Kevin Trenberth discusses the importance of understanding the changes that the Earth’s environment is making and why global warming is a real problem that needs to be addressed immediately.
Ben Lack: Well, I’m here with Kevin Trenberth, head of the Climate Analysis Section of the National Center for Atmospheric Research in Boulder, Colorado. Kevin, thanks so much for giving us some of your time.
Kevin Trenberth: You’re most welcome, Ben.
Ben Lack: Can you talk to us a little bit about what you do as the head of the Climate Analysis Section in Colorado?
Kevin Trenberth: UCAR is University Corporation for Atmospheric Research and NCAR is the primary operating arm of UCAR. So UCAR administers NCAR, but it has also some other offshoots as well which are a lot smaller. In my institution, we deal with all aspects of weather and climate, and I’m a part of the Climate and Global Dynamics Division. And a major activity in our division is actually to build a global climate model and even venturing now into what is called earth-system models. But my role as the head of the Climate Analysis Section is to anchor all of that material in the real world. And so we deal with the analyses, especially from a global perspective as to what has happened in the past, how it all works and fits together what the mechanisms and the processes are. And it provides information about what is happening in the climate system.
So we focus a lot in my group on global energy, the incoming radiant energy, and the flow of energy through the climate system. How it gets translated into heat, both in the atmosphere and in the oceans. And in the oceans, it’s related to sea-level rise, how much goes into melting of our Arctic sea ice and Greenland ice and Antarctic ice and so on which also contributes to sea-level rise incidentally. And how much goes into the land and all of the consequences associated with that and then the radiation ultimately goes back into space as what we call infrared radiation. Funnel radiation going back into space. Now the overall energy balance for the earth is perturbed by human activities because we’re changing the composition of the atmosphere, and it interferes with that flow of energy through the climate system. And this is related to what is called the greenhouse effect. And it’s because of the buildup of carbon dioxide in the atmosphere. Carbon dioxide has increased to thirty-five percent since pre-industrial times, and half of that increase has occurred since 1970. And so global warming is happening. And so one of the things that we’ve focused on recently is can we track that change in the flow of energy through the climate system.
Ben Lack: How big is your team, and how do you do that?
Kevin Trenberth: The team is not that big. There are four or five scientists in my section here. Most of them are doing their own thing, and there are three people that are working closely with me. How we do this is first we’re looking at satellite data, measuring the radiation of the topic atmosphere, how much is coming in from the sun, how much is going back out to space from the earth, and what the net radiation is. And then we’re looking at all of the components of the climate system. The ocean, what’s the change in the ocean heat content. What’s the change in atmospheric temperatures, land temperatures? How much melt has occurred in Arctic sea ice? And we try and track where all of the energy is actually going and ending up and then seeing where they all add up. And what we’ve found actually in recent times is that they’re not adding up, indicating that either there’s a shortfall on the observations or in the processing of those observations. And this is something we need to do better on. And there’s been some major international conferences. The last one was in Copenhagen in December of last year which, in many respects, was a failure in the fact that there was a failure to reach an international agreement about how to limit the emission of greenhouse gases into the atmosphere. So that is an issue. But the reason it’s an issue, especially with regard to carbon dioxide which is a product of burning off fossil fuels, and therefore all of our energy system within the human activity sector, that buildup of carbon dioxide occurs because carbon dioxide has a very long lifetime. Well over a hundred years. And so anything you put into the atmosphere tends to stay there.
It’s gradually building up over time, and it’s been doing that since the industrial revolution, somewhere, I say, about the middle of the eighteenth century. But it’s really only come to the fore since about 1970. And that’s where the effect has grown up to be large enough that it is outside of the realm of natural variability with regards to global mean temperatures. And so this is where the term “global warming” comes from. But global mean temperatures fluctuate because of El Nino and natural variations as well. And it doesn’t mean that the temperature goes up relentlessly year after year. On the hand, the last decade is the warmest decade on record, and probably the warmest decade in the last 2,000 years and beyond for that matter.
And so global warming is happening and is projected to continue to occur because we’re putting more carbon dioxide and other greenhouse gases into the atmosphere. And so we need to start doing something about it. Because what we do now has its biggest impact forty or fifty years from now. And if we wait another forty or fifty years and then find out that, “Oh, we’ve really got a major problem here,” it’s actually far too late to do anything about it. So that’s the nature of the problem we’re dealing with.
Ben Lack: So besides trying to lower our carbon output, are there things that we can do proactively to remove the amount of carbon that’s already in the atmosphere?
Kevin Trenberth: There’s a little bit. Of course, growing trees helps. But then if you cut down a tree and then burn it, the carbon dioxide goes right back into the atmosphere. So deforestation contributes to this problem because we’re actually removing trees as a whole. So trees are one way in which you can take carbon dioxide out of the atmosphere. The loss of carbon dioxide is in the atmosphere is so diffuse, there’s no really good ways of removing it and if we were to set about trying to remove it, it would probably require as much energy and therefore more carbon dioxide coming into the atmosphere as we gained from taking the carbon dioxide out. And so the best thing certainly is not to put it in the atmosphere in the first place.
Ben Lack: True. You know, I know that there are a lot of people in your camp that really feels that global warming is happening and is an issue. How do you get the research and the findings that you guys have out into the marketplace? What types of travels do you do? What types of presentations do you give to make sure folks are finding out about all this research that you guys are accumulating?
Kevin Trenberth: You use the word “feel” and, in fact, it’s not a matter of feeling because there’s a tremendous amount of really hard, solid information. These are facts that we’re dealing with. These are observations of what is happening around the world. The changes in temperature, the melting of Arctic sea ice, the record-breaking heat waves, and all of the storms, changes in storms. Another big part of our work actually deals the water cycle and changes in storms and rainfalls and things like that. And all of those things are happening in a way that are consistent with what the models suggest should be happening. But at the moment, there are relatively modest, and we’re still dominated by natural variability. So as researchers, what we do is we first carry out the research and then submit it for publication. And then it gets into journals. And in that process, it gets reviewed. All of that literature in turn gets assessed from time to time, especially related to climate change, through what is called the Intergovernmental Panel on Climate Change, the IPCC. They have four major assessments now about every six years since 1990. The last one was in 2007. And as a part of that, the IPCC, along with Al Gore, were awarded the 2007 Nobel Peace Prize. A lot of people don’t realize the IPCC was given that award along with Al Gore two years ago now. The IPCC, the Intergovernmental Panel means it’s a process whereby a report is written, but there are quite strong interactions, especially at the final stage, between scientists and government officials around the world. And that interaction turns out to very fruitful, and it means a direct input into policymakers as well as other decision-makers around the world. And that is what has led to United Nations Framework Convention on Climate Change. And the activities, such as the, the official term is the conference of parties, that occurred in Copenhagen last December. So that’s one way in which we have impact. And then, of course, some of the sciences is picked up by the media and there are various reports that appear in newspapers or Time Magazine or something like that that can get out into the public as well.
Ben Lack: Well, I know that an article was released from a science magazine that had you featured in it. Can you us about what was published and your findings?
Kevin Trenberth: The title of our perspective on this, our own assessment, was called Tracking Earth’s Energy. And the subtitle was “Where Has the Energy From Global Warming Gone?” So in this article, we described the holistic of what’s going on with regard to energy and its flow the climate system. And we find that the things hang together reasonably well from 1993 to 2003. They’re consistent with what we’re expecting with regards to models, but the measurements since about 2005 are showing that there’s some energy that we can’t account for. In other words, at the top of the atmosphere from satellites, we’re measuring more energy being trapped in the Earth system, but it’s not showing up in places it’s expected to be, particularly in the oceans. And so the oceans haven’t warmed up as much as we would expect. So this raises the question: Is the observing system adequate? Is the processing of the data adequate? And yet this is very important because any missing energy can come back to haunt us. And one way it can do that is through things like El Nino. And, in fact, we had an El Nino develop last June. And an El Nino has been occurring in the past year and has been a big influence on the weather patterns. In the United States, for instance, it’s been an influence on the tracks of storms. So the storms come barreling into Southern California. Move across the southern parts of the United States where it tends to be colder in El Nino conditions. And then up the East Coast and we’ve seen a number of record-breaking rainstorms and snowstorms. The big snowstorm in the Washington, D.C. area and then rainstorms later on in New England and so on. And so those are actually influenced by this El Nino phenomenon going on out in the tropical Pacific. And so where does the heat from this El Nino come from and can we track it? That’s a research question which we haven’t looked into fully yet. But maybes that’s one manifestation of some this missing heat and how it can come back to haunt us and influence weather patterns around the world.
Ben Lack: And do you think that it’s really more of a phenomenon? Or do you think this is more of a grilling pattern of the types of changing climates and weather patterns that we’re going to see going forward?
Kevin Trenberth: Well, there are two things that are happening. One is natural variability. So we have phenomenon like El Nino, and that changes as I’d mentioned. It changes storm tracks. It changes the patterns of precipitation around the world. So it changes clouds. Cloud can active block the sun, and they can change how much radiation stays on the planet. And so the fluctuations in the energy on the planet Earth are simply from natural variability for those kind of reasons. But then we’re also changing the composition of the atmosphere through the buildup of carbon dioxide in the atmosphere. So this is a global climate change aspect. And that is moving things relentlessly in one direction. And so we have to start planning for that. One part of the planning would be to stop that from happening or slow it down. That’s the mitigation aspects as it’s often referred to. And then the other aspect is to plan for it. And this relates to what is often referred to as adapting to climate change.
Ben Lack: Is part of your responsibilities is to come up with these worse case scenarios of what happens to the Earth and what normal lifestyle would be for the humankind if we were to get to that point?
Kevin Trenberth: As scientists, we try and make projections into the future using climate models. And the climate models are verified based upon what’s happened in the past hundred years and also by looking at much longer timescales where the observations much more fragmentary going back into pre-instrumental times for instance. But there are indicators that this relates to what is often referred to as paleo-climate, going back thousands or even millions of years to see whether we can replicate what’s happened in the past.
So the climate models are validated so to speak using those kind of methods. And then they make into the future. And, indeed, the climate models suggest that fifty years and beyond into the future there could be really major consequences for the environment, in terms of the heat waves in the water and the increased risk of, actually both flooding on the one hand and also droughts and wildfires and the consequences of things like that around the world. In many places, ecosystems which currently exist, so this relates to forests or even agriculture, a managed ecosystem, a managed vegetation and so on, may not be viable where it is now because of the change in the climate that’s occurred. So this could have really very big consequences. At the same time, the population is growing. The demand for food and water continues to grow. The amount of water isn’t growing. It’s being redistributed. And I think water and changes in precipitation are actually going to be one of the ways on which the biggest impacts will occur on society.
Ben Lack: Are there certain spots of the world where you think this effect is going to have more of an impact than others?
Kevin Trenberth: There are certainly are impacts everywhere. And, of course, we’ve seen very recently with regard to the volcanic dust cloud in Europe how interconnected things are around the world. The fact that the farmers in Kenya can’t ship all of their produce to Europe and sell it. And it’s all going rotten in Kenya affects the people in Kenya whether or not simply because of something that’s happened in Iceland. And so this interconnectiveness means that everyone is affected. But there are certain areas of the world that are much more vulnerable than others. And in particular in the subtropics, throughout the subtropics, these are regions where things are already fairly dry or arid probably includes most of Africa. There’s a much greater risk of really severe drought and water shortages for instance. And this includes South Asia. Includes the United States, California and areas extending to where I am in Colorado even. Areas generally more in the South are probably more vulnerable to and more likely to have longer droughts and dry spells and heatwaves and wildfires that along with those kind of things.
Ben Lack: We definitely have a lot of work on our hands, don’t we?
Kevin Trenberth: Well, this requires looking ahead and, at the moment, it seems like politicians can’t look ahead much beyond the next election. And here we are looking ahead at the whole civilization and the future of humankind. And one of the consequences of not planning and dealing with this is apt to be a lot more strife that can actually lead to even warfare and security risks around the world. And indeed, this is one of the things which the Department of Defense is also very concerned about is increased instability arising from climate change as we move further into the future.
Ben Lack: Wow. Well, Kevin, I really do appreciate you giving us some of your time today to talk about some of the work that you guys have been doing. I hope that we can stay in touch because I’m sure that you guys will be coming out with many reports and findings on the climate change and energy as a whole. And I just thank you for the time, and we look forward to speaking with you soon.
Kevin Trenberth: Alright, thank you very much, Ben. You’re most welcome.