Atmospheric concentration of carbon dioxide temporarily topped the 400ppm mark for a few hours at the Mauna Loa observatory in Hawaii precipitating a media frenzy. Typical of the hype is this story from the New York Times which begins: “The level of the most important heat-trapping gas in the atmosphere, carbon dioxide, has passed a long-feared milestone, scientists reported Friday, reaching a concentration not seen on the earth for millions of years.” There are two errors of fact in that sentence: 1) water vapor is the most important heat-trapping gas, and 2) CO₂ concentrations above 400ppm were reported from the 1820s and from the 1940s.

Here is the graph showing the “monumental” event from Mauna Loa:

And here is a graph showing analyses from previous research on atmospheric carbon dioxide:

Note that both the modern measurements at Mauna Loa and the older measurements are measuring point sources which may or may not reflect global concentrations. The older chemical methods reported by Beck used a chemical analysis of air captured in flasks. Lest you think that’s too old fashioned, note that NOAA still uses that method to check the Mauna Loa data. “NOAA’s Earth Science Research Laboratory program also measures CO₂ in weekly flask samples taken at over 60 remote locations around the world.” (See link below)

The Mauna Loa observatory sits on the flank of an active volcano which “emits variable amounts of carbon dioxide (CO₂) and sulfur dioxide (SO₂) from fissures at the summit.” NASA explains how scientists attempt to distinguish between carbon dioxide from volcanic emissions and overall atmospheric concentration here.

There is another fly in the ointment reported by Scripps Institution of Oceanography:

“Starting around May 1, we began experiencing intermittent difficulties with the computer used to control the Scripps CO₂ analyzer at the Mauna Loa Observatory. This led to delays in providing daily values and also some data gaps. Although such difficulties are not uncommon and rarely lead to significant long-term data loss, we have decided to switch over to reporting daily values from second Scripps instrument, operated in parallel at Mauna Loa…”

Whether or not the atmospheric carbon dioxide concentration has topped a “long-feared milestone” is irrelevant. Carbon dioxide rises as a result of increasing temperature which causes carbon dioxide to exsolve from the oceans and also rises from our increasing use of fossil fuels. For most of Earth’s history carbon dioxide has been well above 1,000ppm and Earth not only survived but life was robust and verdant.

Instead of fearing this artificial milestone, we should celebrate it and try to increase the atmospheric carbon dioxide concentration. For the reason see: A Modest Proposal: Triple Your Carbon Footprint.

See also:

Which comes first, rise in global CO₂ or rise in global temperature?

The Eocene climatic optimum and paradise lost

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