And where CO2 is present in greater concentrations, we create thermal convection which may explain why wind speeds over our oceans across the globe are increasing. And with wind speeds rising we are witnessing a rise in average wave height which has implications for low-lying coastal floodplains and wetlands.
In the first detailed study of its kind, researchers at the University of Melbourne, in Australia, have looked at data from 31 satellites and 80 ocean buoys from 1985 to 2018, yielding 4 billion data points. And what they show is that winds in the Southern Ocean that circles Antarctica have sped up by 1.5 meters (4.92 feet) per second in the last 30 years, while at the same time wave height has risen by 30 centimeters (1 foot).
Ocean wind speeds and wave heights serve to control “the flux of energy from the atmosphere to the ocean,” and thus “substantially influence the mechanisms of air-sea interaction,” state the authors of the study entitled “Multiplatform evaluation of global trends in wind speed and wave height,” which follows a decade earlier summation of similar data sources. And although regional variations in wind and wave height can be explained by phenomenon such as the North Atlantic Oscillation, the satellite data from both the earlier and present study continues to show a disturbing global trend.
Ground-based radar gives us some of the data that shows altimeter readings of wave heights. But it is satellites that since 1985 have given oceanographers and climatologists a near-continuous record of both wind and wave phenomena. From the 4 billion data points observed the research concludes “a clear global increase in wind speed.” The two world maps that follow show the results of the mapping of these billions of data points over almost two decades for wind speed trends, and 23 years for wave height. Colour coded with yellow to red indicating increases shows how for both there have been dramatic changes.
The answer, of course, is no as can be seen in the maps. But the authors of the study point out a consistent trend of increasing wind speeds globally, less so with wave heights, but notably, with more extreme conditions for both in higher latitudes, and less near the equator.
It should be acknowledged that the trends described in these two papers based on compiling enormous amounts of data over more than 30 years include some wiggle room for margin of error based on less extensive measuring in the earlier time period. But having stated that openly there is no doubt that the second data series covering more than the last decade trends towards a rising expectation that, in particular, the southern half of the planet is witnessing a future of far more treacherous ocean conditions than have been seen in the past. For global shipping on the South Atlantic, South Pacific, Indian, and Southern Oceans, these conditions mean any storms will be even more dangerous. And because what happens in the southern half of the globe eventually impacts the rest of the oceans north of the equator, one can predict that global shipping overall will be negatively impacted.
And as for coastal erosion, danger to flood plains, potential threats to offshore structures such as wind farms and drilling rigs, there is no doubt that increasing wind and wave height changes will pose a rising threat.
These conclusions contradicted commonly held views by climatologists, that equatorial forest carbon sinks are generally negative emitters. But it turns out the oldest tropical forests on our planet can only absorb so much carbon before starting to give some of it back through vegetation decay and other natural processes.
On the other hand, new research out of the Birmingham Institute of Forest Research at the University of Birmingham in the United Kingdom concludes that young forests are far more significant as terrestrial carbon sinks. And by young forest, the Birmingham researchers define these as having tree ages of less than 140 years on average. That means forest areas that have been harvested in the past or cleared by fire are better at sequestering carbon than any other natural processes other than the ocean, the world’s largest carbon sink.
The research on carbon uptake of forests between 2001 and 2010 shows that regrowing forests absorb carbon because of two reasons: the fertilization effect, and the young effect.
What is the fertilization effect?
The increasing amounts of carbon dioxide (CO2) in the atmosphere is having a greening effect on the planet, increasing the amount of photosynthesis occurring in plants. That contributes to carbon uptake.
What is the young effect?
New forests take up carbon much faster than older ones because young trees need the carbon to grow. The age effect accounts for 25% of all CO2 absorbed by the Earth’s forests.
Where are the young forests?
Not in the tropics, but in temperate to high-latitude climates. We are talking for the most part about the forests of Scandinavia, Russia, Canada, China, and the United States where a combination of farm abandonment, forestry, and wildfires have led to reforestation programs to renew the biomass through new tree growth. The added bonus beyond CO2 uptake derived from young forests is their ability to store water and as a result, alter the climate within their proximity contributing to cooler daytime high temperatures. If you don’t believe this to be true, just sit under a shady tree on a hot summer day.
So why don’t we do more forestry and reforestation in older tropical forests?
These equatorial forests play a significant role in our Earth’s atmospheric dynamics. For example, the atmospheric water vapour generated by the Amazon basin is described as a river in the sky which brings the monsoons to the Indian subcontinent every year. Wholesale cutting of these forests could have unintended consequences. As it is tropical rainforest deforestation, largely through burning, is contributing significant carbon to the atmosphere. When the forests are gone, they are replaced by single-crop plantations for growing sugar cane or harvesting oil from palm trees, or by ranches where beef cattle are raised. And where reforestation projects occur in equatorial forests, the species of trees don’t grow as fast as their counterparts in temperate climates.
One of those who worked on the Birmingham study, Tom Pugh, a professor in the School of Geography, Earth and Environmental Sciences, in a press release is quoted saying “It’s important to get a clear sense of where and why this carbon uptake is happening, because this helps us to make targeted and informed decisions about forest management.”
One of the challenges faced by reforestation programs in young forest areas is the tendency to plant a single species of tree. When my wife and I visited Portugal last fall we saw the folly of such a strategy. Portugal’s forestry industry has reforested and replanted much of the country with Eucalyptus trees. Why? Because they are fast growing and within three to five years can be harvested. The unintended consequences of this strategy became apparent as we toured areas where entire forests had gone up in flame because Eucalyptus turns out to be inflammable in a big way.
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