Monthly Archives: July 2007

Part 4 of 5: Medieval Warming Period

By / Bio / Published: July 5, 2007

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

Global warming and the Fourth of July

By / Bio / Published: July 3, 2007

Today’s post is from Sam Parry, Environmental Defense’s manager of online membership.

As we prepare for July 4th festivities, I wanted to share an inspiring conversation we’ve had with our online supporters over the past several weeks. We asked the question, how do people who love this country approach the crisis of global warming? We must have struck a nerve because we got thousands of passionate responses.

We used these responses to craft a Declaration of New Patriotism. To date, almost 56,000 people have added their “John Hancock.” Last week, we delivered the message to Congress with an ad in Roll Call, one of the most widely read newspapers on Capitol Hill.

So before you head out to celebrate tomorrow, take a look at our Declaration of New Patriotism and add your signature. Happy Fourth of July!

Posted in What Others are Saying / Comments are closed

Climate Models: How They Work

By / Bio / Published: July 2, 2007

Lisa Moore is a scientist in the Climate and Air Program.

Of everything in climate science, what seems to spark the most skeptical questions is our use of computer models. In this post and another to follow, I’ll talk about exactly what these models do, and how they contribute to our understanding of global warming.

I’ll start with why we use models in the first place. We want to project what will happen to our climate in the future – will it be warmer? How much warmer? Will it change in different ways in different places? Climate models use our knowledge of how the climate system works to calculate what different emissions scenarios mean for the future. Here’s how the models are built.

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Posted in News / Read 2 Responses