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Key climate information

For more details via infoboxes: hover, click or double-click on any highlighted text

rise in atmospheric CO<small><small>2</small></small>
The science of climate change
  • Just over half of the CO2 added to the atmosphere by the burning of fossil fuels stays in the atmosphere.
  • So, since the mid-1800's,
    the atmospheric concentration of CO2 has been steadily increasing
    .
  • The CO2 in the atmosphere retains heat.
  • So,
    as more and more CO2 has been added to the atmosphere, global temperatures have steadily increased
    .
  • As well as the increased temperatures, there are more storms, floods, heatwaves and wildfires, sea levels are rising, and tipping points are nearing.
  • These are causing unacceptable and unsustainable levels of climate deaths, climate refugees, and biodiversity loss.
The urgency of action on climate change
  • The urgency of climate action is given by the commitment in the Paris Agreement
    to make efforts to limit global warming to 1.5°C
    .
  • The setting of a limit to global warming implies a limit to how much more CO2 can be added to the atmosphere (the carbon budget).
  • The global
    carbon budget
    for 1.5°C runs out in about 2033, or earlier. The carbon budget runs out even sooner in developed countries, e.g. the UK's fair carbon budget for a 50% chance of limiting global warming to 1.5°C runs out in 2027.
  • This means radical changes in lifestyles for many people until renewable alternatives are developed, if temperature targets are to be met.
What should have been done by governments and wider society
There should have been agreement on a plan to rapidly eliminate fossil fuels in line with the climate science and the commitments given in the Paris and other agreements - and effective implementation of that plan.
What has actually been done
There have been many declarations of a climate emergency, but planning has been of non-emergency policies, and there has been little action. The global total of CO2 emissions, which should have been falling rapidly, has continued to increase.
What has gone wrong, why has policy making been so poor?
  • There has been no general discussion of the extreme urgency from the dwindling carbon budget and the implications of radical change e.g. the closure of most airports within a few months.
  • Instead, inadequate government timescales (such as Net Zero 2050) have dominated discussions and have been little challenged - with inadequate policies being advocated and planned.
  • This seems to be not just misunderstandings but a form of
    climate denial
    , termed implicatory climate denial - exacerbated by wishful thinking, groupthink, overconfidence and other cognitive biases, and pseudoscience
  • There has been a general failure across society: by government scientists, politicians, the media, climate campaigners, climate sceptics, businesses, other organisations, and individuals.
What choices do we have now
  • current lifestyles are unsustainable, so radical change is coming one way or another - we can choose to organise radical change, or have disorganised radical change forced upon us by a deteriorating climate
  • whether to continue with inadequate non-emergency policies or face up to the situation and treat climate change as the highest priority i.e. as an
    emergency
  • whether to continue with the target of limiting global warming to 1.5°C or to accept that the system has failed and consider a higher limit of e.g. 1.6°C.

The science of climate change

Every tonne of CO2 emissions adds to global warming
Global temperature increases with cumulative CO<small><small>2</small></small> emissions
  • Just over half of the CO2 added to the atmosphere by the burning of fossil fuels stays in the atmosphere.
  • So, since large scale burning of fossil fules started in the mid-1800's,
    the atmospheric concentration of CO2 has been steadily increasing
    .
  • The CO2 in the atmosphere retains heat.
  • So, as more and more CO2 has been added to the atmosphere, global temperatures have steadily increased (see chart).
  • As well as the increased temperatures, there are more storms, floods, heatwaves and wildfires, sea levels are rising, and tipping points are nearing.

These changes are causing unacceptable and unsustainable levels of
  • climate deaths: about one climate-related death per 4000 tonnes CO2 put in the atmosphere
  • climate refugees
  • biodiversity loss, e.g. destruction of coral reefs
  • sea level rise
See document 144: Mortality and other harms from climate change

If global warming continues, catastrophic tipping points in the climate system will be passed and changes will become abrupt and/or irreversible. The effects on the planet including mankind will then accelerate. The most important tipping points are
  • melting of ice:
    • irreversible meltdown of the Greenland ice sheet
    • irreversible retreat of the West Antarctic ice sheet, or of Wilkes Basin in East Antarctica
  • ocean currents and atmopheric circulation:
    • collapse of the oceanic Atlantic Meridional Overturning Circulation (AMOC)
    • disruption of the West African monsoon, and of the South Asian/Indian summer monsoon
  • biosphere tipping points including
    • large-scale dieback of the Amazon rainforest and of boreal forests.

What should have happened after the Rio Agreements of 1992

Global temperature increases with cumulative CO<small><small>2</small></small> emissions by 1992
By the late 1980's, it was clear that adding CO2 to the atmosphere does in fact cause global warming - it is not just a theoretical risk.

By the time of the
Rio 'Earth Summit'
of 1992, the cumulative total of global CO2 emissions had reached 1,500 billion tonnes CO2 and the global average temperature had risen 0.5°C (see chart).

At the 1992 Summit, there were several important international agreements. These included the Rio Declaration. Its
Second Principle
states that
States have a responsibility to ensure that they do not cause damage to the environment of other States or other areas beyond their national jurisdiction.

A second agreement was the United Nations Framework Convention on Climate Change
(UNFCCC)
. Its
Article 2
states:
"The ultimate objective of this Convention" is the
"stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system".
and its
Article 3
includes the agreed aim:
to protect the climate for the benefit of present and future generations of humankind, on the basis of equity


The implications of these were that fossil fuel use would be phased out in a fair manner before rising levels of atmospheric CO2 became dangerous - but that is not what happened.

Instead total annual global CO2 emissions increased rather than decreased.

Commitments in the Paris Agreement

Global temperature increases with cumulative CO<small><small>2</small></small> emissions
By the time of the Paris conference of 2015, the cumulative total of global CO2 emissions had reached 2,200 billion tonnes CO2 and the global average temperature had risen by 1.0°C.

It was now clear that adding CO2 to the atmosphere not only increased global temperatures, but also increased the number and intensity of extreme weather events, with large human costs - dangerous climate change had already been effected.

The
most important commitments in the Paris Agreement
were:
to limit global warming to well below 2°C (often taken to mean 1.7°C), and
to pursue efforts to limit it to 1.5°C above pre-industrial levels

Two clarifying reports after the Paris Agreement

Following this agreement, countries should have implemented plans to reduce emissions. The
IPCC
produced two reports to facilitate the process:

1. The SR15 report of 2018
Some key messages were
"limiting global warming to 1.5°C would require rapid and far-reaching transitions" (IPCC, 2018)
"These systems transitions ... imply deep emissions reductions in all sectors" (IPCC, 2018)

2. The AR6 report of 2021
This explained the need for
"immediate, rapid and large-scale reductions in greenhouse gas emissions" (IPCC, 2021)
Global temperature increases with cumulative CO<small><small>2</small></small> emissions
It gave
carbon budgets for limiting global warming to 1.5°C and other values including 1.7°C
. The budget for 1.5°C was given as a further 500 billion tonnes CO2 (total global emissions of 2,900 billion tonnes CO2), and for 1.7°C as a further 350 billion tonnes CO2 (total global emissions of 3,250 billion tonnes CO2).

The urgency has been further emphasized by:
"This is a climate emergency" (UN Secretary-General, 2022)

What should have been done after the Paris Agreement

Following the Paris Agreement, there should have been a discussion of the implications of the Agreement, agreement of a plan to eliminate fossil fuels, and implementation of the plan.
A strategy should have been devised with the following key elements
  • an assessment of the degree of urgency of action: leading to a decision of emergency (not routine) action
  • a decision on the main objective: deciding on a limit to global warming of 1.5°C
  • an understanding of the science of achieving this objective: staying within the appropriate carbon budget
  • including the commitment in the Paris Agreement to equity between nations
  • using a fair accounting system: including all CO2 emissions
  • stating clearly the required speed of change: double digit percentage annual emission cuts
  • detailing credibly compliant policies
  • quality control measures should have worked, e.g. avoiding false solutions.
See more at carbonindependent.org/100.html.

What has actually been done

Global temperature increases with cumulative CO<small><small>2</small></small> emissions
Despite all the reports, agreements and commitments, annual emissions have continued to increase, and the global total is accelerating towards the total at which the 1.5°C commitment will be breached.

There have been many declarations of a climate emergency, but
  • there has been no general discussion of the imminent exhaustion of the carbon budget - inadequate government timescales dominate discussions and have not been challenged
  • the rich countries have generally ignored their commitments to equity between countries and to cutting CO2 emissions faster than the global average
  • there has been no competent plan - planning has been of non-emergency policies
  • there has been little action

The urgency of action on climate change

UK carbon budget chart for net zero 2050
The urgency of action is given by the global
carbon budget
for limiting global warming to 1.5°C running out in 2030, and it's even sooner in developed countries
e.g. 2027 for the UK
.


This means radical changes in lifestyles for many until renewable alternatives are developed, if temperature targets are to be met.

The climate has changed particularly rapidly in the last few years suggesting that even more urgent change is needed.

What has gone wrong: a widespread failure of decision making

  • there has been no general discussion of the imminent exhaustion of a fair carbon budget - 2027 in the UK for compliance with the 1.5°C commitment
  • instead, the urgency of action has been understated - inadequate government timescales (such as Net Zero 2050) dominate discussions and have been little challenged - with inadequate policies being advocated and planned
  • this is a general failure across society: by government scientists, politicians, the media, climate advocacy groups, sceptics of climate action, businesses, the legal system, other organisations, and individuals
  • the evidence is that it is not a sporadic problem, and that it is not a conspiracy of oil companies or billionnaires (as sometimes stated) - instead there is a widespread failure of decision making
  • even climate campaigners have understated the size and urgency of changes needed, with fragmentation of climate advocacy efforts, leading to chaotic, inconsistent and inadequate policy proposals
  • flawed campaigning seems to be not just misunderstanding but a form of
    climate denial
    termed implicatory denial by psychologists.

Why has decision making been so poor

Despite appearances, the squares marked A and B in the optical illusion are
actually the same shade of grey!
Checker shadow illusion Attribution: Edward H. Adelson: Checker shadow illusion
People are fallible - what appears obvious to someone can be incorrect - as in the optical illusion
- resulting in widespread failure of decision making

It seems that decisions are flawed because of
  • ignorance
  • cognitive biases including
    • arrogance/overconfidence
    • groupthink
    • wishful thinking
    • selective recall
    • confirmation bias
    • the bystander effect
    • pluralistic ignorance
  • self-interest
  • lack of accountability.

What choices do we have now

  • whether to face up to the urgency of action, or to continue with the denial
  • our current lifestyles are unsustainable, so radical change is coming - we can choose to organise radical change, or have disorganised radical change forced upon us
  • whether to continue with inadequate non-emergency policies or treat climate change as the highest priority i.e. as an
    emergency
  • What target for climate action should be adopted
    • the Paris Agreement commitment was to limit global warming to 1.5°C or at least well under 2.0°C - the target has been 1.5°C, but the fair UK carbon budget for 1.5°C runs out in 2027 - there is a choice of whether to continue with the target of limiting global warming to 1.5°C or to accept that the system has failed and consider a higher limit of e.g. 1.6°C


First published: 13 Feb 2025
Last updated: 8 Jan 2026     Page No: 184