In a new paper in Geophysical Research Letters, NASA scientists estimate that doubling atmospheric carbon dioxide will result in 1.64 degrees Celsius of warming over the next 200 years. Estimates from the Intergovernmental Panel on Climate Change (IPCC) range from 3-to 5 degrees Celsius.

The problems with IPCC climate models, NASA says, is that they “did not allow the vegetation to increase its leaf density as a response to the physiological effects of increased CO2 and consequent changes in climate. Other assessments included these interactions but did not account for the vegetation down regulation to reduce plant’s photosynthetic activity and as such resulted in a weak vegetation negative response. When we combine these interactions in climate simulations with 2 × CO2, the associated increase in precipitation contributes primarily to increase evapotranspiration rather than surface runoff, consistent with observations, and results in an additional cooling effect not fully accounted for in previous simulations with elevated CO2.”

Reference: Bounoua, L., F. G. Hall, P. J. Sellers, A. Kumar, G. J. Collatz, C. J. Tucker, and M. L. Imhoff (2010), Quantifying the negative feedback of vegetation to greenhouse warming: A modeling approach, Geophys. Res. Lett., 37, L23701, doi:10.1029/2010GL045338.

It seems that as climate models get more sophisticated, the carbon dioxide effect gets closer to zero, which would be consistent with the geologic record.

There are many modeling estimates of the warming effect of carbon dioxide, but there is no physical evidence that human carbon dioxide emissions have a significant effect on global temperature.

For more background, see my blog Natural Climate Cycles and Your Carbon Footprint Doesn’t Matter. See also my Quick Link Index to read more articles about climate, natural history, geology, and energy.

Most of the headlines are grabbed by NASA’s James Hansen, Head of Goddard Institute for Space Studies in New York. Hansen has been the doomsayer-sayer-in-chief of the climate alarmists along with Al Gore. Hansen has been quoted as saying, “The trains carrying coal to power plants are death trains.” But other NASA scientists who use satellites to collect real data, take a different view, and are now saying that “our world should be just beginning to enter a new period of cooling — perhaps the next ice age.”

Here is the complete NASA article:

What are the primary forcings of the Earth system?

The Sun is the primary forcing of Earth’s climate system. Sunlight warms our world. Sunlight drives atmospheric and oceanic circulation patterns. Sunlight powers the process of photosynthesis that plants need to grow. Sunlight causes convection which carries warmth and water vapor up into the sky where clouds form and bring rain. In short, the Sun drives almost every aspect of our world’s climate system and makes possible life as we know it.

Earth’s orbit around and orientation toward the Sun change over spans of many thousands of years. In turn, these changing “orbital mechanics” force climate to change because they change where and how much sunlight reaches Earth. Thus, changing Earth’s exposure to sunlight forces climate to change. According to scientists’ models of Earth’s orbit and orientation toward the Sun indicate that our world should be just beginning to enter a new period of cooling — perhaps the next ice age.

However, a new force for change has arisen: humans. After the industrial revolution, humans introduced increasing amounts of greenhouse gases into the atmosphere, and changed the surface of the landscape to an extent great enough to influence climate on local and global scales. By driving up carbon dioxide levels in the atmosphere (by about 30 percent), humans have increased its capacity to trap warmth near the surface.

Other important forcings of Earth’s climate system include such “variables” as clouds, airborne particulate matter, and surface brightness. Each of these varying features of Earth’s environment has the capacity to exceed the warming influence of greenhouse gases and cause our world to cool. For example, increased cloudiness would give more shade to the surface while reflecting more sunlight back to space. Increased airborne particles (or “aerosols”) would scatter and reflect more sunlight back to space, thereby cooling the surface. Major volcanic eruptions (such as that of Mt. Pinatubo in 1992) can inject so much aerosol into the atmosphere that, as it spreads around the globe, it reduces sunlight and cause Earth to cool. Likewise, increasing the surface area of highly reflective surface types, such as ice sheets, reflects greater amounts of sunlight back to space and causes Earth to cool.

Scientists are using NASA satellites to monitor all of the aforementioned forcings of Earth’s climate system to better understand how they are changing over time, and how any changes in them affect climate.

I note that other NASA pages contradict the statement above and are more alarmist. So much for consensus.

The announcement was exciting. The NASA media advisory, Nov. 29 that said in part: “NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life. Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.”

Many people thought maybe NASA would announce discovery of extraterrestrial life. But, as it turned out, NASA was talking about a study at Mono Lake, California, which showed, NASA claimed, that they had discovered a microbe that could grow using arsenic rather than phosphorus which all other known life uses. If true, even this would be a great advance, but microbial use of arsenic, itself, is not news. The 2004 paper, The microbial arsenic cycle in Mono Lake, California, goes into great detail about microbial use of arsenic. But, these microbes still use phosphorus also.

After several microbiologists analyzed the NASA paper and its methodology, they concluded that laboratory errors caused NASA scientists to think the microbes did not use phosphorus.

In fact, says Harvard microbiologist Alex Bradley, the NASA scientists unknowingly demonstrated the flaws in their own experiment. They immersed the DNA in water as they analyzed it, he points out. Arsenic compounds fall apart quickly in water, so if it really was in the microbe’s genes, it should have broken into fragments, Bradley wrote Sunday in a guest post on the blog We, Beasties. But the DNA remained in large chunks—presumably because it was made of durable phosphate. Bradley got his Ph.D. under MIT professor Roger Summons, who co-authored the 2007 weird-life report. Summons backs his former student’s critique.

But how could the bacteria be using phosphate when they weren’t getting any in the lab? That was the point of the experiment, after all. It turns out the NASA scientists were feeding the bacteria salts which they freely admit were contaminated with a tiny amount of phosphate. It’s possible, the critics argue, that the bacteria eked out a living on that scarce supply. As Bradley notes, the Sargasso Sea supports plenty of microbes while containing 300 times less phosphate than was present in the lab cultures. (Source 1, Source 2)

So NASA hyped the study, but there is nothing nefarious about this incident. It’s the way science works. Researchers think they make a discovery; they write a paper; and other scientists either do experiments to replicate the work or poke holes in it. As it stands, the claimed NASA “discovery” is simply questionable and unverified. The way NASA hyped the story, however, is not good practice. And sadly, NASA has been treating climate data the same way.