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."
"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.
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."