Last week, Sen. Ted Cruz went to Iowa and offered up what has become the go-to argument for the Right on climate change; it’s the environmentalists, not the conservatives, who are anti-science.
The radical left loves attacking people as anti-science when anyone dares question their computer models on global warming. They scream, “you’re anti-science,” when someone points out, for example, that in the last 17 years, satellite data shows there’s been no warming whatsoever.
Conservative activists have been getting a great deal of mileage out of the claim that there has been no global warming for over 17 years and counting. It’s a meme that takes point in the argument that global warming is a fiction or, at the very least, a wildly overblown problem.
Last month, however, Byron Steinman (University of Minnesota), Michael Mann, and Sonja Miller (both at Pennsylvania State University) published a paper in Science that goes a long way in explaining what has happened:
The recent slowdown in global warming has brought into question the reliability of climate model projections of future temperature change and has led to a vigorous debate over whether this slowdown is the result of naturally occurring, internal variability or forcing external to Earth’s climate system. To address these issues, we applied a semi-empirical approach that combines climate observations and model simulations to estimate Atlantic- and Pacific-based internal multidecadal variability (termed “AMO” and “PMO,” respectively). Using this method, the AMO and PMO are found to explain a large proportion of internal variability in Northern Hemisphere mean temperatures. Competition between a modest positive peak in the AMO and a substantially negative-trending PMO are seen to produce a slowdown or “false pause” in warming of the past decade.
Steinman et al. are not the first to argue that the oceans are sequestering the “lost” heat that we would have otherwise expected to drive global temperatures over the past 17 years. Last year, Xianyao Chen and Ka-Kit Tung argued in Science that there is strong evidence that the Atlantic Ocean is playing a major roll in producing the slowdown in global warming:
A vacillating global heat sink at intermediate ocean depths is associated with different climate regimes of surface warming under anthropogenic forcing: The latter part of the 20th century saw rapid global warming as more heat stayed near the surface. In the 21st century, surface warming slowed as more heat moved into deeper oceans. In situ and reanalyzed data are used to trace the pathways of ocean heat uptake. In addition to the shallow La Niña–like patterns in the Pacific that were the previous focus, we found that the slowdown is mainly caused by heat transported to deeper layers in the Atlantic and the Southern oceans, initiated by a recurrent salinity anomaly in the subpolar North Atlantic. Cooling periods associated with the latter deeper heat-sequestration mechanism historically lasted 20 to 35 years.
Oceanic warming thus provides an even clearer signal than atmospheric warming that climate change is real. The fact that atmospheric warming has temporarily slowed down means little. As the Intergovernmental Panel on Climate Change explained in its recently released 5th Assessment Report on the state of climate science:
The ocean influences climate by storing and transporting large amounts of heat, freshwater, and carbon, and by exchanging these properties with the atmosphere. About 93% of the excess heat energy stored by the Earth over the last 50 years is found in the ocean (Church et al., 2011; Levitus et al., 2012). The ability of the ocean to store vast amounts of heat reflects the large mass and heat capacity of seawater relative to air and the fact that ocean circulation connects the surface and interior ocean. More than three quarters of the total exchange of water between the atmosphere and the Earth’s surface through evaporation and precipitation takes place over the oceans (Schmitt, 2008). The ocean contains 50 times more carbon than the atmosphere (Sabine et al., 2004) and is at present acting to slow the rate of climate change by absorbing about 30% of human emissions of carbon dioxide (CO2) from fossil fuel burning, cement production, deforestation and other land use change (Mikaloff-Fletcher et al., 2006; Le Quéré et al., 2010). Changes in the ocean may result in climate feedbacks that either increase or reduce the rate of climate change. Climate variability and change on time scales from seasons to millennia is therefore closely linked to the ocean and its interactions with the atmosphere and cryosphere. The large inertia of the oceans means that they naturally integrate over short-term variability and often provide a clearer signal of longer-term change than other components of the climate system. Observations of ocean change therefore provide a means to track the evolution of climate change, and a relevant benchmark for climate models.
Another problem with the “no warming in 17 years” meme is that it conveniently begins the countdown in 1997, a year characterized by a strong El Niño event which ran through 1998. This is important because El Niño is well known to produce significant, albeit temporary, increases in global atmospheric temperatures. Once we normalize the global atmospheric temperature record to control for episodic events like El Niño and La Niña (which produces significant albeit temporary, decreases in global atmospheric temperatures), there is little mystery left to solve about the “lost” warming.
The “no warming in 17 years” meme is rather easy for mainstream climate scientists to shoot down. Conservatives should cease and desist. There are better arguments at their disposal to counter costly policy initiatives meant to address climate change.