This article throws light upon the three feedback mechanisms of current climate modelling uncertainties. The feedback mechanisms are: 1. Geophysical Climate Feedbacks 2. Biogeochemical Feedbacks 3. Secondary Climate Changes.
Feedback Mechanism # 1. Geophysical Climate Feedbacks:
These are as follows:
1. Increased water vapour due to warmer and water climate
2. Decreased reflectiveness (albedo) of the earth’s surface due to shrinking snow and ice cover; and
3. Increases in clouds due to greater evaporation
Feedback Mechanism # 2. Biogeochemical Feedbacks:
These are as follows:
1. Physical effects of warming (release of methane from hydrates in sediments characteristics in ocean circulation and mixing affecting CO2 uptake).
2. Climate-chemical feedbacks (changes in hydroxyl concentrations and troposphere ozone due to more water vapour, shifts in the CO2 carbonate equilibrium in ocean);
3. Short-term biological responses to warming (increased microbial activity and therefore methane was released from soil organic matter, carbon from the earth. This was occurred between three and five million years ago, in the Pliocene period).
4. A global average warming of 5°F or more would mean a climate not experienced for tens of million of years, when there were no glaciers in the Antarctic, Iceland and Greenland or on mountain ranges like the Sierra Nevada.
Feedback Mechanism # 3. Secondary Climate Changes:
One major effect global warming will have is to create warmer oceans. The warmer oceans will evaporate more moisture. The excess moisture in the atmosphere will make the climate more humid and wetter overall. And global circulation patterns in the oceans and the atmosphere will be affected.
While the uncertainties surrounding more specific predictions of impacts are often very great, the following geophysical and biospheric changes are expected to materialize:
1. Rising sea levels by at-least 0.5 to 1.5 meters over the next few decades, and by as much as several metres over the longer term.
2. Lower snow-pecks and receding glaciers.
3. Shifts in ocean currents and changed precipitation patterns in all regions.
4. More frequent occurrences of weather conditions now considered extreme.