selection26: The Physical Science Basis Of Climate Change.

election 26

• HUMAN AND NATURAL DRIVERS OF CLIMATE CHANGE

the atmosphere contains many gases that contributes to the stability of the earth temperature. Carbon dioxide, methane and nitrous oxide are some of the numerous gases that form the atmosphere. These three gases have increased lately as a result of human activities. Carbon dioxide increase (from 280 ppm to 379 ppm(2005)) was mainly due to fossil fuel usage, the increase of the rest of the gases is due to agriculture.

• DIRECT OBSERVATIONS.

it has been recorded that the last twelve years were ranked as the warmest in the global surface temperature. The average water vapour in the atmosphere has also increased as well as over land and ocean, not to mention that he average temperature of the global ocean has increased to depth of at least 3000m and that the ocean has absorbed more than 80% of the heat added to the climate system, resulting in a sea water level rise and expansion.

The other factor leading Ocean sea water level to rise is the mountain glaciers decline. This is mainly achieved by the increase of the average temperature of the arctic which resulted in a dramatic change in water cycles.

• CLIMATE CHANGE!

The circumstances that were demonstrated above should have had a solid reason for them to see the light. As mentioned earlier, greenhouse gases seemed to be the only strong factors to cause such a dramatic warning. This stimulation is thought to be man-made. To justify this, research in Antarctica demonstrated that there was a greater warming over land than over the ocean. Not to mention that the changes in the northern hemisphere circulation are seemed to be larger than if they were simulated in response of natural forcing changes.

• FUTURE CHANGES.

In general, 0.1 degrees Celsius warming per decade is expected. That is, if greenhouse gas emissions continue at the same rate, important changes are to be expected as well. Geographically, the warming is expected to be greater over land and high latitudes then over southern and northern Atlantic ocean. Sea ice is also expected to shrink causing a unbalance in the ocean cycle resulting in a hot extremes, hear waves and heavy precipitation events to become more frequent. Moreover, tropical cyclones and storms are to become more intense.

However, Anthropogenic warming and sea level rise would continue even if greenhouse gases are stabilized. In other words, the uncertainty in the trajectory of carbon dioxide emissions increases as the magnitude of the added carbon dioxide to the atmosphere by the carbon cycle is uncertain. Greenland ice is still going to be contributing to sea level rise as a result of ice losses. The ice sheets vulnerability to warming would also be increased to the dynamic processes of ice flows which result in sea level rise.