07
Dec
06

Is Global Warming Killing Millions of Innocent Plankton?

It’s always some disaster or another. Global warming will cause hurricanes. No, more intense hurricanes. Oh, and an ice age. Coupled with mass extinctions. We’re already past the tipping point. We’re. Gonna. Die. And it’s all your SUV’s fault.

The latest study in the journal Nature suggests that Global Climate Change is killing off the plankton, and that would spell disaster for marine life, as plankton are the little life forms that get eaten by everything. Here’s an article by the San Francisco Chronicle reporting the details of the article.

Ocean temperatures have generally risen over the last 50 years as the atmosphere warms. And now nine years of NASA satellite data published today in the journal Nature show that the growth rate and abundance of phytoplankton around the world decreases in warm ocean years and increases in cooler ocean years.

The findings are crucial because they show a consequence of the changing global climate at the most fundamental level. Scientists estimate that phytoplankton is responsible for about half of Earth’s photosynthesis, a process that removes carbon dioxide from the atmosphere and converts it into organic carbon and oxygen that feeds nearly every ocean ecosystem.

We’re. Gonna. DIE!

Or are we? Let’s read the first paragraph of the article from Nature:

The period is dominated by an initial increase in NPP of 1,930 teragrams of carbon a year (Tg C yr-1), followed by a prolonged decrease averaging 190 Tg C yr-1. These trends are driven by changes occurring in the expansive stratified low-latitude oceans and are tightly coupled to coincident climate variability. This link between the physical environment and ocean biology functions through changes in upper-ocean temperature and stratification, which influence the availability of nutrients for phytoplankton growth. The observed reductions in ocean productivity during the recent post-1999 warming period provide insight on how future climate change can alter marine food webs.

The bold section is important. Note that this “cool” region where the plankton explosion occurred happened within the 1990s– when we started fretting about global warming and worrying that the past hundred years were dooming the planet to a fiery demise. But notice that it’s not that the oceans suddenly got cooler then– they simply were not as warm as previous years due to external factors, and that provided a plankton boon.

What’s important to also note is the that while the plankton populations are decreasing, they are still not at the low-mass point when the plankton population boom struck in 1998. If we are to take this data as absolute, then it would be simple to conclude that one cool year will cause such a burst of mid-tropical plankton population that the losses would repair any damage that the warming would cause.

Behrenfeld et al describe a change which is linked to climate variability. However, a few pages earlier, we have someone going off the deep end. Scott Doney suggests that Global Warming is the only possible cause of the plankton change:

The recent observed global surface warming (about 0.2 °C per decade) is expected to accelerate in coming decades as we continue to release excess carbon dioxide into the atmosphere. In fact, the planet may soon be warmer than at any time in the past million years6. Extrapolating the satellite observations into the future suggests that marine biological productivity in the tropics and mid-latitudes will decline substantially, in agreement with climate-model simulations.

Doney’s conclusion is not something Behrenfeld argues in his paper– it’s a conclusion Doney jumps to on his own, drawing from other sources to make his point, regardless of the data Behrenfeld presented in his paper.

In addition, while Behrenfeld’s work is solid, it is very short in its scope. There is not comparison to global plankton levels from the 1950s or even the 1930s, when we had another spate of worldwide warming. Doney is extrapolating from something without a truly established curve, and that’s simply irresponsible.

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My name is Doc. Welcome to my blog. If you're visiting from another blog, add me to your blogroll (and I'll happily reciprocate). I have a Ph.D. in Chemistry and live in Wisconsin. If you have any questions, feel free to email me. My email is docattheautopsy at gmail. (No linking to deflate the incredible spam monsters).

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