Some Comments about the Science of Global Change: Part I

Posted by Menas Kafatos

With a lot if not most of the attention paid at and around Copenhagen in the policy process unfolding before the very eyes of the world, we often forget and put the science on the background or we hear statements made by politicians such as “the science says this or that,” without using the scientific methodology that is normally the case in normal scientific meetings or normal science research. In other words, COP15 is mostly an international policy process (led by the U.N.), involving many nations, that is based on general scientific consensus. But it is not itself a scientific process and as such it is not driven by scientists. It is driven by heads of states under the auspices of the U.N.  However, if the world’s leaders really expect definitive answers on the evolving climate of the Earth, they should understand the boundaries of what we know or what we can know. We, as scientists, should be honest and explain to the public and the leaders why the Earth’s systems are so complex and why we can only say certain likely scenarios might occur, rather than will definitely occur. Certainly science is involved in the whole debate and process but it is not the only driver and perhaps not even the strongest driver.

I would like to share some thoughts I have (and they are my own thoughts, although I have been discussing them with other scientists, economists –s uch as the fine ESI team at Chapman) and certainly the Chapman participants in COP15, which includes environment, legal and policy experts. Please understand that what we are participating in here is not just an observing process, but it is a dynamic process which I sincerely believe will be useful for our students and the wider Chapman community, and hopefully beyond Chapman. It may indeed be an important development for our understanding of the Earth and I hope of use to society. But it may not. So it is just a sharing of thoughts.

Therefore, I would like to indulge your attention and ask you to participate in the thought processes here and provide your feedback. That of course is your choice. This, I hope, will propel us to the next levels as a group’s thinking is so much more than a single person’s thinking. I am referring to an unfolding process that in the end will have to respect the scientific process itself. Unfortunately, a lot of what is going on with the climate debate is missing the point of the scientific process and what science can do.

This is the first in a series of blogs. I don’t promise it will lead to anything, in fact I may decide to not continue it, if at any point I feel it is not leading to much of anything. Right now I think it is important, so I will try to stay with you on this for a while. I call the present blog that you are now reading, part I of the science of global change. It may end up having part II, part III, …, part N, where N is several. It may not. This is the nature of blogs! But in what I will be writing, I will of course try to present the science as I understand it and how it connects to the incredibly complex human interactions, including COP15, Copenhagen and beyond. Of course I may be wrong, but I will try my best to be honest with the science as I understand it. Folks, it is complex, don’t let anyone try to convince you the scientific issues are totally understood.

First I would like to refer to several terms that are often used interchangeably but in fact can be confusing: Global warming is not the same as climate change and is not the same as global change. First and foremost, global change is occurring all the time, the Earth is a complex, dynamical system and by definition it is undergoing global change all the time. It always did. If it did not, the Earth would be more like the moon (although the evidence is that the moon itself changed dramatically in the past, albeit now at much slower pace). For example, the Earth was inhabitated, say, 100 million years ago by large reptiles, called dinosaurs. Now the dinosaurs are gone. They were part of the living biosphere and the biosphere is changing all the time. The dinosaurs are gone and we are here. I am sure some day we will be gone (at least in our present form). Who knows? Maybe we will evolve to something much more advanced than we are now, maybe not. But for sure, a million years from now, the human species will not be exactly the same  as it is today. Ergo, the Earth is undergoing global change because the Earth is a living planet and a dynamic planet. The geology of the Earth is changing, the biosphere is changing, the oceans are changing, etc.

Second point, the Earth’s climate is changing all the time. Today’s climate is not the same as during the “little ice age” of several hundred years ago. And it is certainly not the same as the climate when the dinosaurs ruled the Earth. So when I hear good meaning people saying “stop climate change” or politicians say “we need to slow down climate change”, I smile. My friends, it would be like us saying “stop the sun from rising tomorrow”! The climate is changing and there is not much we can do about it. What they really mean when they are saying that, is “stop catastrophic climate change that we as humans may have something to do with”. But that is a different point and is certainly not the same as the Earth’s climate changing.

Now the climate system of the Earth is an important component of the global processes, hence climate change is a subset of global change. But they are not the same. The dinosaurs might have died as species because the Earth’s climate changed (and probably this is what happened, as result perhaps of a massive meteor strike). But they may have died for other reasons. The collapse of a particular human society might have occurred because of changing climate (e.g. the Vikings abandoning North America when the climate turned colder). But other societies collapsed because of internal reasons.  Are such collapses part of global change? Well, it depends on how massive the society was and how it influenced the Earth. Whereas most of my colleagues would probably not classify changes of societies as part of global change, I would. As we are debating the changing climate of the Earth and putting the burden of change (or no change) on human societies, we are implicitly assuming that changing societies are part of global change.

Third point, global warming refers to the view that the Earth’s climate is warming up. This has been happening in the last several thousand years. The Earth’s climate changes over 145 thousand years or so (due to astronomical factors and feedback mechanisms) and most of the time it is getting cooler. Since we emerged from the last ice age, the Earth has been undergoing global warming.

So you get the picture: Global change is more general than climate change which in turn is more general than global warming. They are not the same and they are occurring all the time (and global warming for the last several thousand years). Now how much influence we as species have on global change, climate change, and global warming, is another issue that deserves serious scientific inquiry. But that is enough for this blog. Stay tuned…..


2 Responses to Some Comments about the Science of Global Change: Part I

  1. Thank you, Menas, for helping to bring clarity to terms and to a process that sometimes seems otherwordly, at least to this untrained observer. I look forward to engaging in your ongoing conversation.

  2. Diana McCabe says:

    Interesting post on the various terms. Good perspective for those of us not in the field.

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