To celebrate Earth Day 2017, which is tomorrow, I would like to highlight the important findings of a paper by Campbell et al. published earlier this month in Nature (1). The paper documents, through the analysis of air trapped in ice from Antarctica, that the growth of global terrestrial gross primary production (GPP) –the amount of carbon dioxide that is ‘fixed’ into organic material through photosynthesis– is larger now than it has been at any time during the last 54,000 years. This basically means that the planet is greener and nature is thriving more now than at any time during human history, despite all the havoc we humans are wreaking everywhere.
Indeed, as I will argue in this blog, the observed recent greening of the planet is most likely a direct consequence of one of our most criticized behaviours, namely the emissions of carbon dioxide (CO2) to the atmosphere, through the burning of fossil fuels and forests. The scientific evidence for this is overwhelming, both from theory, micro-level experiments, and global observations.
We all know from biology class that plants use CO2, water and sunlight to build biomass through the process of photosynthesis. If there is too little CO2 in the air, plants will suffer, just as humans suffer where there is too little oxygen in the air. Plants have indeed felt severely constrained during most of human history, because compared to evolutionary history (hundreds of millions of years), the last several hundred thousand years have seen very low levels of CO2 in the atmosphere (2).
In addition, thousands and thousands of carefully controlled experiments, carried out on hundreds of different plant species, have confirmed that plants do indeed grow better if we artificially increase the concentration of CO2 in the air around the plants (3). And not only that, these experiments also show that plants become more drought and heat resistant in environments with higher CO2 concentrations, because they lose less water to respiration. It basically works like this: Plants have little mouths on their leaves, called stomata, through which the vital CO2 enters and the waste product, oxygen (O2), exits. When CO2 is scarce, plants are gasping for air, opening their stomata as wide as possible to get more CO2 in, but in the process they lose water through the big holes in their leaves. When CO2 is more abundant, the plants can breathe more normally through smaller stomata, and they thus lose less water and can better withstand drought conditions (4).
Some researchers have argued that although individual plants do indeed grow better with more CO2 in the air, at the aggregate level we won’t see much of a positive effect from CO2 fertilization, because there will be other constraints to plant growth (e.g. sunlight and soil nutrients) (5). This is a fair objection, and it is the one that most climate change impact evaluation studies have used to justify ignoring the direct, positive effect of CO2 fertilization on agricultural productivity, and instead concentrate on the indirect, but more uncertain, effects of increased CO2, such as changes in rainfall patterns.
However, at the global level, the empirical evidence now convincingly show that the planet is indeed getting greener due to increased CO2. A study by Zhu et al., published one year ago in Nature Climate Change, used very high resolution satellite images to assess the extent of leaf cover across the planet, and they found that the planet has indeed become greener during the last 35 years. Even NASA has admitted the planet has become greener due to higher CO2 (they kind of had to, as it was their satellite data that was used to measure leaf area). Obviously, the satellite record is very short, so this finding could be shrugged off as a temporary anomaly. But, with the addition of the new 54,000 year record to the already abundant empirical evidence, it seems we can be very confident that our CO2 emissions are helping to create a greener planet, where virtually all plants –both crops and wild vegetation– will grow better, at least for now (6).
For people who love food, plants and forests, like me, this should be good news. But that is probably the most positive news you will hear this Earth Day. There are still many other adverse effects from rising CO2 and the resulting rise in temperatures. Glaciers will surely melt more rapidly, and sea levels will surely continue to rise as a consequence. It is also highly likely that we will experience less frequent, but more intense, rainfall events, as warmer air can contain more moisture for longer time, thus causing both more droughts and more flooding. From previous El Niño events, we also know that corals suffer severely from higher water temperatures. All these events will cause adverse impacts in some places. While this type of events will likely become more frequent and/or more severe due to CO2 emissions, they are events that will also occur regularly even without additional CO2 (7). They are adverse events that we have to prepare for in any case, because they will surely happen at some time, but they will be easier to prepare for in a greener world, where our crops are more productive and more drought-resilient, where forests are thriving and reclaiming deserts and previously degraded areas, and where the global population is richer and better equipped to deal with them.
I would argue that we are doing much more harm to the environment in other ways, and we urgently need to address these problems. For example, we need to stop contaminating rivers and ground waters by mining, fracking, and other industrial activities that ruin one of our most vital resources. We also have to do something about the billions of people who shit in their neighbours’ drinking water. Not by punishing them, because we can’t really help ourselves, but rather by investing in adequate sanitation infrastructure and waste water treatment plants.
Another vital resource is clean air, so we should also crack down hard on all the vehicles and industries which spew out highly damaging soot into the air that we all have to breathe. In addition, indoor air pollution from primitive cooking facilities is one of the main killers of women and children in poor countries, and we should prioritize getting cleaner sources of cooking energy to them (e.g. gas and electricity instead of wood and dung) or at the very least give them access to improved cooking stoves that don’t produce so much indoor smoke. There is also another type of greenhouse gas, methane (mainly emitted from oil and gas production, cattle ranching, and land-fills), which is much more worrying, as it is 84 times more potent as a greenhouse gas than CO2, but without any of the positive side-effects in terms of greening the earth.
All the solid waste that we generate is also a huge problem, especially if organic, inorganic, and dangerous stuff are mixed together in huge, toxic land-fills, or flushed into the oceans. Our use-and-throw-away consumer mentality causes way more waste than necessary, and that mentality simply has to change. The remaining waste has to be carefully sorted and recycled, and new, more environmentally-friendly materials have to be developed to replace non-biodegradable waste-products, such as packaging.
Finally, the decimation of common renewable resources, such as fish stocks and forests, constitutes a very direct assault on nature, which ought to be controlled much better.
There is a very high correlation between CO2 emissions and most of the above-mentioned serious environmental problems, so it has been convenient for environmentalists and global development institutions to use CO2 as a proxy for all environmental problems, and just call for reductions in CO2 emissions, in the hope that that will also fix all the other problems.
But that is an extremely inefficient way of dealing with environmental problems. If you worry about clean drinking water for the 700 million people or so who currently lack it, reducing CO2 emissions will do little if anything to achieve that. If you worry about producing enough food to feed the still rapidly growing global population, reducing CO2 emissions will be outright counterproductive. If you worry about women and children suffering and dying from indoor air pollution, refusing to give them gas or coal based electricity in the name of CO2 emissions reductions, then these deaths will continue. If you worry about future generations, they will very probably laugh at our pathetic attempts to reduce CO2 emissions.
It is unfortunate that we have chosen CO2 as our global scapegoat, as CO2 is the one “contaminant” that is actually beneficial for nature. The excessive demonization of CO2 causes a distraction away from much more urgent and severe environmental problems; it severely limits the effectiveness of our environmental policies; and it makes it difficult to convince politicians to implement policies to reduce environmental impacts, because most of them are so clearly ineffective.
I would recommend that we give CO2 a bit of slack, while cracking down much harder on all the other environmental transgressions that we are committing.
I know this will be one extremely unpopular recommendation, since environmentalists and climate change consultants have put almost all their eggs in the CO2 basket, and they are going to hate to see them all smashed. I am going to consider myself lucky if I am called a stunning hypocrite (like Justin Trudeau). Just don’t call me a climate change denier. I am fully aware of what we are doing to the climate. I am just convinced (after 20 years of climate change research (8)) that the net effect is going to be either benign or possibly even positive, and that we instead have to start attacking the real problems head on, instead of in an incredibly indirect and inefficient manner.
* Senior Researcher at INESAD. The viewpoints expressed in this blog are the responsibility of the author and probably do not reflect the viewpoints of all the members of Fundación INESAD.