The danger of climate change continues to be widely misunderstood and ignored.
The COP21 of Paris is starting and trying to gain a slot in the mediaspace. But, at best, it will be a short flare of attention; soon fading in the general indifference. Climate change, it seems, is seen as something remote; its importance dwarfed by more immediate threats; from terrorism to financial concerns. And governments seem to suffer from a split personality disease; with politicians flocking to Paris to declare the absolute need of saving the planet for the future generations and then going back home and declare the absolute need of restarting growth.
But the climate threat is not for the future generations. It is something that's going on now, that has been going on for a century, and that keeps going, taking us along a dangerous path that ends somewhere, probably with a steep cliff.
Here is a summary of the situation as it is today. It doesn't attempt to be exhaustive, but it tries to catch the main points of what's going on.
1. Temperatures. Climate change is not just about rising temperatures, but that's probably its most direct and visible manifestation. The earth as been getting warmer and warmer during the past century or so and, today, the so-called "pause" is over, if it ever existed. 2015 is on track to be the hottest year ever recorded, with good chances that 2016 will be even hotter. We are very close to, or we have passed, 1°C of average surface temperature increase in comparison to pre-industrial times. The effects of this warming are multiple: droughts, heat waves, glacier melting, sea level rise, and more. And the more the earth warms up, the more these effects are important.
2. Greenhouse gases. Carbon dioxide and methane are the main greenhouse gases generated as the result of human activities. Their buildup in the atmosphere continues. About CO2, 2015 was probably the last year in history when humans could breathe an air containing less than 400 ppm of it; from now on, concentrations will be higher. We don't know what effect these concentrations will have on people, but we know that humans had never experienced an atmosphere with more than 300 ppm of CO2 during the more than a hundred thousand years of their existence as a species. We also know that the human cognitive process is already measurably impaired at concentrations under 1000 ppm. Regarding methane, concentrations are also rising after a period of stasis that had lasted until 2006. There exists the worrisome possibility that increasing temperatures will generate a "tipping point" in which the release of methane trapped in the high latitude permafrost would become an independent and out of control source of greenhouse gas. So far, there is no evidence that this is happening, but there are worrisome reports of bursts of methane released from craters in Siberia.
3. Ice melting and sea levels. The melting of the icecaps and glaciers continues unabated. The risk of some major instabilities exists, for instance in Antarctica; even though no spectacular events have occurred, so far. Some studies seem to indicate that Antarctica has been gaining some ice up to 2008 owing to increased snowfall but, even if that turns out to be true, the overall melting trend is evident. The melting of continental glaciers is destabilizing the mountains, causing extensive landslides. The freshwater flow into the oceans is one of the main factors causing a rise in sea levels. At present, we stand at a level some 20 cm higher than when the measurements started, in late 19th century. So far, no coastal city or inhabited island has gone underwater permanently, but if the rising trend continues this is going to become a gigantic problem.
4. Weather and climate related disasters. The changing weather patterns are one of the factors that have generated a rapid increase in natural disasters during the 20th century. The number of disasters appears to have peaked around 2004-2006, even though the damage done keeps increasing in monetary terms. The change in weather patterns is causing considerable damage to agriculture, affected by droughts (as it is happening in the US) and by unstable rainfall patterns. So far, food production has not been heavily impacted, at least on the average and the production of cereals remains stable, or even increasing. However, poor countries are especially at risk since farmers do not have the financial resources needed to adapt. Fishery production is in decline almost everywhere, mostly because of overfishing, but also as a result of oceanic warming.
5. Other effects. All the above are effects that can be classed under the "climate change" label, in turn an effect of the warming caused by greenhouse forcing. However, the ongoing changes in the ecosystem are much more complex and extensive. For instance, oceanic acidification is taking place as an effect of dissolved CO2 to a level of some 0.1 pH units and that may already have negative effects on corals. We would need to consider eutrophication, soil erosion, heavy metal dispersal, land coverage by permanent structures, multiple extinctions, deforestation, and much more.
Even though short, this list shows how gigantic and mostly irreversible changes are taking place. The earth changing, it is being transformed into a different planet, an environment that our ancestors never experienced, but that we cannot avoid facing. In this situation, a certain degree of adaptation is certainly possible for humans. Air conditioning can help against heat waves, agriculture can adapt to droughts by irrigation or by switching to different varieties of plants, engineering works can help against flooding, and fires can be suppressed by various methods. But there are limits to adaptation and the problems tend to come not gradually, but all of a sudden. For instance, when New York suffered a disastrous flood, in 2012, the sea level rise was certainly a factor that worsened the problem.
In many cases, we are seeing a situation in which major climate-related emergencies could occur at any moment. There are various possibilities; such as a new heat waves comparable, or worse, than the one in 2003 that claimed some 70,000 victims in Europe. We may see the collapse of major chunks of ice from Antarctica or from Greenland, that would lead to a disastrous sea level rise. Or changes in the weather patterns badly affecting agriculture and hence food production. Or something else; in any case, as the greenhouse forcing continues to increase, these possibilities become more and more likely.
Capping all this, there is the ominous possibility of the "climate tipping point", the fact that after reaching a certain degree of warming, the whole ecosystem will start releasing methane stored in the permafrost, pushing itself to a new temperature state. This new state could be so hot to make most of the planet uninhabitable for human beings. Obviously, there is no way to adapt to such an event.
Against all this, the efforts of the conference of Paris appear unlikely to have a large effect, to say the least. The conference is not supposed to reach any binding agreement and there is little chance that it will arrive to an agreement sufficiently strong to ensure that temperatures will remain within the "2 C" warming limits, even assuming that such a level could be considered "safe."
Yet, it would not be impossible to stabilize climate by switching to an economy fully powered by renewable energy before it will be too late. But that requires sacrifices that, at present, nobody is willing to make. So, we keep walking along a mountain path with our eyes closed, just hoping that the cliff is still far away.....
Yet, it would not be impossible to stabilize climate by switching to an economy fully powered by renewable energy before it will be too late. But that requires sacrifices that, at present, nobody is willing to make. So, we keep walking along a mountain path with our eyes closed, just hoping that the cliff is still far away.....
