Future Climate Changes, Risks and Impacts

IPCC Climate Change 2014

Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond.
Projections of greenhouse gas emissions vary over a wide range, depending on both socio-economic development and climate policy. …

Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.
Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.
(p 18)

Surface temperature is projected to rise over the 21st century under all assessed emission scenarios.
It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions.
The ocean will continue to warm and acidify, and global mean sea level to rise.
(pp 20-1)

Warming caused by CO2 emissions is effectively irreversible over multi-century timescales unless measures are taken to remove CO2 from the atmosphere. …
[Limiting] total human-induced warming … to less than 2°C relative to the period 1861-1880 with a probability of >66% would require total CO2 emissions from all anthropogenic sources since 1870 to be limited to about 2,900 GtCO2 …
About 1,900 … GtCO2 were emitted by 2011, leaving about 1,000 GtCO2 to be consistent with this temperature goal.
Estimated total fossil carbon reserves exceed this remaining amount by a factor of 4 to 7 …

Climate change will amplify existing risks and create new risks for natural and human systems.
Risks are unevenly distributed and are generally greater for disadvantaged people and communities in countries at all levels of development.
Increasing magnitudes of warming increase the likelihood of severe, pervasive, and irreversible impacts for people, species and ecosystems.
Continued high emissions would lead to mostly negative impacts for biodiversity, ecosystem services, and economic development and amplify risks for livelihoods and for food and human security.
(p 24)

Many aspects of climate change and its impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped.
The risks of abrupt or irreversible changes increase as the magnitude of the warming increases.
(p 31)

Advances, confidence and uncertainty in modelling the Earth’s climate system

Improvements in climate models since the AR4 are evident in simulations of

• continental-scale surface temperature,
• large-scale precipitation,
• the monsoon,
• Arctic sea ice,
• ocean heat content,
• some extreme events,
• the carbon cycle,
• atmospheric chemistry and aerosols,
• the effects of stratospheric ozone, and
• the El Niño-Southern Oscillation.

Climate models reproduce the observed continental-scale surface temperature patterns and multi-decadal trends, including the more rapid warming since the mid 20th century, and the cooling immediately following large volcanic eruptions (very high confidence). …
Confidence in the representation of processes involving clouds and aerosols remains low.

(Box 2.1, p 18)

Figure 1
Yellow indicates that associated impacts are both detectable and attributable to climate change with at least medium confidence.
Red indicates severe and widespread impacts.
Purple … shows that very high risk is indicated by all key risk criteria.

Reasons for concern regarding climate change

Five ‘reasons for concern’ have provided a framework for summarizing key risks since the Third Assessment Report. …
All warming levels in the text … are relative to the 1986–2005 period.
Adding ~0.6°C to these warming levels roughly gives warming relative to the 1850–1900 period, used here as a proxy for pre-industrial times (right-hand scale in figure 1).

The five reasons for concern are:

1. Unique and threatened systems


2. Extreme weather events
   
   Climate-change-related risks from extreme events, such as heat waves, heavy precipitation and coastal flooding, are already moderate (high confidence). …


3. Distribution of impacts
   
   Risks are unevenly distributed between groups of people and between regions; risks are generally greater for disadvantaged people and communities everywhere.
   Risks are already moderate … particularly for crop production (medium to high confidence). …


4. Global aggregate impacts
   
   Extensive biodiversity loss, with associated loss of ecosystem goods and services, leads to high risks at around 3°C additional warming (high confidence). …


5. Large-scale singular events
   
   [The risks of] abrupt and/or irreversible changes … are moderate between 0 and 1°C additional warming, since there are signs that both warm-water coral reefs and Arctic ecosystems are already experiencing irreversible regime shifts (medium confidence).

(p 29, emphasis added)

Richard Wilkinson and Kate Pickett

Green Army: Persons of Interest

Richard Wilkinson & Kate Pickett:
Over the next generation or so, politics seem likely to be dominated either

• by efforts to prevent runaway global warming or, if they fail,
• by attempts to deal with its consequences.

(The Spirit Level, 2009, p 215)


Richard Wilkinson (1943):
[Status differentiation has] deeply ingrained psychosocial effects.
[Inequality is] not just about poverty [or] unfairness.
Its about a response to social hierarchy, social ranking …
It's also about whether people feel valued or devalued.

[In] the Financial Times 100 companies that go into the share index, the average pay difference between the CEO at the top and the lowest paid full time worker, is about 300 to 1.
There's no more powerful way of telling a whole swathe of the population:

You people are worth almost nothing!
Than to pay you one third of 1% of what the CEO gets.

And then of course we say:

The problem with the poor is low self-esteem!

(Inequality and Progress, Big Ideas, ABC Radio National, 5 February 2014)

Richard Wilkinson & Kate Pickett

Economic Justice and Security

In the USA, a child is killed by a gun every three hours.
(p 132)

[The] most powerful sources of stress affecting health [are:]

• low social status,
• lack of friends, and
• stress in early life.

(p 39)

Figure 16.2
The widening gap between the incomes of the richest and poorest 10% in the USA 1975 (=1) to 2004.

[Inequality in the USA rose] through the 1980s to a peak in the early 1990s.
The [rest of the 1990s] saw an overall decline … with an upturn since 2000.
[The] downward trends [in violence and teenage births] through the 1990s were consistent with improvements in the relative incomes of people at the very bottom of the income distribution.
(p 142)

[In] 1978 there were over 450,000 people in jail [in the USA.]
[By] 2005 there were over 2 million: [a four-fold increase.]
In the UK, the numbers have doubled since 1990, climbing from around 46,000 to 80,000 in 2007.
(p 145)

[In the US only] 12% of growth in state prisoners between 1980 and 1996 could be put down to increases in criminal offending (dominated by a rise in the drug-related crime).
… 88% of increased imprisonment was due

• to the increasing likelihood that convicted criminals were sent to prison rather than being given non-custodial sentences, and
• to the increased length of prison sentences.

In federal prisons, longer prison sentences are the main reason for the rise in the number of prisoners.
‘Three-strikes’ laws, minimum mandatory sentences and ‘truth-in-sentencing’ laws (ie, no remission) mean that some convicted criminals are receiving long sentences for minor crimes.
In California in 2004, there were 360 people serving life sentences for shoplifting.
(p 147)

The ratio [of the risk of imprisonment of blacks versus whites] is 6.04 for the USA as a whole and rises to 13.15 for New Jersey. …
[In terms of patterns of youth offending:]

• 25% of white youths in America have committed one violent offence by age 17, compared to 36% of African-Americans,
• ethnic rates of property crime are the same, and
• African-American youth commit fewer drug crimes.

[And yet] African-American youth are overwhelmingly more likely

• to be arrested,
• to be detained,
• to be charged,
• to be charged as if an adult and
• to be imprisoned.

The same pattern is true for African-American and Hispanic adults, who are treated more harshly than whites at every stage of judicial proceedings.
Facing the same charges, white defendants are far more likely to have the charges against them reduced, or to be offered ‘diversion’ — a deferment or suspension of prosecution if the offender agrees to certain conditions, such as completing a drug rehabilitation programme.
(p 150)

[In] more equal countries and societies, [it seems that legal frameworks and penal systems] are developed in consultation with experts — criminologists, lawyers, prison psychiatrists and psychologists, etc, and so reflect both theoretical and evidence-based considerations of what works to deter crime and rehabilitate offenders.
[Whereas, in] more unequal countries and states [the policy response is driven by] media and political pressure [to be seen to be] tough on crime … rather than considered reflection on what works and what doesn’t.
(p 155)

[After] slowly increasing from 1950 to 1980, social mobility in the USA declined rapidly, as income differences widened dramatically in the later part of the century.
(p 160)

Future Pathways for Adaptation, Mitigation and Sustainable Development

IPCC Climate Change 2014

Figure 3.1
The relationship between

• risks from climate change [across Reasons For Concern],
• temperature change,
• cumulative CO2 emissions, and
• changes in annual GHG emissions

by 2050.
(p 35)

Effective decision making to limit climate change and its effects can be informed by a wide range of analytical approaches for evaluating expected risks and benefits, recognizing the importance of governance, ethical dimensions, equity, value judgments, economic assessments and diverse perceptions and responses to risk and uncertainty. …

Adaptation and mitigation are complementary strategies for reducing and managing the risks of climate change.
Substantial emissions reductions over the next few decades can

• reduce climate risks in the 21st century and beyond,
• increase prospects for effective adaptation,
• reduce the costs and challenges of mitigation in the longer term, and
• contribute to climate-resilient pathways for sustainable development. …

(p 32)

Without additional mitigation efforts beyond those in place today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread, and irreversible impacts globally (high confidence).
Mitigation involves some level of co-benefits and of risks due to adverse side-effects, but these risks do not involve the same possibility of severe, widespread, and irreversible impacts as risks from climate change, increasing the benefits from near-term mitigation efforts.
(p 33)

Adaptation can reduce the risks of climate change impacts, but there are limits to its effectiveness, especially with greater magnitudes and rates of climate change.
Taking a longer-term perspective, in the context of sustainable development, increases the likelihood that more immediate adaptation actions will also enhance future options and preparedness. …
(p 36)

There are multiple mitigation pathways that are likely to limit warming to below 2°C relative to pre-industrial levels.
Limiting warming to 2.5°C or 3°C involves similar challenges, but less quickly.
These pathways would require substantial emissions reductions over the next few decades, and near zero emissions of CO2 and other long-lived GHGs over by the end of the century.
Implementing such reductions poses substantial technological, economic, social, and institutional challenges, which increase with delays in additional mitigation and if key technologies are not available.
Limiting warming to lower or higher levels involves similar challenges, but on different timescales.
(p 37)

Climate change is a threat to equitable and sustainable development.
Adaptation, mitigation, and sustainable development are closely related, with potential for synergies and trade-offs.
(p 44)

(AR5 Synthesis Report — Longer Report, 2014)