There has been general conclusion that the global climate will warm more-or-less monotonically in the coming decades. This forecast is based on the predictions of the multi-decadal global climate models, such as summarized in the IPCC reports.
As concluded on the Climate Science weblog and in the peer reviewed literature (e.g see), the changes in ocean heat storage can be used as an effective metric to monitor climate system heat changes. The heat changes, measured in Joules, can be used to evaluate the radiative imbalance of the climate system in Watts per meter squared (see Figure 2 on page 333).
From the Willis et al 2004 paper, we know that the oceans warmed from mid-1993 through mid-2003, which continued a general increase over time since the mid-1950s. This global warming has been used as a foundation to claim that we understand the global climate system and can accurately predict the consequences of the diverse human forcings of the climate (e.g. see and see).
But what if the global average of the upper level of the oceans have cooled since mid-2003? What would be the consequences of such an observation? A recent presentation by Josh Willis at the Oceans Sciences meeting in Honolulu this year shows that the upper ocean has cooled significantly between 2003 and 2005.
Does this mean we should stop seeking alternative energy sources from fossil fuels. Should we stop pursuing energy efficiency? Should we advocate an increase in CO2 emissions to “combat” global cooling?
This straightforward “what ifâ? clearly illustrates the need to pursue alternative energy to reduce our dependence on fossil fuels, and improve energy efficiency, regardless of whether we have global warming and cooling.
We need to separate climate policy from energy policy. This would permit the eight summary bullets that headline the Climate Science weblog to be assessed by the IPCC and the CCSP, rather than continuing to focus on the narrower perspective of long term effects of well-mixed greenhouse gas concentrations (see for a discussion of the need to change the current approach to climate policy).
As is discussed on the Climate Science weblog, the IPCC is not adequately assessing the role of the spectrum of diverse first-order human influences on the climate system, which is much more than the radiative effect of anthopogenic CO2. The observation of a significant cooling of the upper ocean should finally convince them to expand their perspective on climate variability and change.