Plot showing the variations, and relative stab...

Plot showing the variations, and relative stability, of climate during the last 12000 years. (Photo credit: Wikipedia)

Scientists Find an Abrupt Warm Jog After a Very Long Cooling

By ANDREW C. REVKIN (Dot Earth) March 9

There’s long been a general picture of the climate of the Holocene, the period of Earth history since the last ice age ended around 12,000 years ago. It goes like this: After a sharp stuttery warm-up following that big chill — to temperatures warmer than today — the climate cools, with the decline reaching bottom around 200 years ago in the period widely called the “little ice age.” (A graph produced by Robert Rohde for his Global Warming Art Web site years ago nicely captures the general picture.)

A new Science paper includes this graph of data providing clues to past global temperature. It shows the warming as the last ice age ended (left), a period when temperatures were warmer than today, a cooling starting 5,000 years ago and an abrupt warming in the last 100 years.
Science A new Science paper includes this graph of data providing clues to past global temperature. It shows the warming as the last ice age ended (left), a period when temperatures were warmer than today, a cooling starting 5,000 years ago and an abrupt warming in the last 100 years.

In a new study, researchers from Oregon State University and Harvard have analyzed 11,300 years of data from 73 sites around the world and added more detail to this picture. The work, posted online today, is being published Friday in the journal Science.

While the researchers, conclude that the globe’s current average temperature has not exceeded the warmth that persisted for thousands of years after the last ice age ended, they say it will do so in this century under almost every postulated scenario for greenhouse gas emissions.

In a news release, Candace Major, program director for ocean sciences at the National Science Foundation, which paid for the research, said:

The last century stands out as the anomaly in this record of global temperature since the end of the last ice age…. This research shows that we’ve experienced almost the same range of temperature change since the beginning of the industrial revolution as over the previous 11,000 years of Earth history – but this change happened a lot more quickly.

In sum, the work reveals a fresh, and very long, climate “hockey stick.”

The hockey stick climate analogy arose from a variety of studies of the last millennium or two of temperatures in the Northern Hemisphere, Arctic and planet. There’s a general pattern of a sharp warming from the 20th century onward. The shaft of the “stick” has a lot of wiggles and warps and still comes with substantial uncertainty, but the general pattern is well established. The Wikipedia entry is a reasonable starting point for reviewing varied views of this body of science.


While folks have long talked of “abrupt climate change” (as in NRC reports) as a plausible prospect, this paper builds on the idea that we’ve been in the midst of abrupt climate change since the early 20th century.

Dernier reflet de montagne... nuage sous quai....

Image by Denis Collette…!!! via Flickr

Earlier today, I noted a new study the found Earth is soon to be the hottest it has been in 11,300 years. To make matters worse, The Guardian reports that scientists at Hawaii’s Mauna Loa observatory have measured a large increase in CO2 in the atmosphere, suggesting the chances of keeping temperature rise below 2C are “fading fast.”

John Vidal at The Guardian reports on the ominous implications of this CO2 increase:

Earth is Cooking – Official

December 28, 2012

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 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 “


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