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WMO’s classical period for climate observations
30 years
How temperature observations are made
• Weather huts (problems: environment) • Weather balloons (problems: drift) • Ships (problems: size of hull) • Satellites (necessary to make some assumptions to measure surface temperature)
The 2 common methods for interpolating climate data
• Inverse Distance Weighting - Kriging
Explain the Kriging technique
• Uses how similar temperatures are over current satellite data to estimate previous temperatures. • Uses covariance information about spatial patterns. • Always done using anomalies rather than actual temperatures. Advantages of this: anomalies have larger spatial correlation. Smaller impact if one station is temporarily unavailable.
The role of the ocean in the warming hiatus
• Land surface temperature hasn’t increased since 1998, but the ocean has kept warming faster than ever. • During periods of rapid warming at the surface, the ocean is cooling and vice versa. • We don’t know what causes this.
Define climate feedbacks
A collection of processes that either: • reinforce or amplify the effect of an initial forcing • suppress the effect of an initial forcing
List some climate feedbacks
• water vapour feedback (positive) • ice-albedo feedback (positive) • cloud feedback (either) • ocean-carbon uptake (negative) • soil moisture feedback in heatwaves (positive)
When and by whom was the IPCC established
by the - World Meteorological Organisation (WMO) - UN Environment Programme (UNEP) in 1988.
What information does the IPCC review and assess
The most recent - scientific - technical - socio-economic information produced relevant to climate change
Differentiate between IPCC & UNFCCC
• IPCC are the scientists - UNFCCC are the diplomats
In which years were the first two World Climate Conferences?
1st: 1979 2nd: 1990
There have been annual COPs since which year?
1995
What are the 3 IPCC working groups?
WG1: Scientific basis WG2: Impacts, vulnerability, adaptation WG3: Mitigation
Outline Planck’s radiation law
• Hotter objects emit more radiation • The peak wavelength at which objects emit decreases with increasing temperature • Frequency = 2pi / wavelength
Mean global surface temperature • without atmosphere • with atmosphere
with: -19 celsius without: +15 celsius
In which spectrum are ghgs visible?
The infrared spectrum
The canonical value for albedo
30%
The Latent Heat Cycle
Some of the solar radiation absorbed by the surface is used to drive evaporation
The evaporation-heatwave feedback
• evaporation of water at the surface is a cooling term - if there is no more water to evaporate, energy goes into warming surface
The positive cloud feedback
more clouds > more downward emission of infrared radiation > warming at the surface > more evaporation > more clouds
The negative cloud feedback
more clouds > more reflection of incoming solar radiation > cooling at the surface > less evaporation > less clouds
What is the solar radiation imbalance figure (net absorbed)? And how is it measured
0.9 wm^-2 • Too small to be measure directly • Can be computed from the change in mean temperature or from climate models
Outline GWP
Global Warming Potential • defined as warming of a certain mass of ghgs relative to that same mass of CO2 over the next 100 years • is used to compare the relative warming effects of different ghgs
Outline Radiative Forcing
• the amount of energy re-emitted back to earth from ghgs expressed in units of wm^-2 • a method of quantifying the greenhouse effect