Changing climate

What Does Climate Change Have to do with Weather…and Baseball?

By Andy Miller

Nationals Park, Washington, DC

Nationals Park, Washington, DC

A question I often hear is whether a particular weather event or condition is caused by climate change, and my answer is almost always no.  You can’t say that a specific tornado, torrential downpour or 100 degree plus day is caused by climate change.

So if the answer is that the weird weather isn’t caused by climate change, then why are we so concerned?  Before we get to that, let’s remember what climate is.  Climate is the long-term average of the weather.  As has been said, “Climate is what we expect, weather is what we get.”

Climate change means that the expected weather patterns are no longer what they used to be—that is, the long-term average weather is changing.  While the climate has changed in the past, now we are seeing changes that can only be explained by the rising level of greenhouse gases caused by human activities such as burning fossil fuels and cutting down forests.

The question about whether climate change has “caused” a particular weather event is like asking whether a baseball team scored on a specific play because it has a better win-loss record than its opponent. The win-loss record doesn’t determine the outcome of an individual play, but all those individual plays determine the win-loss record.  Climate is like a team’s win-loss record—it doesn’t determine a specific weather event, but rather all the individual events determine the weather patterns that make up climate. And with climate change, it’s becoming clearer that the losses are starting to stack up against us.

If climate doesn’t determine a specific weather event, why do we often hear that climate change is affecting the weather?  What we need to remember is that this is just shorthand for what the science is really telling us.  What the science is really saying is, “higher levels of greenhouse gases in the atmosphere are trapping greater amounts of solar energy, which is causing a change in how the atmosphere and oceans circulate, the amount of moisture in the air, and the amount of ice, all of which are causing changes to weather patterns across the globe.”  That’s a lot to say, so you can see why we simply talk about climate change as the cause of these impacts.

The “impacts of climate change” (which we can use now that we know what that’s really saying) are discussed in considerable detail in the new National Climate Assessment that will be published in the coming weeks.  The assessment explains what changes we are seeing now, and what we expect to see in the coming years.  It shows why we’re concerned about climate change and its impacts. And most importantly, it explains why we need to take action now on climate change.

We are only starting to see the impacts of climate change.  To turn to our sports analogy again, it’s like we’re at the start of a new season.  It’s often hard to see which team is going to be the best after only a few games.  But as the season progresses, it will be easy to see which teams have prepared well by bringing in the best players and training hard before the season starts.

Likewise, taking action on climate change now means that we will be much better prepared to meet the challenges we face in the coming years.  EPA is taking action now on climate change, and that includes EPA’s scientists and engineers.  They are teaming up to develop the scientific information and tools that will help the nation and the world prepare a winning game plan to respond to climate change.

A team that waits to begin training until after it falls behind in the standings has no chance of winning, and waiting to act on climate change until the impacts are even worse is also a losing strategy.

About the Author: Andy Miller is the Associate Director for Climate in EPA’s Air, Climate, and Energy Research Program that conducts research to assess the impacts of a changing climate and develop the scientific information and tools to act on climate change.

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Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Act On Climate: Become a Climate Citizen Scientist for Earth Day 2014

By Rebecca French

Image credit: U.S. Global Change Research Program (

Image credit: U.S. Global Change Research Program (

Did you know that everyone can participate in climate change research? Public participation in scientific research—“citizen science”—has a long and proven track record. And you and your family can join in on the fun!

Using data from a 114-year-old citizen science project, the Christmas Bird Count, EPA scientists have identified an important indicator of the impacts of climate change: on average, North American bird species have moved northward and away from coasts during the winter—some species some 200 to 400 miles north since the 1960s. I grew up in Connecticut, so that would be like my family moving our house to Canada.

Collecting information on this climate change impact would not be possible without the thousands of volunteers who count birds every year. But this is just one of many climate citizen science projects.

One type of citizen science – volunteer environmental monitoring – can be an integral part of understanding the impacts of climate change. The EPA’s National Estuaries Program (NEP) is a network of voluntary, community-based programs that safeguards the health of important coastal ecosystems across the country. Estuaries are particularly vulnerable to climate change, so getting involved with your local NEP can make a real difference.

EPA also supports many citizen science programs through the Volunteer Water Monitoring Program, and EPA’s Region 2 office has launched a citizen science website with resources to support community-based citizen science projects for water, air, and soil.

The projects above can get you involved on a local scale, but there are also climate citizen science projects that go national and even global using a type of citizen science called “crowdsourcing.” Below are some of my favorite crowdsourcing citizen science projects that combine volunteers and the internet to build national data sets for climate change research:

  • Project Budburst, Nature’s Notebook and NestWatch all require you to get outdoors and record your observations of the natural world, such as when plants are flowering or birds are laying eggs. Kids will love these, so bring your family with you.
  • Participating in Old Weather or Cyclone Center can be done from your couch with a computer and an internet connection. The scientists behind these projects need human eyes to analyze images of ship’s logs or storms. When it comes to image analysis, the human eye is still the best technology out there.

You and your family can volunteer for these climate citizen science projects for Earth Day this year to act on climate. Your contributions will be used by scientists to understand climate change impacts on weather, plants and even birds’ nesting habits.

Take some time for Earth Day this year to contribute to climate change research and learn how these projects have partnered with the public to advance climate science. Maybe you will be inspired to create your own citizen science project. Oh yeah, and have fun too!

Happy Earth Day!

About the author: Rebecca French is an American Association for the Advancement of Science (AAAS) Science & Technology Policy Fellow in the EPA Office of Research and Development.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Green Roofs Keep Urban Climates Cooler

By Thomas Landreth

Image of a green roof

Green roof

From conversations I’ve had with friends in construction: roofing is tough work. Steep angles make for dangerous conditions, metal roofing is remarkably sharp, and whatever material you work with, it’s guaranteed to be heavy.

During the summer, heat adds an almost unbearable element. This can be especially bad in metropolitan areas, where ambient temperatures combine with heat coming off numerous nearby roofs, pavement, and other elements to create an “urban heat island.”

EPA researchers and partners recently published findings in the Proceedings of the National Academy of Sciences showing how three types of roofing can help: “cool” (coated in a reflective material to eliminate heat buildup), green (vegetated), and hybrid (vegetated with reflective plants).  Hybrid roofs, which are a new concept and not yet available, would be constructed with light-colored plants that have higher reflectivity similar to cool roofs and also the advantages of green roofs, like water retention.

The authors found that any of these roofing options can have benefits by cooling urban heat islands. Thus, this helps to reduce the impacts of global climate change by cooling metropolitan regions.

Lead author Matei Georgescu, a sustainability scientist at Arizona State University, explains, “What we found for cool, green, and hybrid roofs is that they don’t just offset urban expansion—they can offset additional warming.”

Georgescu partnered with EPA scientists Philip E. Morefield, Britta G. Bierwagen, and Christopher P. Weaver, his co-authors on the study.

Through EPA’s Integrated Climate and Land Use Scenarios (ICLUS) project, researchers  had access to a wealth of modeled data focused on impacts from projected urban growth. Using these data, they explored the three methods of roofing designed to absorb less heat to compare and contrast benefits and trade-offs. What they discovered is that while all three  have positive environmental implications, green roofs have less heat-mitigating power than cool roofs (hybrid roofs cool at least as well as cool roofs alone), but cool roofs may mean that additional heating is needed during the winter in some areas.

Though roofing is a single component among major factors such as urban sprawl and carbon pollution, this study shows it can have an impact on reducing heat in large urban areas.

New roofing alternatives may offer an added component to innovative urban designs, new building styles and grid layouts created to offset urban heat islands. “Green cities” may not be a reality yet, but facets to such future cities are currently being considered and implemented. Interest in cooling down urban heat islands is growing and recently caught the attention of over 40 news outlets, including Popular Mechanics, Scientific American, Christian Science Monitor, USA Today, the LA Times, and several international newspapers.    

Although roof installation may not get any easier, green and cool roofs may soon make American’s urban hotspots cooler.

About the author: Until last week, Thomas Landreth was a student services contractor working with EPA’s Office of Research and Development. He recently accepted a new position with the American Association for the Advancement of Science (AAAS).

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Calculating the Future with Green Infrastructure

Reposted from EPA Connect, the Official Blog of EPA Leadership



NCSE - Gina - 3

EPA Administrator Gina McCarthy speaking at the National Council for
and the Environment. Photo credit: John Mcshane

In his State of the Union address, President Obama said “the nation that goes all-in on innovation today will own the global economy tomorrow.” He made the point that science and research are critical to keeping that competitive edge—but also to protecting our public health and our environment. I couldn’t agree more.

Science has always been at the heart of our mission at EPA. In the State of the Union address, President Obama doubled down on his commitment to using science to address a changing climate and carry out his Climate Action Plan—which aims to curb carbon pollution, build climate resilience in our towns and cities, and lead the world to a sustainable, clean energy future.

EPA science is critical to each part of the plan—and one of those ways is through our newly updated National Stormwater Calculator to help build climate resilience in our towns and cities.

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To Your Good Health: Climate Action May Yield Significant Health “Co-Benefits”

By John Dawson

our_changing_planet_2008_166_20090708_2071842232 (1)Everyone likes a two-for-one deal, and a study published in Nature Climate Change shows we get such a bargain when we reduce carbon dioxide, an air pollutant also known as a greenhouse gas. Carbon dioxide emissions from cars, trucks, coal-fired power plants and other fossil-fuel-burning sources are causing a threat to our health because of the pollutant’s role in warming the atmosphere and causing climate change.

Scientists at the University of North Carolina at Chapel Hill, EPA, and several other institutions identified co-benefits of reducing greenhouse gases. The study was funded by EPA’s Science to Achieve Results (STAR) program.

The team used computer models to simulate global air quality under two scenarios. One depicted a world with no global policy to limit greenhouse gases, allowing carbon dioxide concentrations to increase from present levels of just under 400 parts per million (ppm) to 760 ppm in 2100. A second scenario simulated global carbon emission reductions to achieve concentrations of 525 ppm in 2100. Scientists then calculated how these two disparate policies would affect other air pollutants, or “co-pollutants,” that are emitted along with carbon dioxide.

Their analysis showed that reductions in greenhouse gas emissions would yield major benefits by improving air quality and public health.

The researchers calculated that the second carbon emission reduction scenario (which includes expected economic growth) would prevent one-half million air-pollution-related premature deaths per year globally in 2030; these benefits would grow to 1.3 million fewer deaths in 2050, and 2.2 million in 2100.

These health benefits are estimated to be equivalent to between $50 and $380 per ton of carbon dioxide reduced globally.

The study shows that the health-related economic benefits of reducing greenhouse gas emissions may outweigh the costs of control—even before the benefits of reducing climate change are realized.

While a single scenario is not enough to draw definitive conclusions about the ramifications of future greenhouse gas emission reductions, the research does suggest there may be multiple benefits to reductions: limiting climate change, reducing other air pollutants at the same time and providing a safer and healthier environment.

To read the study, “Co-benefits of mitigating global greenhouse gas emissions for future air quality and human health,” go to

About the Author: John Dawson is a Physical Scientist in EPA’s National Center for Environmental Research.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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