Climate Change: A Scientific Phenomenon #globalclimatechange #science #environment

climate change blue marbleI’ve found the global warming/climate change debate to be frustrating. The Earth is too large a system to grasp intuitively. In such a large system, anyone can “cherry-pick” a small subset of data to illustrate any point. Many discussions seem to distill down to: “You’re lying!”

I posted on the social aspects of the debate previously . Today I will discuss the science of global warming and climate change. (“Global warming” refers to average global temperatures while “climate change” refers to the effects.)

Global warming is complex enough to make my eyes cross. It involves many parameters that must be examined over decades and preferably centuries. I will frequently use information from http://www.skepticalscience.com/. This site provides the largest and most accessible collection of responses to global warming objections I’ve found, with a handy mouse-over glossary in the text. While unabashedly defending mainstream climate science against “climate myths”, the site also provides an exhaustive list of objections: 174 of them!

I leave you to explore as many of the 174 objections as interest you. Here are my favorites:

Objection: Temperature increases have stopped.

Excerpt from SkepticalScience Response: The gif chart presented to show temperature continues to increase has become somewhat famous. I’ve inserted a screen-capture climate change escalator surfaceof the chart at left. It shows an overall upward trend in temperatures with several plateaus along the way. You can view the gif chart here.

Another response: This op-ed by Dr. Peter Gleick is a must-read. “These statements [that global warming has stopped] are scurrilous deceptions and falsehoods. The planet is warming – an observation noted by every climate research institution tracking temperatures, the US National Academy of Sciences (over and over and over), every other national academy of sciences on the planet, and every professional society in the geosciences.”

My Comment: I’ve worked with large sets of data myself (not related to climate). It seems entirely reasonable to me that a trend measured over decades in a complex system will show ups and downs, and that comparing a couple local maximums can give a false impression of stasis.

Objection: There is no consensus.

I have often failed to describe to friends the type of consensus that is meant. If obviously there is discord and disagreement, what is meant by consensus? Here is a fine description from a self-proclaimed denier turned warmer:

“Don’t confuse consensus with consensus. This one had me confused for a long time. Like the word theory, which has a drastically different meaning in science than it does in the vernacular, consensus can mean two very different things. In politics a consensus is an aggregate expression of opinion. It’s only as valid as the majority agrees it is. In science it is a description of where the science has led… [T]he consensus is not what gives power to the conclusion, the science leads to the conclusion.” http://skeptoid.com/blog/2011/06/15/i-global-warming-skeptic/ The entire post is excellent, with advice for left and right-leaning readers.

Excerpt from SkepticalScience Response:In the scientific field of climate studies… the consensus is demonstrated by the number of scientists who have stopped arguing about what is causing climate change – and that’s nearly all of them. A survey of 928 peer-reviewed abstracts on the subject ‘global climate change’ published between 1993 and 2003 shows that not a single paper rejected the consensus position that global warming is man caused (Oreskes 2004).”

My Comment: I wrote a lot of words about “consensus” because it is very important to my thinking. A bumper-sticker doesn’t cut it here – I must say “consensus in the scientific, peer-reviewed literature”. I don’t think I’ve read any significant disagreement with the SkepticalScience response.

Those who object to the consensus statement publish lists of people who disagree with the scientific consensus, but do not dispute that the published, peer-reviewed literature is overwhelmingly in agreement on global warming. The only counter response I’ve seen is a conspiracy theory: scientists are too scared of authority or too corrupted by research grant money to oppose the mainstream theory of global warming. I have worked in a scientific field (though not in the climate sciences). In my experience, most scientists would love to overturn an established theory. It would make their career. I would have to see strong evidence that a conspiracy has controlled climate scientists world-wide for decades. I have not seen such evidence.

In summary:

I am not an expert in climate science and never will be. This is true about most scientific topics. What can a reasonable person do?

I follow a simple heuristic: Accept what the science says when the experts mostly-all agree. Realize that experts change their minds and be alert for updates. Headlines can be misleading, so try to learn about the details.

I accept: The Earth is warming and climate is changing in response. Human activities, including fossil fuel burning and land use practices, are forcing a change unprecedented in civilization’s history. This will lead to negative impacts on ecosystems and people in many ways.

I believe: Everyone in the world deserves a chance to prosper the way America prospers, and that Americans deserve to continue to prosper, too. “You are a child of the Universe, no less than the trees and the stars. You have a right to be here.” [Desiderata] Population growth in wealthy countries is dropping, so encouraging all countries in the world to prosper may be the best win-win tactic we have. It is ironic if the prosperity some Environmentalists tell us we must abandon may actually “save the world.” How decreased populations will sort out economically I can’t tell: our current model of prosperity depends on population growth, and my crystal ball is cracked and cloudy.

I have faith: We can make decisions today that reduce the pain along the way. I see ways we can adapt to specific impacts of climate change, and ways to slow the release of CO2 and other greenhouse gases. Ironically, recent increases in natural gas production are reducing carbon emissions from coal because the free market favors gas, not because of any ideology. We need more improvements like that. Future generations will grapple with these issues and come out ahead.

Note: I’ve tried to select links with a long life, but the Internet is a fickle beast and some links may be broken. Take a look at SkepticalScience or search on the terms that interest you.

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