The Earth seen from Apollo 17.

The Earth seen from Apollo 17. (Photo credit: Wikipedia)

The IPCC report due for release late 2013, early 2014, and which has already been leaked (then pulled), makes for damning reading. One aspect that caught my attention was the amount of global Energy Gain in the most recent time frame, or put another way, the total Heat Content gained globally. In other words, more energy from the sun has been entering than exiting the top of the earth’s atmosphere …. Our planet Earth is in radiative imbalance, and has been for some considerable time now.

The IPCC report stated with “virtual certainty’, an energy gain of 273 ZJ in the period 1971 – 2010, and between 1993 -2010 that figure is 163 ZJ.

Now to explain; the Joule is a unit of energy or amount of heat.

1Joule is the work required to produce one watt of power for one second, or one “watt second” (W·s) (compare kilowatt hour). The zettajoule (ZJ) is equal to 1021 joules is equal to:

1,000,000,000,000,000,000,000 J

For reference, 1,000 ZJ is approximately the amount of energy required to heat the entire volume of water on Earth by 1 °Celsius.

So, lets look at the more recent 1993 -2010 figure of 163 ZJ. This is equivilent to every person on earth (population 6,973,738,433 courtesy of World Bank) turning on a total of 741 single bar 1kW heaters each continuously for one whole year ……or over the same time period 1993-2010, every person on earth turning on 44 single bar 1kW heaters each continuously …..  yikes, either way …….. Earth is cooking !.

OK fun over, and now to add some serious realism …

Adding up the Earth’s energy content

To calculate the Earth’s total heat content, it is necessary to measure the ocean heat content from the upper 700 metres. Then to compute atmospheric heat content using the surface temperature record and the heat capacity of the troposphere. Land and ice heat content are also included.

A time history of the energy going to heat the Earth requires differentiating the heat content using successive linear fits over short time segments. Eight years was chosen as it’s the longest period that still separates the dips due to the El Chichon and Mt. Pinatubo volcanic eruptions (these cause short term cooling effects). The resultant energy imbalance time series is seen below:

Graph 1: An observationally based energy balance for the Earth since 1950 (Murphy 2009)

Graph 1 shows that since the early 1970′s, the planet has remained in positive energy imbalance. This is consistent with the latest IPCC report (see below). Satellite measurements confirm that more energy is coming in than radiating back into space.

cumulative energy flux into Earth 1970-2010 (IPCC)

Graph 2 (replicated here from the IPCC draft in the public interest), shows the cumulative energy flux into the Earth from changes in well-mixed greenhouse gases, short-lived greenhouse gases, solar forcing, surface albedo caused by land use, volcanic forcing, and tropospheric aerosol forcing are shown by the coloured lines; these contributions are added to give the total energy changes (dashed black line).

Energy

Energy Balance 1970-2010 (IPCC)

Graph 3 (replicated here from the IPCC draft in the public interest), shows the cumulative total energy change is balanced by the energy absorbed in the melting of ice; the warming of the atmosphere, the land, and the ocean; and the increase in outgoing radiation inferred from the temperature change of a warming Earth. These terms are represented by the time-varying thicknesses of the coloured regions. The residuals in the cumulative energy budget are indicated by the difference between the red lines and the horizontal zero line.

This energy imbalance is what is causing global warming, and it is this culmative energy that I highlighted in the numbers game above.

This graph from the upcoming IPCC report is for me the most Damning rather than the famous ‘Hockey Stick’ graph often highlighted. It shows all the effects in one shot …….. that the Earth is in energy imbalance with increassing Energy Gain and by implication warming at an increasingly alarming rate, and our oceans are the primary heat sink (as expected). That the culmative effect is driven primarily by the basket of Green House Gases and is therefore caused by human activities, and not Solar Forcing as many sceptics claim. That the outgoing radiation is also increasing (as the Earth warms), and the consequential residual is in positive energy balance ……… In short ……. Earth is cooking.

Finally an extract from the forthcoming IPCC report :

“There is consistent evidence from observations of a net energy uptake of the Earth System due to an imbalance in the energy budget. It is virtually certain that this is caused by human activities, primarily by the increase in CO2 concentrations. There is very high confidence that natural forcing contributes only a small fraction to this imbalance “

Newtz

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