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A photo of tourists looking over Navajo Canyon from a rock ledge at Mesa Verde in 1948.

Tourists overlook Navajo Canyon in 1948 at Mesa Verde National Park, which is now vulnerable to increased flooding and more frequent wildfires.

Photograph by Willard Culver, National Geographic

Brian Clark Howard

National Geographic

Published July 1, 2014

With average global temperatures expected to rise more than 3.6 degrees Fahrenheit (2 degrees Celsius) over the coming decades, a new report from a leading U.S. environmental group warns that future summers are likely to be filled with more misery, from more prolific poison ivy and biting insects to worsened air and water quality and impacts on tourism.

"Summer has always been a time many people look forward to, but climate change is causing more and more threats that we need to be mindful of," says Kim Knowlton, a co-author of the new report and senior scientist with the New York-based Natural Resources Defense Council (NRDC).

"We see more than ever that climate change is affecting people's health here and now in the U.S.," says Knowlton, who was also a lead author of the White House's National Climate Assessment that was released in May and is an assistant clinical professor at Columbia University's Mailman School of Public Health in New York. (See "Federal Climate Report Highlights Risks for Americans.")

The elderly, children, and those with existing circulatory and respiratory conditions are most at risk, she adds.

NRDC's new report builds on recent scientific and policy findings, including the peer-reviewed National Climate Assessment, which argued that climate change is already resulting in substantial financial, public health, and ecological costs, from increasingly severe weather to disruption of infrastructure. The report pointed to droughts in the West and flood-based damage to roads in the East, in particular.

A report released in late June by a bipartisan committee of U.S. political and business leaders warned that climate change over the next century threatens extensive property damage from catastrophic flooding and sea-level rise, dangerous heat waves, and severe disruption of agriculture in the American corn belt and Southeast. (See "5 Dire Warnings From Bipartisan Report on Climate Change.")

And in August 2013, a study published in Science warned that wars, murders, and other acts of violence will likely become more commonplace in coming decades as the effects of global warming cause tempers to flare worldwide.

Added to this list of risks are eight trends that may make summers more miserable—and potentially more dangerous—thanks to global warming. "They will get worse unless we take serious actions to combat climate change," the NRDC report says.

The group adds that President Obama's Climate Action Plan, which includes new limits on carbon dioxide emissions from coal-fired power plants, is a "great start."

The increased summer risks include:

1. Heat Waves

"Summers have always been hot, but they're getting hotter," says Knowlton. Specifically, the NRDC report warns that climate change will make heat waves longer, hotter, and more frequent.

Eight of the nine warmest years since recordkeeping began in 1880 have occurred since 2000, the report notes. "May 2014 was the hottest May ever. And temperatures could be hotter by 4 to 11 degrees Fahrenheit by 2100."

NRDC also warns that heat is the leading weather-related killer in the United States, killing people directly through heat stroke and indirectly by exacerbating conditions such as heart and respiratory disease.

The bipartisan report released in June had noted that heat waves are likely to be especially strong in the Southwest, Southeast, and upper Midwest.

"By the middle of this century, the average American will likely see 27 to 50 days over 95°F each year—two to more than three times the average annual number of 95°F days we've seen over the past 30 years," that report warned. "By the end of this century, this number will likely reach 45 to 96 days over 95°F each year on average."

2. Bad Air Days

"With climate change, days will be hotter and that will amp up ground-level ozone smog pollution and increase the number of 'bad air days,'" the NRDC report cautions.

This will result in more respiratory irritations and will exacerbate problems among those who already suffer from asthma, a population of 27 million Americans.

3. Biting Insects

The report warns that climate change "may create more favorable conditions for the spread of disease-carrying insects."

The Environmental Protection Agency has warned that rising temperatures are likely to increase the spread of ticks carrying Lyme disease and mosquitoes carrying the West Nile and dengue viruses.

"A harbinger: in 2012, Maine recorded its first human case of West Nile Virus," noted the report.

4. Poison Ivy

"Poison ivy seems like a common concern, but there are hundreds of thousands of really serious reactions to it each year," Knowlton says.

The number of those cases "will get worse with climate change because poison ivy grows faster and is more toxic as carbon dioxide pollution increases," the report warns.

Today, poison ivy is found in every state except Alaska, Hawaii, and California, although the similar poison oak grows in the latter. Climate change is likely to cause the plant to spread and "grow lusher and more toxic," says Knowlton.

5. Allergies

Thirty to 40 million Americans suffer wheezing and sneezing from seasonal allergies. That's likely to increase as warmer temperatures and higher carbon dioxide levels encourage weedy plants to grow, the report warns.

A 2011 study found that ragweed, one of the most notorious producers of allergens, sheds pollen up to a month longer than it did in 1995 in some parts of North America.

When high ozone levels combine with high pollen counts, it can produce a "double whammy" for respiratory health, says the report.

6. Food-Borne Illness

Another way climate change may make us sick is by encouraging growth of food-borne bacteria like Salmonella and Campylobacter, the report warns. The rates of salmonellosis and campylobacteriosis are already highest in summer.

Increased growth of toxic algal blooms in coastal waters also increases the likelihood of transmission of illness through seafood.

7. Dangerous Swimming

Algal blooms can also make it risky to swim in affected waters, both through ingestion of water and through damage to the skin.

"It's probably a good idea to avoid going swimming right after a large rain," Knowlton adds, since rain tends to wash pollution and bacteria from the land into the water.

8. Ruined Visits to National Parks

The report warns that many of the U.S.'s "iconic national parks, landmarks and heritage sites are at risk from climate change. Sea level rise, coastal erosion, increased flooding, heavy rains, and more frequent wildfires are damaging park land, archaeological resources, historic buildings, and cultural landscapes across the nation." (See "Can an Iconic Lighthouse Be Saved From the Sea?")

To prevent these threats from becoming inevitable, NRDC asks concerned citizens to support efforts to curb emissions of greenhouse gases.

In Time for Skeptic Conference?

NRDC's report comes just days before the conservative Heartland Institute's 9th International Conference on Climate Change in Las Vegas July 7-9. Billed as "the world's largest gathering of global warming skeptics," the conference is scheduled to present 60 "scientists and policy experts" and is supported by the Competitive Enterprise Institute, the Heritage Foundation, the George C. Marshall Institute, and about 30 other groups.

"This is a great show of unity in opposition to the global warming alarmism of President Obama and radical environmental groups," said Joseph Bast, president of the Heartland Institute, in a statement.

Bast argues that the costs of trying to prevent global warming far exceed the benefits.

"If we don't take action," counters Knowlton, "future summers aren't going to be a picnic for our kids and grandkids because of climate change."

Follow Brian Clark Howard on Twitter and Google+.

52 comments
Guy Holder
Guy Holder

More computer models and projections? We're onto you hoaxters - there's been no global warming for over 17 years.

Jerry Branscum
Jerry Branscum

Climate change is also occurring on Mars.  So, how are Earthlings responsible for it?  And how to we stop it?

Seriously though, climate change is constantly occurring.  The Earth warms, the Earth cools.  We have had numerous ice ages (major and minor), and many warming cycles.  To date, no one has definitive evidence that human influence on this natural cycle will result an an epoc level event.

For the most part, since the Mayan Calander failed to end the world, the drama queens have just been looking for the next 'sky is falling' event.  Heck, I remember back in the late 70s when we are all suppose to die because of global cooling.

Charles Tollefson
Charles Tollefson

You cant fix what is being told because its a lie. Start with telling the truth on what is happening. Carbon taxes will not fix anything. Look at the other planets and whats happening to them also. Why is the government building massive underground facilities stocked to the brim?

Dipanjan Mitra
Dipanjan Mitra

"concerned citizens"? in my country? I wonder how many. National Geographic should conduct a survey to find out how many citizens are actually aware about climate change and what actions are they taking to fight it.would love to see the result.

Stanley Penkala
Stanley Penkala

For the short-memory crowd, please note that Washington, DC was built on a swamp, subject to malaria and other insect-borne diseases that forced people who could afford it to leave the city each summer. Those afflictions are now controlled by suitable amelioration [insect controls, air conditioning, etc.], just as these eight summertime miseries can be controlled, at far less cost to society than the proposed "carbon" controls. Of course, some of these "miseries" are not subject to amelioration [heavy rains, severe storms], but they are also not causally related to CO2 increases. 

The controls that these environmentalists wish to place on anthropogenic carbon dioxide have never been proven to change our climate, positively or negatively. It is only by subjective assumptions that anthropomorphic CO2 has the warming effects predicted by climate models. And that continued warming has not taken place for the past 17 years now, while the model predictions continue to deviate from actuality.

In fact, that lack of continued warming has many advocates of CO2 controls now claiming that severe winter weather is also due to increasing CO2. And it has driven scientists in the government agencies tasked with monitoring the global temperatures to the expediency of modifying the temperature records under their control so as to enhance the APPEARANCE of global temperature increases.


Beto Sabio
Beto Sabio

Republican Speaker of U. S. House of Representatives.... John Boehner says:


"Republicans will not pass Any Legislation, Period, because we cannot trust the President of the United States to carry out the laws".

Flower Jasmin
Flower Jasmin

short version of the article for the ones who don't have time to read "every boo boo is because of global warming that is happening now because it will happen in decades (preemptive warming of the nature ). Instead of living for 150 like we used to for centuries we will be living like 100."


Leo Alapont
Leo Alapont

Climate change believer or denier, you can't escape the fact that human beings are out for ourselves only. Landfills, plastic mass in the ocean, New York, Las Vegas, what is it all for?

Leo Alapont
Leo Alapont

We do it to ourselves and that's why it really hurts... This Earth was so perfect before we screwed things up.

Dennis Shelton
Dennis Shelton

  I think that global warming is happening. I think humans are probably contributing to it in a significant way. I hope I'm wrong. 

    I also think that the news media are unlikely to ever inform the public of the facts -- mainly because I don't think there are many among them who would know a fact if it bit them on the @$$. As evidence of this, I note the list of 800+ stories that have been cited. The story about 15 years without warming is pooh-poohed as being an anomaly, and yet the flimsiest evidence supporting warming is trumpeted from the roof-tops! Note to global warming worriers: YOU CAN'T HAVE IT BOTH WAYS!!! Abandoning logic only hurts your cause.

     I think we have a potentially serious problem. 

     I don't think it's getting much serious thought from either side.

Tu Fur
Tu Fur

I just read a boots on the ground study on emperor penguins that said they move their nesting sites according to weather. Then I read a story that claimed emperor penguins populations are slated to diminish because of global warming. This turned out to based on a computer model projection that didn't take into consideration the penguins lifestyle.


I do enjoy reading these silly alarmist stories. I am waiting for the internet to be blamed on global warming. Just think, if we had never left the ice age, all these click bait stories would have been written only on a cave wall.

Dwayne LaGrou
Dwayne LaGrou

Climate Change, or Global Warming, Whatever you want to call it is here. The amount of atmospheric CO2 in the air has passed the 400ppm mark and is still rising. It took nature Millions upon Millions of years to change and store all of the CO2 that is in Coal, oil, gas and The frozen permafrost. We have burned so much of that stored CO2 that it is now being released all at once what took Millions of years to store. It is simple 2nd grade math. How can anyone deny those facts.

We are just starting to see natures response to burning all of these "FOSSIL FUELS". Why do you think there are called "Fossil Fuels"?!

Peter Vogl
Peter Vogl

I would be happy with 95 degrees, normally most of our summers we see weeks of over 100 and usually 10 to 20 days where it gets over 110 degrees here in north Tx.

Sam Primavera
Sam Primavera

"Expected to Rise"? Haven't you people been paying attention? This "expectation" is based on computer models. The computer models have been shown to be flat wrong. There has been no warming at all for the past 15 years. There may have been even some cooling based on how you correct or don't correct for the urban heat island. The models predicted consistent rapid warming. It did not happen.

Gerard Van der Leun
Gerard Van der Leun

Global Warming, is there anything you can't do!?


Why you even give marginal employment to the otherwise uninspired blatherers such as Howard.


You go, Global Warming!  Lets have more. A lot more.

Chris Crawford
Chris Crawford

@Guy Holder Wrong. Sea level has continued to rise steadily all this time. The sea is rising because the ocean is warming.

And you apparently are unaware of the fact that computer models are used in just about every field of effort. Any medications you take were probably subjected to analysis by computer model during their development. Are you going to stop taking them?

Chris Crawford
Chris Crawford

@Jerry Branscum Climate change similar to that on earth is NOT happening on Mars.


I see that you are parroting one of the latest denier website talking points: that climate change has always happened. That talking point deceptively fails to mention that there is no evidence of any climate change at any time in earth's history as rapid as the current bout. 


"To date, no one has definitive evidence that human influence on this natural cycle will result an an epoc level event."

I suggest that you download and read IPCC AR5 WG1 from www.ipcc.ch. It is 2,000 pages long and presents overwhelming evidence that human emissions of carbon are causing the current warming, and it will get much worse if we continue emitting carbon at increasing rates./

Trent Poole
Trent Poole

@Leo Alapont How do we fix it with 7+ billion people on earth. I can recycle til the day I day, ride my bike, and not flush my toilet but can't solve all the problems of the earth. Are we selfish or is this just what life is?


Jack Wolf
Jack Wolf

@Dennis Shelton  The media is also ignoring the biggest crime story on the planet, ever.  Our government has known about the serious implications of co2 emissions since LBJ was presented with a report in his second term - he spoke to Congress about it.  Scientists have understood for over 100 years.


I don't know what's more shocking - the fact that it is now catastrophic and irreversible, or that our leaders knew about it, And Did Nothing.  Absolutely Nothing.


Chris Crawford
Chris Crawford

@Dennis Shelton I think you're being too harsh on the media. The problem here is the vast chasm between the technical material and the level of education of the average American. How do you explain something as complicated as climate change to people who don't know basic physics? I've done a good amount of teaching, and the primary limitation is always the knowledge level of the students. The more they know, the more you can teach them. And since the average American knows almost nothing, you really can't teach them much. 

I have seen some screwed-up explanations of material that I understand well, but I'd say that maybe 90% of the science news stories I have read get as close to the truth as you can get in a short space. Don't knock their work until you've walked a mile in their shoes.

Let me remind you that this sentence of yours makes some pretty wild scientific judgements:

"The story about 15 years without warming is pooh-poohed as being an anomaly, and yet the flimsiest evidence supporting global warming is trumpeted from the rooftops."

You assume here that the 15-year period is scientifically significant, an opinion that is contradicted by the science -- I'll explain if you wish. I'd also like an example of this 'flimsiest evidence' to which you refer. Let's get specific, shall we?

I'm not defending each and every global warming advocate; there are plenty of nut cases out there. But I've never seen anything wacko in the mainstream media. By contrast, the wacko-count on the denier side is off the scale.

Chris Crawford
Chris Crawford

@Tu Fur If  you think that the second study was flawed because it used a computer model that did NOT take into account their behavior, then you should write up another paper presenting your case and showing that they're wrong. Of course, you'll have to be sure that you're correct. What factors did their computer model take into account? Surely you've read their paper -- I could not believe that anybody would criticize a paper without having read it.

Chris Crawford
Chris Crawford

@Gerard Van der Leun Um, that list is bogus. For example, check the entry "witch burnings". It links to a link from another denier site that quotes the contents of the first denier site -- and adds witchcraft burnings as hyperbole. This is circular nonsense.

Gail Edington
Gail Edington

@Gerard Van der Leun My personal favorite on that list  is that "computer models" are caused by global warming. I was also charmed to read the link labelled "polar tours cancelled" that listed American hotels under  £100. Unfortunately the link that proves that someone claimed that successful lawsuits were caused by global warming is dead.  


Doc Holiday
Doc Holiday

@Gerard Van der Leun you know you can still find scientists that say cigarettes don't cause health problems.



the commonality? paid shrills.


just because you heard it on talk radio doesn't make it true.

Chris Crawford
Chris Crawford

@Sam Primavera Wrong. The computer models have been shown to be right on the money. If you disagree, then please tell us HOW wrong they are. What's mean LSE for their output? You don't know? Gee, that's like saying that the Dodgers beat the Red Sox but you don't know the score. Not very well-informed.  And yes, there has been warming for the last 15 years, but it has been in the oceans, not the atmosphere, and the oceans hold 99% of the earth's surface heat. Don't believe me? Then explain why sea levels have continued their steady rise during these past 15 years.

Jerry Branscum
Jerry Branscum

@Chris Crawford @Guy Holder The sea levels have risen many many times in the history of the Earth.  Just like ice ages have happened many many times.  During these times, mankind either was just a blip on the ecological radar, or non-existent.

The Earth is not a static ecosystem.  It is constantly changing.  Yet somehow, without the meddling of mankind, it has always survived.  It is the ultimate vanity to think that mankind is the cause of the changes, and the ultimate folly to think we can stop it.

Guy Holder
Guy Holder

@Chris Crawford @Guy Holder 

Sea rise has been pretty consistent since long before our co2 emissions could have had any impact. See these Florida trends.

http://tidesandcurrents.noaa.gov/sltrends/sltrends_states.shtml?region=fl

Here's the trend for New York since 1850.
http://1.usa.gov/To9TIe

Models are useful but ultimately data and observations must support the hypothesis and they don't.

The only time where there was some correlation between co2 and temperatures was between the late 70's and late 90's, Historically higher co2 levels followed warmer temperatures not the other way around.

Excluding rising land masses, sea level rise averages under 1mm a year. 

http://stevengoddard.wordpress.com/2013/12/25/average-sea-level-rise-rate-is-0-9-mmyear/

Jerry Branscum
Jerry Branscum

@Steve Offutt @Jerry Branscum Debunked, yes.  However, it is an example of how mythical epoc events are sensationalized and misconstrued to further agendas.  I put the currently fear mongering in the same file as that of the 70s.

David Seabaugh
David Seabaugh

@chris Crawford. I will note that you are under the influence of a dangerous cult and are unaware of it. You are the poster boy for delusional.

Leo Alapont
Leo Alapont

For starters demand that all public companies, like Coke and Procter &Gamble, package their products in biodegradable containers. End of story, otherwise a global tax is to be placed on each and every product sold in any country in plastic.

Chris Crawford
Chris Crawford

@Trent Poole @Leo Alapont We do have choices as to whether we make matters much worse or a bit better. The average American releases 17 tons of carbon per year. The average Chinese releases 5 tons of carbon per year. Is this just life? The average European emits about 10 tons of carbon per year. Are Europeans living that much worse than Americans?

j smith
j smith

@Doc Holiday @Gerard Van der Leun


btw it's "shills" not "shrills".  I get what your saying though, anyone who doesn't agree with this concept of man- induced global climate change is either paid off, or ignorant.  Hmmm, might want to visit that conference in Vegas

Doug Hornby
Doug Hornby

@Chris Crawford @Sam Primavera  There are groups that distrust computer models, and groups that embrace them. I find it interesting that those who embrace, are typically from the "government support and protect me" side, and those that do not trust, are from the "smaller government side.

Essentially from the left, and the capitalistic sides. Those people who know how to make wealth, do not trust those who depend on the taxes from that wealth, for their own wealth.


I wonder why that is?

Chris Crawford
Chris Crawford

@Jerry Branscum @Steve Offutt The moral of the hype over 'global cooling' is that you shouldn't pay attention to anybody but the scientists. While the media were all hyperventilating about global cooling, the scientists were saying clearly that it wasn't happening and wasn't going to happen. Yet people ignored them, just like they're doing today. 


The current science is overwhelmingly backed up by the evidence, and rational people who are motivated by money rather than ideology are treating AGW seriously.  Recently the bosses of several big firms, including Coca-Cola and General Mills, demanded that government stop stalling and negotiate a treaty on greenhouse gases. A report prepared under the auspices of Michael Bloomberg and several other wealthy persons showed how much climate change will cost the US in coming years -- and it starts off in the tens of billions of dollars.

Jerry Branscum
Jerry Branscum

@Chris Crawford @Jerry Branscum @Steve Offutt Yes, the science supporting climate change is indisputable.  It is happening on Earth, Mars, Venus, etc.  Every active planet experiences climate change.  

Yes, mankind lends some to climate change, as does every other living animal on the planet.  However, evidence showing that unless mankind reduces its carbon footprint, the Earth will experience an epoc level event is sorely lacking.

Without evidence, some unscrupulous scientists are willing to play chicken little, and yell the sky is falling, for grant money and recognition.  They will talk of consensus, because they lack irrefutable evidence that we are headed to an irreversible and catastrophic event.  If they had irrefutable evidence, there would not be a need for consensus.  Even the mere mention of consensus casts doubt on the hypothesis.

Of course corporations are want to appear 'green' friendly.  It is good press at no cost to themselves.  They are backing that there will not be any serious costs to them before the whole idea is debunked.  And the wealthy supporting the idea?  They are the ones that own the companies that will rake in millions reducing carbon footprints that they would not be able to make without drumming up all the drama.

Those who hide behind science to justify their agendas should make sure that the scientific method has been satisfied.  In every projection that says we are causing an epoc level event, I can name a plethora of variables that are either not defined, or insubstantially defined in order to create the desired projection.

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