Climate emergency: the third warning of scientists

In 1992, 1,575 scientific eminences, including nearly 100 Nobels, signed a founding text together. Coordinated by Nobel Prize in Physics, Dr. Henry Kendall, this document is sent to heads of government around the world. It calls for states to take immediate action to stop the growing environmental degradation that threatens the life support systems of the planet. “A great change in our stewardship of the Earth and the life on it is required, if vast human misery is to be avoided…” Since then, this manifesto is nicknamed “The world scientists’ warning to humanity”.

In 2017, Emeritus Professor William Ripple, a renowned biologist and ecologist, publishes in BioScience – a leading scientific journal in biology – an article entitled “World scientists’ warning to humanity: a second notice”. Co-authored by 15,364 scientists from around the world and translated into multiple languages, this article examines the evolution of the nine environmental variables described in the first warning. Apart from stratospheric ozone – now partly restored after being destroyed by human-generated freons – all the other indices are in the red: freshwater, marine resources, dead zones of the oceans, forest surface area, species abundance of vertebrate animals, rate of emitted CO2, temperature change and human population. Since the first warning, humanity has thus failed to make progress in solving these environmental problems. Worse, most of the problems only got worse.

The call of Professor Ripple and the 15,000 scientists had a resounding impact in the press, and strongly influenced the public debate. In fact, this article has become a reference because it draws a precise inventory of the planet at its date of publication. Without being dogmatic, it explains in a simple, clear and objective way how humanity, through its unbridled material consumption, is simply destroying the system that keeps it alive. The conclusions of this study are numerical, scientific and therefore difficult to contest. To ensure its survival and those of other species, humanity must: 1) reduce its population growth, 2) challenge the growth economy, 3) reduce greenhouse gases, 4) protect species and habitats, 5) restore ecosystems and 6) reduce pollution.

A third warning

The call of the 15,000 scientists illustrates their fundamental role in our contemporary society. A role that consists not only in describing and explaining the world around us, but also in sounding the alarm. Scientists have a duty to speak in the public sphere and in the political sphere, in a fully independent capacity. Building on the impact of the “second warning”, Professor Ripple published a new study co-authored by 11,258 scientists from 153 countries in the journal BioScience on Nov. 5, 2019, entitled “World scientists’ warning of a climate emergency”.

This third warning focuses more specifically on climate change, for which man is the main cause. The article presents a series of graphs showing the evolution, over the last 40 years, of the variables causing climate change. What these show is that the climate crisis is a direct consequence of excessive consumption and an opulent lifestyle. The richest countries are the main contributors to historical emissions of greenhouse gases and are also the countries with the largest emissions per capita today. Amongst the particularly worrying signs, the authors note a continuous increase in human population, livestock, per capita meat consumption, gross domestic product globally, deforestation, fossil fuel consumption, number of passengers using air transport, CO2 emissions at the global level as well as per capita.

The main consequences of these climatic drivers of human origin are: an increase in the temperature of the planet’s surface, a decrease in the amount of ice in Antarctica, in the Arctic Ocean, in Greenland and in terrestrial glaciers in general, an increase in temperature, acidity and ocean level, an increase in burnt land surfaces and extreme weather events such as storms and heatwaves and an increase in the cost of associated damage. These changes are impacting life on earth, as in the sea. From plankton to forests, including corals, fish, insects or birds, our planet is experiencing the 6th great mass extinction of its history.

Despite 40 years of climate negotiations, humanity continues to practice “business as usual”. The climate crisis is now here, and it is accelerating faster than expected. The article explains how scientists fear “threshold effects”, ie levels of greenhouse gases beyond which, by runaway effect, we could reach a “Greenhouse Earth”, which would become, despite all our efforts, uncontrollable. The resulting chain reactions would be fatal to ecosystems and the societies and human economies that depend on them. From then on, large areas of the Earth would become uninhabitable.

What solutions?

The article concludes with a (non-exhaustive) list of initiatives to be undertaken to reduce the disastrous effects of climate change. As economic growth and human population growth are the main drivers of increased CO2 emissions, it is necessary to address six important and interconnected issues:

1) Energy. Man must quickly replace fossil fuels with renewable energies and leave the remaining fossil energy stocks underground.

2) Short-lived pollutants. Emissions of these pollutants – which include methane, black carbon (or carbon soot) and hydrofluorocarbons – must be reduced immediately, reducing global warming by 50% over the coming decades, while saving millions of lives.

3) Nature. We must protect the ecosystems of the planet. Phytoplankton, coral reefs, forests, savannas, grasslands, wetlands, peatlands, soils, mangroves and seagrass beds, all these contribute to the sequestration of atmospheric CO2. We must fight against their destruction and promote their restoration on a large scale.

4) Food. Consuming more plant-based foods, while decreasing feed intake, will significantly reduce greenhouse gas emissions, including methane. In addition, the areas gained by the reduction of livestock breeding can not only be used to produce plant-based foods, but can also be partially converted into natural areas. Cultural practices that increase the carbon stored in the soil must be used, while food waste must be reduced.

5) Economy. The overexploitation of natural resources, the origin of which is economic growth, must be curbed in order to ensure the maintenance of the resilience of the biosphere. The economy must be decarbonised and explicitly defined in terms of its dependence on the renewable resources of the biosphere. Economic objectives, which are currently growth of gross domestic product and pursuit of wealth, must become the pursuit of ecosystems’ resilience and the maintenance of ecosystem services, as well as the well-being of man through the satisfaction of basic needs and reduction of inequalities.

6) Population. The world’s population is growing by 80 million people a year (200,000 per day). It must be stabilised, then gradually reduced, through policies encouraging access to education and family planning and by protecting the rights of women.

The third warning of scientists gives the measure of the task that remains to be accomplished. While this may seem colossal, this change to our habits is neither a punishment nor a loss of comfort. On the contrary, it is a new quest for happiness, a quest that gives meaning to our lives, since it involves finding a balance between man and nature. The good news is that we can count on scientists to guide us and help us find solutions. But for this, we need to listen to them…

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