Dangerous Denial

​Starting in 2006 John Holdren (was science advisor to the US Obama administration) has given a climate change lecture entitled Meeting the Climate Change Challenge in which he states and explains in full that the world is beyond dangerous interference with the climate system, under the clear intention and terms of the 1992 UN Framework Convention on Climate Change. He also states the question now is whether we can avoid catastrophic interference with the climate system that there is no guarantee that we can even if we take immediate action.  

Incredibly no nation, no scientific organization and no nongovernmental organization has put forward a public position, made a submission or presented a formal statement, that the world is beyond dangerous climate interference.

The climate scientists, with just a few notable exceptions, have a long-standing and firm policy that they will not make a statement on dangerous climate interference (as 1992 UN climte change convention) nor make statements or recommendations on the state of climate danger. The reason that they give is that dangerous climate interference is a value judgment and scientists cannot make value judgments. The scientists say that only the "policymakers" (in the case of the IPCC scientists) or only "society as a whole" (in the case of the 2007 Copenhagen Climate Science Congress) can make such statements. This is not true, scientists cannot avoid making value judgements, but not biased value judgments

Could global climate change bring about a planetary catastrophe?

Yes that has always been the great fear, because catastrophe to humanity and to all all life ​would come about at a heating beyond survival. ​

IPCC 2007 AR 4 WG 3 2.2.4 Risk of Catastrophic or Abrupt Change

The possibility of abrupt climate change and/or abrupt changes in the earth system triggered by climate change, with potentially catastrophic consequences, cannot be ruled out. Positive feedback from warming may cause the release of carbon or methane from the terrestrial biosphere and oceans which would add to the mitigation required.

How is danger defined by science?
Danger is addressed by science as a risk. Risk is assessed as the product of probability when adverse consequence of impact with the magnitude of the impact. This is the definition approved by the IPCC. However the IPCC (incorrectly) claims climate danger cannot be determined by science -It is thus not possible to define a single critical threshold without value judgments and without assumptions on how to aggregate current and future costs and benefits (AR5 2013). The 2013 IPCC AR5 Reasons For Concern illustration clearly shows warming of 1-1.5°C is far too dangerous and 2°C catastrophically dangerous.
The IPCC Reasons For concern covers many impacts, except the greatest risk of all which is Hot house Earth caused by multiple amplifying feedbacks from large Arctic feedback sources and collapse of tropical forests. 

The IPCC 2007 AR4 chart of impacts clearly also showed 1°C was too dangerous for billions of people. ​​
"The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.
Such a level should be achieved within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.

1.​​“Adverse effects of climate change” means changes in the physical environment or biota resulting from climate change which have significant deleterious effects on the composition, resilience or productivity of natural and managed ecosystems or on the operation of socio-economic systems or on human health and welfare.
2. “Climate change” means a change of climate which is attributed directly or indirectly to
human activity that alters the composition of the global atmosphere and which is in addition to
natural climate variability observed over comparable time periods.
3. “Climate system” means the totality of the atmosphere, hydrosphere, biosphere and
geosphere and their interactions."

What are greatest dangers from global climate change?

1.Amplifying positive feedbacks​​-
​The greatest dangers to the integrity of the planet and to all life
B​y definition the greatest dangers​ are positive (amplifying) climate feedbacks, by which global warming from atmospheric GHG pollution causes more global warming, that is an increase in the rate of global temperature increase. There are very many such feedbacks. The largest source of feedbacks is the Arctic, which is now warming several times faster than the rest of the planet. All of these Arctic feedbacks are now operant. 

2. Food insecurity
The ​greatest dangers to human populations or humanity are obviously water deprivation, food deprivation and health deprivation- and their combinations. They are all increased by global climate change and all fall under food security dangers. The world's best food producing regions are in the Northern Hemisphere and since 2000 a number of badly damaging extreme weather events have hit these NH regions. The evidence for causation due to global warming plus Arctic amplification snow and sea ice albedo cooling is looking definite with recent research. 

3.  Extreme weather events​​ which is categorized as one climate change impact is extremely dangerous.
This is most damaging to human health and to crops and in labor intensive agriculture is more than doubly dangerous. ​

Global climate change commitment ​​makes all dangers far worse than they seem today, making the above more than just dangers.
What is runaway?

The ultimate planetary tipping point would be so-called 'runaway'.

​​For many years people concerned about global warming have referred to runaway global warming and climate change​. This is not a scientific term. It is used to convey the risk on a totally uncontrollable self accelerating global warming situation brought about by a very large positive feedbacks boosting each other in a vicious cycle. The scientific term is abrupt, irreversible, rapid warming.
The IPCC uses the term irreversible large-scale singularities
Reasons for Concern 4 Burning embers above.
​The runaway scientific term is the runaway greenhouse effect. This is the ultimate planetary catastrophe leading to the super heated dead planet like Venus, that coud not happen on Earth. 
What are tipping points?
​The term ‘‘tipping point’’ commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system (T Lenton). 
Dangerous climate interferencedefined by the 1992 UN climate convention, is unsafe levels of atmospheric greenhouse gases, but this is seldom recognized. 
The objective of the 1992 Framework Convention on Climate Change is to avoid  dangerous *anthropogenic interference with the climate system )*human caused.
Climate Emergency Institute

The 2°C danger limit target dates back to the EU in 1996 and the EU has always said it a policy compromise that cannot be considered safe. For year the most climate change vulnerable nations at the UN negotiations have compalined they could not survive 2.0°C and the danger limit has to be under 1.5°C. 

At the 2010 UN Cancun Climate Conference it was agreed to have an expert team look at 2.0°C and 1.5°C as danger limits. ​Subsequently the UNFCCC Sec. called this a Structured Expert Dialogue and the findings were published in February 2015. The report made it clear that though 1.5°C is globally disastrous 2.0°C woudd be global catastrophe. 

A paper by one of the experts made it very clear the danger limit is not 2C. ​
​1.5°C or 2°C: a conduit’s view from the science-policy interface at COP20 in Lima,
​Peru 2015 Petra Tschakert

March 28, 2016  Will climate change leave a bleak future for humanity?
​Oxford physicist Raymond Pierrehumbert .. In the immediate future, he says, humanity’s destiny depends on whether the climate change crisis can be minimized — whether the world can “transition to a carbon-free economy” — or whether rampant global warming will turn Earth into a hell-hole. “There is a severe risk civilization will collapse, leaving our descendants with few resources to deal with the unbearable environment we will have bequeathed them,” the Oxford don wrote. The world must stop burning fossil fuels that cause the planetary heat-up, and switch instead to wind and solar power.` 

March 2018, There is no Planet B, Paleoclimaologist, Andrew Glikson 
Following the 2015 UN Paris Agreement the old 2°C limit (certain catastrophe) has changing to 1.5C, but 1.5°C is still globally disastrous. James Hansen published evidence for 1C danger limit and today (2018), which is certainly right and we are at 1.1°C (2018).
COMMITMENT Commitment Fundamental to dangerous climate change is today's commitment (see page), that determines already locked-in future global change will inevitably be much higher than today's degree of climate change. Commitment is due to climate system inertia (mainly long CO2 life-time ocean heat lag) and momentum. 
16 May 2018 Global exposure and vulnerability (with video)
May 2018 UN Secretary General Climate change:
​An 'existential threat' to humanit
y, UN chief warns global summit

Global climate change, the global threat multiplier ​is top world security risk 
James Hansen is the top climate expert in communicating the climate change dangers and climate emergency in his many expert presentations.

Small children are most vulnerable Danger includes vulnerability  
Environmental health risk assessment of total pollution impacts by SOURCES
​(see Health page)
​Climate change should be assessed by an environmental health risk assessment, n
​ot only by a climate change assessment. The IPCC refers to risk but does not in fact apply risk to the assessments.

Sources of GHG emissions ​​The dangers of atmospheric greenhouse gas pollution, are from the greenhouse gas emission sources. The health of human populations is (should be) assessed by the long established standard environmental health risk assessment. The environmental health risk assessment addresses all the sources of all the pollution and the health risks of their source based impacts, of which a greenhouse gas emissions are a part. Presently that is large but still a small proportion of the total pollution health impacts and risks.

​​Small children are the most vulnerable, followed by the elderly and the infirm.  
GHG POLLUTION We should be assessing the dangers of global climate change by assessing the risks of atmospheric greenhouse gas pollution as we normally assess pollution, which importantly includes the effects on the oceans. Global climate change cannot be controlled without addressing the other greenhouse gas emissions, particularly methane and nitrous oxide, in addition to carbon dioxide.
In fact under ​the 1992 UN climate change convention it is safe atmospheric GHG levels that are required.   
Atmospheric greenhouse gas pollution dangers
ToP danger to theplanet (that is all systems of the biosphere) ​which involves tipping points- with the ultimate danger being multiple cascading carbon feedback causing unsurvivable Hothouse Earth .
​This applies t
all of life on land and in the oceans, ​the security and health of human populations, and the future ​of the human race surviving on an increasingly inhospitable planet. This is dangers beyond 2100 (IPCC projects only to 2100)
​'There is no such thing as ‘safe’ climate change.
​Even the global temperature increase to date (about 0.75°C) is contributing to effects that are impossible to adapt to in some regions As the temperature rises further, so will the risk of more widespread and dangerous climate impacts; from sea level rise, increasing frequency and intensity of climate extremes such as heat waves, floods and droughts,' (Royal Society December 2009 ​'Preventing dangerous climate change ​The need for a global agreement').