Climate change getting you down? If you've ever wondered if humanity can really do anything about greenhouse gas emissions, watching David Letterman's recent rant about climate change may help you get it all out of your system. (You can find it here on The Huffington Post. The quick summary: We are dead meat.)

But this week I’ve been feeling more optimistic, and for good reason. On Tuesday and Wednesday I attended the Kansas State Energy Conference to learn more about what’s happening locally and nationally on different energy issues. As part of that, I was lucky enough to get to hear the keynote address from one of the leading experts on climate science, Dr. James Hansen.

Don’t get me wrong, no one is likely to walk away from a lecture on climate change with a rosy view of the Earth’s future. It certainly wasn’t all good news. But at the same time, Hansen wasn’t saying that we’re dead meat or that it’s already too late. Instead, his message was that we still have time to act.

However, it’s a narrow window. We need to take serious action immediately, and it sounds like we’re talking about some pretty major steps — such as figuring out how to get off of coal completely unless we can figure out how to capture and store the carbon. There’s a great article from Hansen here on the Worldwatch Institute Web site with much more information on his views on climate.

Another bright spot: It was exciting to be at the conference and see how much is already happening in the world of wind power. There are a lot of new wind turbines being installed here on the Great Plains and in other windy spots around the world. Let’s keep them coming.

Photo by RUSTY DODSON/ISTOCKPHOTO

Renewable energy has been in the news lately, as the U.S. presidential candidates have been discussing their energy plans, and many other people have been talking about renewable energy, including T. Boone Pickens and Al Gore.

Yesterday, Bill Clinton weighed in with his own recommendations for what the U.S. government should do to promote renewables and combat climate change when he spoke at the National Clean Energy Summit in Las Vegas.

There’s a great summary of Clinton’s top 10 recommendations for cleaner energy here on Earth2Tech. Just a few of the measures he suggested were making improvements to the electrical grid, establishing a carbon cap and trade system, and renewing tax credits for producing renewable energy for the next six to 10 years.

Yesterday, Al Gore gave a speech challenging the United States to set a surprising new goal: To produce 100-percent of our electricity from renewable and carbon-free sources within 10 years.

Here’s the text of the speech, and you can check out video highlights below. It’s already gotten a lot of attention, and there’s a nice roundup of reactions to the speech from the blog Gristmill.

Tell us what you think. Is this goal far too ambitious, or is it achievable? Is setting this kind of challenge just the thing we need to start thinking seriously about renewable energy, or should we be aiming for more realistic goals?

More on this Topic:

An Inconvenient Truth

What You Can Do To Help Solve the Climate Crisis

If you're concerned about climate change, and want to reduce carbon emissions, you might be surprised how easy it is to figure out how much carbon dioxide is produced by, say, driving to work. Sure, there are a lot of carbon calculators out there where you can plug in all the numbers on how much you drive, and how much electricity you use. But it's also surprisingly easy to estimate yourself.

Here’s how you can do it. If you go to the EPA carbon calculator it gives you recognizable units, like gallons and pounds. (And slightly more confusing units like carbon dioxide equivalent.  Essentially, they’re adding the other greenhouse gases into the number for carbon dioxide. But there’s more about that on the calculator page.)

It’s very simple to use, so here are results I got from spending a few minutes with the EPA calculator and playing with the numbers.

* Every gallon of gas burned produces about 22 pounds of carbon dioxide equivalent. (So for simplicity, let's round down to 20.)
* Every therm of natural gas burned produces about 11 pounds. (I think it’s fair to round down to 10.)
* Every kilowatt hour (kWh) of electricity produces about 1.7 pounds.
(If rounding up to 2 seems too painful, consider where your electricity comes from. If it comes from coal, yep, round up to 2. For natural gas, you can figure 1 pound. There are some statistics that help justify those numbers here.)

So when you fill up your gas tank, you have a number in gallons. Take it times 20 and you're awfully close to knowing how much carbon dioxide burning that tank of gas will produce. Same thing goes for your electric bill. Take a look at the number of kilowatt hours. Double it (in most cases) and you’re looking at pounds of greenhouse gas emissions.

Want to think more about pounds of carbon emissions and how to lose them? Here are a few related articles:

Eight Projects for Instant Energy Savings, Mother Earth News 

On Carbon Calculators, Grist 

What Makes a Pound of Carbon Dioxide, The Green Guide