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Jesse Smith, Science Magazine (moderator):

Good morning, and welcome to EurekAlert!'s online chat on climate change. I'm Jesse Smith, and I will be moderating our discussion with our experts, Dr. Michael Oppenheimer and Dr. Daniel Schrag. Michael Oppenheimer is the Albert G. Milbank Professor of Geosciences and International Affairs at Princeton University. He is also the Director of the Program in Science, Technology and Environmental Policy (STEP) at the Woodrow Wilson School, and Associated Faculty of the Princeton Environmental Institute and the Atmosphere and Ocean Sciences Program. His research explores the potential effects of global warming, including the effects of warming on ecosystems and on the nitrogen cycle; and on the ice sheets in the context of defining "dangerous anthropogenic interference" with the climate system. Daniel Schrag is Professor of Earth and Planetary Sciences at Harvard University and the Director of the Harvard University Center for the Environment. Schrag studies climate and climate change over the broadest range of Earth history. He has worked on theories for Pleistocene ice-age cycles including a better determination of ocean temperatures during the Last Glacial Maximum, 20,000 years ago. He has also developed the Snowball Earth hypothesis, proposing that a series of global glaciations occurred between 750 and 580 million years ago that may have led to the evolution of multicellular animals. Welcome to all.



Jesse Smith, Science Magazine (moderator):

Over the past few years, a number of vocal critics have argued variously that global warming is too slight to be a concern, that human activity has nothing to do with the observed warming, or even that no global warming is occurring. What are the bases of these arguments, and what is the present status of the debate?



Dr. Michael Oppenheimer, Princeton University:

There's little doubt that humans are largely responsible for the warming that has occurred over the last few decades. And even more important, there's a certainty that if the greenhouse gases build up at current rates, that the Earth will warm over the century to levels that haven't been seen in a million years. Over the past ten years or so, so-called skeptics have raised a number of objections, but these have been knocked down by research scientists one after the other, like a bunch of bowling pins. Among these were the assertions that the warming was simply a reflection of the urban heat island effect. But since warming has occurred over the land, over the ocean, in the Northern Hemisphere and in the Southern Hemisphere, this argument was dispensed with fairly easily. Because, for instance, there are no larger urban areas floating in the middle of the Pacific Ocean. Another suggestion was that changes in the sun's intensity were responsible for much of the warming. But direct satellite measurements over the past 27 years reveal that changes in the sun's intensity have been very modest, and not enough to cause the observed warming.



Dr. Daniel Schrag, Harvard University:

I have a slightly different perspective from Michael because I haven't been responding to the skeptics as long as he has. I see that there are really three types of skeptics. First, the serious scientific skeptics who are good for our comumunity that ask tough questions and challenge our assumptions, these are people who are generally skeptics about ideas and demand various high standards of proof. And while that's very good for the scientific community the problem has been that the public policy community has failed to understand the difference between scientific uncertainty and the uncertainty that might delay a serious action. Now the second type of skeptic is one who has a very narrow use of their particular area and are not aware of the broader evidence. They see their own little piece of the puzzle that may not fit quite perfectly and therefore they reject the whole idea despite the strong support from other observations. That's just ignorance. The third type of skeptic is a liar. And unfortunately there are industries that essentially paid indivuals and organizations to misrepresent the state of denial. And as a scientist that's the most frustating type of skeptic because it is very difficult to argue with a liar.



Dr. Michael Oppenheimer, Princeton University:

Yes, it looks like we are headed toward a climate change that is largely irreversible on human time scales on the order of centuries, and some of the changes may never be reversed. When I say "never," I mean tens of thousands of years. There is certainly a need to develop adaptation strategies while we move to reduce emissions at the same time. This is particularly true for developing countries that have relatively slender resources that can be devoted to this problem, but it's also true for countries in the North, like the U.S., which showed recently in its responsible to Hurricane Katrina that our ability to deal with climate extremes, whether they have to do with global warming or not, is extremely limited.



Dr. Daniel Schrag, Harvard University:

There are a number of different possible tipping points in the climate system that have me very concerned. One of these is the melting of glaciers that could dramatically affect climate through a number of feedbacks. Second is the thawing of tundra that could release as much carbon to the atmosphere as we are burning with fossil fuels. The problem with all of these types of dangers is that we don't know when this will occur or even whether we have crossed a critical threshhold already. We may have already lost control of the system, but I hope not, because reducing our own carbon emissions is something that is very feasible.



Tobias Huerter, Die Zeit, Hamburg, Germany:

The European Union set the goal to keep global warming below 2 degrees Celsius over the pre-industrial level. Is this mark scientifically well-founded -- or just a political artifact? Under what conditions can it be kept? Do you see any chance that the U.S. will also subscribe to this (or a similar) aim?



Dr. Michael Oppenheimer, Princeton University:

The European goal of two degrees warming above pre-industrial levels as a long-term objective for global warming policy is based loosely on science, in the sense that the science of where key thresholds lie, as Dan Schrag just noted, is itself uncertain. One might view it as a cautionary target. That is, given what we know today, it would make sense to keep the warming below that level if possible, because the risk of dangerous outcomes like disintegration of one of the major ice sheets starts to rise significantly above that level. On the other hand, it's a very tight target, and given what we know today about emissions of the greenhouse gases, I'd say we have at best a 50-50 chance of meeting it. The U.S. is gradually developing greenhouse policy, but only at the state level. We cannot expect a national program to be implemented for a few years. Until the U.S. acts, it is unlikely that developing countries will begin to deal with the problem. Unless the big developing countries, as well as the U.S. and Europe, start limiting emissions significantly over the next 15 years or so, we will have no chance to meet such an objective.



Dr. Daniel Schrag, Harvard University:

I guess I should say it's possible that we may see a 2 degree rise even if the most stringent actions are taken and there is no guarantee that a 2 degree rise is safe. I suspect that some time in the next 30 years there will be public concern for the changes that are occurring that will be high enough that much more dramatic goals will be envisioned.



Sara Newman, Independent:

Does anyone know how much energy and resources we need to save in order to reverse climate change? How many flights am I entitled to a year? How many trees should I plant? What measures need to be taken by each person? There is plenty of coverage and information on the perils of climate change, but I know of no comprehensive set of guidelines by which to live in order to reverse it.



Dr. Michael Oppenheimer, Princeton University:

There are lots of analyses of what individuals can do, and I point you to the Web site of many of the American environmental organizations. I'll point you to www.ed.org, since I used to work for that organization, but there are many others. One can calculate one's greenhouse contribution from an American perspective. Some of the simplest actions to take which avoid significant amounts of greenhouse gases are to replace the five most used lightbulbs in your house with compact fluorescent lamps; buy appliances that carry EPA's "Energy Star" label; and drive a car that gets the highest fuel economy available in its size class. Through those efforts, an individual can significantly reduce his or her greenhouse contribution.



Dr. Daniel Schrag, Harvard University:

Michael is right that there's a lot that individuals can do, especially on the energy efficiency side. At the same time, the problem is bigger than that. We need to reduce our carbon emissions by much more than just what we can accomplish with efficiency. In addition to individual action, we also need to make energy policies and climate change policies a top political priority. There are choices that we as a society can make about where we get our energy. It cannot be made individually.



Jesse Smith, Science Magazine (moderator):

What can be done with existing energy technology to minimize global warming, and what advanced technological energy options might be worth consideration?



Dr. Michael Oppenheimer, Princeton University:

This question was addressed comprehensively in a paper in Science magazine two years ago by my colleagues Steve Pacala and Rob Socolow. They argued that global emissions could be kept more or less constant over the next 50 years with technologies that are both already available and affordable. That would be a strong beginning to solving the greenhouse problem. Some of these suggestions included greater energy efficiency, more use of wind power, so-called carbon capture and storage, and additional use of nuclear power, although I personally am skeptical of the latter. After 50 years, it would be necessary to bring in new energy approaches such as the use of advanced solar photovoltaic energy. The bottom line is this: If we move aggressively to use what's available, and at the same time fund basic research needed to develop new technologies, we have a good chance to avoid a dangerous warming.



Dr. Daniel Schrag, Harvard University:

Unfortunately, I think the paper to which Michael refers to is overly optimistic. The current inertia in the fossil fuel industry, particularly in the use of coal in countries like China, make this problem extraordinarily difficult to solve. There are technologies available today, but the costs are high. What is missing is the political will, not just in this country but around the world, to put those technologies in place. For example, until the major countries of the world decide that capturing carbon from coal plants is mandatory, we will not solve this problem. The irony is that the global cost of rebuilding our energy infrastructure to dramatically reduce carbon emissions is not that high. Probably only a few hundred billion dollars per year, which is less than 1 percent of world GDP, and yet this still seems too expensive to us to protect againt possibility of catastrophic change.



Leigh Dayton, Science Writer, The Australian newspaper:

How do you respond to the recent economic analysis released by a panel coordinated by climate change skeptic Bjorn Lomborg? The key claim of the group is that the cost of tackling climate change is prohibitive and will produce little results, as compared to other pressing expenditures on problems like clean drinking water, HIV, etc. Your thoughts?



Dr. Michael Oppenheimer, Princeton University:

The projections of the cost of stabilizing the climate range very widely, but generally fall in the range of a few percent of global GDP over the course of many decades. Such a program effectively implemented would have almost no noticeable effect on the world's economies. With regard to the so-called "Copenhagan Consensus," it embodies of false dichotomy. At the level of government policy, particularly in the developed countries, such a trade-off has never and will never exist. Finally, it's worth noting that unconstrained climate change would cost the world far more than the price tag for avoiding it, particularly the very developing coutnries that have the problems with water and air quality that the so-called consensus referred to. Climate change will only make every other problem worse.



Dr. Daniel Schrag, Harvard University:

There is also a false assumption by Lomborg that the climate change impact will essentially be restricted to the poorest countries and that, by making those people wealthier, they will be able to adapt to climate change. It is true that many poor people in the world are vulnerable to climate change because they live at the edge of subsistence. However, climate change in economic terms will effect rich countries much more, because we have enormous investments in places that will be threatened. Doing nothing about climate change is simply not an option.



Daniel Grossman, Freelance/Boston:

Are there important feedback mechanisms that have not been incorporated into the IPCC analysis of climate senstivity (such as permafrost melting or Arctic sea ice shrinkage)? If so, what is the current thinking on how warm the planet might get and how quickly this could occur?



Dr. Michael Oppenheimer, Princeton University:

The models that the IPCC relies on incorporate many of the feedback that are thought to be important in influencing future climate. Among those is the sea ice feedback and, more recently, the so-called carbon cycle feedback. These do in fact have a substantial effect on projected warming. What is perhaps of greater concern are potential feedbacks that cannot yet be quantified, and are therefore not embodied in IPCC projections. These may include the potential release of methane hydrates from the ocean, among others. It is also of some concern that feedbacks that are embodied in the models may not be fully described. Here, I would point to some aspects of the carbon cycle such as the potential for release of methane from wetlands. So on the whole, the IPCC projections do about as good a job as can be done with what we know today, but there's a lot we just don't know.



Dr. Daniel Schrag, Harvard University:

I think the important perspective here is that we are sending the Earth back to a state it hasn't been in for more than 30 million years, and no human being can know exactly what is going to happen. There will be surprises. Scientists are working to identify as many potential feedbacks as possible, but I am sure that we will miss some. It is simply a part of the experiment we're doing on the planet.



Suzannah Wright, Biofuels News:

How important will biofuels be to mitigating climate change, and which type of biofuel do you think has the most potential to mitigate climate change?



Dr. Michael Oppenheimer, Princeton University:

From today's perspective, biofuels have the possibility of replacing perhaps 20 percent of future fossil use, though the main constraint is land, because biofuels ultimately will compete with agriculture. However, new technologies for both agriculture and biofuels may make either or both more efficient and change that reckoning. I don't really want to speculate on what particular fuels might become available in the future, but as of now, there is some promise for production of ethanol from cellulose-based material, that would allow a net reduction in carbon dioxide emissions.



Dr. Daniel Schrag, Harvard University:

I think biofuels are a very important option right now, in part because, politically, it is very easy in this country to get support for our agricultural sector. Exactly which technology will be the best for converting plants into liquid fuel still is very much uncertain. I expect that we will see, in the next five years, a lot of new ideas and hopefully surprises that will make it cheaper to do.



Robert Walgate, RealHealthNews:

To be realistic, with massive economies like China's dependent on coal power, and India, just getting going, quite apart from the West's immense dependence on oil, nations are surely not going to react fast enough, or react to anything like an effective extent. So won't we depend on (1) adaption to the effects climate change, and (2) efforts to reduce solar input, like a reflective shade of particles or some other kind? What are the options for these approaches?



Dr. Michael Oppenheimer, Princeton University:

The so-called geoengineering approaches are really only a last resort, because all of them have potentially harmful environmental side effects, such as additional ozone depletion, and we're not at the point yet where we're desperate. Adaptation is a necessary parallel strategy with emissions reduction, and the two approaches should not be viewed as an either/or proposition. China's emissions are a daunting challenge, but there are concepts on how to eventually rein them in. One promising strategy involves carbon capture and storage. Another involves enhanced use of biofuels locally produced. A third would involve some displacement of coal with natural gas. None of these are likely to occur unless the U.S. begins to exert global leadership.



Dr. Daniel Schrag, Harvard University:

I agree with Michael that adaptation is required because we cannot avoid climate change. And as I said before, mitigation is essential. As far as geoengineering solutions, they are, as Michael said, desperate measures to deal with the climate system when we realize we have lost control. However, in the next few decades, if we started to see the rapid disentegration of the Greenland ice sheet, for example, then the potential impact would be so large that we would have to consider engineering soluitions to at least slow it down.



David Shukman, BBC News, London:

I'm just back from Siberia where I reported on the huge releases of greenhouse gases from the thawing permafrost. Is it possible that the projections for global climate change are too gradual, too "tidy," and that abrupt change is a real possibility?



Dr. Michael Oppenheimer, Princeton University:

The reported releases of methane from permafrost in Siberia are certainly troubling, and what's more disturbing is that we simply don't have comprehensive observations that would allow us to understand whether such behavior is imminent on a widespread basis at northern latitudes. On the other hand, we can monitor the growth of methane in the atmosphere, and we would notice a big jump-up as it occurs. The trouble is, given our knowledge today, we wouldn't be able to predict it before it occurs and slow the warming quickly enough to stop it from happening. So an abrupt large release can't be ruled out. We just don't have enough understanding one way or the other to assess the problem.



Dr. Daniel Schrag, Harvard University:

I think that there may actually be a silver lining in the storm cloud of abrupt climate change. Climate change occurs gradually. We may not be able to generate the necessary political will to step up and really solve the problem. It may be that an abrupt change of some sort is required to make people convince governments around the world to take note. I just hope that it isn't too costly in terms of human suffering.



Jesse Smith, Science Magazine (moderator):

Dr. Oppenheimer, Dr. Schrag, thank you very much for your participation in our chat. I hope that our readers have learned something, and have come up with more questions about how to deal with the issue of climate change. Good day, all.