Week 2: Recent Past Climate Change

·         Last 2 million years are called quaterny period.

·        These period of time has seen some big climate change.

·         Over the last 2.6 billion years climate has been affected by many factors of forces.

·         On long time scales of several thousands of years,  climate change is highly predictable because of the way the earth moves around the sun. This is due to the angle and axis of the earth on its orbit around the sun. Variations in the shape of the earth’s orbit and amount of solar radiation received are down to three factors:  Eccentricity (100,000 years wear an almost circular orbit changes into a more elliptical orbit. When circular distribution of energy is equal throughout the year, when elliptical the earth is slightly closer to the sun sometimes, so it receives more energy at that time of the year. ), Obliquity (41,000 years where the earth’s axis tilt varies between 21.5 and 24.5 degree, this also changes the amount of solar radiation on the plane, greater tilt means more insulation at the polls during summer season), Precession (23,000 years where the earth’s axis wobbles like a spinning top, as it wobbles the timing of the seas sons changes, 11,000 years ago the northern hemisphere was tilted towards the sun at the same time as when the earth is at its closest point to the sun, this meant there was a greater difference between summer insulation and winter insulation, causing much more seasonal climates.)

·         The causes of climate change are much more unpredictable on a scale of 100 of years.

·         We can’t predict natural variability precisely because of earth system feedbacks but also other short term inferences on climate variability.

·         Unpredictable variations in climate change such as variations of the energy that the sun puts out, called solar-variability, volcanoes also play a role and a reason for short term highly unprediable changes in weather and climate, effect global temperatures, volcanoes cause cooling, areoles from the volcano reflect sun back into space cooling the planet,.

·         Climate change records from the last 100-150 years natural forcing factors fail to explain what is happening to climate change.

·         If we look at the hockey stick graph, it shows us that temperature has increased dramatically over the last 100-150 years. In a way that can’t be explain by natural forces. Co2 is the big new player in this story