Focusing on Earth, but also a few tidbits on wind, fire, and ice, some current news and observations about global warming.
As humans release greenhouse gas pollutants (mainly CO2) into the atmosphere, the surface of the Earth, and the top 2000 meters of the ocean, heat up. But some of the CO2 is absorbed into plant tissues and soil, as well as in the ocean or other standing water. Historically, about 30% of the extra CO2 is absorbed into the ocean, and another 30% converted into (mainly) plant tissue. We hope that enough CO2 is absorbed that the effects of greenhouse gas pollution is attenuated, at least a little. Unfortunately, there are two things that can go wrong. First, these “Carbon sinks” — places where the CO2 is either stored or converted into Carbon-based tissue, could stop working. Second, some of these Carbon sinks could reverse course and start releasing, rather than absorbing, Carbon.
The CO2 released in the atmosphere during any given time period starts a process of warming that takes years to finish. We know how much CO2 we have added to the atmosphere (we went from the mid 200’s ppm, parts per million, before this all started to 400ppm). We know how much we are currently releasing and we can estimate how much we will be releasing in coming years. Putting this all together with some very fancy physics and math, we can estimate the amount of surface warming over coming years. This calculation includes the Carbon sinks. If the Carbon sinks stop sinking Carbon, or worse, start releasing previously trapped Carbon, then future warming (next year, next decade, over the next century) will be greater than previously expected.
And there is now evidence that this is happening.
This research suggests that some natural Carbon sinks are slowing down in the amount of Carbon they take in, or perhaps switching to releasing Carbon.
The problem is actually very simple to understand. In order for CO2 to be converted to O2 (free oxygen) and some combination of C and other elements (to make plant tissue), the other elements have to be available in sufficient quantity. For many terrestrial ecosystems, CO2 was a limiting factor (keeping water and sunlight out of the picture or constant). So, adding CO2 means more plant growth. But at some point, the other elements that are required to make plant tissue, such as Nitrogen and Phosphorous (otherwise known as fertilizer) are insufficient in abundance to allow plants to use that CO2. This would reduce or flatten out the amount of extra CO2 that can be trapped in solid form. At this point, the terrestrial biomass starts to release, rather than absorb, CO2.
Why would the terrestrial Carbon sink not simply stop absorbing Carbon, and start to release it? Well, because I as fibbing a little when I said this is simple. The more realistic version of the system has Carbon going in and out of the different parts of the system (atmosphere, ocean water, plant tissue, etc.). With warming temperatures, we expect the release of Carbon from terrestrial systems to increase in rate. So, before nutrient limitation is released, there is Carbon going in and Carbon going out, but on average, mostly going in. With Nutrient limitation on the system, when there isn’t enough Nitrogen or Phosphorus to match up with the CO2, the release continues while the absorption stops. But because of warming, the release not only continues, but increases. So, in coming decades, the net effect is that parts of the terrestrial ecosystem contributes to atmospheric CO2.
At present, climate scientists (mainly in the context of the IPCC) have estimates of future warming that involve estimates of how much CO2 we add to the atmosphere. All the known factors have been taken into account, including the Carbon cycle (which includes Carbon moving between the atmosphere, the ocean, and the plant and soil system at the surface. This research indicates that the numbers have to be changed to account for nutrient saturation.
This graph shows how it works. The black line is the increase in plant growth as originally modeled under a “high-emissions” scenario. This shows a 63% increase in plant growth by the end of the century owing to CO2 fertilization. The red line indicates the amount of extra plant growth that would actually happen due to limitations of Nitrogen. The blue lie indicates the amount of plant growth due to the limitation of Phosphorus. These are 29% and 20%, respectively.
If we include the increase in release of Carbon due to warming conditions (basically, more and faster rotting of dead plant tissue), the existing models produce the black line in the graph below. There is still an increase in plant growth, and the plant-based Carbon sink is still working. If limitations on nitrogen and phosphorus are considered, we get the red and blue lines.
This amounts, approximately, to adding about 14 years of human greenhouse gas pollution (at the current rate) to the time period under consideration (from now to 2100).
So that’s the news when it comes to climate change and the Earth. But what about the wind?
No new research here, just an observation. Where does wind really matter? Where do you really feel the wind? Wind is the expression of the large scale climate system (modified by local conditions) which is in turn the result of the spinning of the Earth and the heating of the planet unevenly by the sun, like it does. A valid rule of thumb is more heat, more wind, but that is a gross oversimplification. At a more complex level, more heat equals more wind doing different things in different places than usual, and also more water vapor in the air, and all this has to do with those times and places where we really feel the wind the most: Storms.
Tenney Naumer (of Climate Change: The Next Generation fame) came across an amazing graphic of the Earth, looking mainly at the Pacific, showing some wind.
The graphic is from here, and I added the “Storm World” just for fun. Except it isn’t really fun. The date of this graphic is, I think, July 5th or 6th.
Your homework assignment is to identify the named tropical storms shown in the graphic.
A few years ago there were some big fires. Australia burned, there were fires in California, Texas, Arizona, various parts of Canada, etc. Climate change and fire experts noted that there is an increase in fires because of global warming, but others argued that there was no significant increase, and we had had periods of abundant fires in the past. In truth, there was evidence of an increase, though maybe not very convincing to some. Also, past inclement conditions are a thing … recent global warming did not invent bad weather or extensive wildfires. But some of those past periods, like the 1930s in the US, are not evidence against current climate change, but rather, evidence of what to expect with climate change. Those periods are only barely as severe as the present state, are usually regional and not global, happened after greenhouse gas pollution was very much a thing and between periods of suppression of warming by aerosols (from volcanoes or industrial pollution). So they matter, but not because they disprove climate change (they don’t) but rather because these past events are windows into the future. But I digress.
The point is, a few years ago, those who are rightfully alarmed about climate change were pointing out the problem of increased wild fires referring mainly to research indicating a dramatic increase in wildfire potential, along with some evidence of actual increased wildfires. And others argued that until there were a lot more flames, there was not a problem.
Well, now we have the flames.
Yesterday (anecdote warning, this is not data) I went outside to check the mail and was assailed by a bank of smoke moving through my neighborhood. It smelled really bad. Assuming there was a house on fire, I dashed back into the house to grab my cell phone, in case I had to dial 911. Returning outside, I walked around and did not see anything obvious burning, but the smoke was coming in from the north. That ruled out a burning oil tank train (the tracks are from the south) and the local munitions dump on fire (that is to the west). But I still couldn’t see where the smoke was coming from. So, I hopped in the car and drove north a couple of blocks, and by the time I got to the nearby Interstate, it became clear that the smoke was simply everywhere, pretty uniformly.
I then guessed at the cause, and returned to my computer where I checked the Wundermap and some other sources. Yup: it was Canada and Alaska, thousands of miles away, pretty much on fire. Here are two graphics to illustrate this.
From the Wundermap:
And from here:
Glacial ice is melting, and it is melting faster every year. Earlier in the year we learned that Alaska (on fire, see above) has been losing mountain glacier and ice sheet water at an alarming rate. Now, we are seeing an amazing spike in melting on the surface of Greenland. From here:
The graph is of ice melt extent so far this year. The blue dotted line is the average over recent decades as in dicated. The grey area is 2 standard deviations around that average. The vast majority of observations (nearly 100%) would be in that grey area. The red line is this year. This is what you call unprecedented melting.
Why is this melting happening? Because Greenland is unusually warm, but as expected under global warming. Some of this melted ice will refreeze in the winter. Much of it, however, is going into the sea.