What is the definition of the word 'catastrophic' when it comes to Global Warming?

For most of those who use it, whatever they want it to mean. It's kind of a movable feast, like "kind" for creationists.

For reasonable people, I think you could talk about things like "a statistically significant increase in total deaths from directly or indirectly weather or climate related causes, including droughts, wars over climate-variable resources such as water" as a functional definition of catastrophic warming.

Do you know how evolution works? Well the earth also performs equivalent. As we raise certain gases,everything else is used with it. Like the government printing money but they need money for inc wich is made by a factory and the factory need materials. Catastrophic in this case would never even need a definition with the technology we have. Most resources on earth are genetically made by Us now. Many people don't realize that planets can be in any temp, even the ozone layer is damaged by rays not your f350 diesel.

Kano and the guy who is a symbol have answered your question. I think it is a fair statement to say a lot of events (such as increased flooding and hurricanes) have been discussed in the scientific literature as a consequence of continued fossil fuel use. Media sources describe these events as catastrophic. Scientists tend to stay away from imprecise terms like catastrophic in their papers. I think the word still applies.

A runaway greenhouse effect is a process in which a net positive feedback between surface temperature and atmospheric opacity increases the strength of the greenhouse effect on a planet until its oceans boil away. An example of this is believed to have happened in the early history of Venus. On the Earth, the IPCC states that "a 'runaway greenhouse effect'—analogous to that of Venus—appears to have virtually no chance of being induced by anthropogenic activities.

The worst case scenario would be burning ALL fossil fuels would adversely affect the ability of humans to live on the planet. If non-CO2 greenhouse gases such as N2O and methane (CH4) were to increase with global warming at the same rate as in the palaeoclimate record and atmospheric chemistry simulations they would provide approximately 25% of the greenhouse forcing. The remaining forcing requires approximately 4.8 times current CO2 levels, corresponding to fossil fuel emissions as much as approximately 10,000 Gt C for a conservative assumption of a CO2 airborne fraction averaging one-third over the 1000 years following a peak emission.

Calculated global warming in this case is 16°C, with warming at the poles approximately 30°C. Calculated warming over land areas averages approximately 20°C. Such temperatures would eliminate grain production in almost all agricultural regions in the world. Increased stratospheric water vapour would diminish the stratospheric ozone layer.

Global warming of that magnitude would make most of the planet uninhabitable by humans. The human body generates about 100 W of metabolic heat that must be carried away to maintain a core body temperature near 37°C, which implies that sustained wet bulb temperatures above 35°C can result in lethal hyperthermia. Today, the summer temperature varies widely over the Earth's surface, but wet bulb temperature is more narrowly confined by the effect of humidity, with the most common value of approximately 26–27°C and the highest approximately of 31°C. A warming of 10–12°C would put most of today's world population in regions with a wetbulb temperature above 35°C. Given the 20°C warming that occurs with 4.8 times current CO2 levels, such a climate forcing would produce intolerable climatic conditions even if the true climate sensitivity is significantly less than the Russell sensitivity,[clarification needed] or, if the Russell sensitivity is accurate, the CO2 forcing required to produce intolerable conditions for humans is less than this amount.

disastrous, calamitous, cataclysmic, apocalyptic, ruinous, tragic, fatal, dire, awful, terrible, dreadful.

Perhaps science papers do not use these terms but media often does.

It refers to wholesale flooding of Islands and land.

It refers to the world being battered with storms, floods and droughts.

It refers to widespread crop failure and famines.

If you google "catastrophic global warming" you get 1,300,000 hits.

Edit for Jeff M.

Is Vancouver where you live? so here is NOAA's trend for Vancouver 0.37mm and linear

http://tidesandcurrents.noaa.gov/sltrends/sltrends...

Which is lower than most places because of isostatic land movement, average is somewhere about 2mm

Because of NOAA I can show most port cities in the US and a lot around the world , and believe me, I have checked hundreds of them without seeing any acceleration.

IPCC Working Group 2 deals with the effects of global warming. In general, skeptics are skeptical of these claims.

It's a word put in by deniers. You won't find the CAGW anywhere in scientific literature. Pure denier invention.

If the IPCC has not assigned a special definition to the word, and I don't think they have, then it takes on the normal dictionary definition.

Many things. try failure of the Monsoon. Bangladesh going under water.