It is nothing short of tragic that so many Americans continue to dismiss the scientific veracity of climate change. Deniers are not moved by the coherency of the research that weaves together the different points of measurement. The plethora of data includes higher global mean surface temperatures, melting glaciers, retreating sea ice, increasing water temperature, rising sea levels, ocean acidification, and extreme weather. The data is unequivocal yet there are scores of confused people who are woefully unaware of the facts.

Deniers are not phased by the fact that we are already beyond dangerous climate interference (as indicated by leading scientist John Holdren in 2006). They reject as alarmist the global planetary emergency (as declared by world-renowned climate scientist James Hansen in 2008) and they scoff at the notion that radical reductions in carbon emissions are the only solution to our escalating climate emergency (as recognized by the IPCC).

Deniers ignore the fact that the climate system has moved beyond the patterns of natural variability. They disregard the significant risk of abrupt or irreversible climatic shifts.

They seem oblivious to the fact that based on current trends, the end of this century will be characterized by sea level rises, the collapse of rainforest and marine ecosystems, desertification, and the disruption to the monsoon system that supports more than one billion people.

Even the collapse of the global carrying capacity of the Earth does not soften climate denier resistance. These deniers are not swayed by the evidence of a pronounced warming trend around the globe.According to an EPA report, seven of the top ten warmest years on record for the continental U.S. have occurred since 1990. The report also indicates that tropical cyclone intensity has increased in recent decades and of the ten most active hurricane seasons, six have happened since the mid 1990’s. Sea levels have risen between 1993 and 2008 at twice the rate of the long-term trend. Glaciers are melting and their loss of volume has accelerated over the last decade. The frequency of heat waves has steadily risen since the 1960’s and the percentage of the US population experiencing heat waves has also increased.

Deniers dismiss the relevance of the EPA’s findings along with the fact that seventeen of the warmest years in recorded history have occurred over the last twenty years and the warmest years on record occurred in the most recent decade.

Although extreme weather has made headlines across the world, deniers appear oblivious. The summer of 2011 was one of the hottest on record and the summer of 2010 saw record-setting temperatures in more than a dozen nations. There were record-breaking temperatures all around the world in 2010 and a new record was set for the second highest average global temperature over a 12 month period. In 2011, the U.S. experienced widespread record-breaking heat waves and droughts, which along with other extreme weather events, have been linked to climate change.

In 2010, China recorded the second highest temperatures it had ever seen, and India recorded its warmest year ever. Many heat records were also set in the U.S. in 2010. According to NASA, 2010 was tied for the hottest year ever in the U.S. and NASA’s temperature record showed that it was the hottest January to April in recorded U.S. history. In the U.S. there were more than 4000 daily high temperature records that were tied or broken in June. There were also 159 reports of record high temperatures for June and 42 reports of all-time record hottest temperatures.

Even before 2010, the evidence for a warming trend was building. Researchers have been pointing to a link between weather and climate for decades. Eight years ago, a study published in NatureNews indicated that global warming was partially responsible for the deadly heat wave that scorched Europe in 2003. Hurricane Irene pushed the U.S. yearly record for billion-dollar natural disasters to 10 in 2011, smashing the 2008 record of nine.

A 2009 study by the National Center for Atmospheric Research (NCAR) showed that there is an increasing trend of record-breaking heat in the U.S. There has been a substantial increase in the number of record daily highs and in the last 30 years.

An article from the University Corporation for Atmospheric Research (UCAR) titled “Record high temperatures far outpace record lows across U.S.“ presents some of the findings from a climate study by NCAR, Climate Central, The Weather Channel, and the National Oceanic and Atmospheric Administration (NOAA). They indicate that daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States. They also suggest that the ratio of record highs to lows is likely to increase dramatically in coming decades if emissions of greenhouse gases continue to climb.

“Climate change is making itself felt in terms of day-to-day weather in the United States,” says Gerald Meehl, the lead author and a senior scientist at NCAR. “The ways these records are being broken show how our climate is already shifting.”

Deniers are quick to say that the world has been warmer in the past; however, a 2010 study discovered that even though the Pliocene Epoch (5.3 to 2.6 million years ago) was approximately 19ºC warmer than today, CO2 levels were only slightly higher than they are today. Stefan Rahmstorf, Professor of Ocean Physics at Potsdam University, said that three million years ago, during the Pliocene era, temperatures were just two to three degrees warmer, but sea levels were 25m to 30m higher.

According to some predictions, within a decade, summers in the North Pole will be devoid of ice. Images from NASA support this contention as they show a significant decline in Arctic sea ice thickness between 2003 and 2008. The Arctic’s reserve of thick ice that’s more than 2 years old makes up 10 percent of its winter ice cover, down from 40 percent in the past. And for the first time on record, the Northwest Passage was open to navigation.

Global warming is also melting glaciers around the world. A massive crack in Petermann Glacier in northern Greenland has led scientists to predict that a big part of the Northern Hemisphere’s largest floating glacier will soon disappear. A record amount of Greenland’s ice sheet has already melted.

When it comes to tornadoes and other forms of extreme weather, 2011 is proving to be the deadliest and most destructive year ever. 2011 is already the deadliest year for tornado outbreaks in the United States since 1953, with more than 500 people killed.

Rising seas threaten areas like Grand-Lahou in the Ivory Coast and the Maldives. A 2007 climate change report predicts that sea levels will increase 7 to 23 inches by 2100, speeding erosion and threatening coastal land. Warm air holds more water vapor than cold and on average, the Earth’s atmosphere is about four percent wetter than it was 30 years ago. This has prompted major flooding in Australia, Pakistan, Sri Lanka, Vietnam, the Philippines, Brazil, and Colombia.

According to satellite data, annual sea level rises are 50 per cent higher than last century. Research suggests 1 in 10 people could be at risk of coastal flooding by 2100. Sea levels are rising significantly faster than previously thought and are on track to rise by more than 1 meter by the end of the century, putting entire countries and many of the world’s largest coastal cities at risk of inundation, according to research presented at the Climate Congress in Copenhagen. An increase in sea levels of 1 meter would affect an estimated 600 million people, or almost 10 per cent of the world’s population, putting them at serious risk of coastal flooding.

“You have to remember it is not just the steady increase in sea levels that is the problem, it is that combined with the increased flood risk,” warned Dr John Church of the Centre for Australian Weather and Climate Research. He added that research looking at the impact of a 50 centimeter increase in sea levels on areas of the Australian coast found that under such a scenario “flooding events we today expect once in 100 years would occur several times a year”. Acidification of seawater is another major problem that deniers refuse to link to human activity.

Climate scientist Stefan Rahmstorf warned that there was a very real danger of reaching a tipping point this century, which would result in sea level rises of many meters. Research from the OECD has suggested that the rise of sea levels risk US$35 trillion in property and asset damage due to coastal flooding by 2070, (which represents a tenfold increase).

Climate experts have cautioned that the world is now at significant risk of “abrupt or irreversible climatic shifts” that could make half the globe uninhabitable.

In 2009, climate scientists warned of a ”devastating” five-degree temperature increase. They say that we are currently on track for a “five-degree world” where the global population would be slashed from an expected nine billion in 2050 to just one billion people by the end of the century.

Professor John Schellnuber of the Potsdam Institute for Climate Impact Research and one of the world’s leading climate scientists said a “five-degree world” would activate a number of tipping points such as the collapse of the rainforest, the accelerated melting of the Greenland ice sheet, the disruption of the monsoon system, and the creation of “oxygen holes” within the seas that would have disastrous consequences for the food chain.

According to 2,500 Climate Congress scientists, “observations confirm that, given high rates of observed emissions, the worst-case IPCC scenario trajectories (or even worse) are being realized.

New research clearly supports links between extreme weather and climate change. As reported in USA Today, a new climate report titled “Current Extreme Weather and Climate Change,” suggests that U.S. record-breaking extreme weather, likely enjoyed a boost from global warming. In the study, released by the Climate Communication scientific group, leading climate scientists outlined how industrial emissions of greenhouse gases are increasing climate change effects, contributing to the extreme weather seen in 2011.

“Greenhouse gases are the steroids of weather,” says climate projection expert Jerry Meehl of the National Center for Atmospheric Research. “Small increases in temperature set the stage for record breaking extreme temperature events.” The report indicates that a one-degree global average temperature rise in the last century has contributed to recent extreme weather.

In 1950, U.S. record breaking hot weather days were as likely as cold ones. By 2000, they were twice as likely, and in 2011 they are three times more likely. By the end of the century they will be 50 times more likely, Meehl says.

With global warming’s higher temperatures packing about 4% more water into the atmosphere, total average U.S. snow and rainfall has increased by about 7% in the past century, says the study. The amount of rain falling in the heaviest 1% of cloudbursts has increased 20%, leading to more flooding.

Rather than totally triggering any extreme event, global warming just makes it worse, says meteorologist Jeff Masters of Weather Underground. “A warmer atmosphere has more energy,” he says, contributing to heat waves, tornadoes and other weather extremes. “Years like 2011 may be the new normal.”

“There’s really no such thing as natural weather anymore,” says climate scientist Donald Wuebbles of the University of Illinois, who largely agreed with these conclusions. “Anything that takes place today in the weather system has been affected by the changes we’ve made to the climate system.” Wuebbles says.

“The facts of the matter are this: The planet’s climate has changed over the last 30 years, chiefly because of human activities. This will impact the weather – in the trivial sense that the specific weather we are having is not the same as the weather that we would have had without human actions,” climate scientist Gavin Schmidt said.

The study also suggests over the past 30 years, areas covered by snow and ice at least part of the year is diminishing at more than twice the pace projected by global climate models. The Christian Science Monitor reports that the seasonal cooling effect of light-reflecting snow and ice in the Northern Hemisphere may be lessening twice as fast as predicted by climate models, accelerating the impact of global warming.

Mark Flanner, a climate researcher at the University of Michigan who led the team, says the goal of the new study was to provide a reality check on global climate models.’ This study corroborates research published by a different team in 2009, which showed that on the Canadian Archipelago, the melt season grew at a rate of about seven days per decade during the 1979-2008 period.

Despite the fact that deniers are inundated with countless examples of severe weather, they refuse to make the connection to the role humans have played in driving climate change.

In an op-ed in the Washington Post, environmentalist Bill McKibben said, ”It is vitally important not to make connections. It is [far] better to think of these as isolated, unpredictable, discreet events. It is not advisable to try to connect them in your mind with, say, the fires burning across Texas—fires that have burned more of America at this point this year than any wildfires have in previous years. Texas, and adjoining parts of Oklahoma and New Mexico, are drier than they’ve ever been—the drought is worse than that of the Dust Bowl. But do not wonder if they’re somehow connected.”

McKibben pointed out that the China’s central region is suffering through the worst drought they have ever recorded. Colombia has been experiencing massive volumes of rain prompting the Columbian president to say, “We’ve gotten so much rain in the last year, it’s washed away so much of our infrastructure that it’s as if we haven’t been doing any development work for the last 10 or 20 or 25 years.”

The Great Russian drought of 2010 prompted fires and destroyed 25 million acres of crops. Thousands died around the globe as many parts of the world suffered under the record-breaking heat. More recently, the Amazon faced its second “hundred-year drought” in the past five years.

In 2009, research from Singapore revealed that global warming is 37 percent to blame for droughts. Peter Baines of Melbourne University in Australia found an underlying trend where rainfall over the past 15 years or so has been steadily decreasing, with global warming 37 percent responsible for the drop. “The 37 percent is probably going to increase if global warming continues,” he said.

“The scale of this stuff is immense,” McKibben said. “And as long as we just think about it as just a series of one-off, isolated disasters, we probably are not asking ourselves the most important questions. What can we do to stop this destabilization before it gets much worse?”

The effects of global warming are widespread and diverse. Drought, flooding, and extreme weather are widely reported, but other effects are less well known. Some 4 million acres of mature trees in Alaska have been killed by spruce bark beetles. Scientists believe that warmer temperatures have allowed the beetles to breed and mature twice as fast as normal.

Although disputed by some ill-informed deniers, carbon dioxide (CO2) is the most significant of the greenhouse gases, accounting for over 80 percent of climate change pollution. Atmospheric levels of CO2 are now higher than at any time in the past 420,000 years. And the changes we are witnessing are largely due to human behavior. Around 97 percent of the CO2 emitted by western industrialized countries comes from burning coal, oil and gas for energy. We spew approximately 25 billion metric tons of CO2 into the atmosphere every year, which translates to 800 metric tons every second.

According to an EPA report entitled “Climate Change Indicators in the United States,” U.S. greenhouse gas emissions from human sources are increasing. From 1990 to 2008, emissions have grown by 14 percent in the US.

In 2009, Professor Schellnuber warned that emissions were continuing to grow faster than anticipated, while carbon sinks such as tropical rainforests and oceans were becoming less effective at storing carbon.

“The impact on extremes from human emissions is one of a myriad reasons why we probably don’t want to continue to mess with the planetary energy balance,” said climate scientist Gavin Schmidt. Despite the increasing risk of abrupt or irreversible climatic shifts, deniers are undeterred in their crusade against the scientific evidence.

Although we already have many tools and approaches to manage climate change, deniers stand in the way of the economic, technological, behavioral, and management efforts. These people do not seem to care that climate change already causes more than 300,000 deaths per year, nor do they seem concerned about the wars that are likely to be the result of resource scarcity. Deniers are only interested in the facts that are in line with their partisan agenda. When reality does not conform to their revisionism, they simply ignore the facts or dismiss them as a conspiracy.

The deniers’ propaganda campaign has confused the public and Congress about the science of climate change. Deniers are buoyed by the oil industry, which spends hundreds of millions on lobbying against climate change legislation. A huge well funded disinformation campaign has managed to weave uncertainty into the debate.

It is hard to understand how any thinking person could dismiss the entire body of evidence supporting anthropogenic climate change. After decades of peer-reviewed research, it is obvious to all but the willfully belligerent that the climate is changing and humans are the cause.

Even if you eschew the reams of scientific data that predict a warming planet, there are numerous factual observations that make the point abundantly clear. Rather than being driven by science, much of the debate on global warming has been led by ideologically driven deniers who publish pseudo-science or work to undermine competing research. For those who simply refuse to believe the facts, there is little that will penetrate their fervent dogmatism.

Sadly, Republicans are the legislative mouthpiece of the deniers and they control the House of Representatives. In the spring of 2011, the House voted by a 50-vote majority against a resolution that says climate change poses a significant risk to human health.

The dogmatism of the deniers is not merely driving legislative deadlock, it imperils life. Former Clinton White House chief of staff John Podesta said it best when he called climate deniers the “Know Nothings” of the 21st century.