Installing white roofs (or painting them white) has been promoted as a way to help slow global warming. New research shows that white roofs may actually add to global warming. Credit: NNSA/flickr.
[Update, Nov. 8, 2011: WhiteRoofProject.com has posted a new blog in response to some of the coverage of Jacobson’s recent study on white roofs, including mine below. They offer some important points that I didn’t cover in my piece, so their blog is worth reading. In particular, previous research has shown that in some specific regions, like those near the equator, white roofs probably offer more benefits than drawbacks, from an emissions perspective – something Jacobson’s computer models haven’t yet accounted for.
I should stress that Jacobson’s study is just one piece of research in a broad field, but it’s an important study nonetheless. More than anything, it points out that the science isn’t settled on white and cool roofs, and that more research can help figure out where and how they can be put to good use.]
If you’re interested in staving off climate change without trying too hard, painting your roof white seems like a complete no-brainer. It’s far cheaper than trading in your SUV for a Prius, and it turns the laws of physics to best advantage. Dark roofs absorb sunlight that heats up your house, office tower, or apartment building. That means you’re bound to crank up the energy-intensive air conditioner to keep pace in the summer months — and since electricity in the U.S. comes largely from fossil fuels, the net result is more heat-trapping greenhouse gas emissions, and more global warming.
But a white roof does just the opposite. It bounces...
Coal-fired power plants provide about 45 percent of U.S. electricity. To increase the percentage of electricity coming from clean energy sources, America will likely have to move away from coal. Credit: Cathy Haglund/flickr.
As I recently pointed out, Americans consume immense quantities of electricity each year. Depending on where you live, it might come from a coal or a gas-fired power plant, a nuclear plant, a hydroelectric dam, wind turbines or even solar panels. I must admit, though, that I have no idea where my electricity comes from (other than out of the wall). But since I live in central New Jersey, my electricity probably comes from both coal, gas, and nuclear power plants.
For the country overall, the relative proportions of each type of electricity have stayed constant for about the past 15 years:
- Coal and natural gas produce 70 percent of our electricity
- Nuclear power generates about 20 percent
- Renewable sources (like wind and hydropower) provide about 10 percent.
Now, it looks like those proportions could be about to change.
During the 2011 State of the Union address, President Obama announced a new U.S. energy target: produce 80 percent of electricity from clean energy sources by 2035. Burning coal and natural gas to generate electricity releases billions of tons of heat-trapping carbon dioxide (CO2) gas into the atmosphere, so switching to more “clean” energy sources would help curb a lot of America’s greenhouse gas emissions, which are partly responsible for warming the climate.
So where is all this “clean energy” going to come from? To start with, Obama’s plan counts natural gas as “clean,” since even though it produces CO2, the emissio...
Earlier this week, when I was writing about the potential for generating electricity from tidal power, something stood out to me. I don’t have a reliable resource for understanding energy quantities. I mean, how much is a terawatt — and don’t just tell me it’s 1,000 gigawatts, because that doesn’t help. Or, if I see that Michigan is installing 200 megawatts of wind power, it’s not immediately obvious (at least to me) whether that will satisfy a little or a lot of the state’s electricity needs.
Here at Climate in Context, the blog posts typically cover recent climate change news. But I also think it’s a perfect place to experiment with some useful energy comparisons, for everyone’s benefit. Today, I’m keeping things really simple, using easy-to-understand examples. Next week, I’ll delve into some more surprising comparisons. I’d also love to hear your ideas on some effective ways to explain different amounts of energy. Eventually, we’ll choose the most compelling comparisons to develop a graphic — exactly the kind that I could have used the other day.
A note before I go any further: Units of power (like a watt) represent the rate at which energy is used or generated. When you want to know how much electricity an appliance has used, however, you need to consider how long it was running. If you’re interested in the actual calculations, I’ve included them at the bottom of the post.
One watt (W) is actually pretty small, so let’s consider an ave...
Three things you should know:
1) Along the U.S. East Coast, the sea level has been rising since the late 1800s at a faster rate than at any other time during the past 2,000 years.
According to a new study, in coastal North Carolina the sea level has been rising at an unprecedented rate during the past 100 years. Credit: iStock.
2) This new 2,000-year timeline of sea level rise shows a connection between global temperatures and ocean levels; during warm periods on Earth, sea level rose and during cooler spans, seas either remained level, or even fell slightly.
3) Scientists anticipate that average global temperatures and sea levels will keep increasing, and some now estimate that 20 million Americans will be affected by rising seas by 2030.
What the new science says:
This week, the Proceedings of the National Academy of Sciences published a new study showing that along part of the U.S. Atlantic Coast, sea level rise has been occuring at a faster rate during the past 100 years than at any other time in the past 2,000 years. More importantly, the study's continuous record of change over two millennia shows a distinct connection between global temperatures and sea level:
Historically, when global temperatures have been on the rise, sea level has increased. During cooler times on Earth, sea level has remained stable or has even decreased slightly.
To be fair, scientists have known for years that warmer temperatures cause sea level to increase (there are several reasons why this happens, nicely explained here). And scientists also already knew that sea levels have been rising along the Atl...
Three Things You Should Know:
1) Scientists predict decreasing amounts of annual rainfall in the Southwest in coming years as the concentration of greenhouse gases in the atmosphere increases. This means drought conditions in the region may become more frequent and severe over the next century.
2) As the conditions in the Southwest, and along the Colorado Plateau in particular, become drier, many plants will have a tough time surviving. There could be less vegetation covering the land than there has been in the past several decades.
The beginnings of a dust storm in southern Utah. New research suggests a warmer and drier climate in the Southwest could increase dust production. Credit: Casey Myers/flickr.
3) With fewer plants and grasses growing, scientists now say that long-term drought in the Southwest could cause more dust to develop in region, which could affect everything from human health to the local weather and climate.
What the New Science Says:
For the past decade, a nearly unrelenting drought has gripped the Southwest and depleted a water system of rivers, underground aquifers and canals. Water resources in this region were already stressed by population growth. But the worst of the recent drought is also a harbinger of the warmer and drier conditions that climate scientists say are likely to become more frequent and severe during the rest of this century.
Now, with the help of 20 years of records showing how past climate variability in the Southwest has influenced plant growth in parts of the area, researchers have a better idea of how future warm years could cause an increase in the dustiness of the reg...