*David Easterling … “global warming is real”*

I’d just like to leave the public with the thought that global warming is real. We have certainly seen increases in temperature over the past hundred years, and especially in the last 30 years. The scientific community is at least in large part convinced that it’s mainly due to human activities. And it’s something that I think needs to be taken seriously.

_David Easterling is Chief of the Scientific Services Division at NOAA’s National Climatic Data Center in Asheville, North Carolina, a contributing author to the Intergovernmental Panel on Climate Change (IPCC) Second and Third Assessment Reports, and a lead author for the IPCC Fourth Assessment Report being released this year._

*Elizabeth Holland … “no longer uncertain”*

I’m speaking here from my personal scientific view – not as an author of an IPCC chapter, but my personal view. My view is that most of us scientists are now convinced that global warming is happening. We are now convinced that the most likely cause of global warming is human activity. And we are no longer uncertain about whether the climate is warming. We are actually quite certain that the climate is warming, and we are certain that human activity is the cause.

_Elisabeth Holland is a Senior Scientist at the National Center for Atmospheric Research. She was lead author of Chapter 7 of the IPCC report, which outlined connections between changes in Earth’s climate and biogeochemistry._

*Adam Sobel … “happening now”*

I am a climate scientist, and would like to say this.

Global warming is real, and is happening now. There are details we don’t understand, but the big picture is very clear. The evidence has become overwhelming.

_Adam Sobel is an Associate Professor in the Department of Applied Physics and Applied Mathematics and in the Department of Earth and Environmental Sciences at Columbia University._

*Amber Soja … “a reality we must address”*

Global warming is a current reality and it is driven, in part, by humankind. All but a handful of climate-related scientists, worldwide, are convinced of this reality.

Temperature increases and warming-induced change are progressing faster than had been predicted in some regions, suggesting a potential non-linear rapid response to changes in climate, as opposed to the predicted slow linear response to climate change. The greatest increases in warming are predicted to occur and are occurring in northern hemisphere upper latitudes, and evidence exists in melting glaciers, longer growing seasons, larger and more severe fire seasons, and changes in species assemblages at upper altitudes and latitudes.

There is currently much to be learned about the interactive processes that force and feedback within our climate system, and in this venue, there is much debate. This is not a gloom and doom prognostication, but a reality that we must mindfully and responsibly address today. Climate change is not some future possibility. Climate change is apparent today.

_Amber Soja is a research scientist with the National Institute of Aerospace, currently resident in the Climate Dynamics branch of NASA Langley Research Center._

*Waleed Abdalati … “climate can adversely affect human society”*

Climate is changing. It always has, and it always will. What is different now as compared to past human history is that we are at a point where we humans are having a significant global impact on our Earth environment. We can’t say for certain that those impacts will bring dire consequences , nor can we say that those impacts will be minor. The balance of the evidence, however, suggests that climate will change in ways that can significantly and adversely impact society, and the seriousness of those impacts is going to depend on three things:

1. the magnitude of the changes

2. the rate at which they occur, and

3. our ability to anticipate and prepare for them.

Scientists are working hard to improve our ability to anticipate those changes, and effective policies can help reduce the magnitudes and rates of change. The longer longer we as a society wait to take meaningful steps to adapt to and mitigate climate change, the greater the level or sacrifice will be to meet those challenges. For this reason everyone should be paying attention to climate change and discussing it in real terms, not exaggerated arguments targeted at trying to make a particular point. The more literate the general public is on this issue and the more society as a whole understands the nature of climate change, the more likely we as a society can work to achieve solutions to the climate change challenge.

The bottom line is, I don’t think we should be afraid, but we should all be very concerned.

_Waleed Abdalati is head of the Cryospheric Sciences Program at NASA Goddard Space Flight Center._

*M. Granger Morgan … “we need deep cuts in emissions”*

I want to say two things.

First, the main cause of climate change comes from carbon dioxide produced when we humans burn coal, oil and natural gas.

Second, unlike conventional pollutants that stay in the atmosphere a few hours or days, once carbon dioxide enters the atmosphere much of it stays there for a century. That means that to reduce concentrations (which are what cause warming and climate change) we’re going to have to reduce emissions by 80% or more. We need deep cuts, not just stablization of emissions.

_M. Granger Morgan is head of the Department of Engineering and Public Policy at Carnegie Mellon University in Pittsburgh._

*Bruce Wielicki … “global warming does not mean uniform temperature change”*

When you see climate signals discussed in reports like the IPCC, remember that climate scientists are basing these on the big picture, and that “global warming” does _not_ mean uniform temperature change over the entire Earth.

The climate system is sufficiently complex that like the economic analogy: it does not do anything in a simple uniform way. So even when the global average temperature is increasing, a few places will actually be cooling.

The scientific debate is shifting from whether mankind is causing climate change (we are), to how large a change we can expect in the future, how fast climate will change, and what the regional impacts will be. In the coming decades, even regional climate change will reach levels that exceed natural variability. In some areas like the polar regions, it already has. This will be much easier for the public to understand as their own regional climate change becomes increasingly obvious. But we cannot wait that long to act. (for more, see “Don’t notice climate change yet? You will.”:http://earthsky.org/article/50994/climate-change-you-may-not-notice-it-yetbut-you-will)

_Bruce Wielicki of NASA’s Langley Research Center in Hampton, Virgina is the Principal Investigator for CERES, a project now using four instruments on two different Earth-orbiting satellites to monitor how clouds affect our climate._

*Michael Mann … “false controversy”*

Unfortunately, there are a number of so-called “organizations,” a lot of their funding can be traced back to fossil fuel corporations. They’re often not much more than a p.o. box and an individual or two who are behind them. They have been paid money to manufacture false controversy. They’ve been doing that for years. That has been a particularly profound influence here in the United States. That’ll probably continue to go on for some time.

I’m pleased, and many of us are pleased that Exxon-Mobil has announced that they are no longer going to provide funding for many of these organizations that they were providing to manufacture this false controversy. This was actually detailed in an extensive report by the Union of Concerned Scientists that was issued about a month ago, where they detailed all of the unfortunate ways that Exxon-Mobil had been funding to cloud the public understanding of the science. Well, it looks like they’re backing away from that now. But I don’t think that that means that we’re not going to see some efforts of that sort again, even with this next IPCC report. So we shouldn’t be surprised that there will be some talking heads out there, probably most of them financed by industry, to try to confuse the public’s understanding of the report, to try to raise false criticisms of the conclusions that have been drawn. We’re going to see some of that. There’s no question. So it’s important for us to keep in mind that we’re probably seeing the last gasps of this sort of disinformation effort that is probably in its tail end now that the science has become ever more strong as time has gone on.

_Michael Mann, professor of meteorology and geosciences at Pennsylvania State University and director of the university’s Earth System Science Center._

*Alan R. Townsend … “no longer on the distant horizon”*

Global climate change is no longer just a threat on the distant horizon. It is with us today, and it is already affecting the lives of people around the world. We can do something about it, but now is the time for nations everywhere to begin those efforts in earnest. The more we delay, the more we increase the probability of abrupt and truly significant changes in climate that would have enormous social and economic consequences.

_Alan R. Townsend is the Associate Director for the Institute of Arctic and Alpine Research at the University of Colorado in Boulder._

*Helen Amanda Fricker … “changing habits”*

Yes, global warming is very, very real. It is actually happening and is not a myth. The ramifications around the world are being seen all the time, and this will only get worse unless the major countries contributing to the problem reduce their carbon dioxide emissions significantly. While people are not believing it and not doing anything to change, the problem is getting worse. By the time everyone is convinced, it will be too late. It takes effort to change habits, and I think that is why there are so many people refusing to change.

Changing habits starts at home, and one simple way I could see the average household in the US reducing their energy consumption is to start line-drying their washing instead of using tumble dryers. Millions of people in Europe and Australia hang their washing out to dry, in their back yard or patio. In fact, in Australia the “Hill’s Hoist” washing line in the back yard is commonplace. The same is not true in the US. Here, for some reason, seeing your neighbor’s washing is not tasteful or acceptable, and it is actually forbidden to hang out washing in some places. This needs to change. In some parts of the US, such as California, the conditions are perfect for drying clothes outside. The air is dry and the sun is warm, sometimes it actually takes less time than in the dryer, and consumes no energy at all!

_Helen Amanda Fricker is research geophysicist with the Scripps Institution of Oceanography._

*Bruce A. Boe … “we are stewards”*

The Earth’s climate is changing. The planet appears to be warming, perhaps as much as 2 degrees Fahrenheit in the next 40 or 50 years, according to the newest report by the IPCC. According to the report, this projected change is occurring primarily because of human activities.

Change of any kind, warming or cooling, will certainly have impacts on the world’s weather and economies. Those impacts will be negative in some areas, and positive in others. We humans are the only species on the planet capable of causing such changes, at least so rapidly. It is our responsibility to be good stewards of this planet which we call home.

At the same time, we must recognize that the Earth’s climate has always changed. The “Little Ice Age” which occurred between 1300 and 1850, is a very recent example. Some 12,000 years ago, a mere blink in geologic time, glaciers covered much of the northern hemisphere.

Furthermore, it is well established that the irradiance of our sun, often termed “the solar constant”, is not completely constant, after all.

The bottom line is this: We humans need to be the best stewards of the planet we can, but at the same time should recognize that control of the climate ultimately does not rest with us. The climate has always changed, and will always change. It is absurd to think, even for a second, that the climate can somehow be “steadied” to our liking.

We must also be aware that there are many sources of carbon dioxide in addition to the combustion of fossil fuels. Each of us exhales approximately 1.2 ounces of carbon dioxide per hour, if we choose to breathe. Just for the United States, this is an additional 270,000 tons of CO2 added to our atmosphere per day!

So what should we do? Plant more trees. Drive less. Recycle more. And keep breathing.

_Bruce A. Boe is Director of Meteorology at Weather Modification, Inc. He is a present member and past chair of the American Meteorological Society’s Committee on Planned and Inadvertent Weather Modification._

*Isaac Held … “droughts … environmental justice”*

I am most concerned about the changes in tropical rainfall patterns that will accompany global warming, especially increased frequency and severity of droughts in underdeveloped regions that have the fewest resources to adapt to changing conditions. This is a question of “environmental justice”, with many regions of the developing world likely to be affected adversely, not due to their own actions, but as a consequence of the emissions of greenhouse gases by the developed world.

_Isaac Held is a senior research scientist at the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration._

*W. H. Berger … “sea level rise”*

The history of ice ages for the last 600,000 years suggests that a sea level rise of three feet per century occurred about ten percent of the time during warm periods such as we live in. And there was no excess greenhouse effect to push the system. Thus, to a geologist familiar with ice-age climates, a global sealevel rise distinctly exceeding three feet in a century would hold no surprise whatever.

_W. H. Berger is a professor of oceanography in the Geosciences Research Division in the Scripps Institution of Oceanography at University of California, San Diego._

*Norm Ellstrand … “I am changing my lifestyle”*

As a geneticist whose research addresses the risks of plant biotechnology, people often ask me what I think is the earth’s most pressing environmental crisis. The answer is a no-brainer, “global warming”. It surprises folks because they are waiting for something about genetics. But for the past decade I have been concerned about global warming. It’s so easy to see what a nasty legacy we are handing to our grandchildren. But I don’t just worry, I’m doing something about it. I am changing my lifestyle. I asked my family to donate to tree planting programs instead of buying me birthday presents. I am a commuter cyclist, enjoying hundreds of carbon-free miles a month! We have replaced as many lightbulbs at home with compact fluorescents. Every little decision counts. Do you really need that plastic bag? Finally, I am giving up teaching my genetics for non-majors class so that I can teach a science-of-food class — a venue where it is more appropriate to sneak in a lecture or two on global warming.

_Norman C. Ellstrand is a professor of genetics at the University of California Riverside._

*Bill Patzert … “skeptics going way of dodo bird”*

The global warming skeptics are going the way of the dodo bird – to extinction. The evidence is in. We’re definitely living in a warming world and headed into unknown, dangerous territory. The future of our civilization is at stake! It’s time for each and every one of us to change wasteful habits and cut back on our energy consumption. A good start would be losing the SUV. Real men and women drive hybrids or take the bus. Let’s all think more and use less – of everything. Remember, warming is global, but solutions are local and – bottom line – individual.

_Bill Patzert, scientist at NASA’s Jet Propulsion Laboratory._

*C. Mark Eakin … “coral reef ecosystems”*

Our warming climate has already changed many of the world’s ecosystems, and will continue to affect them into the future. The first recorded mass coral bleaching event happened in 1982. As ocean temperatures have risen since then, coral bleaching and death have increased in frequency and intensity. Coral bleaching occurs when stressed corals expel the symbiotic micro-algae living in their tissues – algae that provide corals with food. Severe or prolonged high temperatures kill corals, leaving reefs devoid of key ecosystem processes and vulnerable to natural processes of erosion that break down the structures that form the basis for major food chains. When this happens over large areas– as it did in 1997-98 in the Indian and Pacific Oceans and 2005 in the Caribbean region– it has wide-reaching ecological, social, and economic impacts on ecosystems that support $375 billion annually in fish, seafood, tourism, and coastal protection worldwide. There is growing scientific evidence that it is unlikely that corals can adapt fast enough to keep pace with even the most conservative climate change projections. This means that as global temperatures rise, we expect to see more reef corals around the world bleaching and dying.

We have two means of addressing this problem: the root issue and contributing threats. Solving the root issue, of course, requires reducing oceanic warming by reducing the human contribution to greenhouse gases. However, reducing global greenhouse gas concentrations is beyond the direct control of coral reef resource managers. Instead, managers need to reduce the local environmental stresses under their control, thus increasing the resilience of coral reef ecosystems to the bleaching caused by oceanic warming. As the world continues to warm, resource managers around the globe will have to take greater actions to mitigate the impacts of climate change through local actions.

_C. Mark Eakin is NOAA’s Coral Reef Watch Coordinator._

*Lisa Graumlich … “national parks”*

For the past 25 years, I have been doing field work at high elevations in the mountains of the Western US. I have worked in the premier national parks, including Glacier, Yellowstone, Mt. Rainier, Yosemite, and Sequoia. In all of these parks, we are seeing the fingerprint of global climate change. Glaciers are disappearing and plants, animals and insect pests are moving upslope at unprecedented rates. Our national parks can no longer be protected from human influence by building a fence or hiring park rangers. Recall that national parks are an American invention. In fact, the writer Wallace Stegner often remarked that the idea of national parks was the best idea that we ever had. It’s my fervent hope that we find the will to address global climate change in order to ensure that the parks and wild places of the West continue to delight and inspire future generations.

_Lisa Graumlich is a professor and director of the School of Natural Resources at the University of Arizona._

*Ken Caldeira … “can we transcend our past?”*

Carbon dioxide is increasing more rapidly and to higher levels than has been experienced on Earth for perhaps 50 million years or more. The consequences of our actions will leave its imprint on the Earth for millions of years to come.

Ecosystems and organisms have not evolved to cope with such rapid change, despite the fact that these changes seem slow by our human standards. If we do not change our ways, and soon, our activities threaten the collapse of ice sheets, loss of entire ecosystems, and shifts in precipitation that could potentially initiate famines and other forms of suffering. We might be lucky, and outcomes might turn out not to be this bad, but who is in the mood to gamble?

Reversing the increasing trend in carbon dioxide emissions will take an effort on the scale of today’s military expenditures. We are willing to spend those resources when the threat is external, but will we be willing to do the same when the threat is from ourselves?

Our hunter-gatherer minds have developed to address problems involving competition and problems that are local in scale, and where planning for the future meant hoarding enough nuts to last the winter. Can we transcend our hunter-gatherer past and develop the wisdom to cooperate to address problems that are global in scale and involve time horizons of decades and longer?

Music and art show that our minds have capabilities that go far beyond what could be reasonably expected to develop out of the brutal forces of evolution. Let us demonstrate that our minds have the equally unexpected capability to solve the environmental problems facing us today.

_Ken Caldeira is in the Carnegie Institution Department of Global Ecology where scientists attempt to understand how humanity can prosper sustainably._

*Kai Lee … “enlightened and active public needed”*

Global climate change is a slow but now unstoppable process that will bring large changes to the natural world. Most of these, however, will not be apparent to people living in rich countries.

In order to contain the long-term damage from human-caused warming, and in order to adjust to the warmer world we are still creating, it is essential for people to make small but important changes in the way they live.

Of these, the most important is energy conservation and efficiency. This does NOT mean a poorer lifestyle necessarily. It does mean insulating one’s attic and exterior walls, using public transit when available and working for there to be better transit options, and it means supporting carbon taxes or other means of building in the real costs of climate change into the everyday economic choices people make. None of this is hard to live with, but it also does not have a strong-enough constituency, yet, to change public policy – particularly the higher charges for energy. For that reason, an enlightened and active public will be needed for the next several years (through and beyond the 2008 presidential election in the US).

We can do this, but we can’t wait for others to do it for us.

_Kai N. Lee is the Rosenburg Professor of Environmental Studies at Williams College._

*Ron Flick and Bob Guza … “sea level rise”*

Sea level rise over the coming century, a consequence of global warming, could reduce drastically the availability of southern California beaches for recreation and protection of public and private infrastructure. If sand supplies are not greatly increased, beaches that are now narrow, with only a small strip of sand between the high tide line and cliffs or seawalls backing the beach, could disappear entirely.

_Reinhard “Ron” Flick is a Research Associate at the Center for Coastal Studies, Scripps Institution of Oceanography, University of California, San Diego. Robert Guza, is a Professor at the Center for Coastal Studies, Coastal Data Information Program (CDIP), Scripps Institution of Oceanography, University of California, San Diego._

*Roger Edwards … “tornadoes”*

Will we have more, fewer or as many tornadoes 100 years from now? As an atmospheric scientist specializing in tornadoes, my short answer is: we simply don’t know.

As of this writing, no scientific studies solidly relate climatic global temperature trends to tornadoes. I don’t expect any such results in the near future either, because tornadoes are too small, short-lived, hard to measure and count, and too dependent on day to day, even minute to minute weather conditions.

Is it _possible_ that any given shift in global temperature patterns may eventually change long-term tornado risk probability? Maybe, just maybe…if we make assumptions built on assumptions built on assumptions, about subtleties of regional warming (or cooling) by a few degrees, and how it might change the distribution of the four basic ingredients for tornado producing storms (for more, see “Will global warming cause more tornadoes?”:http://earthsky.org/blog/50991/tornadoes-and-global-climate-change).

Our challenge is to predict future worldwide changes in something we haven’t sharply defined, can’t even count or measure very well, and that we often can’t predict an hour from now, all based on a model that doesn’t know it exists. That “something” is a most elusive, quick and stealthy quarry: the tornado. We might meet this challenge someday, but right now we’re a long, long way from that place in science.

_Roger Edwards is a meteorologist at the Storm Prediction Center of the National Weather Center in Norman, Oklahoma._

*Colin Price … “worried about surprises”*

The facts are that the temperatures observed today and during the last few decades are the highest they have been for at least 1000 years if not longer (we don’t have accurate data further than that). Furthermore, the concentration of greenhouse gases that are known to absorb heat emitted from the Earth’s surface are now the highest we have seen in at least 600 thousand years, and likely longer (we have no data going back further in time). If you don’t trust the temperature data, take a look outside. 95% of all mountain glaciers around the world are melting and receding. The Greenland ice sheet is dramatically losing mass (ice) due to melting, while the summer Arctic sea ice is continuously shrinking every year. (for more, see “The Earth has a fever!”:http://earthsky.org/blog/50992/the-earth-has-a-fever)

What we scientists are worried about now are surprises. It is much easier to melt the Greenland ice sheet than it is to rebuild it. The ice and snow around the planet have a cooling effect due to their white color that reflects large amounts of solar radiation back to space. Without this ice and snow, additional radiation will be absorbed at the surface and the Earth will warm even more. The thawing of the high latitude permafrost (frozen ground) may result in huge emissions of CH4 that will also accelerate the warming.

_Colin Price is a professor in the Department of Geophysics and Planetary Science at Tel Aviv University._

*Jay Gulledge … “change is the key word”*

Change is the key word in climate change. For most people, this change will involve larger, more frequent extremes. For instance, in 2030 a Midwestern city will probably experience more rainfall, but it will likely come in fewer, larger events, with more frequent flooding. And between these events, there might be more frequent, longer, and hotter droughts. Residents of the city may come to expect 100+ degrees for many days running during extended droughts, when the soil is dry and no longer draws heat from the air. In summer, peak water and electricity demand will probably grow faster than city planners anticipated, requiring emergency infrastructure investments. With fewer hard freezes in winter, more pesticides will likely be needed to control mosquitoes and other pests. We will need to bolster emergency health care funds and disaster response systems to cope with these new extremes. (for more, see “In Climate change, ‘change’ is key word”:http://earthsky.org/blog/50993/in-climate-change-change-is-the-key-word)

_Jay Gulledge is a senior research fellow and staff scientist at the Pew Center on Global Climate Change._

*John Kermond … “I have seen it”*

Having been involved in the U.S. Global Change Research Program from its inception in 1989, I have been exposed to most of the conferences, workshops, reports and assessments that have been made, including those from the International Panel on Climate Change. I have not read every word or watched every animation or talking head, but I have read and seen a lot.

Fast forward to 2007 and I do not have to read another single word with respect to global warming. I have seen it! In both hemispheres of this planet.

In the late summer of 2006, I spent 3 weeks aboard a Russian ice breaker in the Arctic. We found less ice in extent; less ice in thickness; and, very warm water pouring into the Arctic from the Atlantic Ocean. In the fall, I traveled to my native Australia and went to the beach in the town that I was raised — Warrnambool. When I was a kid there, you had to run (fast) over the hot sand before you got to a place on the wide beach where you could put down a towel. You still had quite a hike before your feet got wet. Total sandy beach in the order of 50 to 80 meters. In October of 2006, at high tide, there was 1 to 3 meters of beach available. Even the sand dunes along the two mile crescent shaped beach terminate in a vertical wall with roots of plants exposed. The beach is shrinking. The ocean is rising.

Both of these observations are clinical manifestations of global warming. And they are as predicted. For over a decade we have said that global warming will manifest itself in the higher latitudes. We are seeing the effects of global warming via ice reduction at both Poles, and in a rising sea level in many parts of the world. Already the citizens of Vanuatu (a tiny atoll in the Pacific) have decided to leave and re-settle in new Zealand. The citizens of Shishmareff in Alaska have also decided to leave and re-locate because the sea is taking back their land.

_John Kermond is a UCAR Visiting Scientist with NOAA’s Climate Program Office._

*Tom Knutson … “merely the beginning”*

There is no doubt that the Earth has warmed over the past century or more. The question has been: what role have humans have played in causing this warming, especially through burning of fossil fuels that have caused an increase in greenhouse gases that blanket the planet?

The answer from most scientists who study this problem in detail is that we are now more confident than ever that humans have caused most of the warming, particularly over the last 50 years, and that this man-made warming stands out well above the background of natural climate variability.

But the warming to date is merely the beginning of what is expected to be a much more pronounced global warming in the coming century, although how much warming will occur will depend on how humans continue to modify the atmosphere, and we still have many uncertainties that need to be narrowed in our scientific understanding of the climate system. Warmer global temperatures are just one symptom – perhaps the most obvious one at present – of a global scale change to the Earth’s climate that has great potential to affect future generations in important and varied ways. Some climate change impacts are expected to be beneficial in
some regions. But stronger hurricanes, more heat waves and drought, and increased storm surge damage from rising seas are among the harmful changes we expect to see as we humans continue this global “experiment” with our planet. The challenge facing scientists – and in fact humanity – is to understand and deal with this complex issue in what is already a complicated world.

_Tom R. Knutson is a research meteorologist with the Climate Dynamics and Prediction Group at NOAA’s Geophysical Fluid Dynamics Laboratory._