Climate Change

• The Earth's climate changes, often in short or long cycles.

• Ice ages, droughts

• Orbital shifts, sunspot cycles, ocean currents

• Climate does not necessarily change gradually - meteor impacts, methane releases?

Climate = general pattern of weather for a region over time. F i, in Astana in Jan we expect it to be cold and snowy. Weather is the short-time expression of climate which can vary significantly from day-to-day. Throughout the history of the Earth, climate has changed constantly on a long time scale. This is due partially to the movement of crustal plates and the interaction of weather with changing continent structure. Over the last 2 mln yrs, the earth has experienced Ice Ages that occur on a regular basis, along with smaller patterns of change in weather. Evidence of climate change is abundant in the Earth's record. It is thought that climate change normally follows long term cycles caused by shifts in the orbit of the earth, sunspot cycles, and possibly changes and ocean currents due to the movement of the continents. Certain catastrophic events such as a large asteroid or comet slamming into the earth could cause major climate change in a relatively short period of time. The possibility that a major impact such as this did in the dinosaurs about 65 mln yrs ago is highly likely.

F.I, these figures show the variation in temp-re during 400,000 years. Note that there were relatively large fluctuations in the average T-re of the earth including warmer periods and cooler periods than the present that lasted thousands of years. Note that large decreases and increases in temperatures are part of the climate record.

Дата добавления: 2015-09-01