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On this Earth Day Eve, we asked a panel of experts to dispel one myth about climate change that's been uttered by the 'It's all a hoax' crowd.

CLAIM: There's nothing we can do to stop climate change.



Canadian prime minister

"We are the last generation able to make sure future generations do not pay the full — and incalculable — cost of climate change. We are also the first generation with the tools to do so.

"In Canada, our government's national plan to fight climate change is comprised of practical and meaningful ways to reduce emissions and create good middle-class jobs to grow the economy.

"This includes putting a price on pollution so that it is no longer free to pollute anywhere in Canada; a world-class oceans protection plan; a national strategy on zero plastic waste; investing in clean technologies and public transit projects; cheaper zero-emission cars; and phasing out coal power.

"Our ambitious plan is centered around making a clean economy affordable for everyone, because we know that growing the economy and protecting the environment go hand-in-hand.

""We continue to work together with all Canadians and our international partners to build a cleaner, more prosperous future for our kids and our grandkids."



Chief scientist for climate/land use change, U.S. Geological Survey

"Actually, we have three choices.

"We can mitigate — reduce the emissions driving the change in climate. We can adapt — manage the changes that are occurring. Or we can suffer.

"Right now, we are doing some of all three.

"There is a strong body of knowledge and agreement among scientists around the world about actions that can be taken to reduce the rate of warming and its impacts. The societal responses basically fall into the two categories: mitigation and adaptation.

"Mitigation consists of actions that society can take to reduce human effects on greenhouse gas concentrations, including the reduction of emissions from fossil fuel use and the enhancement of carbon stored in natural systems like forests and wetlands. Temperature rise by the end of this century, or even by 2050, will depend largely on whether human emissions of greenhouse gases are reduced or continue unabated.

"Adaptation, on the other hand, consists of actions taken to reduce the impacts of climate change or enhance the potential positive benefits. This would include actions such as elevating buildings in low-lying coastal zones, retreating from flood-prone areas, and planning for more intense heat waves and hurricanes. Adaptation is already underway in many states and cities across the United States.

"The combination of mitigation and adaptation can help us be more resilient and cope with future changes that we cannot prevent due to lags in the climate system response to historic emissions."

CLAIM: Polar bears are on the verge of extinction because of hunting, not climate change.



Chief scientist, Polar Bears International

"Polar bears can only reliably catch their prey — mainly two species of seals — from the surface of the sea ice. Compared to the early 1980s, summer sea ice extent has declined approximately 965,000 square miles — or about 3.5 times the size of Texas. This forces polar bears to spend much longer periods on land or on ice over deep and unproductive waters, where they are food-deprived.

"These longer periods of food deprivation have resulted in reduced body condition and survival, and polar bear numbers are declining as a result.

"This has nothing to do with harvest. Any farmer or rancher knows that if every year he paved over another portion of his pasture, he progressively will be able to support fewer cattle — regardless of how many he historically was able to harvest and send to market. Unlike cattle or other terrestrial animals, polar bears depend on a habitat that literally melts as temperatures rise.

"If we allow warming to continue, sea ice habitat ultimately will disappear throughout the Arctic and so will polar bears."

CLAIM: A few degrees don't matter that much.



Climate scientist, Environmental Defense Fund

"All we have to do is look around us to see that a few degrees do matter — the Earth has already warmed by nearly 2 degrees Fahrenheit over the past century, and the planet has reacted dramatically.

"Sea ice in the Arctic has halved in just a few decades; nearly all glaciers are shrinking; several islands have been swallowed by rising sea levels and communities in the tropics and Alaska are relocating; over 90 percent of the Great Barrier Reef is dying; and extreme weather events are more intense, frequent, and last longer.

"In the U.S., the number of billion-dollar weather and climate disasters has more than tripled since the 1980s; the average wildfire season is three-and-a-half months longer than it was in the 1970s, leading to more than six times as many acres burned; winter snowpacks that supply communities with water are melting about a month earlier with up to an 80 percent decline in the amount of snow; heavy downpours in the Northeast have over 50 percent more rainfall in them; hundreds of cities have seen an increase in the number of days a year that mosquitoes can transmit diseases; Lyme disease has spread to all 50 states; the length of the ragweed pollen season has increased by up to a month in parts of the country; and some ski resorts have had to permanently close due to lack of snow.

"These impacts, from Earth warming by just a couple of degrees, have negatively affected societies and ecosystems all over the world, and scientists have found that a few more degrees of warming could be catastrophic. The impacts also get incrementally worse with more warming.

"For example, with just one more degree Fahrenheit of warming, around 15 percent of the global population may be exposed to extreme heat at least once every five years, and with two more degrees, the exposure jumps to 40 percent of the population.

"For context, we expect to surpass these levels of warming by mid-century unless we take drastic measures to reduce our emissions of greenhouse gases. Further, throughout modern human civilization, the Earth has never been a few degrees warmer than it is right now, and therefore we are entering uncharted territory, which is certainly concerning."

CLAIM: We've been hearing about the demise of planet Earth for decades. And yet, we're still here.



Washington state governor who is building his 2020 Democratic presidential campaign around one issue — climate change

"Climate denial is based on fear. Fear that we can't solve the problem.

"The fact of the matter is Donald Trump and climate deniers are the pessimists, and we are the optimists. Denial is not a strategy and delay is not an option. We know we can do this because this is just as much a matter of character as it is science.

"We went to the moon because we had a president who called forth that effort, and we did it. This nation just has an incredible capability if we have a vision and a common purpose, and there's no better, more necessary or more urgent common purpose than to defeat climate change."

CLAIM: Global warming is just a ploy to make money.



UI associate professor of atmospheric sciences

"Not sure who's making money here, except for the fossil fuel industries. Economic damages get worse each year, in particular in coastal communities."

CLAIM: There is no global scientific consensus.



UI grad; executive director, Climate Nexus

"Literally thousands of climate scientists have confirmed multiple lines of evidence over the past 20-plus years explaining it.

"There is no longer any scientific doubt whatsoever that climate change is happening and accelerating; that humans are largely responsible for it; and that we only have a narrow window of perhaps 15 years or so to begin to make significant changes in our sources of energy.

"The American public, however, doesn't yet know of this scientific consensus. Less than half of Americans are aware that there is, in fact, a scientific consensus on the root cause of this critical issue.

"So much more work needs to be done to make sure people understand that there is, in fact, a global scientific consensus."

CLAIM: No one can be sure about global warming when the climate computer models are uncertain.



Director, National Snow and Ice Data Center

"Global warming is a fact — all we need to do is look at the data that we have assembled on surface temperatures, ocean heat content, sea level rise and shrinking glaciers.

"And climate models are in universal agreement that as carbon dioxide levels continue to rise, it will get warmer.

"How warm will it get over the next century? There are uncertainties. Our climate models are not perfect, and there will be natural variations in climate superposed upon the general warming trend.

"Also, future carbon dioxide emissions will very much depend on the decisions that we make as a global society.

"Uncertainty, however, is no excuse for doing nothing. Maybe we'll get lucky, and will be able to manage the impacts of global warming, but it's a fool's gamble."



UI professor of atmospheric sciences; served as assistant director of White House Office of Science and Technology Policy, 2015-17

"Scientists use a wide range of observational and computational tools to understand the complexity of the Earth's climate system and to study how that system responds to external forces, including human activities. Models are used to project how climate may further change in the future.

"Some in the media and in online blogs try to claim that one should distrust climate change because the models are 'no good.' But is that distrust warranted? The basic answer is no. There are strong reasons for this conclusion.

"These computer-based models actually are extremely useful tools in our understanding the physics, chemistry and biology affecting the Earth's atmosphere, oceans, biosphere and cryosphere, the components comprising the Earth's climate system, and for studies of how the changing forcing on the climate system may further affect the Earth's climate in the future. And these tools basically give results that look like the observations of the Earth system and the changes that are occurring.

"But we also know they are not perfect, nor should we expect them to be. No model is perfect. Our understanding of physics, chemistry and biology is incomplete, and the models represent those uncertainties.

"Nonetheless, imperfect models are vital to our society — for example, they are used to design the airplanes we fly in and the vehicles we drive. We should not expect them to perfect. So the real question is whether they are good enough for the purpose they are designed for.

"For climate models, the answer is clearly yes. Climate models have proven remarkably accurate in forecasting and evaluating the climate change we've experienced to date. In some cases, model analyses have been overly conservative — for example, in projecting how quickly Arctic sea ice would decline. The models also tend to underestimate the trends in severe weather we are now seeing.

"These models are the only crystal balls we have — and although not perfect, they are very useful tools and provide us with significant insights."

CLAIM: This is a world problem, not an Illinois problem.



President, Natural Resources Defense Council

"Illinois can do its part and help lead the nation down the right path by passing the Clean Energy Jobs Act.

"It would move the state toward 100 percent clean energy, broad efficiency gains and a smaller carbon footprint — and do so with a focus on equity to give all residents a shot at new jobs, energy savings and better health. Illinois already has more than 100,000 clean energy jobs.

"This bill would help generate even more."

CLAIM: As @realDonaldTrump tweeted one nippy winter day: 'What the hell is going on with Global Warming? Please come back fast, we need you!'



UI grad; senior strategist, Union of Concerned Scientists

"A changing climate doesn't mean the end of winter — it means that our winters are changing. And they are changing in a lot of different ways. Here are some examples:

"Many of the weather patterns of our planet are closely connected. So when we see very warm temperatures in the Arctic, like we did this winter, we might expect to see changes elsewhere in the climate system. And that's what happened.

"Repeated Arctic outbreaks of cold air into the lower 48 were a key feature of this cold season, and these outbreaks are tied to a weakening of the stratospheric polar vortex, which allows cold air that has formerly been bottled up in the Arctic to sweep southward.

"An increase in extreme precipitation is a hallmark of climate change in the Midwest; and when that precipitation falls in the winter, that means a lot more snow and ice. The repeated Arctic cold outbreaks helped bring more snow because when precipitation occurred, it often fell in the form of snow versus rain — although winter rain and ice has been a more frequent problem in recent seasons.

"It is rare to have a bomb cyclone within the continental United States, yet two have occurred this season. A bomb cyclone is a rare mid-latitude storm that undergoes a sudden and extreme drop in barometric pressure over 24 hours that leads to rapid intensification. Winter Storm Ulmer (March 12-14) brought blizzard conditions, high winds, sudden melt of ground cover snow and subsequent devastating flooding that destroyed levees. Unfortunately, record-breaking bomb cyclone Ulmer made the U.S. list of billion-dollar weather and climate disasters.

"It all adds up to record-breaking extreme weather for the U.S. during this past winter season. As the Intergovernmental Panel on Climate Change special report on extreme weather has noted, one of the signatures of climate change is more extreme weather events. Winter 2018-19 in the U.S. was no exception."

CLAIM: You can't seriously expect us to believe that parts of Florida will be wiped off the map by the turn of the century.



Climatologist who has been critical of academia's unwillingness to be open to new theories

"This is a nontrivial concern. In the 20th century, global mean sea level rose by about 7 inches. We can expect at least a foot in the 21st century.

"Combined with storm surges from hurricanes, south Florida is very vulnerable."