Climate 411

Part 5 of 5:  The Only Explanation Left

This is the final installment of a five-part series by Bill Chameides on How We Know Humans Cause Global Warming.

1. A 175-year-old Puzzle
2. What Chemistry Tells Us
3. Causes of Past Climate Change
4. The Medieval Warming Period
5. The Only Explanation Left


Compared to 100 years ago, the temperature of the atmosphere is warmer. No one disputes that. And no one disputes that an extra source of heat must be causing it – that’s a basic law of physics. But how do we know that the source of the heat is increasing levels of greenhouse gases from burning fossil fuels and deforestation?

So far in this series I’ve described how the relationship between atmospheric carbon dioxide (CO2) and global warming was discovered, how carbon isotopes prove that rising CO2 concentrations are from the burning of fossil fuels, and how the orbital shifts that cause ice ages cannot explain our recent warming.

That certainly suggests that global warming is caused by increased CO2 from burning fossil fuels, but how can we be sure?

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Posted in Basic Science of Global Warming / Read 22 Responses

Global Warming and the Ozone Hole

Many people have asked me whether global warming and the ozone hole are related. The short answer is "no". The long answer starts with "tangentially". Here’s the scoop.

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Posted in News / Read 4 Responses

Part 4 of 5: Medieval Warming Period

This is the fourth installment of a five-part series by Bill Chameides on How We Know Humans Cause Global Warming.

1. A 175-year-old Puzzle
2. What Chemistry Tells Us
3. Causes of Past Climate Change
4. The Medieval Warming Period
5. The Only Explanation Left


In my previous article in this series, I talked about climate change patterns over geologic time. I showed how today’s spike in temperature and carbon dioxide (CO2) concentration breaks patterns and records going back 600,000 years.

This departure can be seen even more clearly when you look at just the last 1000 years (see graph in previous post). So what is this you hear about a Medieval Warming Period?

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Posted in Basic Science of Global Warming / Read 12 Responses

Part 3 of 5: Causes of Past Climate Change

This is the third installment of a five-part series by Bill Chameides on How We Know Humans Cause Global Warming.

1. A 175-year-old Puzzle
2. What Chemistry Tells Us
3. Causes of Past Climate Change
4. The Medieval Warming Period
5. The Only Explanation Left


An argument I hear frequently from climate change skeptics goes like this: "Climate has undergone warming and cooling cycles for millennia. This is no different. It’s just another naturally occurring warm cycle."

It’s true that climate has undergone warming and cooling cycles for millennia, but it’s not true that this is just another naturally occurring warm cycle. Here’s why.

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Posted in Basic Science of Global Warming / Read 19 Responses

Part 2 of 5: What Chemistry Tells Us

This is the second installment of a five-part series by Bill Chameides on How We Know Humans Cause Global Warming.

1. A 175-year-old Puzzle
2. What Chemistry Tells Us
3. Causes of Past Climate Change
4. The Medieval Warming Period
5. The Only Explanation Left


There’s no question that carbon dioxide (CO2) is a greenhouse gas that warms the planet, and that CO2 has been increasing. The graph below shows it vividly (the measurements were taken at Mauna Loa, Hawaii).

But how do we know that the increase is due to people burning fossil fuels? One way is by analyzing the chemistry of our atmosphere, since human activities leave an unmistakable "fingerprint".

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Posted in Basic Science of Global Warming / Read 12 Responses

RealClimate's "Start Here" Page

The RealClimate blog has great information on the science behind global warming. Recently they posted a resource page with links about climate change. They plan to update the page as they discover new resources, so you might want to bookmark it.

Posted in What Others are Saying / Comments are closed