Lecture 5 - Climate Change

Question 1

The hockey stick revisited: the less important was the … and the …, the more important became … .

Answer 1

The hockey stick revisited: the less important was the Medieval Warm Period and the Little Ice Age, the more important became recent changes.

Question 2

By what is the hockey stick effect characterized?

Answer 2

By a sharp rise or fall of data points after a long flat period.

Question 3

Hockey stick graphs present the global or hemispherical mean temperature record of the past 500 to 2000 years. What do these reconstructions show?

Answer 3

A slow long-term cooling trend changing into relatively rapid warming in the 20th century.

Question 4

With climate change there are clear problems of attribution: people blame CO2, but is CO2 to blame? Explain some of these facts about CO2:

• Diminishing impact on temperature change
• The global carbon cycle
• The water vapour elephant

Answer 4

• Diminishing impact on temperature change – the effect on global temperatures (climate forcing) of increasing concentration of CO2 is logarithmic. The first 20 ppm has the greatest effect.
• The global carbon cycle – annual anthropogenicemissions (greenhouse gases) is only 0,016% of ocean stock of carbon.
• The water vapour elephant – less than 5% of planetary global warming is due to CO2 and other gases. More than 95% is due to water vapour.

Question 5

In concentrating on CO2 are we missing the ‘elephant in the room’? But:

• Nobody worries about water …
• Nobody has suggested a water …
• Nobody dreams about a water … and storage system

Why are we missing the elephant in the room by focusing on CO2?

Answer 5

• Nobody worries about water futures
• Nobody has suggested a water tax
• Nobody dreams about a water capture and storage system

More than 95% of planetary global warming is due to water vapour.

Question 6

What are the steps of ‘disease shift of range’?

Answer 6

1. Emergence
2. Arrival
3. Establishment
4. Spread

Question 7

What do we mean with emergence and arrival?

Answer 7

Emergence of new vectors or pathogens, that invade ‘new’ areas.

Question 8

When can we say that a vector and disease have established themselves?

When does spread occur?

Answer 8

Establishment: a vector must have a net production rate of >1 and a disease must have an transmission rate of >1.

Spread occurs naturally (R>1 or R0>1), possibly aided by humans.

Question 9

Name the two factors that the impact of global warming depends on.

Answer 9

1. How each parameter/variable change with increasing temperature.
2. How R0 changes with changes in each parameter/variable.

Question 10

Biological models with some, but not all, of the appropriate variables and parameters of transmission will give misleading prediction of the impact of climate change.

What will the actual impact depend on?

Answer 10

It will depend upon the relative importance of factors tending to increase R0and those tending to decrease.

Question 11

Which approach provides the only reliable method, in the short term, for predicting climate-induced changes?

Answer 11

The alternative, statistical approach.

Question 12

There is a great deal of uncertainty about climate and environmental futures. This uncertainty arises from which three different causes?

Answer 12

• Uncertainty of the future activities of humans
• Uncertainty that climate/environmental models are correct (e.g. the roles of aerosols, and of clouds)
• Uncertainty inherent in climate systems (chaotic system dynamic; butterfly-wing effect). The same starting point in an exactly correct model can give a wide variety of end-points.