Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century. Most of the observed temperature increase since the middle of the 20th century was caused by increasing concentrations of greenhouse gases, which results from human activity such as fossil fuel burning and deforestation.
The concentration of carbon dioxide (CO2) in Earth's atmosphere is approximately 390 ppm by volume as of 2010[update],[1] and rising by about 1.9 ppm/yr.[2] Carbon dioxide is essential to photosynthesis in plants and other photoautotrophs, and is also a prominent greenhouse gas. The present level is higher than at any time during the last 800 thousand years,[3] and likely higher than in the past 20 million years.
The most direct method for measuring atmospheric carbon dioxide concentrations for periods before direct sampling is to measure bubbles of air (fluid or gas inclusions) trapped in the Antarctic or Greenland ice caps. The most widely accepted of such studies come from a variety of Antarctic cores and indicate that atmospheric CO2 levels were about 260 – 280 ppmv immediately before industrial emissions began and did not vary much from this level during the preceding 10,000 years (10 ka)
computer hacking
Computers are very flexible machines constrained by software to operate in very specific ways. Hackers are individuals who come up with novel, complex, simple or elegant ways of writing new software that restates or replaces the existing constraints thereby exposing either some new functionality or some of the original flexibility of the underlying machine.
Why a person might want to do so varies; thus in computing, a hacker is a person in one of several distinct (but not completely disjoint) communities and subcultures:[1]
- A community of enthusiast computer programmers and systems designers, originated in the 1960s around the Massachusetts Institute of Technology (MIT)'s Tech Model Railroad Club (TMRC) and MIT Artificial Intelligence Laboratory.[2] This community is notable for launching the free software movement. The World Wide Web and the Internet itself are also hacker artifacts.[3] The Request for Comments RFC 1392 amplifies this meaning as "[a] person who delights in having an intimate understanding of the internal workings of a system, computers and computer networks in particular." See Hacker (programmer subculture).
- People committed to circumvention of computer security; also known as crackers. This primarily concerns unauthorized remote computer break-ins via a communication networks such as the Internet (Black hats), but also includes those who debug or fix security problems (White hats), and the morally ambiguous Grey hats. See Hacker (computer security).
- The hobbyist home computing community, focusing on hardware in the late 1970s (e.g. the Homebrew Computer Club[4]) and on software (computer games,[5] software cracking, the demoscene) in the 1980s/1990s. The community included Steve Jobs, Steve Wozniak and Bill Gates and created the personal computing industry.[6] See Hacker (hobbyist).
Today, mainstream usage mostly refers to computer criminals, due to the mass media usage of the word since the 1980s. This includes script kiddies, people breaking into computers using programs written by others, with very little knowledge about the way they work. This usage has become so predominant that a large segment of the general public is unaware that different meanings exist. While the use of the word by hobbyist hackers is acknowledged by all three kinds of hackers, and the computer security hackers accept all uses of the word, free software hackers consider the computer intrusion related usage incorrect, and try to disassociate the two by referring to security breakers as "crackers" (analogous to a safecracker).
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[edit] Hacker definition controversy
The terms hacker and hack are marked by contrasting positive and negative connotations. Computer programmers often use the words hacking and hacker to express admiration for the work of a skilled software developer, but may also use them in a negative sense to describe the production of inelegant kludges. Some frown upon using hacking as a synonym for security cracking -- in distinct contrast to the larger world, in which the word hacker is typically used to describe someone who "hacks into" a system by evading or disabling security measures.
[edit] Controversy and ambiguity
While "hack" was originally more used as a verb for "messing about with", the meaning of the term has shifted over the decades since it first came into use in a computer context. As usage has spread more widely, the primary meaning of newer users of the word has shifted to one which conflicts with the original primary emphasis.
Currently, "hacker" is used in two main ways, one pejorative and one complimentary. In popular usage and in the media, it most often refers to computer intruders or criminals, with associated pejorative connotations. (For example, "An Internet 'hacker' broke through state government security systems in March.") In the computing community, the primary meaning is a complimentary description for a particularly brilliant programmer or technical expert. (For example, "Linus Torvalds, the creator of Linux, is considered by some to be a hacker.") A large segment of the technical community insist the latter is the "correct" usage of the word (see the Jargon File definition below).
The mainstream media's current usage of the term may be traced back to the early 1980s (see History). When the term was introduced to wider society by the mainstream media in 1983, even those in the computer community referred to computer intrusion as "hacking", although not as the exclusive use of that word. In reaction to the increasing media use of the term exclusively with the criminal connotation, the computer community began to differentiate their terminology. Several alternative terms such as "black hat" and "cracker" were coined in an effort to distinguish between those performing criminal activities, and those whose activities were the legal ones referred to more frequently in the historical use of the term "hack". Analogous terms such as "white hats" and "gray hats" developed as a result. However, since network news use of the term pertained primarily to the criminal activities despite this attempt by the technical community to preserve and distinguish the original meaning, the mainstream media and general public continue to describe computer criminals with all levels of technical sophistication as "hackers" and does not generally make use of the word in any of its non-criminal connotations.
As a result of this difference, the definition is the subject of heated controversy. The wider dominance of the pejorative connotation is resented by many who object to the term being taken from their cultural jargon and used negatively,[7] including those who have historically preferred to self-identify as hackers. Many advocate using the more recent and nuanced alternate terms when describing criminals and others who negatively take advantage of security flaws in software and hardware. Others prefer to follow common popular usage, arguing that the positive form is confusing and unlikely to become widespread in the general public. A minority still stubbornly use the term in both original senses despite the controversy, leaving context to clarify (or leave ambiguous) which meaning is intended. It is noteworthy, however, that the positive definition of hacker was widely used as the predominant form for many years before the negative definition was popularized.
"Hacker" can therefore be seen as a shibboleth, identifying those who use the technically-oriented sense (as opposed to the exclusively intrusion-oriented sense) as members of the computing community.
A possible middle ground position has been suggested, based on the observation that "hacking" describes a collection of skills which are used by hackers of both descriptions for differing reasons. The analogy is made to locksmithing, specifically picking locks, which — aside from its being a skill with a fairly high tropism to 'classic' hacking — is a skill which can be used for good or evil. The primary weakness of this analogy is the inclusion of script kiddies in the popular usage of "hacker", despite the lack of an underlying skill and knowledge base.
Fred Shapiro thinks that "the common theory that 'hacker' originally was a benign term and the malicious connotations of the word were a later perversion is untrue." He found out that the malicious connotations were present at MIT in 1963 already and then referred to unauthorized users of the telephone network[8] (which are also called phreakers).
[edit] History
- 1950s: amateur radio enthusiasts defined the term hacking as creatively tinkering to improve performance.
- 1959: hack is defined in MIT's Tech Model Railroad Club Dictionary as "1) an article or project without constructive end; 2) a project undertaken on bad self-advice; 3) an entropy booster; 4) to produce, or attempt to produce, a hack(3)." hacker is defined as "one who hacks, or makes them." Much of the TMRC's jargon is later imported into early computing culture.
- 1963: The first recorded reference to hackers in the computer sense is made in The Tech (MIT Student Magazine).[9]
- 1972: Stewart Brand publishes "S P A C E W A R: Fanatic Life and Symbolic Death Among the Computer Bums" in Rolling Stone, an early piece describing computer culture. In it, Alan Kay is quoted as saying "A true hacker is not a group person. He's a person who loves to stay up all night, he and the machine in a love-hate relationship... They're kids who tended to be brilliant but not very interested in conventional goals[...] It's a term of derision and also the ultimate compliment."
- 1980: The August issue of Psychology Today prints (with commentary by Philip Zimbardo) "The Hacker Papers", an excerpt from a Stanford Bulletin Board discussion on the addictive nature of computer use.
- 1982: In the film TRON, Kevin Flynn (Jeff Bridges) describes his intentions to break into ENCOM's computer system, saying "I've been doing a little hacking here". CLU is the software he uses for this.
- 1983: The movie WarGames, featuring a computer intrusion into NORAD, is released. A gang of 6 teenagers is caught breaking into dozens of computer systems, including that of Los Alamos National Laboratory.[10] Newsweek features the cover story "Beware: Hackers at play."[11] First Usenet post on the use of the term hacker in the media (CBS News) to mean computer criminal.[12] Pressured by media coverage of computer intrusions, Congress begins work on new laws for computer security.[13]
- 1984: Steven Levy publishes Hackers: Heroes of the Computer Revolution. The book publicizes, and perhaps originates the phrase "Hacker Ethic" and gives a codification of its principles.
- 1986: The Mentor writes The Hacker Manifesto, and publishes it in Phrack.
- 1988: Stalking the Wily Hacker, an article by Clifford Stoll appears in the May 1988 issue of the Communications of the ACM and uses the term hacker in the sense of a computer criminal. Later that year, the release by Robert Tappan Morris, Jr. of the so-called Morris worm provoked the popular media to spread this usage.
- 1989: The Cuckoo's Egg by Clifford Stoll is published, and its popularity further entrenches the term in the public's consciousness.
- 2000: Michael Calce (better known as MafiaBoy) attacks and disables Yahoo!, Amazon.com, CNN, Dell, Inc., and E*TRADE. President calls for emergency Cyber Security Summit as a result of the attacks. The estimated losses in the attacks was 1.2 billion USD.
- 2008: Global movement of Hackerspaces emerges. These labs are technological, cultural and social creative places enabling hackers to develop projects together, code, create open source projects or hardware designs.
[edit] Contemporary use
The modern, computer-related use of the term is considered likely rooted in the goings on at the Massachusetts Institute of Technology (MIT) in the 1960s, long before computers became common; the word "hack" was local slang which had a large number of related meanings. One was a simple, but often inelegant, solution to a problem. It also meant any clever prank perpetrated by MIT students; logically, the perpetrator was a hacker. To this day the terms hack and hacker are used in several ways at MIT, without necessarily referring to computers. When MIT students surreptitiously put a fake police car atop the dome on MIT's Building 10, that was a hack, and the students involved were therefore hackers. Another type of hacker — one who explores undocumented or unauthorized areas in buildings — is now called a reality hacker or urban spelunker.
The term was fused with computers when members of the Tech Model Railroad Club started working with a Digital Equipment Corporation PDP-1 computer and applied local model railroad slang to computers.
The earliest known use of the term in this manner is from the 20 November 1963 issue of The Tech, the student paper of MIT:
Originally, the term "hack" was applied almost exclusively to programming or electrical enMany telephone services have been curtailed because of so-called hackers, according to Prof. Carlton Tucker, administrator of the Institute phone system. […] The hackers have accomplished such things as tying up all the tie-lines between Harvard and MIT, or making long-distance calls by charging them to a local radar installation. One method involved connecting the PDP-1 computer to the phone system to search the lines until a dial tone, indicating an outside line, was found. […] Because of the 'hacking', the majority of the MIT phones are 'trapped'.
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