Climate, Agriculture, and the Dead Zone

From Patrick J. Michaels of Cato. 

"Okay, here’s how much of what calls itself science works today: 

1) Find a change in something
2) Say it could be caused by global warming
3) Get more funding
4) Let people ask critical questions
5) Get tenure to protect you from that criticism

Today’s textbook example comes from the Washington Post, in an article, “Large ‘dead zones’, oxygen depeleted water, likely because of climate change”.

This is bad. According to The Post, the authors of newly minted article in Global Change Biology, say,

As global temperatures warm, they will create conditions such as rain [!], wind and sea-level rise that will cause dead zones throughout the world to intensify and grow…

Dead zones are (sometimes) large regions of hypoxic seawater that appear every summer. Because of their seasonality, obviously global warming is making them worse, right? (see 2) above) Or is it due to the fact that, on the average, humans are flushing more agricultural nitrates into the ocean as we produce ever more food? So the nitrates fertilize the ocean, algae bloom and die, bacteria decompose them and in the process, water becomes hypoxic, and fish die.

The authors, Andrew Altieri and Keryn Gedan, both with Smithsonian Institution affiliations, state there’s been quite the change in the number of dead zones (see 1) above). There’s a whole lot of stinking water, as according to Fears, they show that “Dead zone events have doubled each decade since the 1950s”.

But, according to Gedan, “we just don’t know how much of this doubling is due to climate change or nutrient runoff”. According to her, we need more studies and “more sophisticated modelling” (see 3) above).

Math time. That means they doubled from the 50s to the 60s, increased fourfold in the 70s, etc…to the first decade of the 21^st century in which they have purportedly gone up from 16-fold in the 1990s to 32-fold over the 1950s.

Speaking of decadal scales, according to Cato’s Ross McKitrick, the “pause” in warming is now 19 years in length. So how do you get a doubling in the dead zones (and a 32-fold increase over the 1950s) without warming? Perhaps there’s not much of an effect from warming, and a much bigger one from nutrient runoff.

Evidence? The doubling of dead zones in the absence of warming not unique. From the 1960s to the 1970s, global surface temperature actually declined.

Gedan is certainly correct that you really would need “more sophisticated modelling” to pin the huge increase on the tiny amount of warming since 1950, and a doubling per decade even when two decades don’t warm. And wouldn’t the three millennia after the end of the ice age, when it was warmer (at least in our hemisphere) have been a very stinky time?

Given that dead zones maximize during the summer’s hottest temperatures, there is surely some component from warming. But the more obvious answer is that the massive flushing of nitrates into the world’s nearshore regions is changing a minor (and possibly undetectable) amplification into a stinking roar.

Or, given the fact that the earth has been warmer than it is today for about 95% of the last 100 million years, is it possible that the world’s biota really don’t care?

If the dead zone increase is real and caused by human activity, then there actually is some hope. There’s a real ecological problem here—the massive dumping of nitrates into our onshore ecosystems—that can actually be significantly reduced with relatively simple measures. On the other hand, there is simply no way that any conceivable climate policy will have a meaningful effect on global surface temperature."