CLIMATE CHANGE: THE FACTS.

• Author: Takle, Eugene
• Position: Includes discussion - Proceedings of the 43rd Canada-United States Law Institute Annual Conference: Can the United States and Canada Cooperate on Climate Change?

Speaker: Dr. Eugene Takle

DR. TAKLE: Thank you for those kind words. So we are going to jump right into the background, and not being presumptuous in that you studied this, you have probably seen fragments of this, but I am trying to pull this together, the core of why we understand climate change and the significance of it. So I am going to be going in two sections here.

We'll look, first of all, at fundamental science, and then we will look at some of the issues and impacts so we can look at some of the factors that are going to be driving the impacts and things that we have to think about trying to develop resilience to, because some of these are going to be very serious, and we will get into that.

We have a lot of good foundational documents to draw on, to look at both the science and the impact. So for instance, the intergovernmental panel on climate change issues, which is about every five years, state of the climate on the global scale and an update on the science of climate change, and so we have the 2004 issue of that.

And then, we have national documents that parallel the international document. The one for Canada is put out by Natural Resources Canada, and so that's an updated document that you have at your disposal. In U.S., we have two documents, one that was issued about a year ago which covers the science of climate change. So it is just the IPCC document and then updates and focuses on the science for the U.S. And then, the one that was just issued the day after Thanksgiving was the fourth national U.S. climate change assessment, and I was involved in that one as well.

So we will look at some of the fundamentals of why we have this issue, and then, we will look first globally, and then we will look at North America and a few words about the Great Lakes. Well, the clim--when we talk about the climate system, we are really talking about land, ocean, atmosphere, and ice masses. Those are the four components of the climate system, and energy moves between these and among these reservoirs then.

And so to understand the climate system, we have to understand how energy and mass is moved among these reservoirs. So ice melts, and it takes energy to melt ice. So part of this increase in energy that we are seeing is used to melt ice. And so that's the way we look at it.

We use the same laws of physics to build airplanes, to build nuclear power plants, and we have confidence in these laws. Because we ride in airplanes, we have confidence. We can live in the vicinity of nuclear power plants because we know--we use the laws of physics to design these. These same laws are used to look at our climate.

Now, there is a lot of uncertainty because the climate system is a big system, and we need a lot of observation. So there is a level of uncertainty, which is also a part of our science, to quantify our level of confidence in these various statements that we make.

And so when you read these documents, you will see references to how confident we are in the results. Well, there is ten indicators, at least ten that we can look at, and so this is just warming of the globe, but it is sea surface temperatures; it is sea level; it is water vapor in the atmosphere, just going up in the warmer world. The near surface, the lowest two, three miles of the atmosphere, we look at the temperatures of that.

We look at glaciers that are melting. Snow covers are going down sea ice is going down; look at temperature over land, and a very important one is ocean heat content, which doesn't give it much attention, but 90 percent of the heat that comes into the climate system goes into our ocean.

So that's a reservoir that is sitting there, waiting, and could be redistributed in ways that we are only beginning to understand. So that's an important factor in the climate system. So the basic concept, then, is that they meet the greenhouse house, and it is a natural effect, and we are glad we have that because that's what keeps us from having global average temperature of about minus 10 degrees Celsius, or something like that.

So it has a blanket of these gases, mainly carbon dioxide but also nitrous oxide, methane that trap some of the heat and keep it from going back out to outer space, and so it is redirected toward the earth.

Now, what we are doing is we have increased the levels of carbon dioxide, methane, nitrous oxide, and other gases to the point where more of this solar radiation is being trapped, and that means that the temperatures in this vicinity are rather small.

Now, it is always important for me to point out that this cartoon here shows that we have this big thick layer here. In fact, if the earth was the size of a basketball, this layer would be the thickness of two sheets of paper. That's all it is. And it is that thin sheet, and there are two gases: There is carbon dioxide and ozone. If it weren't for those gases in that thin sheet of atmosphere, we couldn't survive. People could not survive.

Lack of ozone means that the ultra-violent light would fry us. And carbon dioxide, not having the right amount of carbon dioxide, means that we know we could not exist. So this very thin sheet of atmosphere is what we are doing, is a gigantic chemistry experiment. Well, we don't know the outcome. So that's the sobering reality of it.

So if we look at carbon dioxide, which I am going to focus on carbon dioxide, but we will talk a little bit about the others, but carbon dioxide, if you look at the record and it is hard to see from where you are at, this is an 800,000-year record. So it goes back 800,000 years, and this is the present.

And you can see that over that time period carbon dioxide has never gone above the blue line. The blue line is 300 parts per million, and so about 1,900 with the industrial revolution having begun 120 years earlier, we introduced a lot more carbon dioxide in the atmosphere. So it went up to about 300 parts per million. Well, about a year ago we finally got up to 400 parts per million, so we increased the carbon dioxide, this key gas that regulates the heat of our planet. We raised it by over 35 percent, and it is going up.

There is no sign that it is going down anytime soon here, so we are now up here at about 400 parts per million. So here is sort of an iconic figure that is often used to show how the temperatures on the planet have changed. And this is a case from 1880 to 2018.

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