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Saturday, October 15, 2011

The Big Picture: Getting Skeptical About Global Warming Skepticism

Skeptical Science
Getting Skeptical About Global Warming Skepticism

The Big Picture

Posted on 24 September 2010 by dana1981

Oftentimes we get bogged down discussing one of the many pieces of evidence behind man-made global warming, and in the process we can't see the forest for the trees. It's important to every so often take a step back and see how all of those trees comprise the forest as a whole. Skeptical Science provides an invaluable resource for examining each individual piece of climate evidence, so let's make use of these individual pieces to see how they form the big picture.

The Earth is warming

We know the planet is warming from surface temperature stations and satellites measuring the temperature of the Earth's surface and lower atmosphere. We also have various tools which have measured the warming of the Earth's oceans. Satellites have measured an energy imbalance at the top of the Earth's atmosphere. Glaciers, sea ice, and ice sheets are all receding. Sea levels are rising. Spring is arriving sooner each year. There's simply no doubt - the planet is warming.

And yes, the warming is continuing. The 2000s were hotter than the 1990s, which were hotter than the 1980s, which were hotter than the 1970s. 2010 is on pace to be at least in the top 3 hottest calendar years on record. In fact, the 12-month running average global temperature broke the record 3 times in 2010, according to NASA GISS data. Sea levels are still rising, ice is still receding, spring is still coming earlier, there's still a planetary energy imbalance, etc. etc. Contrary to what some would like us to believe, the planet has not magically stopped warming.

Humans are causing this warming

There is overwhelming evidence that humans are the dominant cause of this warming, mainly due to our greenhouse gas emissions. Based on fundamental physics and math, we can quantify the amount of warming human activity is causing, and verify that we're responsible for essentially all of the global warming over the past 3 decades. In fact we expect human greenhouse gas emissions to cause more warming than we've thus far seen, due to the thermal inertia of the oceans (the time it takes to heat them). Human aerosol emissions are also offsetting a significant amount of the warming by causing global dimming.

There are numerous 'fingerprints' which we would expect to see from an increased greenhouse effect (i.e. more warming at night, at higher latitudes, upper atmosphere cooling) that we have indeed observed. Climate models have projected the ensuing global warming to a high level of accuracy, verifying that we have a good understanding of the fundamental physics behind climate change.

Sometimes people ask "what would it take to falsify the man-made global warming theory?". Well, basically it would require that our fundamental understanding of physics be wrong, because that's what the theory is based on. This fundamental physics has been scrutinized through scientific experiments for decades to centuries.

The warming will continue

We also know that if we continue to emit large amounts of greenhouse gases, the planet will continue to warm. We know that the climate sensitivity to a doubling of atmospheric CO2 from the pre-industrial level of 280 parts per million by volume (ppmv) to 560 ppmv (we're currently at 390 ppmv) will cause 2–4.5°C of warming. And we're headed for 560 ppmv in the mid-to-late 21st century if we continue business-as-usual emissions.

The net result will be bad

There will be some positive results of this continued warming. For example, an open Northwest Passage, enhanced growth for some plants and improved agriculture at high latitudes (though this will require use of more fertilizers), etc. However, the negatives will almost certainly outweigh the positives, by a long shot. We're talking decreased biodiversity, water shortages, increasing heat waves (both in frequency and intensity), decreased crop yields due to these impacts, damage to infrastructure, displacement of millions of people, etc.

Arguments to the contrary are superficial

One thing I've found in reading skeptic criticisms of climate science is that they're consistently superficial. For example, the criticisms of James Hansen's 1988 global warming projections never go beyond "he was wrong", when in reality it's important to evaluate what caused the discrepancy between his projections and actual climate changes, and what we can learn from this. And those who argue that "it's the Sun" fail to comprehend that we understand the major mechanisms by which the Sun influences the global climate, and that they cannot explain the current global warming trend. And those who argue "it's just a natural cycle" can never seem to identify exactly which natural cycle can explain the current warming, nor can they explain how our understanding of the fundamental climate physics is wrong.

There are legitimate unresolved questions

Much ado is made out of the expression "the science is settled." My personal opinion is that the science is settled in terms of knowing that the planet is warming dangerously rapidly, and that humans are the dominant cause.

There are certainly unresolved issues. There's a big difference between a 2°C and a 4.5°C warming for a doubling of atmospheric CO2, and it's an important question to resolve, because we need to know how fast the planet will warm in order to know how fast we need to reduce our greenhouse gas emissions. There are significant uncertainties in some feedbacks which play into this question. For example, will clouds act as a net positive feedback (by trapping more heat, causing more warming) or negative feedback (by reflecting more sunlight, causing a cooling effect) as the planet continues to warm?

These are the sorts of questions we should be debating, and the issues that most climate scientists are investigating. Unfortunately there is a large segment of the population which is determined to continue arguing the resolved questions for which the science has already been settled. And when climate scientists are forced to respond to the constant propagation of misinformation on these settled issues, it just detracts from our investigation of the legitimate, unresolved, important questions.

The Big Picture

The big picture is that we know the planet is warming, humans are causing it, there is a substantial risk to continuing on our current path, but we don't know exactly how large the risk is. However, uncertainty regarding the magnitude of the risk is not an excuse to ignore it. We also know that if we continue on a business-as-usual path, the risk of catastrophic consequences is very high. In fact, the larger the uncertainty, the greater the potential for the exceptionally high risk scenario to become reality. We need to continue to decrease the uncertainty, but it's also critical to acknowledge what we know and what questions have been resolved, and that taking no action is not an option.


Newcomers, Start Here

Posted on 15 August 2010 by John Cook

Skeptical Science is based on the notion that science by its very nature is skeptical. Genuine skepticism means you don't take someone's word for it but investigate for yourself. You look at all the facts before coming to a conclusion. In the case of climate science, our understanding of climate comes from considering the full body of evidence.

In contrast, climate skepticism looks at small pieces of the puzzle while neglecting the full picture. Climate skeptics vigorously attack any evidence for man-made global warming yet uncritically embrace any argument, op-ed, blog or study that refutes global warming. If you began with a position of climate skepticism then cherrypick the data that supports your view while fighting tooth and nail against any evidence that contradicts that position, I'm sorry but that's not genuine scientific skepticism.

So the approach of Skeptical Science is as follows. It looks at the many climate skeptic arguments, exposes how they focus on small pieces of the puzzle and then puts them in their proper context by presenting the full picture. The skeptic arguments are listed by popularity (eg - how often each argument appears in online articles). For the more organised mind, they're also sorted into taxonomic categories.

Good starting points for newbies

If you're new to the climate debate (or are of the mind that there's no evidence for man-made global warming), a good starting point is 10 Indicators of Global Warming which lays out the evidence that warming is happening and the follow-up article, 10 Human Fingerprints on Climate Change which lays out the evidence that humans are the cause. More detail is available in empirical evidence that humans are causing global warming. Contrary to what you may have heard, the case for man-made global warming doesn't hang on models or theory - it's built on direct measurements of many different parts of the climate, all pointing to a single, coherent answer.

Smart Phone Apps

For smart phone users, the rebuttals to all the skeptic arguments are also available on a number of mobile platforms. The first Skeptical Science app was an iPhone app, released in February 2010. This is updated regularly with the latest content from the website and very accessible in a beautifully designed interface by Shine Technologies. Shine Tech then went on to create a similar Android app which has some extra features missing from the iPhone version. A Nokia app was also created by Jean-Fran├žois Barsoum (this was one of the 10 finalists in the Calling All Innovators competition).

As well as the list of rebuttals, Skeptical Science also has a blog where the latest research and developments are examined and discussed. Comments are welcome and the level of discussion is of a fairly high quality thanks to a fairly strict Comments Policy. You need to register a user account to post comments. One thing many regulars are not aware of is you can edit your user account details (to get to this page, click on your username in the left margin).

Keep up to date by email, RSS, Facebook or Twitter

To keep up to date on latest additions to the website, sign up to receive new blog posts by email. There's an RSS feed for blog posts and for the engaged commenter, a feed for new user comments. I recommend you follow the Skeptical Science Twitter page as I not only tweet latest blog posts but also any other interesting climate links I happen upon throughout the day. New blog posts are also added to our Facebook page.

About John Cook

Lastly, for those wondering about who runs Skeptical Science, the website is maintained by John Cook. I studied physics at the University of Queensland but currently, I'm not a professional scientist - I run this website as a layman. People sometimes wonder why I spend so much time on this site and which group backs me. No group funds me. I receive no funding other than the occasional Paypal donations. As the lack of funding limits how much time I can spend developing the site, donations are appreciated. My motivations are two-fold: as a parent, I care about the world my daughter will grow up in and as a Christian, I feel a strong obligation to the poor and vulnerable who are hardest hit by climate change. Of course these are very personal reasons - I'm sure everyone comes at this from different angles. I go more deeply into my motivations in Why I care about climate change.

The SkS Team

However, there are many more who make invaluable contributions to Skeptical Science. There are a number of authors who write blog posts and are currently in the process of writing all the rebuttals in plain English. Translators from all over the world have translated the rebuttals into 15 different languages. There have been contributors to the one-line responses to skeptic arguments, proofreaders, technical support from boffins who understand computers a lot better than myself and commenters whose feedback have helped improve and hone the website's content. Skeptical Science has evolved from a small blog into a community of intelligent, engaged people with a commitment to science and our climate.

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