WHO emergency definition.
Emergency is a term describing a state. It is a managerial term, demanding decision and follow-up in terms of extra-ordinary measures (Oxford Pocket Dictionary, 1992). A "state of emergency" demands to "be declared" or imposed by somebody in authority, who, at a certain moment, will also lift it. Thus, it is usually defined in time and space, it requires threshold values to be recognized, and it implies rules of engagement and an exit strategy. Conceptually, it relates best to Response.
Emergency preparedness Actions taken in anticipation of an emergency to facilitate rapid, effective and appropriate response to the situation (Inter-Agency Contingency Planning Guidelines for Humanitarian Assistance 2001).

​​​It is clear that governments will take no action on
​GHG emissions unless science and civil society ​organizations declare the planetary emergency.

Already committed global climate change presents all three aspects of an emergency all to unprecedented extents​​

​​First there is the state
emergency governmental declaration after a disaster has happened so as to rapidly bring aid resources to the affected ​population. The world and all nations need to be preparing now for the worst ever populationand environmental health disasters and catastrophes. 

Then there is the medical kind of emergency, in which a possible fatal injury or medical ​condition is recognized and an emergency code is declared so as to rapidly bring emergency medical services to the patient in order to intervene to safe a life or lives. 

There is also an emergency situation that can be declared for a building or other structure on recognition of danger that imperils life. The commonest situation would be a fire. 

CNA in the USA has recognized the needs involved in the CNA publication Why the Emergency Management Community Should be Concerned about Climate Change​​. 

​We must address climate change mitigation as a planetary
​emergency and we must be clear what an emergency response
​is. This is because practically all the published science and almost all
​civil society proposals present climate change mitigation
​in terms of at least a 50 year timeframe from policy action
​to stabilization of atmospheric greenhouse gas concentrations.

​This is because it is assumed that even with an international
​agreement to cut emissions and policy measures to do so,
​fossil energy production will not decline till fossil fuel power plants have run out their operative lifetime.

The Ecoequity (climate change NGO) so called emergency emissions response, based on UNEP's mitigation, takes 80 years to stabilize atmospheric GHGs for 2C and ​​50 years for 1.5C. This is far from an emergency response and ensures rather than prevents catastrophe.   

The science is definite that ​​the only emergency response is a rapid reduction of emissions aimed at zero carbon. 

United Nations High Commissioner for Refugees
​One specific impact of global climate change is increasing refugees.
​United Nations High Commissioner for Refugees Handbook for Emergencıes
​The distinction is one of degree: a definition of a refugee emergency for the purposes of UNHCR and this handbook might be: any situation in which the life or wellbeing of refugees will be threatened unless immediate and appropriate action is taken, and which demands an extraordinary response and exceptional measures.

World Federation of Scientists.
Complete Definition of the Emergency. Disasters related to water/weather In general, droughts, floods, and tropical storms produce the greatest number of water/weather-related disasters. Climate change (greenhouse effects).

UNEP/GC.22/INF/5, 13 November 2002. Environmental emergencies are sudden-onset disasters or accidents resulting from natural, technological or human-induced factors, or a combination of these that cause or threaten to cause severe environmental damage as well as loss of human lives and property

WHO has a long section, Definitions: emergencies, that covers definitions of the terms used here.
Emergency is a term describing a state. It is a managerial term, demanding decision and follow-up in terms of extra-ordinary measures…. it requires threshold values to be recognized.. . Conceptually, … it relates best to Response.
Emergency prepared: actions taken in anticipation of an emergency to facilitate rapid, effective and appropriate response to the situation
Definition of zero carbon

Zero (or virtual zero) carbon emissions is understood by all climate scientists to at least mean our industrial CO2 emissions - and that for sure has to  be reduced to the greatest possible - which is virtual zero usually a 95% reduction on current emissions. That includes CO2 from cement manufacturing and CO2 from deforestation.  Zeo carbon means no more deforestation.

METHANE The are two carbon greenhouse gases- CO2 carbon dioxide and CH4 methane. ​​

In fact methane emissions do ​​contribute indirectly to CO2 emissions. Methane only last in the atmosphere about 12 years because because it is oxidized- the products being other GHGs one which is CO2. This CO2 is not accounted for in calculating the global warming effect of methane. It does mean that for zero carbon methane emissions have to be greatly reduced.

There are two terms in the science referring to ​​carbon CO2 emissions and to atmospheric CO2 concentration. That is CO2 and CO2 equivalent - CO2 eq or CO2 e for short. Incredibly the science is not agreed on what this should precisely mean. 

This is a good article that addresses the confusion that results.
​Avoiding confusion for stabilization targets for climate change and ocean acidification by Chris McGrath November 4, 2008. Here is the gist of it.

​​The important CO2 stabilization targets may be based only on atmospheric carbon dioxide levels or based on all greenhouse gases, commonly termed carbon dioxide equivalents (CO2-e or CO2-eq). There is considerable confusion surrounding these terms in the scientific literature and the policy debate. Because of this confusion some authors avoid using carbon dioxide equivalents altogether when discussing targets for stabilizing anthropogenic climate change (e.g. Hansen et al 2008).
​The major advantage of carbon dioxide only targets is that they are simple to understand and can be measured directly with precision; however, because carbon dioxide is not the only greenhouse gas, targets based on stabilizing the combined effect of all greenhouse gases are important.

The term “carbon dioxide equivalents” is used in two main ways for climate change stabilization targets:

• Some authors use “carbon dioxide equivalents” to refer to the concentration of carbon dioxide that would give the same warming effect as the collective effect of all of the greenhouse gases in the atmosphere. This approach excludes the cooling effect of aerosols (e.g. Stern 2007; Garnaut 2008).

• Some authors define carbon dioxide equivalent concentrations as the net forcing of all anthropogenic radiative forcing agents including greenhouse gases, tropospheric ozone, and aerosols but not natural forcings. This approach includes the cooling effects of aerosols (e.g. Meinshausen et al 2006).

Targets for stabilizing temperature rises between 450-550 ppm “carbon dioxide equivalents” generally refer to the term in the latter usage, thereby considering all components of the atmosphere affecting global temperature rises. However, Gavin Schmidt (2007) noted the confusion surrounding the term on the RealClimate blog in the context of comments by Tim Flannery that “we are already at 455 ppm carbon dioxide equivalents.”

Flannery was right because as pointed out by Rananath, Feng Avoiding climate interference it is not right to defer to future generations the inevitable significant warming from the unmasking of cooling air pollution aerosols​​. Therefore the CO2 equivalant should only include warming emissions- not cooling emissions as well.

The IPCC does not include the cooling aerosols in its calculations of atmospheric GHG stabilization. As a result we are far above a committed 2C already. ​​

The differences between the usages of these terms are very significant and care must be taken not to confuse them. The terms are very different quantitatively as is evident from the following points draw from IPCC (2007: 102):

• Atmospheric carbon dioxide reached 379 ppm in 2005 and was increasing by around 2 ppm per year.

• Including the effect of all long-lived greenhouse gases such as methane, the total concentration of atmospheric greenhouse gases was around 455 ppm carbon dioxide equivalents in 2005 (range 433-477 ppm).

• However, the cooling effects of aerosols and land use changes reduce radiative forcing so that the net forcing of human activities was about 375 ppm carbon dioxide equivalents for 2005 (range 311-435 ppm).

Stabilizing at 450-550 ppm carbon dioxide alone could mean significantly higher levels of stabilization when measured in carbon dioxide equivalents, leading to much higher levels of temperature rise than 2-3°C. For instance, if the cooling effect from aerosols was to approach zero in the future due to improved pollution controls or the imperative to stop burning fossil fuels, stabilization of atmospheric carbon dioxide alone at 500 ppm might lead to a net warming effect around 570 ppm carbon dioxide equivalents.

There is a real potential for governments and policy-makers to misunderstand and misapply information based on using either carbon dioxide only figures or carbon dioxide equivalents. In such circumstances,  the best solution is to clearly flag the differences in the usage of these terms.



Carbon neutral and net zero carbon have no agreed definition or basis in science
They allow the continued combustion of fossil fuels. ​
For just one thing they ignore the other GHGs
If used at all they must be qualified as with zero fossil fuel combustion-or better zero carbon combustion (no wood pellet power plants, no broadcast agriculture burning, no wood stoves​

​Net zero is described as Do your best and remove the rest (CO2 emissions)
Climate Emergency Institute
The Health and Human  Rights Approach to Climate Change