So what does all of this talk about 30% emissions cuts and carbon dioxide mean to the average citizen walking the mall or in the grocery store (http://www.wjla.com/articles/2014/06/epa-to-roll-out-historic-plan-to-cut-pollution-from-power-plants-103694.html)?
I try to explain here without a political or nasty tone. I still don't understand why so much anger and vitriol is evoked on the topic even if you disagree with aspects of either side. But, I digress.
The climate changes naturally. I am still amazed that people bring this up to an atmospheric scientist. That statement is like telling a medical doctor, "you know, that stethoscope is used to listen to the heart beat." But, again, I digress.
We are able to live comfortably on Earth because of greenhouse gases (GHGs) like carbon dioxide (CO2) (http://climate.nasa.gov/causes). Well-established atmospheric physics theory dating back to Callendar (1938) and earlier confirms that just a tiny amount of this gas is critical for sustaining life on this planet. Otherwise, Earth would be too cold.
However, since 1850, the climate has a human-contributed steroid (more CO2 and GHGs) altering the natural cycle. Professional baseball players naturally hit home runs, but with steroids, the "natural" home run cycle was altered in terms of length and numbers. Venus is too hot because its atmosphere is primarily CO2-based.
So irrespective of what you want to call it (e.g. global warming, climate change, anthropogenic global warming), reducing CO2 emissions (mitigation) is one way to address it although there is quite a bit of carbon already accumulated in the atmosphere that will have impacts for decades. We are already passing the 400 ppm (over the past 400,000 to 600,000 years, the natural cycle varied but never really went beyond 290-300 ppm range until after 1850 (Industrial Revolution)--http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/05/10/atmospheric-carbon-dioxide-concentration-400-parts-per-million/). Unchecked, emissions will continue to rise, and we should continue to see weather/climate changes, concern about tipping points (Greenland, West Antarctic Ice Sheet, Permafrost) and system shifts (water stress, agricultural productivity changes, diseases in places they were not, national security challenges from open arctic/climate refugees, sea level rise, economic impacts and so on). Yes, the solution has to be global. The U.S. is not situated in a glass box. Other nations are big emitters now too and that is still a challenge for the global climate. However, the U.S. typically is a leader, and other industrialized nations often follow us.
This is the basis for action. I am not going to touch the politics and global context because it is very complex. However, getting a rover to Mars is complex too. Our job as scientists is to give the best science available for policymakers to make decisions on. Some things to look out for in the coming days:
1. The usual zombie theory tactics and misinformation. I highly recommend skepticalscience.com or realclimate.org. Excellent websites that debunk most of the stuff you will hear.
2. The comments that the economy will suffer because of efforts to reduce carbon. A good discussion is in the NY Times: http://www.nytimes.com/2014/05/30/opinion/krugman-cutting-back-on-carbon.html?_r=0. There is also a good Op-Ed by the past 4 GOP EPA Administrators at http://www.nytimes.com/2013/08/02/opinion/a-republican-case-for-climate-action.html.
3. You will even hear "how can we regulate CO2 when we breath it". When I hear this one, I just go "really? and end the conversation. I also like how a colleague Tom Mote characterizes that question. He notes, "Regarding the fact that we exhale CO2 (item #3)... humans also have other waste products. I am glad that we have water quality regulations and don't let sewage run in the street. Like CO2, that is "natural" too..."
The challenges and misinformation are rooted more in solutions than the science. Clearly, such cuts will impact certain industries and activities. Recall, when the science pointed to nicotine being addictive, the tobacco industry created public confusion or discredited the science ("It is difficult to get a man to understand something when his salary depends on him not understanding it---Upton Sinclair." Already, somebody is thinking, but doesn't that apply to scientists because you want grant money? This is ill-posedbecause 1. scientists are pretty smart and could do a lot of other things to get rich, this is not the business for that, 2. it naively misses that research grant $$ are several orders of magnitude smaller than the $$$$$ at stake with "solutions"/industry aspects, and 3. it illustrates a fundamental lack of understanding of the grant process. Many science grants are funded because of "what we don't know or understand." It would actually be in a scientist's interest to write a grant proposal saying we don't know if climate is changing, give me more money to find out.
This primer isn't comprehensive. There is adaptation, geoengineering, the human dimension and more. And yes, there are still uncertainties with climate science. Guess what, there is uncertainty in an 80% chance of rain, but you grab an umbrella. There is uncertainty in a doctor's diagnosis, but you fill the prescription. Don't be fooled by the notion that uncertainty means unreliable. Science doesn't operate on the premise of reasonable doubt, but the "O.J. Simpsonfication" of our culture has everyone aware of how reasonable doubt works, and the public erroneously applies it to science. Yet, science doesn't work that way. It is not 100% certain that the sun will rise tomorrow, but I have enough evidence to plan my day as if it will.
Do you feel the sun burn your skin in summer or the sidewalk burn your bare feet on a hot day? Yes? So how can an inert gas as CO2 cause such a high temperature to exist? Earth's temperature is controlled by the sun and the ideal gas law. Latent heat due to the whole atmosphere, predominantly water vapour, causes the slowing of temperature swings between day and night (which is why dryer regions such as deserts have larger and faster swings). CO2 does not make the earth warmer than it would otherwise be, if anything, CO2 helps cool the earth as it's one of a few IR responsive gases, able to absorb and emit IR energy, and the only way earth can cool itself is by radiation into space.
ReplyDeleteSolar insolation is primarily UV and visible light due to the Sun's high temperature, this is not reflected by CO2 particles. The cooler Earth emits IR radiation, which is reflected back to the Earth's surface by atmospheric CO2. When the atmospheric CO2 levels rise, this results in a system that is out of equilibrium with the incident radiation exceeding the radiated energy. If there is an influx of energy to the Earth system, then, if the Second Law of Thermodynamics holds true, the atmospheric temperature will rise.
DeleteSunburns have nothing to do with the changes in the Sun/Earth orbit cycles (Milankovich Cycles) or temperatures. Instead they are a result of UV radiation that makes it through our ozone layer. CFCs create Chlorine radicals that disrupt the atmospheric Oxygen cycle, which is responsible for high energy UV absorption. Higher UV = more sunburns.
ilma630--
ReplyDeleteA small amount of a substance can have a major effect. That's why poisons kill.
But in particular, the atmosphere allows most solar radiation to pass through and reach the earth because it is in the visible and ultraviolet range. When the sunlight heats the Earth's surface, the Earth radiates energy outward in the infrared portion of the electromagnetic spectrum.
CO2 and other GHGs are transparent to visible and UV light radiation, but they absorb infrared radiation. As Dr. Shepherd explains, all we need is about 250-300 parts per million of CO2 to absorb enough outgoing radiation to keep Earth warm. Without it, the planet's heat balance would put it at about zero degrees Fahrenheit on average rather than the 50F that we have.
Adding CO2 makes it too much of a good thing. It's like adding a blanket to your bed when you are already comfortable. Your body heat soon makes you want to remove it.
That's why we need to keep CO2 under control and why the extra CO2 can be harmful to our future.
I hope this helps.
What % of warming do you attribute to man made CO2?
DeleteI'm glad to see you don't want any misinformation so it is worth noting that the 30% EPA emissions cuts were based on reduction from 2005 USA CO2 emissions. This means that the USA has already reduced 12-13% of the 30% target prior to today's announcement and going forward we are only looking at a further 17-18% in emissions reduction. Also note that reductions came not from anything the EPA did but rather free market movement away from coal to cheaper natural gas. Seeing as most coal plants that have already been closed have switched to natural gas, one can argue that further reductions in coal would have likely continued without EPA intervention. To be fair technology that led to cheaper and more abundant natural gas should be blamed for the demise in USA coal use rather than the president/EPA as some are suggesting.
ReplyDeleteHowever is the USA 17%-18% reduction significant on a global scale? China's committed to doubling coal use by 2035.
http://www.energychinaforum.com/news/77277.shtml
It is estimated that by 2035 India will be using as much coal as the USA does today. What will the EPA plan to reduce CO2 by 17-18% from this point forward do to stop global climate impacts when China, India, and a slew of other developing countries are committed to ramping up for coal use equivalent to 10 times the USA's reduction? My answer is that it can only DELAY effects of growing global CO2 impacts by a handful of years, but the EPA action will do nothing to stop it. As such the EPA action is symbolic and mostly political in nature IMO.
This week's "Cosmos" on Fox TV is all about carbon dioxide and greenhouse warming. Matt, CO2 does not reflect radiation, it absorbs and re-emits it by changing vibrations in the bonds between the atoms. But when it re-emits, half of it goes back down to earth, leading to a net increase in energy near the surface.
ReplyDeleteYou're right Pam. In my attempt at simplifying things I incorrectly conflated reflectivity with absorption/ re-emission. Thanks for clearing up my mistake.
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