Here are some of the "business-as-usual" projections that my colleagues and I find most striking and disturbing:

You think August is hot now?

By the end of this century, we could be in for much more severe summers all across the country.

• If you live in New Hampshire, summer could feel like it does today in North Carolina (p.107).
• If you live in Michigan, brace yourself for summers that feel like today's summers in Oklahoma (p 117).
• And if you live in Texas, you now experience 10 to 20 days a year over 100 °F. By the last two decades of this century, look for 100 such days – that's more than three months (p. 90).
• In 1995, Chicago suffered a heat wave that killed more than 700 people. Chicagoans could experience that kind of relentless heat up to three times a year (p. 117).
• The Southwest, including cities like Los Angeles and Phoenix, will face worse and more frequent droughts, as spring rains decline by as much as half, snowpacks shrink and melt earlier, and water evaporates more rapidly (p. 129-130).

People who live on the coasts could be a lot closer to the shore

Sea level is projected to rise up to 3 to 4 feet. Here's what that means for various parts of the country:

• Portions of New York City and Boston could be regularly flooded by storms and even high tides (p. 150).
• On the Gulf Coast, approximately 2,400 miles of roads and 250 miles of freight rails are likely to be permanently flooded (p. 62). This area is home to seven of the nation's ten largest ports and much of our oil and gas industry.
• Some coastal freshwater sources will be contaminated with saltwater, meaning we can no longer use them for drinking water without expensive desalinization (p. 47)

Your grandchildren will miss out on local icons and specialties

The foods and activities that define different parts of the country are changing.

• Some western ski resorts could face a 90 percent decrease in snowpack, making the country's most iconic ski locations just shades of what they are today (p. 133).
• Thanksgiving might no longer include cranberries produced in the Northeast's cranberry bogs (p. 73).
• In the Northwest, salmon will be driven out of about one-third of their habitat. We could start to see the changes in the next ten years (p. 137).

This very thorough scientific report paints a bleak picture of what life will be like in this country if we let pollution continue at today's rate. The report's good news is that if we act now, we can avoid the most severe consequences. But the more sobering news is that even if we cut emissions aggressively, not everything in this report can be avoided. This is a first step toward understanding how to prepare for the coming changes.

The American Clean Energy and Security Act, which would take us off the "business-as-usual" path, will come in front of the U.S. House for a vote in a matter of days. This report gives our leaders yet another reason to do the right thing for our country's future.

With the political debate heating up over the American Clean Energy and Security Act, it's easy to lose sight of what the fight is about.

Yes, this is about people and jobs and freeing ourselves from foreign oil and creating a clean energy economy for the 21st century. But it's also about our natural heritage and the wildlife with which we share this planet.

Species from blue whales to butterflies confront growing threats. Their habitats are rapidly changing along with the climate. Global warming is pushing nature to the brink.

That's why we launched a new campaign, Warming and Wildlife, where we document the story through the prism of seven "ambassador species" from across America already struggling to survive.

Without action, there's a good chance these species won't make it – we could lose them in our lifetimes.

Our seven ambassador species are:

• Sugar maple
• Monarch butterfly
• Leatherback sea turtle
• American pika
• Canada lynx
• Tufted puffin
• Polar bear

The bumper sticker is right: Extinction is forever. But, it doesn't have to be inevitable, not if we each do our part to cap America's global warming pollution and unleash the clean energy economy of the 21st century.

Hurricane Ike storm surge hits Jetty East, by Flickr user eh3k.

For some, it’s hard to care about global warming because its impacts on everyday life aren’t obvious. It’s too abstract. It’s not tangible. It’s too wonky. It’s just not real enough.

Well, what if you learned that global warming could literally push you out of your home? Is that real enough for you?

Texas cities Houston and Galveston just got a wake-up call – conservative estimates of sea level rise due to climate change will displace 78 percent of households over the next 100 years in Galveston County alone, according to a new study that EDF and the British Consulate-General commissioned from the Harte Research Institute at Texas A&M Corpus Christi.

And that's the conservative estimate. In a business-as-usual scenario, Galveston-area sea levels could rise as much as 1.5 meters in the next 100 years, which could displace more than 100,000 households and create more than $12 billion in infrastructure losses for Houston and Galveston.  Rising sea levels will also damage at least 23 public facilities, industrial sites and water treatments plants, begging many questions about where to move or how to protect these sites. (See a related post on sea level rise.)

For cities like Galveston, which is still rebuilding from Hurricane Ike, these findings reinforce the notion that planning for how to adapt to climate changes or mitigate their effects is critical. Current discussions have centered around building a large, expensive and likely ineffective “Ike Dike” to protect the city from future storm surges, though there are likely more realistic adaptation measures that will make people safer quicker. Passing federal climate legislation and ramping up local municipal energy efficiency are surely the most effective ways to begin reducing the rate of sea level rise.

So, for all of you out there who don’t think global warming could happen to you, take a hard look at the harsh reality that these coastal communities face.

Until recently, most of the attention paid to these pollutants has centered around their detrimental effects on air quality and human health – the pollutants include fine particles such as black carbon and gases that form smog.

But because these pollutants disappear from the atmosphere relatively quickly, they also give us an important opportunity to put the brakes on the rapid rise in global temperature. If people around the world can reduce the amounts that they emit, everyone will see an immediate benefit and help avoid dangerous tipping points in the climate system over the next few decades.

My colleagues Nadine Unger and Drew Shindell at the NASA Goddard Institute for Space Studies (GISS) and I just published a paper in the journal Atmospheric Environment that offers additional insight into the climatic role of these pollutants. Our findings come at a time when activity on domestic and international climate policy in general and on black carbon policy in particular is ramping up.

For this paper, we delved into emissions from two key sectors, transportation and power generation, for the U.S. and the world. We primarily used a global climate model developed at NASA GISS that simulates the transport of pollutants by wind and the chemical and physical reactions that transform the pollutants into smog and particles. The model also calculates the warming or cooling effect of the different pollutants.

One of our important findings is that transportation is a particularly good sector to target quickly for emissions controls because it produces a lot of black carbon (think: diesel exhaust) and ozone-producing gases, in addition to CO₂. In contrast, emissions cuts in the power generation sector do not offer the same short-term opportunity. That sector emits little black carbon, but it does create much sulfate particle pollution. Sulfate particles are bad for air quality and acid rain, but in the short term actually counteract the warming effects of CO₂ emissions. Of course, it is essential to clean up the power sector to address long-term climate damage from CO₂, as well as health problems from sulfate particles, ozone smog and other pollutants. But short-term opportunities to slow global warming are more significant in the transportation sector.

We also considered a hypothetical example of switching the transportation sector to a zero-emissions or electric power source, such as in plug-in hybrid electric or pure electric technologies.The result: A hefty benefit for the climate.

The switch to a zero-emissions or electric power source would decrease the warming effect if you just consider CO₂ emissions.  (Though increased CO₂ emissions from the electricity generation sector would offset the decrease in direct emissions from vehicles to a certain extent.)

But reducing the non-CO₂ pollutants provides even more benefit for the climate. Zero-emission or electric transportation would greatly reduce black carbon emissions.  The short-term benefits to be gained from focus on the transportation sector are important for policymakers to note.

Last week's announcement by President Obama on national greenhouse gas emissions standards for passenger cars and light trucks is a significant step in this direction. Further action is needed to clean up the exhaust from existing heavy-duty trucks and other diesel-powered transport, both in this country and internationally.

Unger and her colleagues are working to expand the published analysis to include a full suite of economic sectors, including industry, non-road transport and agriculture, and additional greenhouse gases such as methane and nitrous oxide.

Look for another paper in the near future.

According to internal reports dating back to 1995, scientists working for the Global Climate Coalition, an industry-sponsored group set up to wage a lobbying and public relations war against global warming action, were telling their bosses that human-caused global warming could not be refuted. But, that didn't stop industry lobbyists from waging a cynical campaign to undermine the science and cloud the debate.

Read the full story here.

Americans were outraged a decade ago when cigarette makers made similar claims about the evidence linking smoking and lung cancer. And then we discovered reams of damning research hidden away in tobacco company vaults.

The only real difference between then and now is that global warming stands to threaten more than just people — millions of species face extinction, entire ecosystems altered beyond recognition, the natural world as we know it today irreparably diminished.

The leader of the South Pacific island nation of Kiribati laid out an extraordinary plan Monday (Sept. 22) that would scatter his people through the nations of the world as rising sea levels submerge the islands they have called home for centuries.

Rising sea levels are submerging the land. Land not yet submerged is being rendered uninhabitable by salty ground water.

This post is by Sheryl Canter, an online writer and editorial manager at Environmental Defense Fund.

The idea of injecting sulfates into the atmosphere is based on the observation that large volcanic eruptions can cause short-term global cooling. But in addition to the usual problems with geo-engineering (for example, it does nothing to stop ocean acidification from excess CO₂), scientists have found a new one. Sulfate geo-engineering could endanger food and water supplies for billions of people in Africa and Asia, according to a recent paper in the Journal of Geophysical Research [PDF].

A Study with Some Scary Findings

Continuous sulfate injections into the stratosphere might cool the Earth, but does it matter where you do it? And what else might it do? To address these questions, the researchers ran a global climate model under four scenarios:

1. Business-as-usual with no geo-engineering
2. Low-level sulfate injections in the Arctic
3. Medium-level sulfate injections in the tropics
4. High-level sulfate injections in the tropics

In all the geo-engineering scenarios, sulfate was injected continuously for 20 years, and then abruptly turned off. The medium-level is roughly equivalent to a Pinatubo eruption every four years, the high-level every two years.

Compared to business-as-usual, the geo-engineering strategies slowed or even reversed global warming and the loss of Arctic summer sea ice. So far so good. But scientists found serious drawbacks when they looked at (1) regional effects and (2) the consequences of suddenly ending sulfate injections.

One of the most prominent dangers was the effect on summer monsoons in Africa and Asia, on which billions of people rely for food and water supplies. Both monsoon systems decreased markedly when sulfate was injected into the atmosphere – regardless of how much or where.

And what about when sulfate injections stopped, as might happen if a real-world geo-engineering strategy encountered technical difficulties or lost political support? The resulting warming rebound and sea ice loss was "more rapid … than has occurred in the past century or than is projected with business as usual." Since the rate of warming can be as damaging as temperature alone, warming rebound could have tremendous environmental and social consequences.

Best to Tackle the Root of the Problem

This paper adds to the growing list of geo-engineering risks (for example, see 20 reasons why geoengineering may be a bad idea [PDF]). As RealClimate scientists put it in their coverage of the latest paper, geo-engineering is like methadone: "an emergency treatment to substitute one addiction (carbon emissions) with another." What we really need to do is tackle the root of the problem and decrease greenhouse gas emissions.

This post is by Lisa Moore, Ph.D., a scientist in the Climate and Air program at Environmental Defense Fund.

The scrolling text at the end says this:

Alaska's northern coastline is eroding at rates as high as 30 meters (100 feet) per year. Climate change may be large responsible. As Arctic sea ice seasonally recedes, large regions of ocean become exposed to the sun's energy. The seas transfer this heat to the shoreline, melting the once permanently frozen land. Meanwhile, longer open-water periods allow storms to batter the weakening coast. These feedbacks may intensify as sea ice continues to shrink. Learn more at cires.colorado.edu.

This post is by Sheryl Canter, an online writer and editorial manager at Environmental Defense Fund.

One reason for the acceleration in CO₂ concentrations is higher fossil fuel emissions. Despite rising fuel prices, global CO₂ emissions from fossil fuels rose 3 percent in 2007. That's just slightly below the average increase of 3.5 percent per year since 2000.

The rate of increase for emissions lies at the upper end of the range projected by the IPCC, suggesting that we're headed towards the most disruptive scenarios they envision. Action to stop climate change is urgent.

Check out the full report for details on what factors account for the increase. Also, the Dot Earth and Climate Progress blogs have interesting takes on the report.

This post is by James Wang, Ph.D., a climate scientist at Environmental Defense Fund.

But new research shows that old-growth forests are even more important than previously thought. According to a new study in Nature, old-growth forests aren’t just standing there maintaining the status quo. They still actively take up CO₂ from the atmosphere.

The dominant trees in old-growth forests are about as big as they're going to get. So for a long time, scientists thought that old-growth forests were carbon neutral – that the plants took up as much CO₂ from the atmosphere as was released from plant and soil respiration. (To learn about respiration, see Bill's post on agricultural offsets.)

To check this assumption, researchers compiled data from 519 studies that reported one or more components of the carbon cycle. Because data for tropical forests was scant, the study included only boreal (northern) and temperate forests.

Their analysis showed that even centuries-old forests are active carbon sinks – they take up more CO₂ than they release. In fact, old-growth forests in temperate and boreal zones take up as much as 1.3 gigatons of carbon (Gt C) a year. To put that in perspective, that's approximately 17 percent of global fossil fuel CO₂ emissions in 2005.

It's been estimated that deforestation accounts for 20 percent of current global greenhouse gas emissions. This study adds to the urgency of protecting forests. As the study's authors put it:

The present paper shows that old-growth forests are usually carbon sinks. Because old-growth forests steadily accumulate carbon for centuries, they contain vast quantities of it. They will lose much of this carbon to the atmosphere if they are disturbed, so carbon-accounting rules for forests should give credit for leaving old-growth forest intact.

We agree! EDF's market-based plan to give credit for leaving forests intact is called Compensated Reduction (CR), and we're working hard to make this a reality. EDF is an active participant in the international negotiation towards a post-Kyoto agreement. We're pleased that deforestation was a major topic at the Bali talks, and the more recent talks in Accra, Ghana, as well.

This post is by Lisa Moore, Ph.D., a scientist in the Climate and Air program at Environmental Defense Fund.