For at least 400 years, "science" has been defined as knowledge gained through study or learning acquired through the scientific method. Initially, this definition made scientific knowledge the property of a very small number of people who had access to universities and libraries or who could establish private laboratories. With the invention of the printing press and increasing literacy and available public education, scientific knowledge became more and more accessible, but adherence to the scientific method remained a constant.
The scientific method is based on the use of measurable data obtained through observation or experimentation. The Oxford English Dictionary says that the scientific method is "a method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses." The chief characteristic that distinguishes the scientific method from other methods of acquiring knowledge is that scientists seek to let reality speak for itself, supporting a theory when a theory's predictions are confirmed and challenging a theory when its predictions prove false.
In other words, no piece of scientific knowledge is ever considered the last word on the subject, no matter how many times it has been confirmed, though certain highly consistent bits of information are considered so reliable that they are termed "laws." The next level of certainty is theory, and then hypothesis.
Some time in the past 25 or so years, however, scientific knowledge has become conflated with political and religious agendas, and these bedrock principles have been ignored -- not by scientists, but by the general public. So, for example, the term "theory" in "Darwin's Theory of Evolution," instead of being properly taken as denoting a highly reliable set of principles to describe the development of living species over time has been termed "just a theory" (i.e., up for argument) and posed against the so-called "theory" of creationism, which has no scientific basis at all.
Similarly, an overwhelming majority of relevant scientists (only laws such as gravity have virtually 100 percent agreement among scientists) accept the theory that the Earth's climate is changing in the direction of global warming. Notwithstanding that, climate change has become an issue that somehow divides politically along ideological lines, the way evolution divides along religious lines. Neither opinion is valid or relevant scientifically, and last week's superstorm on the East Coast flooded, destroyed property, and killed without regard to the political positions of its victims.
Climate change is real, period, and it is reaching dangerous proportions. New York City demonstrates that urban design and engineering built to meet 19th century challenges are inadequate to 21st century challenges. After the blizzard of 1888 choked off the life of the city because all transport and power were above ground, New York built the subways and put power lines underground. Great idea if your biggest problem is heavy snow. With catastrophic rain, wind, and their consequences, not so much.
I'm talking here about the undeniable facts of climate change -- scientists are not nearly as unanimous about what causes climate change, though a considerable majority of scientists hold the view that human activities contribute significantly to it, with the discussion tending much more to how much, not whether. Particularly since the development of quantum theory, scientists tend to be skeptical about the notion of "cause," taking the view that any observed phenomenon is the result of a complex of causes. Still, if human activity is a contributor to climate change, and climate change is a threat to human life and welfare, it doesn't seem logical to say that if it's not the whole thing, we shouldn't do anything about it and alleviate at least that contribution.
The debate over climate change (if you can call a bunch of lay people arguing against scientists as if their respective opinions deserved equal standing) has significantly impeded our ability to get out ahead of it, and New York is a case study in what happens when your response to natural disaster is reactive and insufficiently proactive. We didn't learn from Katrina, and whether we can learn productively from Sandy remains to be seen -- as long as we accept that it is valid to deal with climate change as a matter of opinion and a political issue, it seems unlikely we will learn.