Hubbert’s prediction on Global Peak Oil and Hansen’s prediction on Global Warming by CO2: Whether the observed deviation is associated with (a) the unprecedented technological advancement or (b) the inadequate understanding of the concerned system holistically?
Suresh Kumar Govindarajan
The prediction of Hubbert's curves ins the oil quantities are finite and as they are exploited with disappear in a somewhat bell curve
Hansen's prediction are showing that global warming patterns are related to amounts of greenhouse gases. His prediction has largely borne out.
Hansen has been showing that his predictions of accelerated warming are bing outpaced by actual global warming and he is suggesting more insights are needed into the unforeseen forcing factors in his model.
Dr. James Hansen: Accelerated global warming
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- Published on October 19th, 2020
TAGGED: CLIMATE CHANGE, DATA, DR JAMES HANSEN, GLOBAL WARMING, SCIENCE
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In the past five years global temperature has jumped well above the trend which has been stable at about 0.18°C per decade for the past half century (see figure above). This deviation is too large to be explained by unforced climate variability.
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By Dr James Hansen and Makiko Sato
The immediate suspect is human-made greenhouse gases and amplifying climate feedbacks, but that explanation does not work. Yes, the growth rate of the greenhouse gas (GHG) climate forcing has experienced a disturbing uptick in the past several years (Fig. 2), starkly inconsistent with global pledges to reduce emissions, creating an enormous burden for today’s young people.[1] However, there is another variable forcing that is being measured accurately: solar irradiance.
There is no significant trend in solar irradiance during the past half-century, but there is a solar
📷Fig. 2. Annual growth of GHG climate forcing (red area is trace gases, mainly CFCs).
cycle (10-13 year) with a full amplitude of about 0.25 W/m2 with annual changes within a range of about ±0.03 W/m2. This cyclical solar variability is unimportant for long-term climate change, but it is important for interpretation of the global warming acceleration that has occurred over the past five years.
When we add the two well-measured climate forcings, GHGs and solar irradiance, we get the black curve in Fig. 3 for the
📷Fig. 3. Black curve is the annual change of measured climate forcings, GHGs + Solar.
annual climate forcing growth. It is apparent that the measured climate forcings cannot account for an acceleration of global warming.
We will draw the conclusion that the warming acceleration must be due to the one other large climate forcing, atmospheric aerosols, which has intentionally been left unmeasured. However, first let’s examine other possibilities.
First, is there another place in the climate system capable of supplying such added heat? Yes, there is one: the ocean. In that case the ocean interior would have lost heat content during the period of accelerated surface warming. Thanks to international cooperation in the Argo floats program, we are able to measure ocean heat content change, which makes up about 90% of Earth’s energy imbalance. What we find is that Earth’s energy imbalance increased from 0.6 W/m2 in 2005-2010[2] to 0.87 W/m2 in the past decade.[3] Therefore, Earth’s energy imbalance provides additional evidence that the total climate forcing has been increasing.
Second, could the accelerated global warming be a result of a sudden jump in the magnitude of fast feedbacks? The biggest fast feedback, atmospheric water vapor amount, is a smooth function of atmospheric temperature – there is no basis for faster growth of atmospheric water vapor in the absence of an increased forcing that drives an increased rate of global warming.
The other substantial fast feedback, sea ice cover, is not quite as easily dismissed, because sea ice responds more slowly to global temperature change and is capable of sudden change as the ocean temperature profile changes. However, Arctic sea ice shows little trend since 2007.[4] Antarctic sea ice decreased during the past five years, but recently it has grown back close to the prior levels. We have shown that melting ice shelves have a substantial cooling effect on the Southern Ocean.[5] This effect has kept Southern Hemisphere sea ice cover approximately stable, and as Antarctic melt increases the sea ice cover is likely to increase. Southern Hemisphere sea ice cover does not provide an explanation for accelerated global warming.
We conclude that the accelerated warming is caused by an increasing global climate forcing, specifically by the one large unmeasured forcing: atmospheric aerosols. This topic is discussed in detail in Chapter 33 of Sophie’s Planet. We will make a draft available later this week and welcome any criticisms.
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I opened a Twitter account @DrJamesEHansen, (https://twitter.com/drjamesehansen), but I am focusing mainly on finishing Sophie’s Planet.
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