Greenhouse Effect. Global Warming. Climate Change. It’s been talked about for years now. It is our fault, it isn’t our fault, yes it is, no it isn’t. The truth is, whilst we don’t actually know for 100% certain, we can be 90% sure that yes, it really is our fault. Not just ours, but our predecessors going back a few generations too. It isn’t unfixable, but we do need to change our attitude and grow up a bit, take responsibility for our actions- both as individuals and as a species. The trouble is, the subject has been talked about, and the phrases at the beginning of this paragraph have been bandied about so much that their meaning and importance have been all but lost. Before you start to panic, this isn’t going to be a science lecture. I just want to give a brief overview so that a) I can make sure I’ve got my facts right, and b) anyone that doesn’t know really what it is (and there must be loads as even I’ve only recently been bothered to read up on it- and I’m interested!) can at least have an idea.
Most of the things you hear or read, be they newspapers, experts or whoever, include theory, interpretation and opinion masquerading as fact. Simply because they have to. Some of them are valid and some aren’t. One of the laziest arguments I’ve seen used is “it’s too complicated to explain.” It’s not complicated, it’s dead simple. It’s slightly lengthy, but is not hard to understand. In a nutshell, the sun emits heat. When the heat hits the Earth’s surface, some is absorbed and some is reflected. Attached to the Earth’s surface is Earth’s atmosphere. Some of the gases in the atmosphere reflect both of these heat sources in random directions. These are called Greenhouse Gases. The heat that is reflected back to the Earth’s surface is called the Greenhouse Effect. This occurs naturally, and keeps the Earth’s surface about 33°C warmer than it otherwise would be. It gets more complicated than that, but only because there are other factors to be taken into consideration. The different Greenhouse Gases reflect heat in different ways and amounts, and they naturally sit in different parts of the atmosphere. Increasing, decreasing, or replacing these gases in the atmosphere can have major (or indeed, minor) effects on temperature. The name given to the heat reflected by the Earth’s surface is the Albedo, and clouds are responsible for around 55% of this as water is a greenhouse gas.
I’m going to quickly address some of the arguments against Global Warming being our fault, and then that’s it for now. The most common argument basically goes along the lines of “The average temperature naturally goes up and down, and our high temperatures are happening at a time when they are about due to rise anyway.” This is partly true. Yes, the average global temperature does rise and fall in general trends. If you look back across the last 400,000 years or so, you’ll see that the temperature reaches a peak roughly every 100,000 years or so, and yes, we are about due for one, so the peak we are currently experiences could be natural. But it’s highly unlikely. What they miss out of these facts is that the peak doesn’t last and temperature trends start to drop down again almost immediately. Except the one we are in. Not only that, but it’s had a smaller increase reasonably consistent since around 1850. Is it a coincidence that this basically parallels trends in industry? Of course it IS possible, but to my mind it’s preposterous to think it likely.
“It’s been warmer than this in the last 2,000 years.” Really simple answer to this. You’re right it has. But only locally. The Global temperature is an average, so local hot (or cold) spots are no indication of a worldwide trend. After all, you wouldn’t look at either Death Valley or the Antarctic and say that they represent the temperature of the whole planet. There is no evidence of a prolonged warming on a global scale like the one happening now.
“The problem isn’t us, it’s due to variations in the Sun’s emissions.” The Sun is only one factor in the equation, and as there hasn’t been an increase in the amount of heat coming from the Sun since the ’60’s, it isn’t that. Most arguments follow the same pitfalls of ignoring part of the equation. Some miss or ignore the parts that don’t suit, while others just don’t understand or know about the correlations. It isn’t hard, and the info here isn’t even difficult to find. The charts came from the Open University’s free 18hr course on Climate Change (http://openlearn.open.ac.uk/course/view.php?id=2805).
I’d like it to be understood that this is really only my understanding of it, and so welcome any correction as long as it not presented in an argumentative way! I’m happy to argue, but in private if you don’t mind!