State of the world - what has happened in 25 years
Lauantai 18.11.2017 klo 12:40 - Mikko Nikinmaa
Twenty five years ago the Union of Concerned Scientists wrote "World Scientists' Warning to Humanity" (with the major authors and 1700 scientists' signatures) where they were concerned about population growth, freshwater availability, climate change, extinctions etc. Now, scientists have looked at what has happened in the past 25 years, and concluded that "World Scientists' Warning to Humanity: Second Notice" was in order. This article was published on November 13 in Bioscience with William J. Ripple as the first author (in addition to the major authors the article had 15,364 scientist signatories from 184 countries). Apart from the ozone hole, which is now starting to shrink, all the environmental problems recognized in 1992 have become worse, and are still continuing to be more detrimental. For example, the amount of carbon dioxide emissions has increased in the last year after it had stabilized or even slightly decreased in the previous two years. In the past 25 years, the availability of fresh water has decreased by 25 %, mean global temperature increased by 0.5 degrees C, carbon dioxide emissions have almost doubled, the dead zones in marine areas increased by almost a third, forests decreased by about 5 % and vertebrate species number decreased by about 30 %. Although human population growth has stopped in the developed countries, the same thing has not happened in Africa and most Asian countries, whereby the total world population has increased by almost 40 % with no sign of increase rate to be slowing down. The number of extinctions in vertebrates is probably much smaller than that of invertebrates - for example insect biomass in certain protected areas in Germany has decreased by 75 %. A significant problem is also that despite increased catching effort, the marine fish catches have decreased by about 20 % from the best years. One final note of the gloomy statistics, we consider almost always only deforestration as causing a decrease in carbon dioxide removal. However, because of the prevalence of sea area, almost half of global photosynthetic activity takes place in marine algae. Marine pollution has decreased algal photosynthesis by approximately 10 % in the past 25 years.
Although most of the indices show radical worsening in the state of global environment, the situation with ozone hole indicates that if mankind heeds the warnings, we are able to make the changes required to keep the environment in satisfactory state. The stratospheric ozone layer above Antarctica is now strongest since 1988. If similar united actions were done for the other questions pinpointed by the authors of the Bioscience article, they could also be solved in reasonable fashion. Changes of diet, schooling, improvement of women's situation, discontinuation of fossil fuel use could all be done if we so decided.
Avainsanat: deforestration, population growth, fisheries, climate change, extinctions