Introduction to Climate Science

IPCC AR5 Synthesis Report

OUTREACH EVENT ON THE IPCC FIFTH ASSESSMENT REPORTIstanbul – Turkey

Lučka Kajfež BogatajReview editor for WGII

Climate Change is a Large Issue

Majority of the sciences and engineering disciplines are involved.

Social sciences are interested.Business/Industry has a stake.Involves citizens, politicians, public policy experts,

and advocates.Every sector of the economy affected.All aspects of our lives touched:

environment, jobs, health, politics, national security, arts, religion, etc.

What is happening in the climate system?

What are the risks?

What can be done?

Evolution of primary energy


Sources of emissionsEnergy production remains the primary driver of GHG emissions

35% 24% 21% 14% 6.4%

2010 GHG emissions

Energy Sector

Agriculture, forests and

other land usesIndustry Transport

Building Sector

AR5 WGIII SPM

Fate of Anthropogenic CO2 Emissions

26%

32.4±1.6 GtCO2/yr 91%

3.3±1.8 GtCO2/yr 9% 29%

44%

–18°C +15°C

Earth without air Our planet

+ 33°C

If the world had no atmosphere, it would be very cold

Natural GHG effect

33 °C

Other GHG <1 °C

CO2 2 °C

H2O 31 °C

–18oC

+15oC

BUT THE COMPOSITION OF AIR IS CHANGING RAPIDLYdue to human activities:

→ more GHG (CO2, CH4, NOx...)→ more aerosol (air pollution)

Enhanced GHG effect

33 °C+ 1 °C

Other GHG <1 °C

CO2 2 °C + 1oC

H2O 31 °C

–18oC

+16oC


YearGlobally averaged combined land and ocean surface

temperatures

It is extremely likely that we are the dominant cause of warming since the mid-20th century

AR5 WGI SPM

Humans are changing the climate


2014 is the warmest year in the record

YearGlobal average annual temperatures since 1880 ( NOAA )

The dark red columns represent the 10 warmest years in the record


Antropogenic forcings are extremely likely the cause of warming


Oceans absorb most of the heat

More than 90% of the energy accumulating in the climate system between 1971 and 2010 has accumulated in the ocean

AR5 SYR


Impacts are already underway• Tropics to the poles• On all continents and in the ocean• Affecting rich and poor countries

(but the poor are more vulnerable everywhere)

AR5 WGII SPM


HUMAN INFLUENCE: Some changes in extreme weather and climate events observed since ~1950 are linked to human activity

AR5 WGI SPM

In a number of regions, impacts are already underway:

• decrease in cold temperature extremes

• increase in warm temperature extremes

• increase in extreme high sea levels

• increase in the number of heavy precipitation events

Global natural disasters 1980 – 2013Geophysical, meteorological, hydrological events


Projected climate changesContinued emissions of greenhouse gases will cause further warming and changes in the climate system

Global glacier volume will further decrease

Global mean sea level will continue to rise during the 21st century

It is very likely that the Arctic sea ice cover will continue to shrink and thin as global mean surface temperature rises

Oceans will continue to warm during the 21st century

AR5 WGI SPM

Warming over the 21st century

Based on WGII Figure SPM 4

Projections Europe (RCP4.5)2081-2100 versus 1986-2005

Temperature (oC) Precipitation (%)

winter summer winter half summer half

+2°+4°

PROBLEMATIC• 1 - 2 billion additional people with water stress• Impacts on cereal productivity at low latitudes• Increased coastal flooding and storms• Greater depth of seasonal permafrost thaw

DISASTROUS• A 16 ºC increase in the Arctic• 1.1 - 3.2 billion additional people with water

stress• Widespread coral mortality; risk of major

extinctions around the globe• Substantial global impact on major crops• Long-term prospect of sea level rise

Global temperature rise


Potential Impacts of Climate Change

Food and water shortages

Increased poverty

Increased displacement of people

Coastal flooding

AR5 WGII SPM

Climate Change impacts

Climate ChangeImpacts

Physical systems(ice, rivers, etc.)

Biological & seasonal cycles

Economy: infrastructure, output, growth

Stern Report (UK, 2006)

Human Well-being

Indirect impacts Wealth (and distribution);

local environment; etc.

Direct health impacts (heat, extreme events...)

Food yields

Climate change: A Multiplier for Instability


Climate Change Poses Risk for Food ProductionPe

rcen

tage

of y

ield

pr

ojec

t ions

AR5 SYR SPM

Facing the dangers from climate change……there are only three options:

Mitigation, meaning measures to reduce the pace & magnitude of the changes in global climate being caused by human activities.

Adaptation, meaning measures to reduce the adverse impacts on human well-being resulting from the changes in climate that do occur.

Suffering the adverse impacts that are not avoided by either mitigation or adaptation.


Limiting Temperature Increase to 2˚C

A combination of adaptation and substantial, sustained reductions in greenhouse gas emissions can limit climate change risks

Implementing reductions in greenhouse gas emissions poses substantial technological, economic, social, and institutional challenges

But delaying mitigation will substantially increase the challenges associated with limiting warming to 2°C

AR5 WGI SPM, AR5 WGII SPM,AR5 WGIII SPM

Measures exist to achieve the substantial emissions reductions required to limit likely warming to 2°C (40-70% reduction in GHGs globally by 2050 and near zero GHGs in 2100)


Mitigation Measures

More efficient use of energy

Greater use of low-carbon and no-carbon energy• Many of these technologies exist today

Improved carbon sinks• Reduced deforestation and improved forest management

and planting of new forests • Bio-energy with carbon capture and storage

Lifestyle and behavioural changesAR5 WGIII SPM


Ambitious Mitigation Is Affordable

➜ Economic growth reduced by ~ 0.06% (BAU growth 1.6 - 3%)

➜ This translates into delayed and not forgone growth

➜ Estimated cost does not account for the benefits of reduced climate change

➜ Unmitigated climate change would create increasing risks to economic growth

AR5 WGI SPM, AR5 WGII SPM

Comparison of the global 2oC carbon budget with fossil fuel resertves CO2 emissions potential


The window for action is rapidly closing65% of our carbon budget compatible with a 2°C goal already used

Amount Used1870-2011:

1900GtCO2

Amount Remaining:

1000GtCO2

Total Carbon Budget:

2900GtCO2

AR5 WGI SPM


The Choices We Make Will Create Different Outcomes

With substantial mitigation

Without additional mitigation

Change in average surface temperature (1986–2005 to 2081–2100) AR5 WGI SPM

Future CO2 concentrations

Long term limit for reefs

Countries‘ individual proposed efforts not sufficient !!!

Intended Nationally Current trendsDetermined Contributions


Key Messages

➜ Human influence on the climate system is clear

➜ The more we disrupt our climate, the more we risk severe, pervasive and irreversible impacts

➜ We have the means to limit climate change and build a more prosperous, sustainable future

AR5 WGI SPM, AR5 WGII SPM, AR5 WGIII SPM


IPCC Fifth Assessment Report

Introduction to Climate Science

Environment

Transcript of Introduction to Climate Science