A new paper by Dr. Nicola Scafetta of Duke University examines the relationship of natural, solar-driven ocean oscillations such as the Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), and the North Atlantic Oscillation (NAO) to the changes in rate of sea level rise. He finds no correlation with atmospheric carbon dioxide or temperature.

Before I get into the Scafetta paper, here is some background.

Measuring sea level is more complicated than pounding a stake into a beach. Ideally, global sea level would be a rotating oblate ellipsoid of polar radius of 6365.752 km and equatorial radius of 6378.137 km in absence of any other forces. Gravity distorts this ideal shape to make it lumpy.

There are daily and seasonal variations, and storm surges in addition to the oscillations mentioned above. There are tectonic events: is the ocean rising or is the land sinking? Also, extraction of groundwater near coasts may cause the land to sink and present an apparent rise in sea level. All these confounding factors can produce a local rate of sea level change very different from global rate of change.

Since the end of the last glacial epoch, sea level has risen 120 meters (393 feet), about one meter per century. Sea level is still rising at the rate of 1- to 3mm per year, according to NOAA, about the thickness of one or two pennies.

As you can see from the figure, the rate of sea level rise has changed on broad time scales. Scafetta has found patterns of acceleration and deceleration of rise at much smaller time scales.

Scafetta studied six long-term tidal gauge records sited to represent all of the world’s oceans. He found the rate of sea level rise “…to be characterized by significant oscillations at the decadal and multidecadal scales up to about 110-year intervals. Within these scales both positive and negative accelerations are found if a record is sufficiently long. This result suggests that acceleration patterns in tide gauge records are mostly driven by the natural oscillations of the climate system. The volatility of the acceleration increases drastically at smaller scales such as at the bi-decadal ones.”

“Tide gauge accelerations oscillate significantly from positive to negative values mostly following the PDO, AMO and NAO oscillations. In particular, the influence of a large quasi 60–70 year natural oscillation is clearly demonstrated in these records.”

A conclusion from this paper has implications for climate model predictions: “at scales shorter than 100-years, the measured tide gauge accelerations are strongly driven by the natural oscillations of the climate system (e.g. PDO, AMO and NAO). At the smaller scales (e.g. at the decadal and bi-decadal scale) they are characterized by a large volatility due to significant decadal and bi-decadal climatic oscillations. Therefore, accelerations, as well as linear rates evaluated using a few decades of data (e.g. during the last 20-60 years) cannot be used for constructing reliable long-range projections of sea-level for the twenty first century.”

The cyclical nature of the rate of sea level rise, and its quite variable accelerations and decelerations at different time scales may explain why different researchers get different rate values. So, scary stories saying we are doomed because of acceleration in the rate of sea level rise, such as the ‘science fiction” stories linked below, should be taken with a grain of salt.

Reference: Scafetta, N., 2013, Multi-scale dynamical analysis (MSDA) of sea level records versus PDO, AMO, and NAO indexes, Climate Dynamics, DOI 10.1007/s00382-013-1771-3.

See the full paper here.

See also:

Science Fiction from the University of Arizona?

More science fiction from the University of Arizona

University of Arizona dances with sea level

Sea Level Rising?

Sea Level Rise in the South Pacific: None

Sea Level Rise Declining says EU

Obama parts the waters, sea level drops

Size matters in sea level studies

Sea level rising fast along American East Coast – or not

Dr. Roy Spencer presents the latest measurements of lower troposphere temperature as measured by two sets of satellites. See his post here. He presents a graph showing measured temperatures versus model predictions.

You can see that actual global temperatures have flattened out since about 1998. The “spaghetti” on the graph represents predictions of 44 models and the black line is the average of model predictions.

Spencer presents three possible explanations for the divergence:

“1) the real climate system is not as sensitive to increasing CO₂ as the models are programmed to be.” (His preferred explanation).

“2) the extra surface heating from more CO₂ has been diluted more than expected by increased mixing with cooler, deeper ocean waters (Trenberth’s explanation)”

The oceans have a high heat capacity and can absorb great quantities of heat. But have they? The subject is controversial. Anthony Watts discusses the problem here. He notes a recent study which says that between 1955 and 2010, the temperature of the global ocean, between the surface and a depth of 2,000 meters increased in temperature by 0.09 C. That’s not much and Watts wonders if we can even measure to that precision.

“3) increased manmade aerosol pollution is causing a cooling influence, partly mitigating the manmade CO₂ warming.”

However, a 2007 satellite-based NASA study shows that aerosols have been decreasing steadily since 1992. In particular, sulfate aerosols have been greatly decreasing since establishment of the 1970 Clean Air Act in the U.S. and similar measures in Europe.

Explanations #2 and #3 seem to have problems. That leaves #1: the climate is not very sensitive to carbon dioxide and is much less sensitive than models assume. The forcing effect of carbon dioxide, if any, is apparently easily overcome by stronger natural forces.

If Spencer’s first explanation is correct, the political war on fossil fuel emissions is futile and will have little or no effect on global temperatures, but that war will cost us dearly by raising energy prices and making our electric grid less reliable.

See also:

Global warming theory fails again

Failure of the Anthropogenic Global Warming Hypothesis

Dr. James Hansen, chief global warming alarmist and head of NASA’s Goddard Institute for Space Studies has a new paper in Environmental Research Letters wherein he says that burning coal has caused the hiatus in global temperature rise for the past 15 to 20 years (see here also).

Hansen attributes this to the fact that more carbon dioxide in the atmosphere stimulates plant growth, which, in turn, takes more carbon dioxide out of the atmosphere. “We suggest that the surge of fossil fuel use, mainly coal, since 2000 is a basic cause of the large increase of carbon uptake by the combined terrestrial and ocean carbon sinks. One mechanism by which fossil fuel emissions increase carbon uptake is by fertilizing the biosphere via provision of nutrients essential for tissue building, especially nitrogen, which plays a critical role in controlling net primary productivity and is limited in many ecosystems.” In Hansen’s figure 3, he notes that even though carbon dioxide emissions have been increasing, the airborne fraction of CO₂ [the ratio of observed atmospheric CO₂ increase to fossil fuel CO₂ emissions] has decreased over the past 50 years, especially after the year 2000.

That means that natural processes are compensating for increased emissions. This mechanism is noted in a report by the Center for the Study of Carbon Dioxide and Global Change in which they state: “The productivity of the planet’s terrestrial biosphere, on the whole, has been increasing with time, revealing a great greening of the Earth that extends throughout the entire globe. Satellite-based analyses of net terrestrial primary productivity reveal an increase of around 6-13% since the 1980s.”

Some scientists claim that part of the lack of temperature rise is due to the cooling aerosol effect of sulfur dioxide, also a byproduct of burning coal. Hansen rejects this and is supported by an earlier NASA paper which says that sulfur dioxide (SO₂) aerosols in the atmosphere are due mainly to increasing volcanic activity, not from burning coal.

Hansen also notes that the effect [forcing] of man-made greenhouse gas emissions has fallen below IPCC projections, despite an increase in man-made CO₂ emissions exceeding IPCC projections.

This paper is quite an admission from someone who once said, “The trains carrying coal to power plants are death trains. Coal-fired power plants are factories of death.”

Hansen’s reasoning seems somewhat circular to me. He’s saying that more carbon dioxide is creating less carbon dioxide. He is also ignoring the fact that as the globe warms (such as warming from the Little Ice Age of the 1850s), the oceans exsolve more carbon dioxide into the atmosphere. He is assuming that carbon dioxide is the major driver of global temperature, a contention for which there is no physical evidence. More likely, the “hiatus in global temperature rise for the past 15 to 20 years” has been caused by something other than carbon dioxide, such as solar cycles which overwhelm the weak warming force of carbon dioxide acting as a greenhouse gas. It is true, however, that as atmospheric carbon dioxide increased, there has been a great greening of the earth as plants respond to the aerial fertilization.

In spite of all the scary scenarios put forth by IPCC climate models, we see that modeling results are an artifact of modeling inputs; that’s a polite way of saying “garbage in – garbage out.” And perhaps Hansen is now realizing the implications of something he wrote back in 1998: “”The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change.”

UPDATE: The New York Times reports that James Hansen will quit his NASA  job this week to become a full-time climate activist.

See also:

Failure of the Anthropogenic Global Warming Hypothesis

Global warming theory fails again