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.