“Kerry and Gingrich announce climate showdown”

http://thehill.com/leading-the-news/kerry-gingrich-announce-climate-showdown-2007-04-05.html

Former House Speaker and possible presidential candidate Newt Gingrich (R-Ga.) and 2004 Democratic nominee Sen. John Kerry (Mass.) are set to square off on climate change next week, their staffs announced Thursday.

The debate, hosted by New York University’s John Brademas Center for the Study of Congress, will take place next Tuesday, April 10, at 10 a.m. in the Russell Senate Office Building.

In looking around the archive area, I ran across this interesting paper from 1979 that charts the arctic ice anomalies from 1953 to 1979.

I looks like 1960 was the lowest ice area, nearly 4 million sq kms lower than the average over the period versus the modern record low of about 1.75 million below the 1979-2000 average.

http://ams.allenpress.com/archive/1520-0485/9/3/pdf/i1520-0485-9-3-580.pdf

I finished my first reading of the Schlenker and Roberts paper linked below and have concluded that they are very much interested in making the case for global warming having a very detrimental and unavoidable effect on the major crop yields.

http://www.stat.columbia.edu/~gelman/stuff_for_blog/SchlenkerRoberts.pdf

Their study concentrates on temperatures and sees a relationship much the same as my temperature/precipitation product does with crop yields. They report an increase of yields with increasing temperatures and then a plateau and finally a sharp decrease with temperatures. I saw the plateau and sharp decline with my product indicating that low temperatures were not a limiting factor. I am sure that they have validity in pointing to yields being reduced by the time crops see temperatures over a given threshold, much as indicated in this discussion by Barry B. I do, however, suspect in their rush to show the negative effects of global warming on crop yields that their analysis does not take precipitation sufficiently into account and particularly when its deficiencies are paired with higher temperatures associated with droughts.

They do mention CO2 fertilization, but dismiss accounting for it in their pessimistic prognosis for crop yields by noting the controversy surrounding its effects.

They note that through their analysis they are able to determine that soybean and corn yield genetics have not been changed in the past 50 years to compensate for higher growing temperatures as derived from yields of southern grown crops. I was not able to understand how they came to this conclusion and as a result compared corn and soybean yield trend lines from southern and northern states over the past 44 years. Corn and soybean yields are lower for southern states, but the trend line for corn is somewhat more steeply increasing for southern states than northern ones indicating that temperature effects are not yet limiting. I used those southern states where acreage was increasing or stable as one could conjecture that in states with falling acreage the acreages eliminated where the inherently poorer yielding ones.

Soybeans trend lines were not as steep for most southern states as was seen for northern ones, but what I saw was more recent yields having a significantly larger spread as though affected by diseases. Perhaps Barry B. has some inputs on that matter. For soybean reaction to higher growing temperatures I looked at Brazil and the state Mato Grosso where temperatures are higher than in our southern states. Here soybean yields have been increasing at a steady linear rate and have out-yielded US soybeans over the last 5 years. I have read articles that stated that soybeans varieties have been developed specifically for these tropical climates ‘€” something not noted in the Schlenker paper.

What also puzzled me was that, while the maximum temperatures in the GW scenarios presented in the Schlenker paper would be detrimental to crop yields, by extending the growing season and accommodating earlier planting and maturing of crops could avoid some of the effects of these maximum temperatures. I do not recall a discussion or mention of this by the authors. Perhaps the photosynthetic effects would alter my reasoning here.

I found a paper linked below that took into account the precipitation, temperature, soil moisture content and satellite surveillance of the amount of green the crops showed during the growing season. I would think that the amount of green would be strongly correlated with the other variables measured. These studies where designed to provide crop yield predicting tools from remote sensing during the season to estimate final yields. They discuss the breakpoints associated with predicting yields and the need for using 2 regressions.

http://home.iitk.ac.in/~ramesh/publications_pdf under crop yield IOWA PDF

SteveS,

Did any polar bears make it across the bridge this year?

Quiet Neighbor
One of our closest stellar neighbors is a near twin to the Sun. It’s about the same size, mass, and temperature. It’s a little older, though, and right now, it’s a good bit quieter.

The star is Alpha Centauri A. It’s the brightest member of the triple-star Alpha Centauri system. The system is 4.3 light-years away — closer than any other stars.

Right now, Alpha Centauri A isn’t quite as bright as normal. It’s putting out far less ultraviolet and X-ray energy than average — something that might have happened to the Sun about three centuries ago.

Astronomy satellites have found that last year, the level of X-rays from the star dropped to just about one percent of what it was five years earlier. And its ultraviolet energy dropped to just four percent of what it was.

A star’s energy output varies on a natural cycle. But astronomers from Villanova, who watch Alpha Centauri A and similar stars, say this is the biggest drop ever recorded from a Sun-like star.

The Sun might have experienced a similar drop for several decades around 1700. We don’t know about its X-ray and ultraviolet energy, but we do know that sunspots all but vanished. These magnetic storms are an indication of the Sun’s energy output. During this period, Earth’s temperature dropped by about a degree.

Keeping an eye on Alpha Centauri A and similar stars may help scientists figure out what causes these dropouts — and when the Sun might produce another one.

From http://stardate.org/radio/program.php?f=detail&id=2007-03-30

Now, if they are changing their methods to give a more-accurate picture of ice extent, that’s fine and welcomed. But, I hope they don’t graft a new method onto historical records that were created by a different methodology.

We shall see.

Um, why can’t they ever discuss the sun?

Because it’s the elephant in the room.

But it does help raise the question that the model used here is oversimplistic

It is over-simplistic.

The reason is because as evidenced in the Schlenkar and Roberts study they only look at rainfall during the growing season and do not account for moisture that has been stored in the soil prior to the growing season. Any agronomist will tell you that moisture is everything in crop production and adequate moisture will mitigate the effects of excess heat. Across the cornbelt (with the exception of the irrigated lands in the plains) our soils have the ability to hold a considerable amount of plant available water which can be utilized far into the growing season. A failure to take this into account will result in erroneous conclusions. This also comes into play in future predictions because as your link shows, the Hadley and Canadian models both show an increase in precipitation along with an increase in temperature. Why one would not account for stored moisture is beyond me.

The CO2 link is also worth noting. There’s some research that shows a positive benefit to increased CO2 levels but the authors of these papers tend to dismiss it as the great unknown. Heaven forbid we show a positive effect to global warming.

Probably the most egregious of these people’s errors is that they make no mention of future advancements in varietal technologies. I fully understand that it would be difficult to quantify future technological improvements – reasonable assumptions could be made – but to make no mention of such possibilities and assuming the status quo as they so diligently do in their predictions for the future, they seriously misrepresent the implications of climate change. It makes one wonder whether these so-called “studies” are in effect co-opted to produce a message of doom and gloom rather than add to the scientific database.