lecture climate change - max planck society

Lecture Climate Change

Rene [email protected]


● Part of the module “Klimatologie und Klimawandel”– Lecture “Klimatologie”, mondays 14:15-16:00

https://www.bgc-jena.mpg.de/bsi/index.php/Services/LectureFSUClimatology

– Lecture “Klimawandel”, thursdays 10:15-12:00https://www.bgc-jena.mpg.de/bgi/index.php/Lectures/HydroBioClimClimateChange

– Seminar, wednesdays 9:15-10:00, starts 2 December,https://docs.google.com/document/d/1MQmHJrQokFNPjOdp3EiLXq-a5ormvA3yYg2QWLIXjA4

● 6 LP for passing written exam, and presenting and participating in seminars


● Learning about physical processes which translate increased greenhouse gas concentrations into climate changes

● Introduction into international climate policy, including climate-policy game

● Given by Rene Orth (9 weeks, in German) and Sungmin O (3 weeks, in English)


● No fixed textbook

● Slides serve as script

● Most information on www.ipcc.ch/report/ar5/

Course webpagewww.bgc-jena.mpg.de/bgi/index.php/Lectures/HydroBioClimClimateChange

Lecture 1Introduction to Climate Change

1) Greenhouse effect2) Climate variations before 18503) Climate variations after 18504) Why we know it’s our fault5) The ozone success story

Greenhouse effect[simple version]

KLEINE GASE – GROSSE WIRKUNG DER KLIMAWANDEL ein Buch von: DAVID NELLES & CHRISTIAN SERRER

Solar radiation heats Earth’s surface (short-wave radiation),Earth radiates back into space (long-wave radiation)

→The latter is partly suppressed by greenhouse gases

1

Greenhouse effect[advanced version]

Solar = short wave radiationThermal = long-wave radiation

IPCC (2013)

2

Main greenhouse gases

● Water vapour is the most important greenhouse gas on Earth● Given their low concentration, methane and ozone have

considerable warming contribution

wikipedia.org

3

Main greenhouse gases

Methane molecules have stronger warming potentialthan CO2 molecules

wikipedia.org

4

Greenhouse effect

Each greenhouse gas has a characteristic absorption spectrum

wikipedia.org

5

Summary

● Greenhouse effect is a natural phenomenon● Atmospheric gas molecules absorb outgoing long-wave

radiation and send it back to the surface● Without this warming mechanism, average surface

temperature on Earth would be -18 C

Climate reconstructions

Where can we find information on climate in the past 100’000s of years?

→ Ice cores!

6


Lastice age

Lastwarm time

wikipedia.org

7


● Last ice age was 20’000 years ago, last warm time was 120’000 years ago

● Glacial-interglacial cycles driven bylong-term changes of the Earth’s orbit around the Sun(Milankovic cycles)

● CO2 evolution is lagging behind (!) temperature evolution

8

Climate reconstructionszooming in to the last 1000s of years

Jahre vor heute

9

Climate reconstructionszooming in to the last 2000 years

While greenhouse gas concentrations can be inferred directly from bubbles in ice cores, there is more uncertainty in the resulting

temperature reconstructions

10

Climate reconstructionszooming in to the last 2000 years

● Hockey-stick curves allow to compare the magnitude of variations before 1850 (handle) and after 1850 (endpiece)

● Maximum natural variations approximately 20 ppm CO2 and 0.5-0.8 C per 100 years

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Summary




● In the past 100’000s of years, climate has varied between ice ages (4-5 C colder than today) and warm periods as today

● This is driven, and can be predicted, from the changing Earth orbit around the sun

Introduction to Climate Change


Temperature record in Jena

High inter-annual variability → long-term trend can only be detected with multiple decades of data

www.bgc-jena.mpg.de/~martin.heimann/weather/co2.html

12

Global temperature record

More variability than for CO2 due to

complex response of climate system

Strong agreement across datasets

IPCC (2014)

13

Strong spatial variability, Land warms faster than oceans

IPCC (2014)

14

CO2 record in Jena

Seasonal cycle induced by vegetation variabilityDaily variations controlled by weather

Long-term trend is human-made

www.bgc-jena.mpg.de/~martin.heimann/weather/co2.html

15

Global CO2 mixing

Model simulation

CO2 mainly emitted in northern hemispheredistributed around the globe within weeks-months

wikipedia.org

16

The path of anthropogenic CO2

Le Quere et al. (2018), ESSD

17

Global CO2 record

interpolated from several stations

Accelerating increase

IPCC (2014)

18

Strong drying across Africa“Dry gets drier, wet gets wetter” holds in Europe and North America

Climate change is more than CO2 & temperature

… it also concerns precipitation

IPCC (2014)

19


… it also concerns the sea level

Controlled by meltwater addition and thermic expansionThreatening millions of people living close to sea level

IPCC (2014)

20


… it also concerns the sea level

Different ice mass development in Greenland and

AntarcticaControlled by

temperature and precipitation

IPCC (2014)

21


… it also concerns the sea ice

Almost half of the Arctic summer sea ice is goneOpening up new shipping routes, decreasing reflectivity of the Earth

IPCC (2014)

22


… it also concerns wind storms (?)

No trend in number of storms

But strength might (have) increase(d)?Vulnerability also

needs to be considered

IPCC (2014)

23


… it also concerns water vapour

Warmer air can hold more water →

increasing concentration of the

strongest greenhouse gas on Earth

wikipedia.org

24

Summary






● Many aspects of the climate show accelerating change across the past 50-100 years

Introduction to Climate Change


Why we know it’s our fault

(1) From comparing reconstructions and modern measurements:

Fastest climate changes 0.5-0.8 C and 20 ppm CO2 per 100 years,In the last 100 years: 1 C and >100 ppm CO2

Today’s CO2 higher than ever before since homo sapiens exist

25

Why we know it’s our fault(2) From quantifying solar and volcanic forcing:.There is no other explanation than human influence for the observed climate changes

IPCC (2014)

26


(2) From quantifying solar and volcanic forcing:

There is no other explanation than human influence for the observed climate changes

IPCC (2014)

27


(3) From climate models:

Only when using the observed, increased greenhouse gas levels, the models can reproduce observed climate changes

CMIP3 and CMIP5 models using

observed greenhouse gas concentrations

CMIP3 and CMIP5 models using constant,

pre-industrial greenhouse gas concentrations

IPCC (2014)28


(4) From high-altitude temperature trends:

Increased greenhouse gas concentrations lead to cooling of stratosphere

Less long-wave radiation from surface reaches higher altitudes

Lübken et al. (2013), JGR

29

Greenhouse gas emissions

Only a fraction of the emissions stays in the atmosphere, the rest is taken up by land and oceans

IPCC (2014)

30


Emissions are continuously increasing

CO2 is main contributor of growing emissions, fluorinated gases contribution also growing

IPCC (2014)

31


Many sectors contributing similarly to emissions, rendering significant emission decreases difficult

IPCC (2014)

32


Most (industrial) CO2 originates from burning coal and oil


33


US & EU account for most historical emissions, but China catching up rapidly


34

Summary● Greenhouse effect is a natural phenomenon● Atmospheric gas molecules absorb outgoing long-wave radiation and

send it back to the surface● Without this warming mechanism, average surface temperature on

Earth would be -18 C



● Many aspects of the climate show accelerating change across the past 50-100 years

● There is strong evidence that this is caused by human emissions which intensify the greenhouse effect

The ozone success storyConcentrations of ozone-depleting human-emitted gases

1989: Montreal protocol“Perhaps the single most successful international agreement to date”(Kofi Annan)

wikipedia.org

35

The ozone success story

1989: Montreal protocol

● All member states agreed to phase out the production of ozone-depleting substances

● Regulation installed only 14 years after scientific discovery of ozone depleting effects, and before comprehensive scientific consensus was reached

● First treaty ever ratified by all United Nations member states

● Includes funds provided by industrial countries to support adaptation in developing countries

● Uncommonly for international treaties, with a 66% majority of member states, the list of banned gases can be updated, forcing all states to phase out the production of these gases

36

The ozone success story

Montreal protocol helped to recover global ozone levels

IPCC (2014)

20102000199019801970

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Ozone levels have not yet recovered everywhere

The ozone success storyIPCC (2014)

38

Summary● Greenhouse effect is a natural phenomenon● Atmospheric gas molecules absorb outgoing long-wave radiation and send it back

to the surface● Without this warming mechanism, average surface temperature on Earth would be

-18 C


● This is driven, and can be predicted, from the changing Earth orbit around the sun● Many aspects of the climate show accelerating change across the past 50-100

years

● There is strong evidence that this is caused by human emissions which intensify the greenhouse effect

● Coordinated international action can help to tackle global environmental challenges

lecture climate change - max planck society

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