Network News

X My Profile
View More Activity
The new Washington
Post Weather website
Jump to CWG's
Latest Full Forecast
Outside now? Radar, temps
and more: Weather Wall
Follow us on Twitter (@capitalweather) and become a fan on Facebook
Posted at 1:45 PM ET, 11/ 9/2010

Do Americans think global warming is manmade?

By Jason Samenow

* Sun and 60: Full Forecast | Von Karman vortex streets *

Andrew Freedman, in yesterday's piece Scientists launch climate science counter attacks, wrote "a majority of Americans already accept manmade climate change as a reality."

Capital Weather Gang's Matt Rogers challenged Freedman with the following comment:

Andrew, what is your source for this statement: "a majority of Americans already accept manmade climate change as a reality"? The Yale poll you linked in a previous article said 50% and a recent Rasmussen poll is running at 39%.

Then reader marcusmarcus cited a New York Times op/ed by Stanford researcher Jon Krosnick who stated his polling indicates "...huge majorities of Americans still believe the earth has been gradually warming as the result of human activity."

But as Matt Rogers then pointed out, a closer read of the polling data might lead one to a more nuanced conclusion. It indicates 45% of Americans think natural causes and human activities contribute to global warming equally, 30% believe it's mostly human and 25% mostly natural. Also, 24 percent of respondents - in a separate question - indicated they didn't think the Earth was even warming.

Other polls out there offer varying results:

* The latest poll I could find, released by Pew Research on October 27, indicates just 34% of respondents replied there is "solid evidence" the Earth is warming due to human activities compared to 18% who stated the warming is due to natural causes. Thirty-two percent responded the Earth isn't warming.

* A survey from Angus-Reid, published October 21, found 42% of Americans think "global warming is a fact and is mostly caused by emissions from vehicles and industrial facilities."

* A Gallup poll from March shows 50% of Americans attribute warming more to human activity than natural causes.

The variability in these results likely reflects the different way the poll questions and responses were designed.

Notice the different questions and response options among the various polls I've mentioned:

* From Rasmussen: "Is Global Warming caused primarily by human activity or by long term planetary trends?" Potential problems: There is no option for a roughly equal mix of causes. Also, the question forces those who don't believe warming is happening to pick a cause, which is odd.

* From Yale: "Assuming global warming is happening, do you think it is...Caused mostly by human activities, Caused by both human activities and natural changes, Caused mostly by natural changes in the environment, None of the above because global warming isn't happening, Other, Don't know." Potential problems: The option of both human and natural causes had to be volunteered by respondents and was not provided as stated option, likely biasing that option's result on the low side (just six percent). Also, only seven percent chose "none of the above because global warming isn't happening" whereas as in separate question 19% of respondents said global warming wasn't happening, and 19% said they didn't know if it was happening.

* From Stanford (Krosnick): "[Assuming global warming is happening] Do you think a rise in the world's temperature is being (would be) caused mostly by things people do, mostly by natural causes, or about equally by things people do and by natural causes?" Potential problem: This wording forces people who don't believe warming is happening to attribute a cause. Twenty-four percent of respondents in a previous question indicated they thought warming had probably not occurred over the last 100 years.

* From Pew Research: "Is there solid evidence the Earth is warming? Yes, [and if yes], Because of human activity, Because of natural patterns [or] Don't know; No; or Don't Know." Potential problem: The poll doesn't allow respondents to say it's a mix.

* From Angus-Reid: "Which of the following statements comes closest to your view of global warming (or climate change)? Global warming is a fact and is mostly caused by emissions from vehicles and industrial facilities, Global warming is a fact and is mostly caused by natural changes, Global warming is a theory that has not yet been proven, and Not sure." Potential problem: The option of a mix of natural and human activities is absent.

* From Gallup: "And from what you have read or heard, do you believe increases in the Earth's temperature over the last century are due more to the effects of pollution from human activities or natural changes in the environment that are not due to human activities?" Potential problems: This question doesn't allow respondents to indicate it's a combination. Also, you could argue that Gallup's use of the word "pollution" might bias results because the notion of global warming gases being "pollutants" might be controversial to some respondents.

Clearly, one can find shortcomings with the design of all of these questions and response options. Considering all of the results together, what seems to be evident is that of Americans who believe the globe is actually warming, about half believe it is mostly manmade - per the Yale and Gallup polls. But, as about 20-30 percent of Americans don't believe warming is happening at all (depending on the survey), it seems well less than half - probably between 35 and 40 percent per the Pew Research and Angus-Reid poll - believe warming is both occurring and mostly manmade.

Because few polls explicitly provide an option for a partial contribution of human activities to the observed warming, it's difficult to say whether Freedman's statement "a majority of Americans already accept manmade climate change as a reality" is supportable. That appears to be a gray area that better polling design might help clarify- which excludes those who don't believe warming is happening from voting on the cause and allows those that do believe warming is happening to indicate it might be a result of a combination of factors (rather than mostly/all natural or mostly/all manmade).

So here's a challenge for readers: How would you design a poll question to more accurately gauge public opinion about global warming and its causes?

By Jason Samenow  | November 9, 2010; 1:45 PM ET
Categories:  Climate Change  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: The mystery of the von Karman vortex street
Next: PM Update: Sunny and 60+ tune keeps playing


Suggest that you fix the first word in the title of this post -- it should be "do", as in "Do Americans think global warming is manmade?"

Posted by: natsncats | November 9, 2010 1:59 PM | Report abuse

natsncats - hi there, does it read better now? thanks for flagging.. I think it is fixed

Posted by: Camden-CapitalWeatherGang | November 9, 2010 2:21 PM | Report abuse

I think you've summarized the issues with wording pretty well. The only thing I would add is that the mix is a complex subject. Last winter's El Nino came and went and the peak temperature essentially reached the 1998 peak. But 1998 was a super El Nino. So that would indicate to me a bit "baseline" warming that I would attribute to manmade GHG, not a "mix". But then again, natural trends from the end of the Little Ice Age may still be contributing some warming.

Posted by: eric654 | November 9, 2010 2:24 PM | Report abuse

Jason, great post- really appreciate all the insight on the various polling questions. I'm surprised with the sometimes 1/4 of respondents who don't believe there is any warming at all. Now does the climate change consensus believe in a potential roughly equal mix (man-made/natural)? I was under the assumption that it did not.

Posted by: MattRogers1 | November 9, 2010 2:37 PM | Report abuse

Thank you Camden :-)

Posted by: natsncats | November 9, 2010 2:46 PM | Report abuse


The IPCC concluded most (without specifying what most means, but presumably more than 50%) of the warming in the last 50 years is very likely (probability greater than 90%) the result of human activities.

Posted by: Jason-CapitalWeatherGang | November 9, 2010 2:49 PM | Report abuse

No one can say with anything close to certainty what percentage of global warming/climate change is caused by man-made activity. And any set of data is apt to be challenged by naysayers.

But the correlation between increased use of fossil fuels and the rise of global temperatures, particularly in the past century, strongly suggests that mankind is the primary cause.

Globally, the enviornment is being ravaged by so many activities that originate with mankind. The vanishing marshes in southern Louisiana, overgrazing in many countries, air and water pollution, etc.

There's an old adage, "It's an ill bird that fouls its own nest." The enviornmental havoc we wreak is enough to convince many that mankind surely has to be one of the most self-destructive species ever to populate this planet.

Posted by: JerryFloyd1 | November 9, 2010 3:19 PM | Report abuse

Unpredictable energy changes from the sun seem to be the most obvious choice that was not made available. We can not predict changes in sun activity and we have no science that can predict how different changes in different parts of the sun affect the earth. We have along way to go before sun activity can be predicted or used to forecast accurate changes on the earths temperature. Long term changes in temperature are not predictable at this time. Hysteria over the unpredictable is great fun for politicians and fear mongers.

Posted by: cosciousness | November 9, 2010 4:14 PM | Report abuse

What seems to be missing is a question to get at the why of the responses

Posted by: SteveT-CapitalWeatherGang | November 9, 2010 4:22 PM | Report abuse

I'd design the question like this.

1. Do you believe that the climate is warming, regardless of the cause?

Question 2 would only be asked if the answer to 1 was "Yes."

2. What do you believe is the cause of global warming?
-Predominantly human activity, such as vehicle and industrial emissions.
-Predominantly natural phenomena, such as normal climate cycles.
-A combination of human activity and natural phenomena.

To me this is the only way to go. I use the term predominantly, because a lot of people would shy away from a 100% answer. Even the science cannot determine the exact percentage of causation. I use the term "combination" without getting into the gritty details because most lay people probably have not thought about whether it is 50/50 or 70/30. If they believe both factors play a significant role, the "combination" answer is easy to pick.

Posted by: jahutch | November 9, 2010 5:25 PM | Report abuse

I wonder if one of the reasons ostriches stick their hands in the sand is they are allergic to sun burn?

Posted by: JerryFloyd1 | November 9, 2010 5:30 PM | Report abuse

It doesn't matter what polls say. Americans can believe whatever they want, it doesn't change the fact that the earth is heating up.

We have two choices: do nothing and go extinct or try to do something to stave that off. Even if it fails, it's got a better chance of succeeding than pretending it isn't happening.

Posted by: AxelDC | November 9, 2010 6:17 PM | Report abuse

Two clarifications I'd like in a good poll question (or at least, a good poll question for scientists... precision doesn't always improve clarity):

1) timescale: since the 1950s? 1900s? The LIA? The last glaciation? The answer changes a lot depending on where one starts from.
2) substances: just GHGs? GHGs and aerosols and other human influences? Just GHGs is a simpler, cleaner question, but the other influences matter for climate too.

The IPCC addresses "since the mid-20th century" and states that "most" of the warming is "very likely" due to anthropogenic GHGs.

The warming in the early part of the century is attributed by the IPCC (if I recall correctly) to a mix of GHGs, a pause in volcanic activity, an increase in solar forcing, and natural variability.

So... if you ask me, what % of warming does the IPCC attribute to GHGs, the answer can vary from >50% since the 1950s, to maybe something like >35% since 1900 (though the central estimate of the IPCC is likely much higher than that lower bound).

So what is a good question? Maybe the following?
1) Has there been warming (averaged over the surface of the whole planet) in the past 50 years?
2a) If so, have humans emissions of GHGs from burning fossil fuels and other sources contributed most of that warming, about half of that warming, some of that warming, or none of that warming?
2b) If not, was the net effect of humans warming, cooling, or near-zero?

Posted by: marcusmarcus | November 9, 2010 6:27 PM | Report abuse

Yes, a small part of climate warming (the Urban Heat-Island Effect) is indeed man-made (and the urban heat-island effect, from paving and building, has been proven scientifically). But most of the rest of the Al Gore-type "Greenhouse-Warming" theories from fossil-fuel-burning are a bunch of nonsense......just a bunch of hot air, if I can use a pun.

Posted by: MMCarhelp | November 9, 2010 8:49 PM | Report abuse

MM, I fail to see your logic and reasoning with that post. You state that it is a fact that human activity can have effects on the climate on the city/county-scale. Yet, you assert that there is no way that human activity could possibly effect the large scale climate. Given the time scales of planet, it just seems hypocritical to me.

The approach that AGW-skeptics seem to be taking is, in simple terms: The atmosphere is too big, what miniscule amounts of substances we put into it could not possibly have any drastic effects. We've taken that approach before too. In the 19th and 20 centuries, lax regulations allowed industrial waste and other chemicals to be minimally treated and expunged into the rivers/lakes. The reasoning was the same, They're too big to be affected, and whatever problems might arise will be washed downstream. Ask the people of Cleveland how that line of logic turned out. The only difference is, if the effects of AGW are allowed to come to fruition, there's no river to take them downstream.

Posted by: Brian-CapitalWeatherGang | November 10, 2010 9:13 AM | Report abuse

Nice post, Jason. And thanks for pointing out the flaw in my statement, Matt.

Posted by: afreedma | November 10, 2010 4:20 PM | Report abuse

The comments to this entry are closed.

RSS Feed
Subscribe to The Post

© 2012 The Washington Post Company