David Roberts, former climate and energy writer at Grist.org Presents Climate Change is Simple at TEDxTheEvergreenStateCollege. Here is the full transcript.
Listen to the MP3 Audio here: Climate change is simple by David Roberts at TEDxTheEvergreenStateCollege
Hi, this talk started out of a Twitter conversation. I haven’t decided whether to be embarrassed about that or not.
But I was on Twitter one day and a relatively prominent left of center pundit, piped up and said “You know, climate change seems like a really big deal, why are so few people talking about it? Why have so few thought leaders made it their signature issue?”
And another reasonably prominent left of center pundit piped up and said “Well, for my part, the reason I don’t talk about it is it seems really complicated, I don’t feel like I have a good grasp on all the science and so I just don’t feel qualified to go out and assert things publicly about it.”
You know, anybody who has ever so much as mentioned climate change on television or on the internet will understand why this person thinks the way they do. Any time you mention it, the hordes descend, bearing complicated stories about the medieval ice age, or sunspots, or water vapor, and there is a lot of myths about climate change borne by these climate skeptics but to debunk those myths you have to know, you have to go online, and research, and read, and be able to respond to them in detail, and a lot of people just find that prospect dreary, and so they don’t bother. And this, of course, drives me crazy.
So I piped up on Twitter and said “You know, climate change is not actually that complicated. What you need to know to be able to speak out publicly about it, just about the basic structure of the problem, is really not that complicated, I could explain it to you in 15 minutes” so, let this be a lesson to you: don’t go talk smack on Twitter, unless you are willing to back it up. So, one thing led to another, and here I am with 15 minutes to explain climate change to you.
So, let’s get started. Why is the Earth not a cold dead rock floating in space? The reason is that it is enveloped by this tiny, tiny thin layer of gases and chemicals that we call our atmosphere. So, the Sun’s energy, rather than just coming down and bouncing right back off, it comes down and is held close to the surface of the Earth for a while and then bounces off, and that — this simple process is why we have evaporation, and precipitation, and photosynthesis, and life on our planet.
So, scientists discovered, well over a hundred years ago, that the atmosphere and the systems on the Earth are in this dynamic relationship and you can change the chemical composition of the atmosphere and hold more of the Sun’s energy for longer. The energy still has to escape, of course, but in the meantime it will cause changes in these biophysical systems of the Earth.
And, you often hear people say, “The Earth has always changed, the climate has always changed”, and that’s true, it has. This relationship between the atmosphere and the systems, they go through cycles, but these cycles have typically taken hundreds of thousands of years, millions of years.
The key thing to know first is that for the last 10,000 years on Earth, the climate has been relatively stable, unusually stable, and by stable I mean temperature has varied, it’s gone up and down, but it’s stayed on a fairly narrow band of about plus or minus 1 degree Celsius, and all of advanced human civilization has taken place during these 10,000 years, the development of agriculture, the written word, the wheel, the iPhone, everything we know, everything we have built, we have done in this period of relative climate stability.
So, what we have been doing for the last couple of hundred years is digging up carbon out of the earth, and throwing it up into the atmosphere, and changing the chemical composition of the atmosphere, like has happened in the past except for way, way, way, way, faster. In geological time, the blink of an eye, we are substantially changing the chemical composition of the atmosphere and all of climate science has been about, “What’s going to happen? What is the Earth going to do in response to this?”
And so, we’ve already seen that the process is underway. We have measured, we have witnessed, observed with our eyes and our thermometers about a 0.8ºC rise in global average temperature since before the industrial age, since before we started digging all this carbon up. And this may not seem like a lot — less than 1ºC — but the thing to know about it is these greenhouse gases we throw up stay in the atmosphere for a very long time, there are very long time lags involved here. So this 0.8º temperature rise is a response to what we were doing 50 to 100 years ago. And what we see in the first half of this century will be a response to what we’ve done in the last 50 years and what we’ll see in the latter half of this century will be a response to decisions we make today.
So the question is, “Temperature’s rising, how high does it have to rise before we need to worry, before we’re in danger, before bad things start happening?” The typical answer to this question has been 2ºC. Anyone who has followed climate change discussions knows that this 2º number has taken on a kind of iconic quality. Typically, climate scientists who model impacts of what’s going to happen, model 2ºC rise, typically economists who try to model what it would cost to do something about climate change or what it’s worth or what various policies would cost, model 2º centigrade.
So obviously, what counts as not dangerous versus dangerous, is not a hard scientific question, it’s a political question, and this was a political decision to take this 2C number, mainly made by European climate negotiators well over 10 years ago, and it’s just sort of stuck since then. All the countries involved in climate negotiations have basically signed on saying “Yes, this is what we want to avoid, 2ºC temperature rise.”
The bad news on this 2C number is two-fold. First of all, all the latest science done in the last 10 to 15 years has pointed to the conclusion that those impacts we thought were going to happen around 2ºC are in fact going to happen much earlier than that, the climate is more sensitive to these added greenhouse gases than we thought.