Our Burning Planet

CLIMATE

CHANGE

in the Anthropocene

OUR
BURNING

PLANET

missed opportunities and ruthless profiteers

 

 

 

 

 

 

Words and data by Andreas Sanders

 

1.5 or 2 degrees of global warming? Doesn’t sound too bad. The Earth has actually seen far greater changes in its climate throughout its 4.6 billion or so years of history. But temperature change in degrees Kelvin (or Celsius) is only one of the significant parameters. Earlier shifts in planetary conditions and later, during the course of geological development, in conditions of life took place over a timeframe of thousands or even millions of years. These were periods in which life was able to adapt and evolve naturally to the new conditions, by moving into different regions corresponding to shifting of climatic zones. For animals, this took the form of migration; for plants, natural dispersion by seeds or root suckers. Processes at a slow pace, made possible by the slow pace of habitat change. A further process involved evolutionary developments that enabled beneficial mutations to prevail in changing habitats, and for which there was likewise plenty of time.

 

The period of Anthropocene climate change covers scarcely 170 years or so—some orders of magnitude too few for natural adaptation. This fact, and the heavy load of pollutants to which the natural world is exposed, likewise by humanity, are the triggers for the current rapid pace of species extinction. The start of this global warming corresponded to an explosion in the use of fossil fuels from the mid-19th century in industry, in households and in the public realm. The idea that the prosperity which has accompanied industrialisation is closely linked to the use of fossil fuels is an assumption that has long lost any factual basis—yet it is still hampering a shift to a resource-conserving, renewables-based economic path.

 

Under the laws of nature, temperature trends go hand in hand with greenhouse gas levels in the atmosphere. This is why it is possible to speak in relatively concrete terms of the remaining carbon budget before we reach an average level of global warming of 1.5 or 2 degrees Celsius compared to the pre-industrial era. This budget can be given in gigatonnes (Gt, one billion tonnes) in terms of the atmosphere as a whole, or as a relative proportion of a defined part of the atmosphere. Portrayal of this relative proportion as parts per million (ppm), i.e. parts of greenhouse gases per million parts of the atmosphere, conveys a far more powerful impression of the extent to which the atmosphere is already exposed to greenhouse gases (see Fig. 1).

 

These threshold limits of 1.5 or 2 degrees are no mere random numbers. They are based on danger levels for living conditions, and thus for habitats—such as the serious damage and loss suffered by warm-water coral reefs, the shrinkage and irreversible disappearance of permafrost, and the enormous thawing and loss of Arctic sea ice. Global warming is already having a dangerous impact on soil moisture and groundwater levels. Plummeting levels of soil moisture have caused damage to forests and lengthening periods of drought are bringing increasingly frequent forest fires; the largest to date occurred in the southern summer of 2019 / 2020 in Australia and consumed an area around one-third of the size of Germany. In addition to the devastation caused to vegetation, an estimated over one billion animals died in these fires.

 

he gigantic areas of inland ice in the polar regions have also long been dramatically affected by global warming. They are of critical importance for the global climate system, and thus for the basic conditions for life. The ice shields in the polar regions act like refriger­a­tors, providing a contrast to the heat of the equatorial regions and thus creating global air currents, which again have influence on the global ocean current system. These in turn transport immense quantities of energy and form further pillars of our climatic system.

 

At its present level, the inland ice thawed by global warming in Greenland alone has reached a scale that—if logistically feas­ible—could supply the annual drinking water consumption of the world’s entire population at an equivalent level to Germany, simply from the meltwater created during the four-month thaw season
(Fig. 2).

 

Warming calculated on a global basis since the beginning of industrialisation is currently somewhat over 1 degree Celsius. Our remaining carbon budget, which will result in warming by 2 degrees and cause accompanying habitat losses, is around 1,060 Gt of CO₂. Using up just 310 Gt of CO₂ from this would inevitably raise the global average temperature by 1.5 degrees Celsius above the pre-industrial level. Based on our current annual level of approx. 42 Gt of global emissions, the time we have left before triggering incalculable consequential effects will be up at around the end of 2027 (based on figures from August 2020). A little time can be gained by reducing emissions rapidly and substantially. However, the true meaning of carbon budget is that once it is used up, an immediate drop to zero emissions is necessary to prevent warming from entering the stage of uncontrollable catastrophic scenarios and putting life at direct risk. Moreover it is important to take account of sharing this budget with natural greenhouse gas emissions, which increase in an unforeseen rapid way, e.g. due to melting permafrost ground and wildfires. Expressed as ppm, atmospheric CO₂ has already reached average levels of 410 ppm; an average of 430 ppm causes warming of 1.5 degrees. In the pre-industrial age, the CO₂ level of the atmosphere was 287 ppm (see Fig. 1). Despite numerous (half-hearted) efforts to cut emissions, a significant increase in greenhouse gas emissions can be observed unchanged at global level. The atmosphere is being misused as a dump.

 

These figures represent global averages. However, warming manifests itself very differently in different regions. In Germany, for instance, that annual 1.5 degree average has already been exceeded, while virtually every area in the Arctic has long overstepped 2 degrees and many are already over 3 degrees (annual average in each case).