Friday, March 21, 2014

Climate Change: Part 1 Introduction

Note: This program first aired March 1, 2014.

Its time for another series here on the World Around Us, so the next big thing we’re going to spend a few weeks talking about is something that is happening to the world around us. That big thing has the potential to change where a billion of us live, where and how we grow our food, where it rains and where it doesn’t, how ocean currents circulate around the globe, or not, what can even live in the ocean. In short, this phenomenon stands to transform the world beyond the experience of any of us, of any human being that has ever lived. I’m talking of course about climate change, and we’ll spend the next several weeks looking in detail at science behind this multi faceted phenomenon.

Climate change simply refers to a change in the overall global average temperature and the associated shifts in weather patterns that accompany the change. The Earth’s climate has changed many, many times over the course of Earth’s history, generating climates both colder and warmer than what we experience, on average on Earth today. These shifts typically take thousands of years. There are various reasons the climate changes, for example the intensity of the sun has changed over time, the Earth’s orbit and thus distance from the sun varies, the processes of plate tectonics move the continents around which changes ocean and atmospheric circulation and thus heat distribution patterns, the composition of the atmosphere has changed, climate has even been effect by extra terrestrial objects. For the past 2 million years, the Earth has experienced, not a steady temperature, but a consistent pattern of alternating average temperatures, with cooler periods that resulted in long stretches of glaciation in the northern hemisphere, alternating with warmer periods, during which time the glaciation receded. We’re in one of those warmer in between glacial periods now. But instead of cooling back off and plunging the northern hemisphere back into ice, evidence points to a small increase in average temperature having occurred already, and puts us on the brink of larger increases in the near future. We are perhaps leaving this ice age pattern and moving into a different climate regime.

It should be clear then, that climate change is a normal occurrence on Earth. What is all the fuss about then? Because, just as we have loads of evidence about how climate has changed in the past 500 million or more years, we also have loads of evidence about what the consequences of those climate changes have been. What we find is that rapid and dramatic climate change represents an existential crisis for most living organisms. Rapid changes in climate often accompany mass extinction events, when 60, 70, 80, 90% of families of organisms disappear from the fossil record. So that dear listeners, is the thing to be worried about. If you like how things are on this planet currently, be aware, things are likely to change, not quite on the time scale of your life, but possibly not too much longer than that. The processes of evolution have done an amazing job of repopulating the Earth after these mass extinction events, in fact evolution seems to happen most rapidly when the physical environment changes. Knowing that, I have no doubt that life on Earth will go on and even flourish. No, climate change is ultimately an existential crisis for us. Humans have evolved in a very narrow window of relative climate stability, and all of what we would call the development of agriculture and modern civilization has occurred in this briefest of moments in this interglacial period. As far as we know biologically, its only ever been about this warm, or colder, in our evolutionary period. Its never been warmer, and warmer is where it appears we are going, fast. While the Earth has certainly been there before, we never have, and that reality could have serious consequences.

Join us in the coming weeks as we attempt to explain the science of what is happening, how we know what we know, where all this might be headed and what we can do about it. It’s a topic laden with emotion, political and economic baggage but I think you will find, the science is fascinating. From that point of view, we are truly living in interesting times.