Your assertion that CO2 is needed to warm the earth for 4,200 years is not supported by the “peer-reviewed” comments at RealClimate. Jeff Severinghaus speculating in an email that CO2 must be one of the supporting causes is no more than that, speculation. Caillon et al, 2003, nail down an 800 year lag but nothing in that paper supports the assumption that CO2 provides the strong feedback needed for a 5,000 year warming.

Yes, 800 years is less than 5,000 years. CO2 may have been a strong driver for the warming of Termination III, or it may have been an inconsequential bystander. The RealClimate postings and the referenced paper provide no evidence that it was one or the other.

A summary is here: http://www.scienceblog.com/cms/feds-release-massive-climate-change-report-16553.html

The full report is available here: http://www.climatescience.gov/Library/sap/sap4-3/final-report/default.htm

In fact, Molly is correct. There is growing experimental evidence about the effect of CO2 on plant growth, and the news is not all good. Plants do not all respond well to increasing CO2. The composition of many plants changes; for example, some plants grow more woody stalk than leaves. And some plants, notably weeds, grow better than crops as CO2 increases, thereby making crop growing harder. Here is a starting point for reading, but there are many more recent publications as well:

http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=136326

Pieter’s statement is incorrect. For example, the glacial periods each took about 5,000 years to end–5,000 years for temperatures to start and end rising. 800 years into those 5,000 year periods, CO2 started rising and kept rising for the remaining 4,200 years, contributing to the temperature rise. Orbital variations probably were the triggers of the initial temperature rises, but the full rise of temperature need CO2 as a contributor.

Then there is the current driving of temperature by CO2. We know that CO2 is not lagging temperature rises currently–not even for the initiation of this modern period of temperature increase.

More details, and links and references to the original, peer-reviewed articles, are here: http://www.realclimate.org/index.php/archives/2004/12/co2-in-ice-cores
and here: http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/

Thanks for the info. One might infer that progress away from dependence on homefires would be a good thing.

“Data is pretty much in that historically, the rise in CO2 FOLLOWS the rise in temperatures, not the other way around. There is no historical evidence that an increase in CO2 drives the increase in temps.”

Wow! If true, then AGW is a walking zombie or given the grant money involved, a vampire. Someone get stake!

1) Methane would be a better comparison than lead since both CO2 and methane are metabolic products. You’d then be comparing apples to oranges, not apples to screw drivers.
2) The natural seasonal flux of CO2 is rather wide, with the highest concentrations occurring in winter and the lowest in summer. What is meaningful for the argument is the increase in the residual CO2 load which is the net difference between that emitted and the uptake/sequestration. That increase in the residual CO2 is what should be tracked more closely, not the average PPM of CO2. There are a number of papers out there that point out the residual increase is a result of deforestation and ocean pollution (restriction to uptakes) as much as excess emissions. This might be a good place to point out that, according to a paper in Nature in 2000, the majority of anthropogenic CO2 comes from Third World homefires and rural burning, not fossil fuel emissions.
3) Data is pretty much in that historically, the rise in CO2 FOLLOWS the rise in temperatures, not the other way around. There is no historical evidence that an increase in CO2 drives the increase in temps.

The jury seems to be out on:
1) whether increasing CO2 concentration necessarily increases global temperature.
2) whether increasing CO2 concentration (to a point) is bad since it might increase crop yields.
3) whether some global warming is bad since this might also increase crop yields.
4) whether the additional CO2 might not be helpful in preventing or alleviating a drastic drop in global temperature.
5) whether changes to the world economy brought about CO2 reductions aren’t worse than the problem they purport to change.

So as far as life is concerned, lead is a poor choice to compare to CO2 since an increase in lead concentration has NO benefit that I am aware of. So it is comparing apples and screw drivers. So, yes I would be alarmed about an increase in lead concentration even from a small baseline but no I would not be alarmed by an increase in CO2 since this might be good or bad.

The point of the lead example was that arguing that something is unimportant simply because it is at very low concentrations, is a logically invalid argument. She was not comparing lead to CO2. She was disputing the argument that something can’t have an important effect simply because it is at very low concentrations, by giving an example of another substance that clearly has an important effect at very low concentrations.

CO2 has a substantial effect on the heat balance of the atmosphere, even at its low concentration – the science for that statement is very, very solid. Saying it cant have an effect because it is at low concentrations is NOT a logically valid argument against that solid science – and counterexamples of other materials that have effects at low concentrations is a logically valid counterargument. It doesn’t matter that this counterexample is lead – it matters that this is a valid counterargument, whatever the material.

Some folks seem to have an intuition that if the average temperature is rising, lots of new records must be set very frequently. But that intuition comes from some big assumptions that definitely do not hold true for global warming.

New records will be set very frequently only if the variability around the mean (average) is nearly the same as or smaller than the trend in the mean.

No, CO2 above 3% concentration is toxic, for instance. I was just pointing out that lead is an extremely poor thing to compare to CO2. Do you disagree?

Really?

Back in a previous life, I was involved in a project monitoring mud flat biotic response to outflow from a tertiary sewage treatment plant. Basically, we looked at changes in biota in response to being flooded with a continuous supply of high-concentration, high-quality nutrients – to fertilizer. In my part of the project, we measured macrofauna – mostly polychaete worms, molluscs, and crustaceans, visible with dissecting scope.

We analyzed samples 15cm square by 10cm deep.

Pre-fertilization, before the plant started operation, we counted 2000 – 3000 animals per sample, with typically in excess of 30 species represented by more than 100 individuals. Post-fertilization, after the plant started operation, we observed a rapid chance to more animals on average but with dramatically reduced complexity and dramatic variability. Within 3 months, we were getting highly variable counts of 2000 – 6000+ animals, but with typically only 3-5 species represented by more than 100 animals, and with regular collapse and recovery of the macrofauna component of that ecosystem over time.

Productivity, primary or otherwise, is important to understanding ecosystems, but it is a piss-poor (yes, that is a waste-treatment-plant pun) way to measure the health or stability of that ecosystem.

REPLY: I would expect different responses to Chemical Fertilizer (wastewater) than CO2, I don’t know that a parallel could be drawn – Anthony

Imagine that I now change that, and start turning the temp up 1C on Jan 1 of each year, for 10 years. In that 10 year period, I will set only 10 temperature records, one per year. The rate of setting new records will be only 1/365 what it was during the first year. And yet, at the end fo the 10 years, that room will be 10C warmer than right at the end off the period of a record a day.

Rate of new records is not a valid way to measure temperature changes. The only reason to try to use it to argue about temperature records is if one has some reason to avoid showing the actual temperature record in an attempt to confuse the argument..

Are you arguing that something that is a normal and necessary waste product of humans, and that is a food for plants, can’t be a pollutant? Or can’t have negative impacts on the biosphere?

Really?

Answer: Regression toward the mean. 1998 had an unusually high temperature–unusually high above the average (mean) temperature, due mostly to an unusually powerful El Nino. Subsequent temperatures of course are closer to the mean (average). So of course a trend line starting from an outlying high will not trend higher.

This isn’t about climate, it’s about basic statistics. Look up “regression to the mean” in a statistics textbook.

And feel free to plot the temperature trend starting in 1997, and another trend line starting in 1999. Surprise!

A legitimate way to calculate the trend is to create moving averages starting way, way, back in the 1800s. A moving average reveals trends by reducing noise. To be thorough, you should calculate three-year moving averages, and five-year moving averages, and seven-year moving averages, and so on.

Sussman’s statistic of “record high” filters out all other temperature change until the next record high occurs. Record highs occur by random fluctuations of temperature around the average. So a graph of record highs confounds the average temperature with the variability, and any trend over time of the variability with the trend over time of the average.

The best measure of average temperature is…(anybody? anybody?)…the average.

REPLY: Read the post carefully, note the source. That’s not Sussman’s, I added it. The source is NCDC.

You shot yourself in the head with that lead comment.

1. Humans and animals don’t normally exhale lead so it cannot be said to be a natural and NECESSARY waste product.

2. Lead is not a food source for plants, much less a NECESSARY one.

Good luck dear, we all have to start somewhere. Perhaps you are just young.