Introduction

Climate System

Causes of Climate Change

Empirical Study of Climate

Climate Modelling

Palaeoclimatic Change

Contemporary Climate Change

Epilogue
Appendix
References

It has conventionally been assumed that, prior to the Industrial Revolution (»1765), the carbon fluxes into and out of the atmosphere were in equilibrium. Since that time, anthropogenic emissions of CO2 have added a further source of atmospheric carbon. In response to this forcing perturbation, the disturbed equilibrium is currently in a process of readjustment, and consequently the atmospheric concentration of CO2 has risen. A simple mass balance calculation from flux values in Figure 6.1 reveals a current net imbalance of 3.2Gt of carbon per annum entering the atmosphere.

Equation 18 demonstrates the nature of this disequilibrium that has existed since 1765.

dDM/dt = I + D_n - F - X [Equation 18]

where DM = M - M₀ (atmospheric CO2 mass change from pre-industrial, M₀, to present, M);

t= time (years);

I = CO2 emissions from fossil fuel burning and cement production (source);

D_n = CO2 emissions from land-use changes (source);

F = net oceanic uptake of CO2 (sink); and

X = the net terrestrial uptake of CO2 (sink).

Estimates of present day values for the terms in Equation 18 have been made by the IPCC (1990a, 1992, 1995). The most recent estimates, together with their associated ranges of uncertainty, are detailed in Table 6.1.

Inserting these estimates into Equation 18 reveals a present day figure of 3.2Gt/a for dDM/dt, equivalent to that calculated from flux values in Figure 6.1.

Greenhouse Effect

Enhanced G-Effect

Greenhouse Gases
 -Carbon Dioxide
  ·Sources
  ·Sinks
  ·Carbon Cycle
  ·Concentrations
  ·Equilibrium
 -Methane
  ·Sources
  ·Sinks
  ·Concentrations
 -Nitrous Oxide
  ·Sources
  ·Sinks
  ·Concentrations
 -Halocarbons
  ·Sources
  ·Sinks
  ·Concentrations
 -Ozone
 -Other Gases
 -Lifetimes
 -Summary

Greenhouse Forcing
 -Forcing Factors
 -GWPs
 -ΔF-ΔC
 -1765 to 1990
 -Ozone

Aerosols
 -Sources & Sinks
 -Forcing
  ·Direct
  ·Indirect
 -Total Forcing

Climate Variations
 -Surface Temp.
 -Precipitation
 -Other
  ·Stratosphere
  ·Cryosphere
  ·Atmos. Circulation
  ·Cloudiness

Detection
 -Modelling
 -Attribution
  ·Latitudes.
  ·Stratosphere
  ·Precipitation
  ·Sea Level
  ·Fingerprints
 -When?

Future Climate
 -GCM Simulations
 -Feedbacks
  ·Water Vapour
  ·Clouds
  ·Ice Albedo
  ·G-house Gases
 -21st Century

Impacts
 -Agriculture
 -Forestry
 -Ecosystems
 -Water Resources
 -Oceans/Coasts
 -Human & Health

Responses
 -Stabilising
 -FCCC
 -Kyoto Protocol
 -UK Programme
  ·Energy Demand
  ·Energy Supply
 -Evaluation