Climate change

Question 1

What is the difference between climate and weather?

Answer 1

Weather - The short-term (i.e. hourly and daily) state of the atmosphere in a specific place. It may change very rapidly.

Climate - The average weather conditions over a longer period of time (e.g. 30 years) and possibly over a larger area. It changes slowly.

Question 2

What is the “greenhouse effect”?

Answer 2

Increase in greenhouse gases concentration in the atmosphere

→ ‘stronger’ greenhouse effects → increase in the Earth’s temperature

Question 3

Climate is variable, what are 4 processes that influence climate at numerous timescales?

Answer 3

– Solar radiation
– Atmospheric composition
– Land surface characteristics
– Ocean circulation

Question 4

Why are greenhouse gases concentrations increasing?

Answer 4

In decreasing order;
CO2 from fossil fuel use & other sources
CO2 from deforestation, decay & peat
CH4 from agriculture, waste & energy
N2O from agriculture & others

Question 5

List at least 4 consequences of climate change for water-related risks.

Answer 5

decrease in spring snow cover

increase in frequency of intense rain

increase in evaporation

impacts on
water resource

Question 6

Why are climate projections uncertain? List 3 sources of uncertainty.

Answer 6

Which processes to include and which to neglect?

How to best represent the processes included in the model?

What spatial resolution?

Which parameter values?

Question 7

How can we plan water resources under climate change?

Answer 7

(1) Use historical observations with care.
(2) If using models, recognise (and try to estimate) the uncertainty in their projections.
(3) Analyse tradeoffs between possible costs and benefits to define what is “acceptable risk”.

Question 8

What are the implications of climate change for water resource planning and
management?

Answer 8

Sea level increase projections for the UK

Temperature and precipitation projections for the UK

Change in summer mean temperature (°C) under high emission scenario

Question 9

Modelling climate change impacts

Answer 9

(1) Regional Circulation Models (RCMs) are used to downscale climate projections from global to regional scale; further statistical downscaling can be applied to obtain projections at the catchment scale.
(2) Then, hydrological-hydraulic models can be used to estimate the effects on the water cycle and water resources at regional or local scale.