans and other life on the planet. This makes it difficult for all people to come together and agree on what, if anything, should be done. Scientists are working on reducing the uncertainties, but due to the complex nature of the climate system, we should not expect certain answers to all questions. We have to make decisions which weigh uncertain risks against the costs of taking action. See Global Warming Facts and Uncertainties

If nothing else, the human race is in the process of performing a huge experiment on global climate by increasing greenhouse gas concentrations. The concentration of carbon dioxide in the atmosphere is probably greater now than at any time over the last several hundred thousand years. The outcome of this experiment is uncertain. Are we ready and willing to take the risks? So far the answer is yes, because in spite of all the talk about global warming, greenhouse gas levels in the atmosphere continue to increase. This is especially relevant for the people of the United States who emit more greenhouse gases per person than any other large nation on Earth. By the way, if you are one of those people who believe that even though adding greenhouse gases is probably not a good thing, but think we should wait to deal with the issue until we are more sure that greenhouse gases are causing us problems, you need to keep in mind that there will likely be no "quick fix". Once released into the atmosphere, greenhouse gases remain for quite some time, and there is a significant delay before the complete climate change, at the higher greenhouse gas concentrations, is fully realized. In accordance with those who believe that we should not take the potential risks associated with climate change here is an interesting comparison between possible climate change caused by emissions of greenhouse gases and possible cancer caused by tobacco use.

Still others do not perceive much risk at all. While most anthropogenic global warming "skeptics" do not deny that the world is getting warmer, they do doubt that human activity is the cause. Some say the changes now being witnessed are not extraordinary in that there is evidence similar changes have happened at other times in Earth's history when humans either did not exist or were incapable of affecting climate change. There are some reputable physicists and climatologists who have concluded that natural variations in the Sun's energy output are the prime influence on both historical and recent temperature trends. These researchers claim that many of the historical climate changes that have occurred on Earth, including recent climate changes that have been documented by human civilizations, are caused by variations in the energy output of the Sun. An appealing aspect of the solar theory of climate change is that it may partially explain many of the long ago fluctuations in climate. If changes in solar output mattered in the past, then there is a good chance that it is still an important factor in modern climate changes. Certainly changes in greenhouse gas concentrations cannot explain all the historical changes in climate ... though possibly changes that have occurred in recent decades after human activities significantly increased the amounts of these gases in the atmosphere. It is difficult to sift through and evaluate all of the arguments for and against variaitions in the sun as being the most important driver of long term climate changes. I will try to briefly summarize here. Some researchers have reported strong correlations between various measures of solar activity (e.g., number of sunspots, length of the ~11 year solar cycle, etc.) and climate changes in temperature and precipitation patterns. Reconstructions of past changes in solar activity and past changes in temperature and precipitation are uncertain, so there are disagreements about the degree of correlation. One significant issue is that the changes in solar activity are seemingly too small to explain the changes in temperature. This is because climate models predict that the temperature changes related to changes in the total energy output of the Sun are very small and insignificant compared to changes caused by increases in greenhouse gases. While it is true that the variations in the energy output of the Sun have a smaller direct influence on the radiative forcing of the Earth's surface than the increase in greenhouse gases over the last century, some scientists believe there are natural solar amplification factors in Earth's climate system that are not included in most climate model simulations. These would be indirect effects initiated by the changes in the energy output of the Sun that result in significant climate changes in temperature and precipitation patterns. The names of the three most publicized proposed mechanisms for solar amplification are (1) the UV-Ozone hypothesis, (2) the current density-cloud hypothesis, and (3) the Sun-CN-CCN-Cloud-Climate hypothesis, which is mentioned in this Wall Street Journal editorial, The Other Climate Theory. If you are interested in these ideas, you can search for recent publications. Discussion of those theories is beyond the scope of the course. You are not expected to know them by name. Although correlation does not prove causation, there must be correlation for there to be causation and there is evidence of correlations between past climate changes and changes in solar activity. Also noting that there is much about the climate system that we do not understand (and are not able to simulate with climate models), there is a reasonable chance that changes in solar activity are important in understanding both past and recent climate changes. Until we can prove otherwise, the solar theory of climate change should not be dismissed simply because most current climate models do not indicate a strong connection between changes in solar activity and global average near surface air temperature. The models may be missing an important, but unidentified, process that has a significant impact on climate changes.

As mentioned on the previous page, other research groups point to known geophysical oscillations, such as the Pacific Decadal Oscillation (PDO), to explain recent and past temperature changes. Thus there are a good number of researchers who believe that recent temperature changes are not much influenced by human emissions of greenhouse gases. Recent climate changes are just part of natural variations in climate, and humans and most other forms of life have survived past changes just fine. Nevertheless, there are many climate scientists who believe that, even on top of the natural variability of the climate, something out of the ordinary is happening and humans are to blame. The next 30 years or so may help us better determine what is most responsible for for modern climate changes. There are quite a few researchers that are predicting a decades-long period of global cooling based on their assertions that we are beginning a period of lower solar activity and/or a cold phase of the PDO. This contrasts strongly with global climate models that predict continued warming due to greenhouse gas forcing.

Yet another group of people do not deny that temperatures are warming and also believe that it may be caused by human activity (although we cannot be sure at this point mainly because climate models are not good enough to answer this question), but they are unconcerned about the possible consequences. In essense they do not believe the doom and gloom future senarios projected by the IPCC reports. This group wonders why we should go through economic and personal hardships required to signficantly reduce our emissions of greenhouse gases, since in comparison, those hardships will be much worse than the consequences of any climate changes that we may or may not cause. For example see the Newsweek article written by Havard atmospheric scientiest Richard Lindzen Learning to Live with Global Warming: Why So Gloomy?

Based on recent public opinion polls, it appears that many Americans implicitly agree with Dr. Lindzen, i.e., although many believe human activity may be responsible for recent climate changes, taking action to reduce greenhouse gas emissions is not considered a high priority, see ( Polls show most Americans believe in climate change, but give it low priority). A more recent poll, which asked Americans to rank what they consider to be the top priorities for government in 2015, Public’s Policy Priorities Reflect Changing Conditions at Home and Abroad, found that action on global warming came in 22nd out of 23 priorities listed. Government action on global warming has consistently been considered low priority by the American public. An International Poll in June 2013 shows that US citizens are less concerned about the threat from global climate change compared with all other countries included in the poll.

There are some who take this a step further by claiming that higher levels of CO2 will result in beneficial climate changes for life on Earth. The basis for this argument is that global plant productivity will continue to increase due to the combination of higher levels of CO2 and warmer temperatures. The current concentration of CO2 at 401 ppm is much lower than it was during past periods, such as the Cambrian Peroid (~550 Million years ago), when it estimated to have been around 6000 ppm. Thus, some say the current global environment is CO2-starved. Life on Earth flourished during this period of higher CO2. Ancient plants grew so prolifically that over time CO2 levels in the atmosphere dropped and much of the carbon accumulated as fossil fuels. These people claim that all we are doing today is returning this carbon back to the atmosphere.

There are many diverse opinions on how to deal with the global warming issue. Each of us needs to make up our own mind. Are you willing to make sacrifices now to reduce the potential (and uncertain) consequences of global warming? Personal sacrifices would be consciously limiting your activities which release greenhouse gases (like driving or energy usage). Do you support societal sacrifices and regulations to reduce greenhouse gas emissions? Do you feel strongly enough to actively advocate for such regulation? Societal sacrifices would be government regulations that force individuals and companies to reduce emissions of greenhouse gases.

Topic Outline for Further Discussion

This outline is used to stimulate discussion in the lecture class. You are not expected to study over and understand all the issues presented below. These are just some additional topics to think about. There are many other debatable topics within the anthropogenic global warming issue than are presented here.

  1. Since we are unable to accurately predict future climate changes due to adding greenhouse gases, surprises are possible. There is the real possibility that future climate changes due to anthropogenic greeenhouse gas emissions will be even more severe than the predictions of current climate models.
  2. Ocean acidification is sometimes called the "other CO2 issue." A good portion of the CO2 emitted into the atmosphere by human activities ends up in the oceans. The absorption of CO2 by the oceans could in fact be slowing down the potential climate changes related to human emissions of CO2. As CO2 is dissolved into the ocean water it alters water chemistry, making it more acidic and lowering its pH. This may affect the life cycles of many marine organisms. This issue is gaining attention, but as with other possible effects of human emissions of greenhouse gases, the outcome is uncertain. Below are links to two articles, the first discusses the possible negative environmental effects as more CO2 is dissolved into the oceans, while the second claims that global average ocean acidification may not be much of a problem at all, especially when compared with the huge daily swings in pH that have been observed at single locations:
  3. Although Al Gore and and others claim there is a consensus among climate scientists on global warming due to greenhouse gas increases, this is not true at all. This I know from experience. Atmospheric and climate scientists have debates all the time about the effects of increased greenhouse gases and how much we should be concerned about it. The often repeated assertation that 97% of scientists believe that human-caused climate change is an urgent problem is false (see the linked article below, which explains the history of this false statement). People like Al Gore like to say things like "the science on [human-caused] global warming is settled" and what is left to do is determine how to reduce emissions. Be careful about the motives of the people who are spreading this myth of scientific consensus on global warming. They are preying on the fact that many non-scientists don't want to bother tying to understand the science behind complex issues like global warming. By claiming consensus among scientists, it gives the public an excuse not to think about the issue. It is as if Al Gore is saying, "just believe me, this issue is far too complex for you to understand." Scientists need to be able to explain complex environmental issues to the public.
  4. Try to think about the issue objectively and not emotionally. Just becuase we are perturbing our environment does not guarantee disaster.
  5. There are people and organizations who will tell you that their main concern is the the environment and negative effects of global warming, but in reality they have hidden agendas.
  6. You should realize that humans may be significantly altering the global climate in a variety of ways besides the radiative effects of adding greenhouse gases. When we put all of our focus on carbon dioxide emissions in terms of its perturbation to the greenhouse effect, we are neglecting other, and potentially more important, aspects of the impact of human activities on climate. If we are serious about mitigating anthropogenic climate changes, then we need to consider the effects of everything that we do, not just the radiative effects of added greenhouse gases (see A broader view of the role of humans in the climate system). Examples of other human activities that may influence climate changes include landscape changes, aerosol production, and the widespread use of fertilizers.
  7. In focussing too much attention on reducing carbon dioxide emissions, we often ignore adaptation strategies that could save millions and reduce our exposure to loss in the future (see Lifting the Taboo on Adaptation).
  8. If you are someone who believes that immediate action should be taken to reduce greenhouse gas emissions, consider what it would take to significantly reduce the possible effects of global warming.
  9. Perhaps becuase anthropogenic global warming and its possible effects remain uncertain, we should focus on making changes that make sense even if there were no global warming fears. We need to sensibly plan for the future energy demands of the world as fossil fuels will run out someday. I think that most people agree that conservation, preservation, and the development of sustainable alternative energies are important and should be carried out. However, we should try to avoid making hasty and poorly thought out decisions on energy policy that only marginally influence possible anthropogenic global warming, but have far reaching negative impacts on people, such as the widespread production and use of corn-based ethanol or imposing high "energy taxes" that will be disproportionately paid for by the poor.

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